Dasibi 1008 Ozone Monitor Manual

DASIBI ENVIRONMENTAL CORP. TM920805
Preface
This Operating & Maintenance (O&M) manual contains information for
use by operating personnel of the Dasibi Environmental Corporation
(Dasibi) Series 1008 Ultraviolet (UV) Photometric Ozone Analyzer,
also referred to herein as the unit or instrument. This
information includes descriptions of installation, theories of
operation, basic operation, calibration, preventive & corrective
maintenance procedures and troubleshooting techniques for the unit.
Experience indicates that the user will obtain maximum performance
and utility from the instrument when time has been spent studying
the information provided herein. It is therefore recommended that
this manual be fully reviewed before proceeding with installation
and commissioning of the unit.
Dasibi continually strives to remain current with the latest
electronic developments. Hardware/software improvements are
incorporated into its products as soon as development and testing
have been accomplished. Sometimes, due to printing and shipping
requirements, these changes are not immediately incorporated into
the manuals, but are rather presented as individual technical
update pages provided in Appendix C. Information about
modifications that have taken place since the copyright date listed
on the front page of this manual, are detailed there; It is highly
recommended that this section be reviewed for any unit purchased.
Modifications that have occurred since the last copyright date of
this manual will be carried in Appendix C until they may be
permanently entered into the manual. If no update pages are
included in this section, then this manual is correct as printed.
Any feature described in this section that is applicable to the
unit shipped with this manual will have an asterisk (*) hand-
written next to its listing in the Table of Contents when this
manual is inspected before shipment. Although every effort is made
to keep the manual accurate and up-to-date, it is possible that
errors have been made. If an error in the manual is found, or
further information or assistance is desired, please contact
Dasibi's sales department.
Dasibi Environmental Corporation
506 Paula Avenue
Glendale, CA 91201
Phone #: (818) 247-7601 Fax #: (818) 247-7614
L--
This manual was prepared exclusively for use by the owners of the
Series 1008. The material contained herein is proprietary and is
to be used only for the purpose of operating this product. Any
other use or duplication without prior written consent of Dasibi is
prohibited. Any modifications made to the unit without prior,
written consent of Dasibi may void the following warranty.
,
i iLo

Warranty
This warranty covers two specific areas that may occur after
delivery to the original purchaser by Dasibi, or by an authorized
Dasibi representative:
1) Defective instrument operation according to guaranteed
. performance specifications.
2) Defects in materials or workmanship.
The warranty is applicable, provided that inspection and analysis
by Dasibi discloses that any defects in instrument performance or
defects in materials and workmanship developed under normal and
proper use, and that the instrument was maintained and operated in
accordance with the operations and service manuals supplied with
the instrument. Dasibi will be released from all obligations under
this warranty in the event repairs or modifications to the
instrument have been made by persons other than Dasibi's own
representatives, unless such repairs were made with the prior,
written consent of Dasibi.
t.-
I
Any item claimed to be defective must be returned to Dasibi,
transportation charges prepaid, and will be re-shipped to the
customer collect, unless the item is actually' found to be
defective, in which case, Dasibi will pay transportation charges.
Defective Instrument Operation
Dasibi agrees to correct any unit that does not function within the
limits of the published performance specifications, either by
repair or, at the option of Dasibi, by replacement, for one year
after delivery to the original purchaser, the only exception being
consumable items.
I-
Defective Materials or Workmanship
Dasibi agrees to correct any defects in materials or workmanship in
any unit either by repair or, at the option of Dasibi, by
replacement, subject to the following conditions:
1. Dasibi extends to the original purchaser a two vear warranty
on all Dasibi-manufactured electronic parts and a one vear
warranty on all Dasibi-manufactured mechanical parts.
I--
2. Dasibi extends to the customer whatever dated warranty is
given to Dasibi by the suppliers of component items purchased
by Dasibi and incorporated into the instrument.
3. This warranty does not cover expendable items, because their
duration and performance may vary from case-to-case.
iii

Claims for Damaged Shipments and Shipping Errors
Damaged Shipments
Merchandise should be inspected immediately upon receipt as
described in Section One of this manual. A packing list is
supplied with every shipment, and all items received should be
checked against this list. If there appears to be shipping damage,
both the carrier and Dasibi should be notified immediately (if the
instrument appears to have only operational problems not associated
with shipping damage, only Dasibi should be notified).
Claims for Shipping Discrepancies
It is important to check the contents of all shipments promptly
against the packing list. Dasibi reserves the right to disavow all
claims of deficiency that are not promptly reported.
If a claim is to be made, report the following:
1. Sales Order Number
2. Purchase Order Number
3. Model Number
4. Serial Number
5. Date Received
In addition, the following documents may be necessary to support a
claim for shipping damage:
1. Copy of original invoice
2. Copy of packing list
3. Original freight bill and bill of lading
4. Photos of damaged equipment and container (if possible)
Conditions of Shipment
F.O.B. DESTINATION means that Dasibi pays all expenses and assumes
all risks until actual delivery of the merchandise at the point
agreed upon with the buyer.
F.O.B. GLENDALE means that the purchaser will pay all expenses and
assumes all risks of merchandise damage.
iv

1)
2)
3)
4)
5)
6)
Procedure For Returns/Repairs
Contact Dasibi to describe the problem. Obtain a return
authorization number from the sales/service department. This
number aids Dasibi in "trackingtt returned items and in
determining whether or not the item is still under warranty,
or considered out-of-warranty.
Warran~h3ns: Please enclose a written description of the exact
problem as accurately as possible. If strip charts or other
such test documents are available, please include copies of
them in the return shipment as they will help in the swift
troubleshooting of described problems.
&d-of-WarrantyItems: Providing a written description of the exact
problem as accurately as possible, guarantees that Dasibi
technicians will only perform repair work on the requested
areas. If additional repairs/upgrades are desirable, Dasibi
customer service will notify the customer to first obtain
approval.
Upon receipt of an out-of-warranty item, Dasibi will draft an
estimate of the repair work required (there is no charge for
this). The estimate will contain probable replacement
parts/assemblies and the respective costs of each. In
addition, there will be an estimate of "hands on" labor time.
Dasibi's service department will contact the customer with the
initial estimate. Dasibi will not comnlete the required work
until proper authorization from the customer is obtained.
Because of the nature of some problems, though, some repair
work may have to be performed before authorization is obtained
in order to draft the initial estimate.
If repair work is going to exceed the initial estimate, Dasibi
will draft an estimate revision, provide an explanation for
the additional work required, and submit this to the customer
for re-approval. Once such approval is either given, or
denied, work will commence. This prevents any unauthorized
work from being performed.
Dasibi will ship repaired out-of-warranty items back to the
customer with appropriate strip charts and quality control
reports verifying performance, along with a detailed listing
of all replaced parts and assemblies. Dasibi will return any
replaced component upon customer reauest onlv.
V

DASIBI ENVIRONMENTAL CORP.
Operating Warning Information
*** DANGER ***
TOXIC EXHAUST GAS
Route exhaust gas from rear panel outlet to
outside vent or laboratory fume hood through
tubing with an O.D. of l/4-inch and an I.D. of
l/8-inch or greater.
*** DANGER ***
ELECTRICAL SHOCK HAZARD
There exists HIGH VOLTAGE within portions of
the circuitry of this analyzer. Please refer
to material within this manual before
performing any servicing inside the unit,
itself.
TM920805
vi

TM920805
Section Title
1.0
1.1
1.2
1.2.1
1.2.1.1
1.2.1.2
1.2.1.3
1.2.1.4
1.2.2
1.2.3
1.2.4
1.2.5
2.0
2.1
2.2
2.3
2.3.1
2.3.2
2.3.3
3.0
3.1
3.2
3.2.1
3.2.2
3.2.3
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.4
3.4.1
3.4.2
3.4.2.1
3.4.2.2
INSTRUMENT DESCRIPTION
General
Optical
Lamp
Detector
Optics Bench
Pneumatic
Gas Valve(s)
Flowmeter
Pump(s)
Fittings and Tubing
Ozone Scrubber
Electronic
Mother Board
Electrometer Assembly
Physical Description
3.4.2.2.1
TABLE OF CONTENTS
Preface
Warranty
Claims for Damaged Shipments and Shipping Errors
* Procedure for Returns/Repairs
Operating Warning Information
EPA Designation
CE Declaration of Conformity
TABLE OF CONTENTS
INTRODUCTION
Purpose and Organization of Manual
Description of Instrument
Functional Description
Ambient Air Monitor (1008-AH)
Internal Zero/Span Checks (1008-RS)
Calibration Standard (1008-PC)
Pase
ii
iii
iv
V
v i
vii
viii
ix
l-l
l-l
l-2
l-2
l-2
1-2
l-2
High Concentration Monitor (Model 1008-HC)l-3
Physical Characteristics l-3
Operation l-3
Maintenance l-4
Performance l-4
INSTALLATION 2-1
General 2-l
Receiving Inspection 2-l
Installation 2-2
Gas Sampling Requirements 2-2
Electrical Connection 2-3
Recorder Connection 2-3
3-l
3-l
3-l
3-l
3-l
3-l
3-l
3-l
3-2
3-2
3-2
3-3
3-3
3-3
3-4
3-4
3-4
3-5
Signal Detection and Processing
Sample Channel
ix

TABLE OF CONTENTS (continued)
Section Title
3.4.2.2.2 Control Channel
3.4.2.2.2.1 Integrating Electrometer
3.4.2.2.2.2 Fixed-Frequency Electrometer
3.4.2.2.2.3 652 VFC Electrometer
3.4.2.2.2.4 Temperature Sensor Board
3.4.3 CPU Board
3.4.4 Memory Board
3.4.5 Counter Board
3.4.6 D/A Board
3.4.7 I/O Board
3.4.8 Display Board
3.4.9 LDHC Board
3.4.10 Ozone Control Board (Model 1008-PC)
3.4.11 Ozone Control Board (Model 1008-RS)
4.0 PRINCIPLES OF OPERATION
4.1 General
4.2 Symbols Used
4.3 Description of Instrument Operation
4.3.1 General
4.3.1.1 Principle of Operation
4.3.1.2 Calibration
4.4 W Photometer
4.5 Sample Handling System
4.6 Electronic System
4.7 Measurement of Ozone Concentration
4.7.1 Theory
4.7.2 Calculation of Proportionality Factor, K
4.7.2.1 General
4.7.2.2 Conversion Factors at STP, K,,,
4.7.2.2.1 KSTP' c,in [ppml (by volume)---
4.7.2.2.2 KSTP' c,in [percent] (by volume)
4.7.2.2.3 KSTP, c,in [ppm] (by weight)
4 . 7 . 2 . 2 . 4 KSTP' c,in [percent] (by weight)
4.7.2.2.5
4.7.2.3
KsTp, c,in [gl/h31
Correction for Temperature & Pressure,CFTP
4.7.3 Specific Measurement Considerations
5.0 OPERATION 5 - l
5.1 Controls and Indicators 5-l
5.1.1 Ozone Generator (Models 1008-PC & -RS Only) 5-2
Pase
3-5
3-6
3-7
3-7
3-7
3-8
3-a
3-8
3-9
3-9
3-9
3-9
3-9
3-10
4-l
4-l
4-1
4-2
4-2
4-2
4-3
4-4
4-5
4-6
4-8
4-8
4-10
4-10
4-10
4-12
4-12
4-12
4-12
4-13
4-13
4-14
5.2 Remote ItZero" or llSpanll Operation of Model I008-RS 5-4
5.3 Start Up 5-4
5.3.1 Turn On 5-4
5.3.2 Error Code 5-4
5.3.3 Warm Up 5-4
X

Section Title Pase
5.4 Recorder Operation 5-4
5.5 Shut Down 5-5
6.0 MAINTENANCE 6-1
6.1 General 6-1
6.2 Test Equipment Required 6-1
6.3 Preventive Maintenance 6-1
6.3.1 Maintenance Schedules 6-1
6.3.2 Scrubber Cartridge Replacement 6-1
6.3.3 Cooling Fan Filter Pad Cleaning 6-2
6.4 Corrective Maintenance 6-2
6.4.1 Trouble Isolation 6-2
6.5 Performance Checks 6-3
6.5.1 Sample Flow Check 6-3
6.5.2 Span Check 6-3
6.5.3 Recorder Span Check 6-3
6.5.4 Zero Check 6-3
6.5.5 Control Frequency Check 6-3
6.5.6 Sample Frequency Check 6-4
6.5.7 Temperature Check 6-4
6.5.8 Pressure Check 6-4
6.5.9 System Leak Check 6-5
6.5.10 Solenoid Valve Leak Check 6-5
6.6 Adjustment Procedures 6-5
6.6.1 Flow Adjustments , 6-5
6.6.2 Span Adjustments 6-6
6.6.3 Recorder Adjustments 6-6
6.6.4 Zero Offset Adjustment 6-7
6.6.5 Light Level Adjustments 6-7
6.6.6 Analog Voltage Adjustments 6-8
6.6.7 Pressure Adjustments 6-9
6.7 Optics Cleaning Procedure 6-9
6.8 Teflon Particulate Filter Pad Replacement 6-9
7.0
7.1
7.2
7.3
7.4
7.5
REPLACEMENT PARTS LISTS
General
Ordering Information
Service Kit for One Year of Operation
Service Kit for Two Years of Operation
Replacement Component/Assembly Stock Numbers
7-1
7-1
7-1
7-1
7-1
7-3
APPENDIX A MODEL 1008-HC INFORMATION A-l
A.1 General A-2
A.2 Assembly of Sample Cell A-2
APPENDIX B INSTRUMENT CALIBRATION B-l
B.l General (New W Calibration procedure) B-2
TABLE OF CONTENTS (continued)

1 . 0 INTRODUCTION
1.1 Purpose and Organization of Manual
This O&M manual presents operating and service information for
the Dasibi Model 1008-AH, -PC, -RS, and -HC UV Photometric Ozone
Analyzers. Past experience indicates that the user will obtain
maximum performance from the instrument when time has been spent
studying this information. It is therefore recommended that this
manual be reviewed before installing, operating or servicing the
analyzer.
The information is presented in seven sections which include
a description of the instrument design and operating theory, as
well as discussions of its installation, operation, and
maintenance. Appendices include specialized information on the
1008-HC (high concentration) unit, general instrument calibration
procedures, update information to this manual (when applicable),
and general references for further information. For each section,
the information is presented as descriptive text, followed by the
referenced figures, in order, at the end of the section. The
information presented is outlined in Table l-l, below.
Section
1
2
3 '1
4
5
6
7
Appendix
Appendix
Appendix
Appendix
TABLE l-1
Outline of Organization of Manual
Topics Covered
General instrument description, performance
specifications, and physical characteristics.
Instrument installation.
Instrument description.
Theory of operation.
Routine operation.
Maintenance procedures.
Replacement parts lists.
A Model 1008-HC (high concentration)
information.
B Instrument calibration.
C Manual update information (as appropriate).
D References
l-l

Included with this manual is the final factory quality control
report for the analyzer, which includes'recorder traces with zero
and span gas that were obtained during final factory testing prior
to its shipment. These data are of great value in determining if
the analyzer, as received by the user, has experienced any change
in performance due to shipping problems. The user is encouraged to
recheck the performance of the instrument immediately after
installation by running a zero and span record to.ensure that the
factory results can be duplicated.
1.2 Description of Instrument
1.2.1 Functional Description
The basic analyzer is a self-contained instrument which
measures the concentration of ozone in ambient air. This is
accomplished by measuring the absorption of ultraviolet (UV) light
in a sample of gas flowing through the optics bench (often called
an absorption cell) contained in the instrument. The instrument is
designed to provide a highly stable measurement capability for
extended periods without repeated adjustments, and it operates over
a wide range of ambient conditions without adverse effects on
measurement accuracy.
The analyzer is a component in a system whose end purpose is
to provide a continuous stream of high quality, .non-ambiguous,
ozone concentration data. The feasibility of this system is
predicated on good design, proper system maintenance and frequent
performance checks.
The analyzer is available in four different configurations
which are discussed briefly below and presented in detail in
Section 3.0.
1.2.1.1 Basic Air Monitor (Model 1008-AH)
This configuration of the analyzer is used to determine the
level of ozone in ambient air and has been designated by the U.S.
EPA as an equivalent method. This configuration represents the
llbasiclt analyzer.
1.2.1.2 Monitor With Internal Zero/Span Checks (Model 1008-RS)
The addition to the basic analyzer of an internal ozonator,
selection valve, scrubber, pump, and flowmeter allows both zero and
span gases to be generated and utilized within the analyzer for
manual or remote self-check purposes.
1.2.1.3 Ozone Calibration Standard (Model 1008-PC or 1008-PS)
The basic analyzer may be configured as a UV photometer
calibrator in accordance with EPA regulations (commonly referred to
as a transfer standard, or the Model 1008-PC). This configuration
includes an ozonator, valve, scrubber, pump, and flow meter.
l-2

The catalytic converter used in the transfer standard may be
removed, and the sample handling system modified to incorporate use
of an additional internal manifold used in conjunction with an
external zero air source (commonly referred to as a primary
standard, or Model 1008-PS).
1.2.1.4 High Concentration Monitor (Model 1008-HC)
Model 1008-HC is electronically and functionally identical to
Model 1008-AH except that it measures much higher ozone
concentrations (from 0 to 10 percent by weight, or 0 to 60,350 ppm
by volume). The special features are described in Appendix A.
1.2.2 Physical Characteristics
The physical characteristics of the analyzer are presented in
Table l-2.
TABLE l-2
Physical Characteristics
Dasibi Model 1008
Dimensions: W- 17.20 in (43.69 cm)
H- 5.25 in (13.34 Cm)
D- 22.50 in (57.15 Cm)
Weight (including pump):
Power:
28 lbs (12.73 kg)
105-125V AC, 50/60 Hz
220-240V AC, 50/60 Hz
1OOV AC, 50/60 Hz
Options: Rack mounting, RS232C interface, dual ozone output
generator, Isolated Analog Output or 4/20 mA Output.
1.2.3 Operation
Sample gas is continually supplied to the optics bench by a
self-contained pump and sample handling system. The intensity of
the UV light beam traversing the optics bench is attenuated in
proportion to the concentration of ozone present in the sample as
prescribed by the Beer-Lambert Law (Beer's Law). This signal is
detected and processed digitally for presentation by the readout
system.
Two reference subsystems ensure a high degree of measurement
stability by correcting for variations in source intensity and
detector response, and interference components in the sample gas.
Self-zeroing and interference removal is accomplished by comparison
of alternate sample and reference measurements. Because of the
operation of these reference, zeroing and interference removal
subsystems, there is virtually no span or zero drift. These
features are described in detail in Sections 3.0 and 4.0.
l-3

All operating controls are contained on the front panel. The
ozone concentration is indicated on the digital display mounted on
the front panel and is also provided at rear panel terminals as an
analog signal. The various operational and sample gas inlet
connections, filters and conditioning elements are also mounted on
the rear panel for accessibility and ease of replacement.
1.2.4 Maintenance
All systems are designed for reliability and ease of
maintenance. Electronic components are mounted on plug-in printed
circuit boards, so that equipment operation can be restored quickly
in the event of a component failure.
1.2.5 Performance
The performance specifications of the analyzer and optional
ozone generator are presented in Tables 1-3 and 1-4, respectively.
The instrument will operate within these specifications under the
conditions listed.
TABLE l-3
Analyzer Performance Specifications
Dasibi Model 1008
Range:
Noise:
Flow Rate:
Precision:
O-0.5, - (instrument
can readO ~~~he$p?~an 1 ppm)
+O.OOl ppm
2 l/min (nominal)
0.001 ppm
Linearity:
Temperature Range:
Pressure Range:
+O.OOl ppm
o-45O c
0.66-1.20 atm (500-900 torr)
Zero Drift:
Display t digital outputs: Zero
Span
Analog outputs:
Drift:
Zero
Display t digital outputs: Zero
Analog Outputs: 20.5% of digital reading
Offset: Adjustable to 9 ppb in steps of
1 ppb or to 90 ppb in steps of
lo ppb (specify when ordering)
+0.5% of digital reading
l-4

Response Time (99% final value): 50 Seconds
Cycle Time:
20 Seconds (No Averaging) '
reading every 10
Ozone Concentration Corrections:
Temperature
Pressure
Analog Output
kO.30 c .
k0.003 atm (2 torr)
Standard 1 volt forofl ppm.(with
3 digits
ZzYectable).
display
Other ranges
available.
Digital Outputs:
Display
RS-232C
5 Digits
Optional
TM920805
* The instrument does not have a range switch, but reads
continuously from 0.001 ppm to 1.000 ppm. It meets the EPA
designated range requirements for 0.5 and 1.0 ppm.
TABLE 1-4
Ozone Generator Performance Specifications
Dasibi Models 1008-PC & 1008-RS
output: 0.040-1.000 ppm @ 5-6 l/min
Stability: kO.002 ppm @ 0.500 ppm
Response Time:
Manual Control 2 Minutes
Automatic Control 5-10 Minutes (1008-PC)
Drift:
Manual Control
Automatic Control
1% per week
Zero (1008-PC)
Notes :
The Automatic Control (Digital Feedback) of the ozone
generator by the UV Photometer onlv applies to Model 1008-PC.
The UV Photometer is used in conjunction with the ozone
generator only in Model 1008-PC in order to provide a W
Photometric system to be used for the calibration of other
ozone analyzers not necessarily operating on the principle of
UV Photometry. For more details, see Reference 11.
l-5

2.0 INSTALLATION
2.1 General
This section of the manual describes installation of the
instrument. It is advisable to read this section before
installation is begun. The information presented includes
receiving. inspection, and pneumatic, electrical, and recorder
connections.
2.2 Receivins Inspection
The instrument was carefully inspected and packed prior to
shipment. After the
the following:
instrument has been delivered, please check
1. Verify that the package contents are complete as ordered.
2. Inspect the instrument for external physical damage due
to shipping such as scratched or dented panel surfaces,
broken knobs or connectors, etc.
3. Remove the instrument cover and remove all interior foam
packing and save for future shipments. Make note of how
the foam packing was installed.
4. Inspect interior of instrument for damage, broken
components, loose circuit boards, etc. Make sure that
all of the circuit boards are completely secured (loose
boards could short-out the motherboard). If no damage is
evident, the instrument is ready for installation and
operation. If any damage due to shipping is encountered,
please contact Dasibi (see preface page iv, l'Claims for
Damaged Shipments and Shipping Errors").
5. If shipping damage is found, and it becomes necessary to
return the instrument, please repack it in the same way
it was delivered (using both the Dasibi shipping
container and the internal foam packing material).
6. The Dasibi shipping box and interior packing materials
are specifically made for shipment of the unit. This
material should be retained for future possible re-
shipment to Dasibi in case subsequent service or warranty
conditions should occur.
7. If it becomes necessary to return the instrument to
Dasibi at some future time, and the original shipping
materials and container cannot be found or were not
saved, please contact the Dasibi sales office before re-
shipment, with the model number of your instrument, and
we can sell you the appropriate shipping container and
materials to prevent damage to the instrument during
shipping. It is not recommended that the instrument be
shipped usinq shippinq materials and containers unsuited
for the purpose.
2-l

2.3 Installation
The installation of the instrument consists of connecting the
sample tubing to the sample gas inlet fitting located on the rear
panel shown in Figures 2-1, 2-2, 2-3, and 2-4. In addition to the
pneumatic fitting, the primary power a n d the.recorder s i g n a l
connections are also located on the back panel.
. . .
2.3.1 Gas Sampling Requirements
The sample inlet line connection should be made with l/4 inch
(0.64 cm.) O.D. Teflon tubing (not supplied). Remove the nut on
the inlet bulkhead connector and slip it over the end of the tube.
Insert this into the connector marked INLET and tighten the nut
finger-tight. This connector is off-white in color, because it is
made of Kynar, a fluoroplastic similar to Teflon which does not
react with ozone.
CAUTION
To avoid damage to the fitting, do
not over-tighten.
The entrance of the sampling system should have provision for
a water drop-out, or some way to ensure that water (i.e., rain)
cannot enter the system. It should be placed as far as possible
from any sources that could contaminate the sample.
Since the analyzer is an optical instrument, it is possible
that particulate in the gas sample could cause interference in the
ozone readings, although the sampling/referencing cyclic operation
of the instrument is designed to eliminate such interference.
However, in order to avoid frequent cleaning of the optics and
flow handling components, it is recommended that the Teflon filter
(that comes standard on the inlet port) should be installed in the
inlet line, especially if the monitoring site is in the area of
high particulate concentrations. It has been determined that a 0.5
micron Teflon filter will not degrade the ozone concentration in
the air sample if the filter is clean. However, if dirt builds up
on the filter, it will destroy some of the ozone in the sample.
Therefore, if a filter is to be used, it must be changed regularly
(see Maintenance Schedule Check List, Tables 6-2 and 6-3) and
should be held in a Teflon filter holder.
Some users feel that filter maintenance may not be reliably
performed and that this will put an unknown factor into the data,
and they prefer to monitor without the use of a filter. If a
filter is used, all calibrations should be done with the filter in-
line so that any effect the filter may have on the sample will be
included in the span. Sample air should be drawn through a
standard glass or Teflon manifold with enough flow to ensure the
sample residence time in the filter is less than 10 seconds.
2-2

The instrument does not use any reagents and is safe to vent
into a working area. The exhaust is actually ambient air with some
ozone removed. For this reason, the exhaust should also be
Prevented from reentering the sample system.
2.3.2 Electrical Connection
The instrument is designed to operate on standard, single
phase AC electrical power, 50-60 Hz and 105-125 or 220-240 volts.
A three conductor power cable is supplied with the instrument. The
round pin on the plug is the ground lead and is connected to the
instrument chassis. To provide protection to personnel when
operating the instrument on a two wire receptacle, use a three
prong adapter plug and connect the pigtail wire to the power outlet
box or to a nearby ground such as a wa,ter pipe.
HAZARD WARNING
Operating the instrument without a
proper third wire ground is a
dangerous electrical practice.
If a DC to AC inverter is used as the power source, it should
be capable of delivering 125 watts within the specified line
frequency and voltage ranges and should have a sine wave output.
Some inverters have a square wave output which will cause the
instrument to malfunction.
NOTE
This equipment should not be used in
the presence of high electric and
magnetic fields (>O.lV/m and >O.lA/m
50 Hz - 1 Ghz) due to the very
sensitive nature of its detection
system.
2.3.3 Recorder Connection
If a strip chart recorder is used, it should be connected so
that the high side of the recorder is connected to the RECORDER
terminal marked (+) on the rear of the instrument. The low side is
connected to (-1 which is chassis grounded.
The nominal analog output is 1.000 volts for 1.000 ppm.
Other, more sensitive ranges can be used, e.g., 100 mv for 1.000
PPm, or 10 mv for 1.000 ppm. This requires an adjustment of the
RECORDER SPAN potentiometer on the front panel of the instrument or
a specific request when ordering.
2-3

All recorder and remote control connections should be kept as
short as possible (not greater than 10m) and always use a braided
screened multicore cable where the braided screen is only connected
at the 1008 instrument rear ground/OV terminal, the far end of the
cable screen being left unconnected and insulated. The screen MUST
NOT be used as a OVolt return path for recorder or control signal
lines.
2-4

FITTING, Nylon
/
GUARD, FINGER
I-
TERMINAL STRIP
( A-0261 ) ( S-0082 ) ( A-0222 )
RACK PANEL
( Z - 0 4 6 4 )
RECEPTACLE J
ASSEMBLY, AC
(D-0111-A)
FITTING, Kynar
( A-0260 )
PARTICULATE
.FILTER A S S Y
( 6-0104-A)
HARDWARES LIST
SYM DESCRIPTION QTY
A 6-32 X 5/8” Flat Head Screw w/ nut 6 washer 4
B 4-40 X 112” Pan Head Screw WI nut 6 washer 2
C 4-40 X 3/b Pan Head Screw w/ nut L &her 4
D HEAT SHRINK TUBING AIR
E SPIRAL WRAP AIR
FUSE HOLI
( A-0219 )
FUSE
( A-0438 )
Figure 2-1 Back Panel (Model 1008-AH)
2D-1

2x
I-
FITTING
f
GUARD, FINGER
( A-0262 ) (S-0082)
/-
ETING
( A-0260 )
3 OZONE OUTPUTS I VENT / ZERO AIR 0
r

ga @2
.
Q
PARTICULATE -/
FILTER ASSY
( B-0104-A )
3
DASIBINET I R-S252 I L - -
OPTION
0
RECEPTACLE
ASSEMBLY, AC
( D-01 11-A )
REC
I HARDWARES LIST
I
SYM 1 DESCRIPTION lQTY ;
6-32 X 616” Flat Head Screw v&’ nut 6 washer
4-40 X 112” Pan Head Screw w/ nut L washer
/-
TERM
( A-02
FUSE HOLDE
( A-021 9 )
FUSE
( A-0438 )
Figure 2-2 Back Panel (Model 1008-PC)
2D-2

FI-ITING.
(A-0261 )
/--- TERMINAL fTpd
- FUSE HOLDER
(A-0219 )
‘WX PANEL
( Z-0135 )
FITTING,
’
( A-0400 )
‘

( D-0114 )
PARTICUIATE FILTER
ASSY
(B-0104-A)
.
Figure 2-3 Back Panel (Model 1008-RS)
2D-3

3ACK PANEL
( Z-0464 )
2x
C
o
GUARD, FINGER
( S-0082 )
TERMINAL STI
( A-0222 )
PARTICULATE
FILTER ASSY
( B-0104-A )
0C
2 x
BACK VIEW
HARDWARES LIST
SYM DESCRIPTION 1QTY
A 6-32 X 7/B” Flat Head Screww/ nut & washer 4
B 1 4-40 X 112” P a n H e a d S c r e w WI nut 6 w a s h e r 1 2
4-40 X 318’ Pan Head Screw WI nut 6 washer
FUSE HOLC
(A-0219)
FUSE
( A-0438 )
Figure 2-4 Back Panel (Model 1008-HC)
2D-4

DASIBI ENVIRONMENTAL
3.0 INSTRUMENT
3.1 General
CORP.
DESCRIPTION
TM920805
This section provides a brief physical and operational
description of the instrument. Further operating details and
theory are provided in Section 4.0, Principle of Operation. The
two sections should be read together to obtain a full overview of
the instrument's construction and capabilities. Section 5.0
describes instrument adjustments for routine operation.
3.2 Optical
3.2.1 Lamp
The source of UV radiation is a low pressure, cold cathode,
mercury vapor lamp with 92% of its output concentrated at the 253.7
nm. emission line, where absorption by ozone is maximized.
Emission at wavelengths shorter than 200 nm is eliminated by an
Ozone-free quartz shielding around the source. Presence of the
shielding prevents any emission at 185 nm, an emission line which
generates ozone.
3.2.2 Detector
The detector is a tlsolar blind" Cesium Telluride vacuum diode
with a broad passband centered near 253.7 nm. The total optical
selectivity of the lamp and detector together is such that better
than 99.5% of the detector current is due to 253.7 nm. light.
3.2.3 Optics Bench
The optics bench (absorption cell) is a 71 cm. folded chamber
consisting of stainless steel tubes and quartz windows to
physically isolate the gas from the lamp and detectors, and quartz
mirrors mounted in a triangular optical block to reflect the UV
light through 180'.
3.3 Pneumatic
3 . 3 . 1 Gas Valve(s)
The gas valve is a dual-input/single-output teflon diaphragm
valve. It is operated by a plunger actuated by a +24 V solenoid,
which is turned on and off by a signal from the electronic sub-
system timing circuitry. It is connected in such a way as to
perform the function of either switching the sample gas or the
reference gas into the absorption cell. There may be up to two
valves in the unit, depending upon its configuration. In the Model
1008-RS, there is a second valve used for remote activation,
allowing the unit to perform remote zero and/or span "self-checks@'.
The 1008-RS remote valve would be located nearer the back panel.
3-1

Required replacement parts for the gas valve, such as O-rings
and diaphragms, etc. are available from Dasibi. However, because
of the calibration requirements after re-assembly, it is strongly
recommended that the user does not attempt to service or replace
parts associated with the gas valve (see following note).
NOTE
If any users wish to service the gas
valve, or disassemble and/or replace
any parts for whatever reason, they
are hereby notified that they do so
at their own risk.
3.3.2 Flowmeter
The analyzer's front panel flow indicator is plumbed between
the output port of the optics bench and the instrument exhaust
port. The flow rate is determined by the flush delay time and the
ozone scrubber requirements (the ozone measurement is independent
of flow rate). For a given flush delay time, T, a lower limit of
the flow rate is defined by the need to flush the system completely
during time T. This lower limit is 1.5 l/min. An upper flow rate
limit of approximately 3.5 l/min is defined by the rate of the
reaction of ozone to diatomic oxygen in the catalytic scrubber:
higher flows will not give the scrubber time to do its job.
If the unit is a Model 1008-PC, 1008-PS or 1008-RS, there will
be two flow meters on the front panel. The second one, for the
ozone generating subsystem, has an upper range of 6 liters per
minute and would be located on the left side of the front panel
(when looking at the unit from the front).
3.3.3 Pump(s)
The pump, which pulls sample through the system, is an AC
diaphragm vacuum pump utilizing a Teflon coated synthetic rubber
diaphragm. It is capable of 15 inches of water vacuum at
2.5 l/min, which is much more than adequate for the analyzer's
requirements.
If the unit purchased is a Model 1008-PC, 1008-PS or 1008-RS,
there will be a second pump for the ozone generator's flow. This
pump I which is also an AC diaphragm vacuum pump utilizing a Teflon
coated synthetic rubber diaphragm, is capable of more than
5.5 liters per minutes of flow.
3.3.4 Fittings and Tubing
In order to maintain sample integrity, all fittings and tubing
in contact with ozone containing sample are Teflon or Kynar. Kynar
is a fluoroplastic, off-white in color, with chemical properties
similar to Teflon, but superior in mechanical strength. All other
fittings are nylon, and tubing is either tygon or Teflon.
3-2

i.
3.3.5 Ozone Scrubber
The ozone scrubber is a two-piece aluminum assembly that
contains a replaceable cartridge. All consumable elements in this
cartridge (copper screens coated with manganese dioxide (MnOz)) are
inserted into the cartridge at the factory.
The MnOz catalyzes the reaction of ozone to diatomic oxygen,
and does not itself react with the sample. _ Thus, the sample
entering the absorption cell after passing through the filter is
preserved intact except for the ozone.
Since the ambient air sample may contain a number of
substances in addition to ozone which to some extent will absorb
253.7 nm UV light (such as benzene), it is imperative that these
substances be of the same concentration during the reference and
the sample cycles. The single-cell design used in the instrument
does provide equal concentrations of these substances.
If the unit purchased is a Model 1008-PS (a special version of
the 1008-PC, called a "primary standard"), the ozone scrubber
assembly is removed and an additional manifold is installed to be
used with an external zero air source. This zero air is used for
the reference portion of the measurement cycle.
3.4 Electronic
3.4.1 Mother Board (Figures 3-1 and 3-2)
The mother board provides all the circuit interconnections for
the instrument, and has a minimum of electronic components mounted
on it. This approach reduces electronic troubleshooting to simply
interchanging boards. The major components mounted on the mother
board are the power transformer Tl, bridge rectifier, filter
capacitors, and connectors. The power transformer provides the
various voltages for the electronic circuitry of the instrument.
The unregulated DC voltages supplied by Tl are:
1) +B, for either +15 V or +12 V, used for analog circuits,
PROM's, and the DAC's.
2) -B, for either -15 V or -12 V, used for analog circuits
and the DAC's.
3) +5 V, for the digital circuits.
4) -5 V, for the PROMIs.
5) +24 V, for the pumps, heaters, UV lamps, and the solenoid
valve.
All the boards that plug into the mother board use on-card
regulators. The regulated voltages utilize integrated circuits for
a high order of regulation.
3-3

The boards described in section 3.4.2 to 3.4.7, use the common
DAS-80 Bus (shown in Figure 3-3). This common bus structure
enables the user to plug any of these boards into any DAS-80 Bus
connector, provided that the board components face the front of the
instrument.
Electrometer Assembly (Figures 3-4 and 3-5)
3.4.2.1 Physical Description
The electrometer assembly consists of a universal adapter
board (Figures 3-4al and 3-4a2) which plugs directly into the
Mother Board by means of an edge card connector. Electronic sub-
assemblies contained on the adapter board include two independent,
detachable electrometer circuit boards for both the sample and
control channels. These circuit boards are attached to the Adapter
Board by means of individual, multi-pin connectors. In addition,
a separate, detachable Temperature Circuit Board is also included
in a similar manner on the Adapter Board.
The Adapter Board, and its associated circuit boards, may be
removed from the Mother Board as a unit, and the individual circuit
boards may then be removed from the Adapter Board for repair or
replacement. Input signals from the remote detectors and the
temperature sensor are supplied directly to the appropriate circuit
boards by means of integral, multi-pin connectors mounted on the
circuit boards, themselves. The signal leads are therefore also
individually detachable from the electrometer assembly. Thus, the
electrometer assembly is of completely modular design for
flexibility in configuration, and ease of maintenance, trouble-
shooting, and repair or replacement of sub-assemblies or
components.
The operation of the sample and control channels and the
Temperature Board are described next. Options exist for the signal
processing circuit boards, and these are also discussed.
3.4.2.2 Signal Detection and Processing
Two separate functions are accomplished by the sample and
control channel circuit boards, respectively:
1) Measuring the signal from the sample detector for both
the sample gas (measurement) cycle. and the zero gas
(reference) cycle.
2) Controlling the timing of the sample gas and zero gas
signal measurement cycles. As described in Section 4.0,
it is essential that the time interval during the lQplt
counts for the zero gas reference cycle be exactly the
same as the time interval for the ttdownll counts for the
sample gas measurement cycle.
3-4

3.4.2.2.1 Sample Channel
The low-level current output from the UV sample detector in
the optics bench is measured by the sample channel circuit board
Containing an electrical circuit called an electrometer. The
electrometer converts the extremely low-level detector current to
a frequency which is directly proportional to the magnitude of this
current. -This frequency is applied, in turn, as a pulse train to
the input of an integrating counter (totalizer) remotely located in
the logic circuitry section which totalizes the pulses obtained
during each measurement and reference cycle. Subsequent signal
processing of these pulses accumulated in the totalizer yields the
ozone concentration for presentation on the numeric display on the
front panel of the instrument and as an analog voltage at the
output terminals on the back panel. The signal processing
methodology employed by the electronics section of the analyzer to
calculate ozone concentration from the pulses obtained during the
sample gas and zero gas cycles, respectively, is described in
Section 4.0.
For this electrometer, the sample frequency should be in the
range of 450 KHz to 480 KHz for an input clock frequency of 1.0 MHz
(common for most analyzers). To adjust for proper sample
frequency, set the mode selector switch to SAMP/TEMP with T/P off.
The number appearing on the front panel numeric display will be
0.10 of the internal sample frequency (consider, in this case, the
decimal point as a comma). The sample frequency is changed by
adjusting the position of the UV lamp in the Light Source Block
which alters the input light level to the optics bench. This is
accomplished by loosening the dual thumbscrews which hold the lamp
in place. The lamp is pulled out of the housing to decrease the
frequency or pushed into the housing to increase the frequency.
Alternatively, the lamp may also be rotated to change the
frequency. It takes only very small movements of the lamp to make
large frequency changes, and one thumbscrew should be tightened
while making a frequency reading. After the proper frequency has
been established, tighten the second thumbscrew.
This process can be made considerably less tedious if a
frequency counter is available. However, verification that the
frequency counter correctly counts square wave pulses must be made
by comparing its count with the displayed value. Both the sample
and control frequencies can be continuously monitored at test
points on the Mother Board. If this method is used, the display
readouts can be disregarded because the test points (labeled SAMPLE
and CONTROL) provide the frequencies directly.
3.4.2.2.2 Control Channel
The timing for the sample gas and zero gas signal measurement
cycles is provided by the control channel circuit board. A fixed-
frequency oscillator/counter is generally utilized for this
purpose. The fixed-frequency output of this circuit board is also
3-5

applied as a pulse train to the input of a separate integrating
counter also located in the logic circuitry section. The frequency
produced by the control channel circuit, and the resulting pulses
accumulated in the control channel counter, provide the necessary
clock function. This method of sample and zero gas measurement
cycle timing is totally adequate for a stable UV lamp and lamp
drive (short-term drift less than 100 Hz/min).
For specified analyzers, the control channel. frequency may be
generated by a circuit board containing an electrometer which
functions much like the sample channel electrometer. The input
current to this control electrometer is provided by a separate
control detector. The source of UV radiation for the control
detector is the same UV lamp in the optics bench used for the
sample channel. For this control detector, however, the radiation
is not attenuated by absorbing gases because it is positioned in a
location separate from the optics bench and in direct view of the
W lamp. It only responds to changes in radiation due to the lamp,
itself. The control channel output frequency is therefore not
constant, but varies slightly if the intensity of the UV lamp
varies. For this reason, the total pulses accumulated in the
control channel counter no longer represent a direct clock function
for measurement cycle timing, but are modulated by the radiation
flux from the UV lamp. This provides a method of adjusting, or
lltrimming,lt measurement cycle times to account for variations in UV
lamp intensity during the measurement process itself. This is
discussed in more detail in Section 4.0.
Once the sample frequency has been set, it may be necessary to
reset the control frequency. The control frequency should be set
in the same range as the sample: 450 KHz to 480 KHz. To adjust the
control frequency,
with T/P off.
Set the function switch to CONT/PRESS, again
The control frequency can be increased by loosening
the set screw which holds the control detector in the detector
housing. The control detector is the 1 inch diameter cylinder
aligned perpendicular to the long optic tube.
Screw requires a 1/16th inch allen wrench.
Loosening the set
For fine adjustments,
move the detector into the housing to increase the frequency and
pull it out to decrease the frequency. There is also a coarse
adjustment screw located in the middle of the detector block which
varies the Size of the light aperture between the uv lamp and the
control detector.
3.4.2.2.2.1 Integrating Electrometer (Figures 3-5al and 3-5a2)
This electrometer totally eliminates the unexplained drift
(and the frequent re-calibrations required) by all other
electrometers. While this electrometer may exhibit a minute
increase in noise over the VFC electrometers, it is the one used
for all sample channel electrometers; it is NOT recommended for the
control channel because its extreme accuracy is of minimal benefit
as a control frequency source, and the lower noise of the VFC
electrometer is much more desirable to the operation of the control
function.
3-6

This electrometer saturates at l/2 the input clock frequency
and is totally linear up to saturation. Due to lamp drift,
however, it is recommended that the frequency should never be set
to a value higher than 96 percent of the saturation frequency. For
a 1.0 MHz input frequency (common to most analyzers), this
translates into 480 KHz, or lower. There is NO absolute lower
frequency limit, but if the frequency drops below 300 KHz, an error
message will be displayed.
3.4.2.2.2.2 Fixed-FrequencyElectrometer (Figures 3-5dI & 3-5d2)
For standard 1008 analyzers, this simple circuit provides all
the timing that is required by the control channel, while also
keeping expense as low as possible. A slide switch on the board
allows selection of the output frequency to either 250 KHZ for
Model 1003 analyzers or to 500 KHz for Model 1008 analyzers.
3.4.2.2.2.3 652 VFC Electrometer (Figures 3-5bl and 3-5b2)
Although this electrometer is still subject to drift and
requires re-calibration, it is 10 times more linear than the older
650 VFC Electrometer design and is not as subject to temperature
and humidity variations as other VFC electrometers. It is offered
as an option for the control channel side of 1008 electrometers.
It is intended to switch over to the 653 VFC .as soon as it
becomes available (and in all probability long before any "advance
informationtt is released), and this board will then be given the
653 VFC designation to reinforce the fact that Dasibi remains on
the cutting edge of technology. Although this electrometer does
not currently use the 653 VFC, but rather the 652 VFC, Dasibi has
been promised first receipt of the 653 VFC as soon as it performs
as promised.
This electrometer saturates at l/2 the input clock frequency
and is totally linear up to saturation. Due to lamp drift,
however, it is recommended that the frequency should never be set
to a value higher than 96 percent of the saturation frequency. For
a 1.0 MHz input frequency (common to most analyzers), this
translates into 480 KHz, or lower. There is NO absolute lower
frequency limit, but if the frequency drops below 300 KHz, an error
message will be displayed.
3.4.2.2.2.4 Temperature Sensor Board (Figures 3-5el and 3-5e2)
Using the two-trim adjustment, the temperature circuit has an
accuracy of LO.3' c over a temperature range of O-50' C, when
calibrated at 25' C. This eliminates the need to perform two-point
calibrations using ice baths, high temperature standards, etc.
This temperature circuitry features an integrated temperatUre
transducer which produces an output current proportional to
absolute temperature. Laser trimming at the wafer level in
conjunction with extensive final testing ensures that the sensors
are interchangeable.
3-7

This circuit is so accurate that some NBS thermometers are
actually referenced to it. Since a 1 percent error in ozone
reading requires a 3.0' C error in temperature, the maximum,ozone
reading error due to the temperature from the temperature circuit
will never exceed 0.20 percent, worst-case.
3.4.3 CPU Board (Figures 3-6, and 3-7)
The CPU board has on it a central processing unit (CPU), a
real time clock, an asynchronous reset circuit, a 1.0 MHz system
clock, and buffers for the data, address, and control busses. The
CPU controls the entire instrument with the exception of the
asynchronous reset circuit. If for some reason the CPU becomes
stuck in an unintentional program loop, the reset circuit puts the
CPU back into the proper operation on a first priority basis. The
real time clock works in conjunction with the CPU to do all the
timing required for the operate and frequency modes.
3.4.4 Memory Board (Figures 3-8 and 3-9)
The memory board consists of the address decode circuits, 4K
bytes of read only memory (ROM) and 256 bytes of random access
memory (RAM).
3.4.5 Counter Board (Figures 3-10 and 3-11)
The counter board contains the sample and control channel
integrators. These integrators consist of six cascaded 4-bit BCD
up-down counters, driven through dual four-input NAND gates by the
sample and control frequencies. The counters have BCD parallel
outputs as well as tlcarrytt and ttborrowll outputs for cascading.
During the reference cycle, the solenoid valve is switched so
that the reference gas enters the optics bench. After a four
second flush time, both of the integrators are enabled for 1.5
seconds. The sample integrator counts the sample frequency pulses
and the control integrator counts the control frequency pulses.
The CPU then stores the count of the sample integrator, resets it
to zero, switches the solenoid valve to the sample gas containing
ozone, and waits another four seconds. This is the end of the
reference cycle and the beginning of the sample cycle.
After another four second flush time, the CPU again enables
the integrators. This time the sample integrator counts up as
before but the control integrator counts down from its previous up
count. When the control integrator reaches zero, it toggles a
flip-flop which stops both integrators. The CPU then stores the
count of the sample integrator, resets both integrators, and
switches the solenoid valve to the reference gas, thus repeating
the cycle.
3-8

3.4.6 D/A Board (Figures 3-12 and 3-13)
The analog output is obtained by converting complemented BCD
information from the CPU to a DC voltage by means of a weighted
ladder network, precision switches and an output buffer amplifier.
The complete D/A converter and buffer amplifier is housed in an
encapsulated module. The input to the D/A converter depends on
which 3 digits of the display are selected by the Digit Selector
Switch: the recorder output will always follow the selected 3
digits of the front panel display no matter what mode the
instrument is in.
The D/A converter has a 10 volt capability, but this is
normally scaled down by a feedback resistor. If the full scale
output is 1 volt, then the output is 0 to +0.999 V for 0 to 0.999
wm . This value can be scaled down by turning the analog span
control on the front panel until the desired full-scale range is
achieved. The D/A board also has on it the Digit Selector Switch,
Zero Offset Switch, Recorder Zero Offset Pot, and the Span
Switches.
3.4.7 I/O Board (Figures 3-14 and 3-15)
The I/O board multiplexes eight different analog signals into
a 10 bit analog to digital converter. At this time only three of
the eight channels are used:
1. Source Block Heater Voltage
2. Pressure Amplifier Output
3. Temperature Amplifier Output
The Span and Zero Pots, R6 and RlO respectively, are adjusted
so that a O-10 V input corresponds to a OOOH-3FFH binary output.
3.4.8 Display Board (Figures 3-16 and 3-17)
The displays and the update LED are driven by the CPU through
two I/O ports. These I/O ports also carry signals for Mode
Selector, solenoid drive circuit, and the Temperature and Pressure
Mode Switch.
3.4.9 LDHC Board (Figures 3-18 and 3-19)
This board has on it all the drive circuits for the analyzer.
These include the lamp drive, lamp heater, and the solenoid drive.
3.4.10 Ozone Control Board (Model 1008-PC, Figures 3-20 & 3-21)
This board is used in conjunction with the built-in ozone
generator in the Model 1008-PC. It contains the ozone generator
lamp drive and heater and the regulators for the ozone generator
and drive pump.
3-9

3.4.11 Ozone Control Board (Model 1008-RS, Figures 3-22 & 3-23)
This board is used in conjunction with the built-in ozone
generator in the Model 1008-RS. It contains the ozone generator
lamp drive and heater.
3-10

F O R A H 5 H C D O N O T U S E CONNECTOh
Jl,J4,JlS,f’UMP DC,OZONE P U M P , A N D R E S I S T O R (Rl)
f38 J9
1 0 5 8 6
Figure 3-la Motherboard Assembly (Model 1008~AH, -PC, and -HC)
3-11

’.
f
-i
IJI-i
I
.
SCHEMATICFOR(1008-AH&-HC)
..-._.__.-_

DA!XDI VALCORP. . . -
--...__-.. .- -..-_ _-- -.-_
.Figure 3-2b Motherboard Schematic Diagram (Model 1008~PC)
3-14

.
Figure 3-2~ Motherboard Schematic Diagram (Model 1008-RS)
3-15

UffRt?GU.A T..D
DC
40 /N 3 h!!A T
A/O iN *2 PRES
n/o I!! */ ?-a-&n..
A/D GAXD
D/A +I GRND
D/A *I OUT
RECORDER
GROUXD
A/b
A N
At3
A&i
All
AJO
A9
A8
A 7
A6
A 5
A4
A 3
A2
AI
A 0
z
A D
MRZQ
ISa
.
Figure 3-3 DAS-80 Bus Schematic Diagram
3-16'

DASIBIENVIRONMENTALCORp.
--L_
rlti
ii
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. 0
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zi
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‘FE -: F
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11366
Figure 3-4al Universal Adapter Board Assembly
3-17

U 0
t ?T t - - - t
a
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Figure 3-4a2 Universal Adapter Board Schematic Diagram
3-18

JJAMJSJ. riNv1lwmALCORP. lwo1101
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11953
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Figure 3-Sal Integrating Current Electrometer Assembly
3-19

DASIBI ENVIRONKENTAL CORP. TM901101
.
n ‘n n
I%r---.
11364
Figure 3-5bl 652 VFC Electrometer Assembly
3-21

Q2
100
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c4
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DASIBI ENVIRONMENTAL, CORP.
C E L L
TM901101
1
Pnn?n?nn!
11358
Figure 3-5~1 650 VFC Electrometer Assembly
3-23

DASIBI ENVIRONMENTAL CORP. 5
0
cf
a!
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IL
2
I-+'--+ I
IL
a .
TM901101
Figure 3-5~2 650 VFC Electrometer Schematic Diagram
3-24

DA!XBI J%VIRONMEYTAL CORP. TM901101
Figure 3-5dl Fixed Frequency Oscillator Assembly
3-25

P4
PG
F7
P8
)---------PC +5v
IMN: 9
A
LLK2
FrzEC O U T
1
l 5
1 1 2 Q2 107
,CLKI
74
L PI
7
TM901101
Figure 3-5d2 Fixed Frequency Oscillator Schematic Diagram
3-26

TM901101
TO
OPT
i R4
Figure 3-5el Temperature Circuit Board Assembly
3-27

DASIBI ENVIRONMENTAL, CORP. TM901101
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Figure 3-5e2 Temperature Circuit Board Schematic Diagram
3-28

u9 U?
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c7
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I
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Figure 3-6 CPU Board Assembly
3-29

DASIBI JZNVIRONMENTAL CORP.
Figure 3-7 CPU Board Schematic
n4901101

DASIBI JZNVIRONMENTAL CORP. l?4901101
C6
0
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Figure 3-8 Memory Board Assembly
3-31

--
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Figure 3-9 Memory Board Schematic Diagram
3-32

DASIBI JWVIRONMENTAL CORP. lM901101
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Figure 3-10 Counter Board Assembly
3-33

DASIBIENVIRtNMENTALCORP. nl901101
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1 0 6 5 8
Figure 3-12 D/A Board Assembly
3-35

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Figure 3-13 D/A Board Schematic Diagram
3-36

DASIBI JWVIRONMENTAL CORP. TM901101
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1 0 5 8 5
Figure 3-14 I/O Board Assembly
3-37

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TM901101
Figure 3-15 I/O Board Schematic Diagram
3-38

DASIBI ENVIRONMENTALCORP. m901101
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Figure 3-16 Display Board Assembly
3-39

DASIBI JZNVIRONMENTAL CORP. TM901101
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Figure 3-18 Lamp Drive Heater Control Board Assembly
3-41

..
1 '
Figure 3-19 Lamp Drive Heater Control Board Schematic Diagram
3-42

DASIBI ENVIRONMENTAL, CORP. TM901101
Figure 3-20 Ozone Control Board Assembly (PC)
3 - 4 3

t;
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i
Figure 3-21 Ozone Control Board Schematic Diagram (PC)
3-44

DASIBI ENVIRON?3f#TAL CORP. TM901101
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Figure 5-22 Ozone Control Board Assembly (RS)
3 - 4 5

Hf1001IOZONECONWL
-4I‘?‘I’,r-
JIOOWI.IOWER
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BACK S I D E
TM901101
Figure 3-24 Pressure Sensor Board Assembly Diagram
3 - 4 7

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'Figure 3-25 Pressure Sensor Board Schematics Diagram
3-48

4.0 PRINCIPLES OF OPERATION
4.1 General
This section describes the operating principles and the data
processing techniques used by Dasibi 1008 ozone analyzers. These
analyzers utilize "monochromatic ultraviolet (UV) absorption
spectrophotometry'l to provide an electrical. signal which is
proportional to the ozone concentration. This signal is
subsequently used for data processing and concentration read-out.
This section is also intended to furnish the reader with a
comprehensive understanding and a high level of confidence about
the gas concentration readings obtained from the analyzers. A
discussion of the theory of operation and method of measurement is
presented. Also, adjustments to instrument operation and
application of corrections to the data to allow for Standard
Temperature and Pressure conditions (STP) (as well as to convert to
different engineering units) are given.
4.2 Symbols Used
A =
a =
C =
C =
CF,, =
e =
I =
I, =
K =
KSTP =
L =
CMli =
CWb =
P =
R =
S =
SF =
STP =
T =
absorption coefficient of ozone (308.3 [cm-'][atm-'1
at 253.7 [nm] wavelength and STP)
approximate ozone concentration for linear form of
Beer's law
ozone concentration as partial pressure [atm]
ozone concentration in desired units
temperature and pressure conversion factor to STP
natural logarithm (2.71828)
intensity of UV radiation during measurement cycle
(with ozone present in sample gas)
intensity of UV radiation during reference cycle
(with ozone removed from sample gas, i.e., zero
gas)
proportionality factor relating concentration, C,
to concentration, c, and correcting from ambient
conditions to STP
proportionality factor relating concentration, C,
to concentration, c, at STP
optics bench path length [cm]
Molecular weight of gas of interest, (i.e., ozone)
Molecular weight of background gas.
ambient pressure [atm]
instrument Reading
instrument Span Number
instrument Scale Factor
Standard Temperature and Pressure (0' [Cl, 1 [atm])
ambient temperature [OK]
4-l

For the discussion in this section only, units are enclosed in
square brackets, i.e., [ 1, to avoid alphabetical confusion with
the various constants and variables that are also used. Commonly
accepted English and/or metric units are used, thus, [l] is liters,
[m] is meters, [in] is inches, [set] is seconds, etc.
4.3 Description of Instrument Oneration
4.3.1 General
Dasibi analyzers are self-contained instruments which measure
the concentration of ozone in a sample of ambient (background) gas,
such as air, oxygen I nitrogen, etc. This instrument is a
monochromatic, UV absorption spectrophotometer, specific for ozone.
Control of instrument function and data processing is performed
automatically by the electronic system, and only minimal
front-panel adjustments are required for proper operation.
4.3.1.1 Principle of Operation
A fixed quantity of Itzero gas" and the same quantity of
"sample gas" are drawn-in alternately to the optics bench in the
instrument by utilizing a pump and sample handling system. The
zero (reference) gas is ambient gas, but with the ozone '*scrubbedI*
(removed): the sample gas is the pure, unaltered ambient gas, with
the ozone still present. The optics bench is often referred to as
an "absorption cell," since absorption of the W light (radiation)
by various constituents in these gas samples: i.e., ozone (as well
as unwanted background constituents) takes place there.
A stable W light source is placed at one end of the optics
bench, and the level of UV radiation transmitted across the optics
bench is measured by a UV detector which is placed at its opposite
end. Alternate, consecutive measurements of the absorption of W
radiation during the zero gas (reference) cycle and the sample gas
(measurement) cycle are made by the photometer. A continuous
record of ozone concentration is then obtained by the sequential
sampling of a group, or "stream," of such I'measurementw;~~;s~l of
alternate reference and measurement cycles for the
instrument's timing circuitry has been designed.
Continuous auto-zeroing and removal of interferences are
accomplished by this paired measurement technique, which may be
thought of as "gas chopping." Some people have been surprised by
Dasibi's claim of absolute interference removal and no zero drift.
A familiar technique to achieve automatic zero stability for normal
spectrophotometer operations involves chopper stabilization, or
"light chopping." The technique of gas chopping achieves the same
zero stability, with the added advantage of inherently eliminating
all interferences.
4-2

Span stability is achieved by ensuring that the reference and
measurement cycle times for each measurement pair are identical -
by utilizing a special "clock/countertt control circuit (much like
a stopwatch) which is set by each reference cycle time interval,
controls the subsequent measurement cycle time interval, and then
is reset for the next measurement pair. A fixed-frequency
oscillator is generally utilized for this purpose which is
completely adequate for a stable lamp and lamp drive.
Any variations that might be caused by short term lamp drift
resemble llnoise,@l but operational experience with many Dasibi ozone
analyzers over many years indicate that this noise is minimal, WELL
BELOW the 1 percent span drift specified. However, short term
drift in the intensity of the UV lamp during any given measurement
pair can be compensated, if desired, by an optional, optical
subsystem.
For this, an alternate, control detector (external to the
optics bench and sample photometer) is arranged to independently
monitor the UV lamp intensity directly. This provides a method of
adjusting, or Ittrimming, *I the control clock/counter if short term
drift (variations) in the intensity of the lamp should occur. Long
term drift in lamp intensity between measurement pairs is
unimportant (whether the control detector is used or not) due to
the very nature of the paired measurement technique (unless, of
course, the lamp totally fails, or its output falls below analyzer
cut-off). Because of the operation of the zeroing,, interference
removal and control subsystems, there is VIRTUALLY NO Span or Zero
Drift in instrument readings under any conditions or for any
instrument configuration.
,
,--
Appropriate signal processing of each individual measurement
pair by the electronic system yields the instantaneous ozone
concentration (i.e., within the update cycle of the instrument) in
accordance with the Beer-Lambert law (Beer's law). A complete,
general discussion of Beer's Law is beyond the scope of this
document, but a comprehensive discussion can be found in Reference
# 14 listed in Appendix D. The signal processing methodology
utilized by the Dasibi ozone analyzer to obtain gas concentration
values utilizing the measurement pairs mentioned (as well as the
practical aspects of Beer's law) above is discussed in detail in
Section 4.7.
4.3.1.2 Calibration
When operated according to this O&M manual, the analyzer will
provide accurate data. However, continued data quality assurance
will depend upon periodic calibration and zero and span check
programs. Appendix B describes these programs as well as the
procedures required for a complete calibration. The information
presented is sufficient to perform the calibration, but for more
information, the user is referred to References 13 and 11 listed in
Appendix D. For detailed guidance in setting up a quality
assurance program, refer to References 12 and 13) listed in
Appendix D.
, 4-3_~

Zero and span checks should be performed once each month
during continuous monitoring operations. A complete calibration
should be performed at least once every three months or whenever a
major disassembly of components occurs. The analyzer is intended
to be a component in a system whose end purpose is to provide high
quality gas concentration data. The accuracy and reliability of
this system is predicated on good design, proper system
maintenance, and appropriate calibration and zero and span checks.
4 . 4 UV Photometer
A photometer is a device which'guantitatively determines the
amount of light crossing a prescribed area. The W photometer in
the Dasibi ozone analyzer consists of a stable W light source
which is placed at one end of the optics bench, and a suitable W
detector (sample detector) which is placed at the opposite end.
The detector provides an electrical output which is directly
proportional to the amount of W radiation striking its sensitized
surface. The intensity of the UV radiation traversing the optics
bench is attenuated by the ozone present in the sample gas during
the measurement cycle in accordance with Beer's law. This
attenuated signal is detected and compared with the unattenuated
signal from the previous reference cycle. The two signals are
processed digitally by the electronics for presentation directly as
ozone concentration.
The UV light source is a low pressure, cold cathode mercury
vapor lamp with 92 percent of its output concentrated at the 253.7
[nm] emission line. The absorption of UV radiation by ozone has
been found to be maximum at this wavelength. The absorption
coefficient of ozone, A, has been determined to be 308.3 [cm-']
[atm-'] at this wavelength by at least five separate investigators
using more than one independent method. Emission at wavelengths
shorter than 200 [nm] is eliminated by a Vycor optical filter
around the lamp, which prevents any emission at 186 [nm], an
emission line which actually generates ozone. The detector is a
l'solar blind" Cesium Telluride vacuum photodiode with a broad
passband centered near 253.7 [nm]. The total optical selectivity
of lamp and detector is such that better than 99.5 percent of the
system response is due to 253.7 [nm] light. This results in a
monochromatic instrument.
The optics bench is a sealed chamber to contain and physically
isolate the sample gas. Quartz windows allow the beam of W
radiation to pass through the chamber from the lamp to the
detector, both of which are mounted externally. For monitors with
long optical paths that must be llfoldedl@ to fit in the instrument
(all of the 1008 analyzers, except the 1008-HC), quartz mirrors are
mounted in a triangular optical block to bend the W radiation
through 180'.
4 - 4

4.5 Samnle Handling Svstem
-.
The sample handling system includes the gas inlet and exhaust
ports, an optics bench (the W absorption cell), a solenoid
actuated gas selection valve, a source of zero air (either a
catalytic converter or a zero air manifold), a flowmeter, and a
Pump-
The reference cycle is implemented by use of either the
catalytic converter (which selectively converts ozone in the sample
gas to oxygen, but does not affect any of the other constituents)
or a zero air manifold. During this cycle, the gas selection valve
routes ambient gas through the catalytic converter or selects gas
from the zero air manifold (to obtain the ozone-free, zero gas
sample) and then directs this gas into the optics bench for
measurement by the photometer. During the measurement cycle, the
gas selection valve bypasses the catalytic converter or zero air
manifold and routes the sample gas directly into the optics bench
for measurement by the photometer.
L...
The gas selection valve is a 3-way (dual-input/single-output)
valve constructed from inert materials. It is solenoid operated by
a signal from the electronic system timing circuitry. It is
connected in such a way as to perform the function of routing
either the sample gas or zero gas alternately into the optics
bench.
The catalytic converter (for analyzers so equipped) catalyzes
a reaction which converts ozone in the sample gas to diatomic
oxygen, but does not otherwise overtly react with the sample gas.
Thus, the sample gas entering the optics bench after passing
through the catalytic converter is preserved predominately intact
except for the removal of ozone, which has been converted into
oxygen (which does not, itself, absorb UV radiation). However,
since the sample gas may contain other substances (interferences)
in addition to ozone which will absorb some W radiation, it is
important that these substances be of the same concentration for
both the reference and measurement cycles (which is ensured with
this scrubber for all practical requirements).
The front panel flowmeter is plumbed between the output port
of the optics bench and the pump. The ozone measurement is
relatively independent of flow rate. However, an upper limit for
the flow rate which may affect instrument concentration readings is
the decreased pressure (from ambient) occurring in the optics bench
due to the increased pressure drop in the sample supply lines
resulting from an excessively high flow rate. Also, setting the
flow rate higher than required consumes the functional elements
contained in the catalytic converter at a faster rate, so that they
must be replaced more often.
4-5

On the other hand, for a given flush delay time, a lower limit
for the flow rate is defined by the need to completely flush the
optics bench between update cycles. This lower limit is
approximately 1.0 [WWninl for a 20 second update cycle.
Therefore, we recommend a minimum flow of 1.5 [l]/[min] to ensure
that the bench is totally flushed. For more rapid update cycles
(i.e., shorter flush time) the flow rate must be increased in
inverse proportion to the update cycle time, and for less rapid
update cycles, it may thus be reduced.
The sample gas is drawn into the instrument by a vacuum pump
located downstream of the optics cell. For instruments with
internal pumps (standard in every 1008 except the 1008-HC), the
pump has excess vacuum versus flow capabilities to provide
sufficient margin for all requirements of the flow system. In
order to maintain sample gas integrity, all internal surfaces in
contact with the sample gas upstream of the optics bench are
manufactured from materials which minimize sample gas degradation.
4.6 Electronic System
The sample detector in the photometer converts the UV
radiation striking its surface to a low-level current by the
photoelectric effect. This current is directly proportional to the
incident radiation. The detector dark current is so small in this
application that it can be ignored. The current from the detector
is applied to the input of an electrometer which converts it to a
frequency. This frequency, in turn, is directly proportional to
the input current and thus also to the intensity of the UV
radiation transmitted through the optics bench.
The control circuit consists of either a fixed-frequency
oscillator or a control detector electrometer, either of which
provides a clock function (the control timing for the reference and
measurement cycles associated with the sample circuit). Analyzers
that have the control detector and associated electrometer are
continuously and directly monitoring the W lamp intensity during
both the reference and measurement cycles. This detector is
contained in an independent optical path not associated with the
optics bench, and is in direct view of the lamp. Its output is not
affected by absorption due to ozone or any interferences. The
physical process of converting the W radiation intensity to
frequency for the control detector and electrometer is similar to
the process described above for the sample detector and
electrometer. The control frequency, in this case, is only a
function of the lamp intensity and varies only if the lamp
intensity varies (drifts).
The signal frequencies from the sample circuit (sample
photometer, detector, and electrometer) and the control circuit
(fixed-frequency oscillator or control detector and electrometer)
are each applied as a train of pulses to the inputs of separate
counters where the pulses are totalized independently. This
totalizing is actually an integration or averaging process. Figure
4-l is a block diagram of this arrangement.
4 - 6

A complete measurement cycle is performed as follows:
1) The sample and control totalizers are set to zero and the gas
valve is switched so that zero gas enters the optics bench.
A pre-determined amount of time is allowed to pass while the
new amount of zero gas is allowed to flush out the previous
amount of sample gas. The W radiation transmitted through
the zero gas is then measured by allowing the sample and
Control counters to totalize until the sample t&alizer counts
reach a pre-determined value, S, the "S anP Number ". The
counts then residing in the control totalizer are proportional
to S and are retained in memory. For a fixed-frequency
control circuit, these counts will be directly proportional to
the time elapsed. For a control circuit utilizing a control
detector and electrometer, the counts are modulated, or
"trimmed" from this value if the output intensity of the UV
lamp either increased or decreased during this time interval.
2) The gas valve switches again, and now an amount of sample gas
with ozone present is brought into the optics bench. The
flushing of the optics bench described above is again repeated
to remove the previous amount of zero gas and replace it with
the sample gas. Another measurement is then taken, with the
counts from the sample and control circuits arranged to
subtract from those previously accumulated in the sample and
control totalizers, respectively. The control totalizer is
allowed to count down to zero, ensuring that the same total
amount of time (or total UV radiation for the case of an
analyzer with a control detector and electrometer) was
utilized for the measurement and reference cycles. If the
radiation level from the UV lamp did not vary during the "up"
and "down" cycles for an analyzer with a control detector and
electrometer, or if the control circuit contained the
fixed-frequency oscillator instead of the control detector and
electrometer, then the frequency from the control circuit acts
much like a 'lclock," so that the "up" and "down" cycles would
then be of exactly the same length.
3) The counts now remaining in the sample totalizer (termed R in
the following discussion), correspond to the difference
between the reference cycle "up" counts (with no ozone
present) and the measurement cycle "down" counts (with ozone).
If there is no ozone in the sample gas, the sample tOtaliZer
"down" counts will be the same as the previous "up" counts and
R will be zero. However, R will have a positive value if
ozone was present in the sample gas, since the total
measurement cycle "down" counts in the sample totalizer will
be less than what it was for the reference cycle "up" COUntS
(the ozone would have attenuated the radiation during the
measurement cycle).
4 - 7

The following section explains how the analyzer utilizes the
values of S and R to obtain the ozone concentration from Beer's
law. So far, the discussion has involved a functional description
of analyzer operation. The following discussion involves the
quantitative relationship of the measured radiation intensities in
Beer's law obtained during the reference and measurement cycles.
It provides quantitative values for adjusting the analyzer's Span
Number to obtain ozone concentrations in various, desired units.
It also provides the corrections necessary to convert the
concentration data from ambient to standard conditions of pressure
and temperature. This discussion requires some mathematical
expertise by the reader.
4.7 Measurement of Ozone Concentration
4.7.1 Theory
As previously described, the analyzer measures ozone
concentration directly by the attenuation of UV radiation by ozone
molecules in the optics bench. The ozone concentration is obtained
by measuring the relative intensity of transmitted W radiation for
a '*measurement pair" consisting of a consecutive zero gas cycle and
a sample gas cycle. The exact algorithms utilized by the
instrument's signal processor to obtain concentration are presented
next. The degree to which the UV radiation is attenuated depends
on the optics bench path length, the absorptivity of the ozone
molecules, and the number of ozone molecules present.
The quantitative relationship between these factors is shown
below by Beer's law. For this form of Beer's law, the values for
the two W radiation intensities, I and IO, can be in any arbitrary
(although consistent) set of units, because they always appear as
a ratio. For the case of the Dasibi ambient ozone analyzer, they
are calculated on the basis of the ttdownlt counts and the tlupW1
counts in the sample totalizer for the sample and zero cycles,
respectively. The operating and calculation procedures are
described in detail in Sections 4.7.3 and 4.7.4, respectively.
First, consideration is given to expressing the concentration in
the desired units in Section 4.7.2.
Beer's law is normally written as:
I
I ,
= e-(ALC)
The units for ozone concentration,
(4-l)
C, are partial pressure of
ozone, in atmospheres, which is a fractional basis of the total gas
volume for expressing concentration. For 100 percent ozone at STP,
the concentration, C, would be 1.0 [atm]. For a different
volumetric fraction of ozone in the sample gas (the usual case), C
would be different than one atmos
-if
here, For instance, for 1 [ppm]
ozone (by volume), C would be 10 [atm] at STP.
4 - 8

However, "atmospheres," is not the manner in which gas
Concentrations are normally expressed, and users of Basibi ozone
analyzers are generally interested in employing more conventional
units, such as &pm] (by volume or weight), [percent] (by volume,or
weight), W3l/[m I, etc. Also, for relative concentration units
expressed in terms of weight, such as [ppm] (by weight) or
[percent] (by weight), the molecular weights of both the gas of
interest -and the background gas must be utilized in order to
calculate correct results. In addition, concentration is usually
desired at conditions of standard temperature and pressure, and
under most ambient monitoring situations, conditions are not
usually standard, so corrections to the data must be made.
For this reason, the above form of Beer's law is rewritten to
include a proportionality factor, K, which relates the
concentration in partial pressure, C (upper-case), with more
conventional units for the concentration, c (lower-case). That is,
K will be used as a concentration conversion factor. In addition,
the gas law corrections are included in K which may (or may not, at
the operator's discretion) be used to automatically correct the
concentration readings displayed by the instrument to standard
conditions of temperature and pressure.
It should be clearly understood that concentration, C,
expressed here as an upper-case letter, refers to the concentration
from Beer's law in the form given in Eqn. (4-l) in the units of
atmospheres. The concentration, c, expressed here as a lower-case
letter, is the equivalent concentration, but expressed in any
desired set of units more convenient for the user. C and c are
related linearly by K, and different quantitative values for K are
required for each of the desired units of interest for C. A
discussion of the methodology for calculating K is presented in
Section 4.7.2. Thus, utilizing the proportionality factor, K, the
relationship between c and C is given by:
'-- C = KC, so that ,
Substituting this form for the concentration into Beer's law
results in:
I = e
-(A&c)
I,
(4-2)
Solving Eqn. '(4-2) for the concentration, c, yields:
c= (ALK 1 (ln[+?I,
.
4-9
(4-3)

4.7.2 Calculation of Proportionality Factor, K
4.7.2.1 General
This section presents the method of calculating the
proportionality factor, K, used in Beer's law expressed in Eqn. (4-
2) or (4-3). K is comprised of two terms, a concentration
conversion factor at standard temperature and pressure, qTP, and a
temperature and pressure correction factor, CF,,, so that in
general:
K = (KS,,) VT& l
Determination of the concentration conversion factor, K '
discussed in Section 4.7.2.2. It presents selected nurng?ici!?
values of KSTP utilizing example calculations as well as summarized
in tabular form for various common units of concentration at STP.
Determination of the temperature and pressure correction
factor, CF
'&'
is discussed in Section 4.7.2.3. This factor will
allow K to e corrected to STP from ambient conditions, which will
cause the instrument to display the concentrations at standard
conditions. Some people prefer to have the instrument display the
concentration data at ambient conditions and perform their own
temperature and pressure corrections manually. For this situation,
assume CF,, = 1, and adjust the instrument using K = K,,
instrument will then read in the units desired, L
only. The
ut at the
conditions of ambient temperature and pressure. The corrections to
standard conditions must be performed manually by appropriate data
reduction procedures later using the actual value of CF .
As described in Section 4.7.3, the instrument is a'8*lusted to
read directly in the desired units (corrected for ambient
temperature and pressure, if desired), by using K to establish and
set the Span Number, S.
4.7.2.2 Concentration Conversion Factors at STP, KSTP
This discussion assumes a two component gas system only. That
is, the concentration of a single component gas of interest, i, is
to be determined in a single background gas, b. Where appropriate,
properties and characteristics of the gas of interest are indicated
as ( )i and of the background gas as ( )b. The background gas may
be a single component, itself (as for the case of oxygen or
nitrogen), or it may be a mixture, such as air. However, the
background gas will be treated as if it were a sinsle component by
using commonly accepted values for its combined, average properties
(such as the average tlmolecular weight" determined for air). Here,
the gas of interest is ozone, and the background gas can be air,
oxygen I nitrogen, etc. only dilute solutions of ozone in the
background gas are considered.
Table 4-l presents some relevant physical constants and
properties for various gases that will be useful for this
discussion.
4-10

1.
2.
3.
4.
5.
6.
7.
TABLE 4-1
Useful Physical Constants and Gas Properties
(Reference 15)
puantitv Value
Molar gas volume 22.414 [l][atm]/[mole]
Absolute zero temperature -273.15' [CJ
Molecular wt of ozone 47.9982 [g]/[mole]
Molecular wt of dry air 28.964 [g]/[mole]
Molecular wt of oxygen (Oz) 32.0000 [g]/[mole]
Molecular wt of nitrogen (Nz) 28.0134 [g]/[mole]
Furthermore, various useful conversion factors and
derived gas properties are calculated and presented
below:
1 D31 = 1000 [l]
Density of dry air at STP:
= (28.964 [g]/[mole])(lOOO [1]/[m3])(l [atm])/22.414
Cl1 CatW/Cmolel
= 1292.2 [g]/[m3]
Density of ozone at STP:
= (47.9982 [g]/[mole])(lOOO [l]/[m3])(l [atm])/22.414
PI Wml/[molel
= 2141.4 [g]/[m3]
Density of oxygen (Oz) at STP:
= (32.0000 [g]/[mole])(lOOO [l]/[m3])(1 [atm])/22.414
El1 CaW/Wlel
= 1427.7 [g]/[m3]
Density of nitrogen (Nz) at STP:
= (28.0134 [g]/[mole])(lOOO [l]/[m3]) (1 [atm])/22.414
VI Wml/[moW
= 1249.8 [g]/[m3]
The following relationship is given for expressing relative
concentration units by weight fraction, c', rather than volume
fraction, c. K,,, is first determined for the volume fraction units
and then modified to weight fraction units, KtSTP, by this
relationship.
Assuming a dilute solution of the gas of interest, i, in the
background gas, b:
4-11

.
Since KSTP is proportional to c, it is then also the case that:
. (4-6)
4.7.2.2.1 K,,, for concentration, c, in [ppm] (by volume)
For a concentration, c, of one part per million by volume, c
= 1, and the fractional concentration, C = l/lOOOOOO = 10-C
Since K,,, = c/C, then K,,, = 1/10a6 = 1000000 [ppm]/[atm].i
4.7.2.2.2 K,,, for concentration, c, in [percent] (by volume)
For a concentration, c, of one percent by volume, c = 1, and
the fractional concentration, C = l/100 = 10s2.
Since K,,, = c/C, then KSTP = 1/10m2 = 100 [percent]/[atm].
4.7.2.2.3 K,,, for concentration, c, in [ppm] (by weight)
From 5.2.2.1, K,,, = lo6 for @pm1 (by volume).
Therefore, from Eqn. (4-4) (and dropping the prime sign):
In air: K,,, = (47.9982/28.964)(1000000)
= 1.657 x lo6 [ppm]/[atm].
In oxygen: K,,, = (47.9982/32.0000) (1000000)
= 1.500 x lo6 [ppm]/[atm].
In nitrogen: K,,, = (47.9982/28.0134)(1000000)
= 1.713 x lo6 [ppm]/[atm].
4.7.2.2.4 K,,, for concentration, c, in [percent] (by weight)
From 5.2.2.2, l& = lo2 for percent by volume.
Therefore, from Eqn. (4-4) (and dropping the prime sign):
In air: KsTp = (47.9982/28.964)(100)
= 1.657 x lo2 [percent]/[atm].
In oxygen: K,,, = (47.9982/32.0000) (100)
= 1.500 x lo2 [percent]/[atm].
4-12

In nitrogen: KSTP = (47.9982/28.0134) (100)
= 1.713 x lo* [percent]/[atm].
4.7.2.2.5 K,,, for concentration, c, in [g]/[m3]
C = (2141.4 [g]/[m3]/[atm])(C [atm]).
But c = KC = (K,,,) x (C) for CF,, = 1 (i.e., at STP), so that:
KSTP
= 2141.4 [g]/[m3]/[atm].
Here, concentration, c, is in absolute units and is
independent of the composition of the background gas. The values
for %TP
calculated above are summarized in Table 4-2. Using these
values, two examples, to demonstrate how to convert from one set of
units to the other (in dry air), are given below. Conversions for
other units and gases are accomplished in a similar manner.
1 [percent (by wt in dry air)] = 2141.4J165.7
= 12.92 [g]/[m], and
1 [percent (by wt in dry air)] = (1000000)/165.7
= 6035 [ppm] (by volume in dry air).
TABLE 4-2
Summary of Concentration Conversion Factors, KsTp
K
Desired Units rdesiredSTAnitsl/ratml
[ppm] (by volume in any background gas)
[percent] (by volume in any background gas)
[ppm] (by wt in dry air)
[ppm] (by wt in oxygen)
[ppm] (by wt in nitrogen)
[percent] (by wt in dry air)
[percent] (by wt in oxygen)
[percent] (by wt in nitrogen)
[sl/ [m31
1000000
100.0
1657000
1500000
1713000
165.7
150.0
171.3
2141.4
4.7.2.3 Correction Factor for Temperature and Pressure, CF,,
In order to correct K for ambient conditions to those at STp,
the gas laws must be utilized. Because of the definition of STP
for the absorption coefficient (i.e., 1 [atm], 0' [Cl), STP is
defined as 1 [atmosphere] and 273.15' [K].
4-13

Thus,
CF,, =
(273.T5) (P) .
4.7.3 Specific Measurement Considerations
Now, the two UV radiation intensities for Beer's law in the
form given in Eqn. (4-3) will be related to the counts for the
Span, S, and the Reading, R. S is entered into the instrument
manually by the operator in accordance with the procedure presented
below. R is obtained in the sample totalizer and displayed as the
instrument reading after each pair of zero and sample cycle
measurements are made.
With reference to the discussion in Section 4.4 regarding the
zero and sample cycle counting procedures, it can be seen that the
"upw counts in the sample totalizer, S, are proportionalto I,, and
the "down" counts, S - R, are proportional to I. Thus, Beer's law
can be expressed for Dasibi's measurement and data processing
methodology as:
c = ($1 (InI:-%
S - R I
or, dividing each variable in both the numerator and the
denominator of the logarithmic term by S in order to obtain a
non-dimensional form in R/S, yields Eqn. (4-5):
4-5)
which is the exact form to determine ozone concentration from
instrument counts. For R/S small (i.e., ltsmallN as discussed
below), Eqn. (5-5) can be further simplified using a standard
series expansion of the logarithmic term to yield an approximate
concentration, a:
a = (K/AL) (R/S). (4-6)
By setting the Span such that:
S = K/AL
in Eqn. (4-6), the approximate concentration, a, will be given
directly by:
a = R, the Reading displayed by the instrument, itself.
4-14

i
,..
The Reading, R, is arranged to be presented on the
instrument's numeric display on the front panel and on the recorder
output terminals on the rear panel. Thus, the instrument is direct
reading when the appropriate Span number has been properly set for
the optics bench path length and desired concentration units (with
optional corrections for STP conditions), and the quantity R/S is
sufficiently small.
To obtain the exact concentration, c, from the approximate
concentration, a, a calculation must be performed by dividing Eqn.
(4-5) by Eqn. (4-6) to obtain:
c C
z-z
2 R
1
. (4-7)
Eqn. (4-7) can be easily solved, since both R and S are known.
For example, for several representative values of R/S, c/R is given
in Table 4-3. The user must solve Eqn. (4-7) for his particular
set of Readings and Span numbers. The table also shows the error
in the reading (given by 1 - c/R, expressed as percent) if the
correction is not made, and it shows the value of R/S (R/S =
0.0198) below which this error is 1 percent or less, which thus
defines R/S llsmall.l'
TABLE 4-3
Representative Values for
Concentration Calculation Corrections Due To
Non-linearity Due In Beer's Law
(1 - c/R)xlOO
R/s c/R rpercentl
0.0001 1.0000 0.00
0.0010 1.0005 0.05
0.0100 1.0050 0.50
L. - 0.0198 1.0100 1.00
0.1000 1.0536 5.36
The 1008 analyzers contain a microprocessor which solves the
exact form of Beer's law, Eqn. (4-5), so that concentration
corrections are not necessary. However, from Table 4-3, the error
in ozone reading (1 - c/R) is only 1 percent for a value of R/S of
0.0198. For lower R/S, the error becomes smaller, but for larger
R/s, the error is also larger. Below 1 percent error,
concentration corrections are made at the option of the operator,
but for errors exceeding 1 percent, corrections are required.
All analyzers function perfectly as described above to the
point at which the ozone concentration is sufficiently high to
totally extinguish the UV radiation that strikes the sample
detector. This *lcut-offW1 point will vary according to the path
length of a given optics bench as well as the ozone concentration
(total number of ozone molecules present). The relationship
between path length and ozone concentration required for cut-off is
given in Table 4-4.
,~~- 4-15

TABLE 4-4
Analyzer Cut-off Characteristics
Bench Length Ozone Concentration
rcml rPDm1 rpercentl (bv wt)
c
0.0762 70,000 11.6000
0.300 7,000 1.1600 3.
71.000 70 0.0116
TM920805
rs/m31
150.00
15.00
0.15
4-16

DASIBI ENVIRONMENTAL CORP. T M 9 2 0 8 0 5
‘..
uv
LlOHl
S O U R C E
(OPTIONAL) C E A S E I~TESRATION
T 1
CONTROL
DETECTOR
C O N T R O L
DETECTOR
CATALYTIC
.SCRUBBER
SAhiPLE
INLET
Figure 4-l Block Diagram, Optic and Pneumatic Subsystems
4-17

-
5.0
5.1
This
OPERATION
Controls and Indicators
section contains information for the operation of the
front panel controls and indicators. Also described are the turn-
on procedure, error code definitions, recorder operation, and
shutdown procedure.
1) POWER switch - Push button switch used for turning the
instrument ON or OFF.
2) ANALOG SPAN pot - Used for adjusting the recorder output
voltage gain.
3) DISPLAY - User interface for obtaining visual readings.
An LED indicates a new valve.
4) MODE SELECTOR switch - Used for selecting different
instrument operating modes.
a) ZERO position - All zeros are displayed and the
recorder output is set to zero.
b) SPAN position - The photometer SPAN and ZERO OFFSET
are displayed.
cl OPERATE position - See T/P switch described below.
d) SAMP/TEMP position - See T/P switch description
below.
4 CONT/PRESS position - See T/P switch description
below.
5) T/P Switch - This switch affects only the OPERATE,
SAMP/TEMP, and CONT/PRESS modes.
a) In the OPERATE mode, the T/P Switch works as
follows:
i) OFF - Ozone readings are referenced to STP if
the ANALYZER SPAN is set to 308. ,
ii) ON - Ozone readings are automatically
corrected for temperature and pressure
changes.
b) In the SAMP/TEMP mode, the T/P switch operates as
follows:
5-l

6) VALVE Switch - Controls the photometer's valve.
7)
8)
9)
5.1.1
1)
i) OFF - The sample frequency is displayed. The
displayed value is updated every 1.5 seconds
and corresponds to one ten thousandth of the
actual frequency. To determine the frequency
in KHz, move the decimal point one place to
the right (i.e. a reading of 42.301 would be
423.01 KHz).
ii) ON - Temperature is displayed in 'C.
cl In the CONT/PRESS mode, the T/P switch operates as
follows:
j-1 OFF - A fixed control frequency of 500 KHz is
displayed. The control frequency is displayed
in the same manner as the sample frequency -
see i) under SAMP/TEMP mode above.
ii) ON - The pressure is displayed in atmospheres.
4 In the OPERATE mode, the VALVE Switch works as
follows:
i> OFF - The solenoid is de-energized. The valve
remains in the reference gas position.
ii) ON - The solenoid switching cycle is enabled.
The valve Cycles between the reference gas and
sample gas every 10 seconds.
b) In any other mode (except the OPERATE mode) the
VALVE Switch works as follows:
i) OFF - The solenoid is de-energized. The valve
remains in the reference gas position.
ii) ON - The solenoid is energized. The valve
remains in the sample gas position.
PUMP switch - Turning the photometer's pump ON or OFF.
FLOWMETER - Indicates the rate of flow in l/min through
the analyzer. The flow should be between 1.5-3.0 l/min.
FLOW CONTROL - Used for adjusting the analyzer flow.
Ozone Generator (1008-PC and -RS; Figures 5-2 & 5-3)
FLOW METER - Indicates the rate of flow in l/min through
the 0, generator. The flow should be between 5-6 l/min.
5-2

2)
3)
4)
5)
6)
7)
8)
FLOW CONTROL - Adjusts the ozone generator flow.
OZONE Switch - Used for turning ON the ozone generating
lamp. Whenever using the photometer in conjunction with
an external ozone generator, it is recommended that the
ozone generating lamp be switched OFF. This will
increase the life of the lamp.
PUMP Switch - Turns the ozone generator pump ON or OFF.
OZONE Adjust - Three thumbwheels that give the operator
control of the O3 generator's concentration (1008-PC).
OZONE Adjust - Two push button numbers that give the
operator control of the ozone generator's level of
concentration (1008-RS only).
NOTE
There is no direct correlation between the
numerical value of this Pot and the
concentration of ozone being produced. Any
correlation observed will be merely a
coincidence.
AUTO/MAN Switch - In the Manual mode, increasing the
OZONE ADJ Switch will increase the ozone concentration.
Because of the instability of the photometer during the
first 30 minutes of warm-up, it is recommended th;: Ezz
switch be in the MANUAL position for this period.
AUTO mode, the ozone generator is put into feedback with
the photometer. The operator selects the desired ozone
concentration using the OZONE ADJ Switch (1008-PC only).
NOTE
When in the "Auto" mode, turning the
thumbwheel digits to 1~0001' will not completely
shut off the ozone generating lamp. The
"Ozone" switch must be turned off as well. If
it is not, ozone generation may occur
sporadically, as the internal computer
attempts to create this low level of ozone
dialed into the thumbwheel.
REMOTE/LOCAL Switch - Gives the user the capability of
operating the ozone generator locally or by remote
command (1008-RS only).
5-3

5.2 Remote ttZerolt or ttSpanll Operation for the Model 1008-RS
The Model 1008-RS is designed to be remotely switched into a
zero and/or span-check mode upon contact closure via datalogger.
To activate either of these modes from the back panel, the operator
must have the front panel first switched to the ?emotelt position.
Then the operator must short between the screw labeled II+5 VI' and
the desired function. The unit will remain in .these modes until
the shorts are removed by the datalogger.
To activate the "zero" mode, simply short between the tt+5V1t
screw and the "Zero" screw and the pump and valve will be activated
(thus, allowing the zero air source attached to the "Zero" back
panel port to be sampled by the analyzer). To activate the I1span"
mode, though, the operator must also short between the *‘+5V" screw
and the ltSpanll screw. By doing this, the internal ozonator lamp is
enabled to generate a level of ozone as determined by the front
panel "03 Adjust It thumbwheel switch.
5.3 Start Up
5.3.1 Turn On
Connect the instrument as described in Section 2.0 and turn on
the power switch (remember to open the instrument and check for
loose PC boards first). The front panel will be lit up as soon as
power is applied.
5.3.2 Error Code
If the instrument is in the OPERATE Mode when it is first
turned on, or if an error ever occurs while in the OPERATE Mode, an
error code is generated, consisting of the number 3. This is
displayed since the sample frequency is below 300,000 Hz.
Only applicable the error code is displayed: all other digits
are blanked. The error code is only functional in the OPERATE Mode
and does not affect the RECORDER OUTPUT (i.e., the RECORDER OUTPUT
continues to give ozone information when the error code is being
displayed).
5.3.3 Warm Up
The instrument should be given thirty minutes to warm up from
the time it is first turned on. If the error code is still
displayed after 30 minutes warm up, refer to the maintenance
section.
5.4 Recorder Operation
The recorded voltage on the back panel of the instrument is
derived from a 12 bit digital to analog converter (DAC).
Therefore, only three digits of any displayed value are recorded.
See Section 6.6.3, Recorder Adjustments.
5-4

..-.
5.5 Shut Down
If the analyzer will not be used for an extended period of
time, turning it off will extend the life of the pump, valve, and
the UV light source. To do so, push the power button to the OFF
position.
5-5

TM920805
I I /II4
6 ? 8
1 2
Figure 5-1 Analyzer Controls and Indicators
5-6

I I ..I
[*y
.
‘ 0 @
d
63 @
I 1 H. ._... .... @
Figure 5-2 Ozone Generator Controls and Indicators (PC)
5-7

6 8
I /
Figure 5-3 Ozone Generator Controls and Indicators (RS)
5-8

6.0 MAINTENANCE
6.1 General
.-
Test equipment required to perform maintenance is listed, and
preventive maintenance and maintenance schedules are detailed. An
introduction to corrective maintenance explains the general
approach to trouble isolation. Performance checks are described.
Detailed adjustments and optics cleaning procedures are covered.
6.2 Test Eouipment Reouired
1) Oscilloscope - frequency response, DC to 2 MHz
2) Frequency Meter - frequency response up to 2 MHz
3) Power Supply - adjustable, O-10 volts
4) Voltmeter
5) Barometer - accurate to +O.OOI atm.
-. 6) Thermometer - accurate to +O.l" C
6.3 Preventive Maintenance
Preventive maintenance is a quality control procedure and MUST
be done periodically in order to maintain the integrity of the
instrument.
6.3.1 Maintenance Schedules
It is highly recommended that a log be kept with the
instrument, since the maintenance schedules are done according to
total hours of "instrument ON" time.
,
'.--
6.3.2 Scrubber Cartridge Replacement (Figure 6-l)
The precise life span of the ozone scrubber is directly
proportional to the level and characteristics of the pollutants
flowing through it. The higher the concentration of the
pollutants, or the "harsher" their characteristics (such as
sulfuric acid), the less the life span of the scrubber will be.
Dasibi recommends initial replacement of the scrubber cartridge
every four months, until an "average 11 life span can be determined
based upon experience with actual operating conditions at each
installation site.
To replace the scrubber cartridge, the scrubber assembly must
first be removed from the instrument. To accomplish this, loosen
the two Kynar nuts from both ends of the scrubber assembly and
remove it from the chassis.
6-1

While holding the cartridge with the heads of the four
thumbscrews facing up, remove the thumbscrews. Gently lift-off the
top end cap to expose the cartridge assembly. There are O-rings on
each side of the cartridge to provide the pneumatic seal. Remove
both of the O-rings along with the cartridge assembly and discard
all.
Position each of the replacement O-rings into the end caps.
It is important that the outer edges of the O-rings touch the wall
of the end caps to ensure an adequate seal. If there is any
clearance between the O-ring and the wall, stretching the O-ring
about a quarter of an inch will take-up the slack.
Insert the replacement cartridge into the end cap with the
four threaded holes and set the other end cap on top of it, paying
attention to the orientation of the Kynar fittings. Start the
thread of all four thumbscrews before tightening any one of them.
To prevent the end cap from t*cocking,*l rotate each screw
alternately one turn, until each is finger-tight. DO NOT
overtighten these screws.
To re-install the scrubber assembly in the instrument chassis,
reverse the process described above for removal from the chassis.
It is NOT necessary to use a wrench on the Kynar nuts (unless they
have been damaged previously).
6.3.3 Cooling Fan Filter Pad Cleaning (Figure 6-2)
It is important that the instrument has an adequate air supply
through the cooling fan at the back panel. To ensure this, the
filter pad must be maintained clean.
It is suggested that the filter pad be cleaned weekly.
However, this will depend upon the operating environment, and this
can de determined by experience for each installation site.
To clean the filter pad, remove the outside cover by gently
prying-up the locking tabs with a flat blade screwdriver. Remove
the filter pad and wash in a mild solution of liquid detergent in
warm water. Rinse thoroughly in clear water and allow the filter
pad to dry before re-installing.
Replace the filter pad and outside cover in the opposite order
indicated above, making sure that the curved struts in the cover
are aligned with those in the fan housing. The cover snaps in
place with the locking tabs in the appropriate slots in the fan
housing.
6.4 Corrective Maintenance
6.4.1 Trouble Isolation
The approach to trouble isolation is shown in Figure 6-3.
Once a general problem area has been determined, the user is
referred to the appropriate block diagram, flowchart, and
accompanying paragraphs to further diagnose the malfunction.
6-2

6.5 Performance Checks
6.5.1 Sample Flow Check
Tap the analyzer flowmeter to make sure the float is not stuck
and is actually reading the proper value. The flowmeter should
read about 2 l/min. If it does not, see Section 6.6.1, Analyzer
Flow Adjustments.
6.5.2 Span Check
Turn the mode switch to SPAN. Record the displayed value from
the front panel. The first three digits MUST read 30.8 and the
last two depend on what zero offset has been selected. If it does
not, see Section 6.6.2, Span Adjustments.
. 6.5.3 Recorder Span Check
With the MODE switch still in the SPAN position, read the
analog value from the recorder. If the display reads 30.800, then
the recorder should read 0.800 or 80% of full scale. If it does
not, adjust to the proper value (see Section 6.6.3, Recorder
Adjustments). If the last three digits of the SPAN number are
higher than the maximum full scale value for the recorder, switch
the SPAN number to a lower value, check the recorder, and then
switch the SPAN value back to its original setting.
NOTE
The SPAN number must be set to 30.8
when in the OPERATE mode.
6.5.4 Zero Check
Set the mode switch to ZERO. The front panel display should
read 00.000. Check the recorder to make sure that it is reading
zero. If it is not, adjust the recorder to zero or the instrument
zero as described in Section 6.6.3, Recorder Adjustments. If a
recorder zero adjustment is made, repeat Section 6.5.3, Recorder
Span Check.
6.5.5 Control Frequency Check
1) Front panel controls should be set as follows:
a) MODE Switch set to CONT/PRESS.
b) T/P Switch set to OFF.
2) Record the value. It should be 500 KHz, or 50.000 on the
display, unless the optional control detector is
installed; in which case, this value should be above 200
Khz.
6-3

6.5.6
1)
Sample Frequency Check
Front Panel Controls should be set as follows:
2)
a) MODE Switch set to SAMP/TEMP.
b) T/P Switch set to OFF.
cl VALVE Switch set to OFF.
Record the value. If it is below 35.0, see Section 6.7,
Optics Cleaning Procedures.
6.5.7
1)
2)
Temperature Check
Disconnect all gas lines from the back panel.
Front panel controls should be set as follows:
a) MODE Switch set to SAMP/TEMP.
b) T/P Switch set to ON.
cl Analyzer PUMP Switch set to OFF.
d) VALVE Switch set to OFF.
3) Connect the leads of a digital voltmeter between the
GROUND test point and the TEMP CAL test point on the 1008
Universal Electrometer Adapter Board Assembly. Adjust
the trimpot on the Temperature Circuit Board until the
voltmeter reads 5.463 volts.
4) After the appropriate stabilization period, the display
should read approximately 30' C.
5) If this reading is not observed, carefully remove the
temperature sensor by unscrewing the Kynar nut at the
output of the optics bench. Remove the nut from the
sensor. Tape the sensor to the bulb of a mercury
thermometer. If the instrument was just turned on, allow
30 minutes warm-up, otherwise allow 10 minutes for the
temperature to stabilize. The display and the
thermometer should agree to within kO.3' C; if not, there
is a problem with the temperature sensor, and the factory
should be consulted.
6.5.8 Pressure Check
1) Disconnect all lines from the back panel.
2) Front panel controls should be set as follows:
a) MODE Switch set to CONT/PRESS.
b) T/P Switch set to ON.
cl Analyzer PUMP Switch set to OFF.
6-4

3)
6.5.9
/. 1)
2)
3)
6.5.10 Solenoid Valve Leak Check
1)
2)
3)
4)
5)
. .
6.6
6.6.1
Compare the displayed value with the barometer: if they
do not agree, see Section 6.6.8, Pressure Adjustments.
System Leak Check
Remove the sample line from the SAMPLE INLET on the back
panel.
;;
MODE Switch set to CONT/PRESS.
T/P Switch set to ON.
cl Analyzer PUMP Switch set to ON.
d) VALVE Switch set to ON.
e) Analyzer flowmeter set to 2 l/min.
Plug the SAMPLE INLET (a finger may be used). The flow,
as indicated on the flowmeter, should drop to zero. If
it does not, there is a leak in the system.
Remove the sample line from the SAMPLE INLET on the back
panel.
Remove the ozone scrubber, and locate the Kynar elbow on
the solenoid valve. This is the ZERO AIR INLET.
;;
MODE Switch set to CONT/PRESS.
T/P Switch set to ON.
cl Analyzer PUMP Switch set to ON.
d) VALVE Switch set to OFF.
e) Analyzer flowmeter set to 2 l/min.
Plug the ZERO AIR INLET (a finger may be used). The
flow, as indicated on the flowmeter, should drop to zero.
If it does not there is leak in the system.
If no leaks were found, reconnect all in-cabinet plumbing
and repeat Section 6.5.9, System Leak Check.
Adjustment Procedures
Flow Adjustments
The flow should be adjusted to 2.0 l/min with the flow control
valve on the flowmeter. Flow is not critical since the instrument
is flow independent. However, it should not be less than 1.5 l/min
nor greater than 3.5 l/min.
. 6-5

6.6.2 Span Adjustments
The ozone readings are proportional to the span number
electronically set into the instrument by the SPAN Selector
Switches on the D/A board. Since this number never changes once
set, there is no span drift. The recommended span number is 308.3
atm-' cm-' (refer to Reference #9 in Appendix D of this manual for
additional information about the determination of this span
number).
To use this span simply dial the numbers 3, 0, and 8 in that
order (left to right) on the switches. To verify the span number,
switch the MODE switch to SPAN. The reading should be 30.8Xx.
Where XX is the zero offset.
6.6.3 Recorder Adjustments
1) Digit Selector
The DIGIT SELECTOR Switch determines which group of three
digits on the display go to the RECORDER OUTPUT.
Normally the three digits following the decimal point are
of the most interest. These digits correspond to ozone
concentrations in the range of 0 to 999 ppb. These
digits are selected by setting the DIGIT SELECTOR Switch
on the left side of the D/A board to position IIll'.
However, if the ozone concentration ever exceeded 999 ppb
the most significant digit would not show up on the
recorder chart. For example, if the ozone concentration
was 1.018 ppm, the recorder would read 0.018 ppm if the
DIGIT SELECTOR Switch was set to position "1~~. Switching
the DIGIT SELECTOR Switch to position 112" will make the
chart read 1.01 ppm (and by switching to position @1311 the
chart would read 01.0 ppm).
2) Recorder Zero Offset
The RECORDER ZERO OFFSET Pot is located on the D/A board
between the DIGIT SELECTOR Switch and the SPAN Switches.
This pot is initially adjusted at the factory and
normally is not used unless the operator cannot zero the
recorder with the recorder's controls. Turn the MODE
SELECTOR Switch to ZERO. When the digital display is
reading all zeros, the strip chart recorder should read
zero.
3) Recorder Span Adjustment
The nominal analog output is one volt per ppm. Other
more sensitive ranges can be used, e.g. 1OOmV per ppm or
1OmV per ppm. This requires an adjustment of the ANALOG
SPAN Pot on the front panel of the instrument, or a
specific request when ordering.
6-6

6.6.4 Zero Offset Adjustment
The zero offset is designed to allow the operator to use the
insztrument with a fixed zero offset, if desired. The offset is
adjustable from 0 to 9 ppb in steps of 1 ppb by use of the right
hand digital selector switch on the D/A board. The control is
labelled ZERO. The offset adjustment does not affect the span or
linearity but simply adds a fixed number to all readings. To
verify the zero offset, set the MODE Switch to SPAN. The last or
second to the last digit (depending on the option ordered) on the
display should correspond to the number selected on the ZERO
Thumbwheel Switch.
The simplest procedure to make this adjustment is to turn the
sample flow OFF with the analyzer PUMP Switch. Set the ZERO
Thumbwheel Switch to 5 and the MODE Switch to OPERATE. The average
of the numbers which are read out will be 5 PPB plus or minus the
instrument offset. (For example, suppose that the instrument
offset is -3 ppb. Following the above procedure the operator will
observe an average of 00.002 on the display. Thus 2 ppb will be
the total reading offset which should be subtracted from all
subsequent readings to obtain the true ozone reading.) This total
offset can be canceled with the ZERO Switch for direct readings.
_
6.6.5 Light Level Adjustments
Turn the MODE Switch to SAMP/TEMP, and set both the T/P Switch
and the VALVE Switch to the OFF position. The number displayed in
this position is l/10,000 of the internal sample frequency. The
sample frequency is proportionalto the amount of light transmitted
through the optics bench.
The instrument is designed to operate over a wide range of
light levels. Set the frequency at a point which will allow
maximum operating time before new adjustments must be made. The
optimum points for setting the frequency are between 48.0 to 45.0.
As previously mentioned, these numbers are not critical, and an
instrument would still operate properly if they were 30.0, or even
in the extreme, 15.0. However, if the frequency has dropped from
45.0 to 30.0, for example, the amount of accumulated dirt which
would cause this would begin to destroy the ozone as it passed
through the system, causing low readings for that reason.
Therefore, before making light level adjustments, the optics must
be cleaned (see Section 6.7, optics Cleaning Procedure).
HAZARD WARNING
Ultra Violet light can cause burns
of the cornea. Use glasses to view
the lamp or look at it for only a
couple of seconds at a minimum
distance of 0.5 meters.
6-7

To adjust the proper frequency (light level), the thumbscrews
which hold the lamp in place should be loosened and the lamp pulled
out of the housing to decrease the frequency, or pushed into the
housing to increase the frequency (Figure 6-4). Alternatively, the
lamp may be rotated to change the frequency. It takes very small
movements of the lamp to make large frequency changes, and the
thumbscrews should be tightened to take a frequency reading.
: .
6.6.6 Analog Voltage Adjustments
The analog to digital converter (ADC) on the I/O board
measures the voltages from the photometer lamp heater and the
temperature and pressure sensors. The ADC is set at the factory so
that a O-10 V input corresponds to a OOOH-3FFH binary output. This
can be checked and adjusted as follows:
1)
2)
3)
4)
5)
6)
7)
8)
Turn the instrument OFF.
Locate the connector labelled CELL TEMP on the
motherboard next to the Temperature Bridge Amplifier.
Make a note as to which pin on the connector has a solid
red wire attached and then unplug the connector.
Put a piece of wire into the socket where the red wire
was connected. This is the input for the temperature
signal. A O-10 V signal corresponds to O-50' C.
CAUTION
Be careful not to touch any of the other pins
on this connector when the instrument is
turned ON. Some of the pins in this connector
have 115 VAC.
Connect a +lOV power supply to the temperature signal
input. Adjust the power supply voltage to 7.5 volts.
Put the MODE Switch in the SAMP/TEMP position and set the
T/P Switch to ON.
Turn the instrument ON. After the displayed value has
stabilized, it should read 37.5' C. If it does not,
adjust the ADC span pot, R6, on the I/O board.
Disconnect the power supply and short the temperature
signal input to ground.
After the displayed value has stabilized, it should read
zero. If it does not, adjust the ADC zero pot, RlO, on
the I/O board. If a zero adjustment is made, repeat
steps 1 through 8.
6-8

6.6.7 Pressure Adjustments
The only adjustment required for the pressure measurement is
the SPAN. The SPAN Pot is located on the Pressure Amplifier
mounted on the optics bench. Perform span adjustment as follows:
1) The instrument should be set up as described in Section 6.5.8,
Pressure Check before continuing this procedure.
2) Adjust the pressure SPAN Pot until the barometer and the
displayed value compare. If after adjusting the SPAN Pot, the
readings do not compare, see Section 6.6.6, Analog Voltage
Adjustments.
6.7 Optics Cleaninq Procedure
1)
2)
3)
4)
5)
Turn power off to the instrument and remove its cover.
Remove the LDHC board.
Loosen the top knurled retaining nut and remove the absorption
tube (Figure 6-4).
Loosen the bottom knurled retaining nut and remove to clean
both absorption tubes. The absorption tubes may be cleaned by
inserting a Kim Wipe, and pushing it through the tube using a
length of Teflon tube, or an optics cleaning rod (refer to
Section C.7 in Appendix C).
The mirrors may be cleaned in place, using a Q tip, thereby
eliminatinq the need to disassemble the optical relay block.
If
a)
b)
cl
d)
the procedure is not satisfactory, proceed as follows:
Remove the triangular optical relay block by loosening
two screws. This may be done by inserting a screwdriver
through the access hole in the side of the chassis. Hold
the block to prevent it from dropping to the bottom of
the case and damaging the mirrors.
Remove the two screws holding each mirror cover plate.
Carefully remove the two mirrors and clean with a soft
tissue. If further cleaning efforts are required, a
solvent may be used, provided it does not leave a film on
the mirrors. Isopropyl alcohol is recommended. Handle
the mirrors at the edges, to prevent fingerprints.
Before re-inserting the mirrors, thoroughly clean the
optical relay block. After cleaning the mirrors and the
block, carefully reseat each mirror in the block. If the
mirrors are installed in a cocked position, mirror
breakage will result.
6-9

6)
7)
8)
9)
6.8
e) Assemble the mirror, O-ring and cover plate, using the
two cover plate tie-down screws. Tighten each screw
gradually, so as to apply pressure on the mirror evenly,
to avoid cracking the mirrors.
f) Re-install the triangular optical relay block. The
recessed holes on the block should face out.
The windows may be cleaned in place, using a Q-tip, thereby
eliminating the need to disassemble the I/O block. If
unsatisfactory, proceed as follows:
a) Remove the lamp heater electrical connector.
b) Remove the screw holding the window assembly block, and
clean each of the two windows with a soft tissue (Kim
Wipes are recommended). Upon disassembly, hold the block
in place to avoid accidentally dropping and breaking the
windows. Re-install the two windows and reconnect the
block using the tie-down screw.
cl Re-insert the lamp heater electrical connector.
Re-install the bottom absorption tube. A light film of
Stopcock grease may be used on the threaded tube section to
prevent galling the Aluminum. Special care should be taken to
avoid contaminating the absorption tube inner surfaces with
lubricant.
Re-install top absorption tube (note comments in # 7).
Perform Section 6.5.9, System Leak Check.
Teflon Particulate Filter Pad Replacement (Figure 6-5)
The unit is delivered with a particulate filter holder
assembly attached to the sample inlet port on the rear panel. The
Teflon pad inside of this assembly reduces the amount of
particulate matter that will enter the instrument, thus preventing
problems from occurring, while reducing the frequency with which
the optics cell must be cleaned. This pad should be replaced
periodically; how often, is dependent upon the flow rate used and
the concentration of particulate matter in the air stream. A
"trial and error" method of determining how often this pad should
be replaced must be conducted by the end user, much in the same
manner as for the replacement of the unit's ozone scrubber. To
remove the Teflon filter pad for replacement, follow these
instructions:
1. Remove the Filter Holder Assembly located on the Sample
inlet port by loosening the nut on the Sample port
fitting and pulling the assembly off.
6-10

2. Use the two green wrenches that were delivered with the
unit's manual to grasp the two clamps on either side of
the filter assembly. Move the wrenches in opposite
directions to unscrew the clamps: this may require quite
a bit of torque as the seal may be very tight (in order
to prevent leaks).
3.
4.
Remove the Teflon filter element. .
Install the new filter element making sure it is centered
on the filter holder's "gridI'.
5. Start the re-seal of the filter holder's clamps by
turning the inlet clamp clockwise. Once it is as tight
as it can be made by hand, turn it l/4 turn using the
wrenches.
6. Re-apply power and check the flow of the instrument.
7. If a leak exists in the
clamps further, using
disappears.
filter holder, turn tighten the
the wrenches, until the leak
Section
6.5.1
6.5.2
6.5.3
6.5.4
6.5.5
6.5.6
6.5.9
6.8
6.5.10
6.5.7'
6.5.8
6.5.9
Performance Checks
Sample Flow Check
Span Check _ -
Freauency (Hrs. of Operation)
24 hrs*
168 hrs
Recorder Span Check 168 hrs
Zero Check 168 hrs
Control Frequency Check 168 hrs
Sample Frequency Check 168 hrs
System Leak Check 168 hrs
Teflon Particulate Filter Pad Replacement 168 hrs
Solenoid Valve Leak Check 720 hrs
Temperature Check 720 hrs
Pressure Check 720 hrs
Scrubber Cartridge Replacemen hrs (recommended)
y,Or each day of which an operator is in attendance.
TABLE 6-l
Maintenance Schedule**
I** See Tables 6-2 and 6-3 for check lists.
6-11

(1 et YEAR OF OPERATION)
Section Performance Check
Performance Time
. S c h e d u l e
6.5.1 Sample Flow Check Pbiformed each Check
6.5.2 Span Check Performed Weekl’y:
-- __-_- -_._ .--
_-- _-
6.5.3
--- - __._--
Recorder Span Check Performed Weekly
I
-_-. - - .- - - - -
___- .- .
.--_----
6.5.4 zero Check brformed Weekly
--_-_ - - .
,--*-
__.-, ..--.--
6.5.5 Control Frequency Check Performed Weekly
- _--I--. -.-. -- - - .-- --_ . . . -_.-.---
____ _____- ---- VI-.-- .-- --.
l
i
6.5.6 Sample Fre’quency Check Performed Weekly,’
Maintenance Check List (A)
6D-1

Performance Check
Solenoid Leak Check Performed Monihly
Presstie. check-. I Perior.med Monthly
TABLE 6-3
Maintenance Check List (B)
6D-2

TM920805
FILTER PA0
( S - 0 2 1 3 )
CARTAIOOE
CAP
( t - 0 2 8 2 )
O-RING
(S-02 14)
REFILL
CARTRIDGE
(t-0284-S)
O-RING
(S-02 14)
CAP
(Z-0283)
.fHlJMB SCREW
(S-0338)
Figure 6-l Scrubber Cartridge Replacement
6D-3

TM920805
FILTER PAD
TAB
/--
COVER
I
Figure 6-2 Cooling Fan Filter Pad Removal
6D-4

TURN 1008 ON
N O e
CHECK
POWER PLUG,
F U S E AN0 8UL6
A
YES ) PROBABLE CAUSE
LAMP NOT LIT
YES a
i
PROBABLE CAUSE
I) SYSTEM LEAK
2) BAD SCRUBBER
NO
NO 0
PROBABLE CAUSE
YES b
I ) LAM/’ FL ICKERING
2) ELECTROMETER
MALFUNCTION
Figure 6-3 Trouble Isolation Flow Chart
6D-5

OPTIONAL
c#88UI# CONTROL
TRANBDUCER DETECTOR ul$iJ::2~
8ET 8CAEW T H U M B aCREW

-5
Ei2
DiTl
SET
/
T-CONNECTOR
ABSORPTION
TUBES
VALVEIRhJLATOR
BOARD
KNURLED
REfAlNlN~
NUT8
MIRROR
COVERS
Figure 6-4 Optics Assembly
6D-6

WRENCH
OUTLET ‘STEM’
- INLET PORT
.
Figure 6-5 Teflon Particulate Filter Pad Replacement
6D-7

7.0 REPLACEMENT PARTS LISTS
7.1 General
This section contains a list of major components in the
instrument. Electronic boards are listed as complete assemblies.
A more detailed parts list can be obtained on request.
. . .
7 . 2 Ordering Information
All inquiries regarding ordering spare parts should be
addressed to:
Dasibi Environmental Corporation
506 Paula Avenue
Glendale, CA 91201
Phone: CSIS) 247-7601 or Fax: (818) 247-7614
7 . 3 Service Kit for One Year of Operation:
For All 1008 Models:
Fifty (50) Teflon Filter Pads
For Models 1008-AH, loo&PC & lOO&RS Only:
Two (2) Ozone Scrubber Refill Cartridges
A-0000
Z - 0 2 8 4 - S
For Model lOOS-RS Only:
If Unit is Purchased With On-Board Zero Air Source Option:
Five (5) Refill Packages (.3 lbs/pkg) S-0189
For Model 1008-HC Only:
One (1) O-Ring for Optics Bench s - 0 3 7 0
One (1) O-Ring for Optics Bench S-0369
Three (3) Internal Filter Refill (.5 lbs/pkg) S-0189
If Unit is Purchased With Reference Measurement Charcoal Filter:
Three (3) Refill Packages (.3 lbs/pkg)
7 . 4 Service Kit for Two Years of Operation:
For All 1008 Models:
One Hundred (100) Teflon Filter Pads
S-0189
A-0000
7-l

For Models IOOS-AH, IOOS-PC, IOOS-PS & IOOS-RS Only:
Two (2) O-Rings for Absorption Tubes
Two (2) O-Rings for Optics Bench Mirrors
A-0205
S-0346
For ModelsIOOS-AH, loo&-PC, lOOS-PS & IOOS-RS (1lOVolti Only:
One (1) U.V. Lamp Assembly A-0204-S
For Models1008-AH, lOOS-PC & IOOS-RS Only:
Five (5) Ozone Scrubber Refill Cartridges
For Models IOOS-PC, IOOS-PS & 1008-RS Only:
One (1) Ozone Generator Pump Repair Kit
For Models IOOS-PC, IOOS-PS & IOOS-RS (110 Volt) Only:
One (1) Ozone Generator Lamp Assembly
For Models 1008-AH & IOOS-RS Only:
One (1) Photometer Pump Repair Kit
For Models IOOS-PC & IOOS-PS Only:
One (1) Photometer Pump Diaphragm
Z-0284-S
R-0089
c-0120-s
R-0089
R-0005
For Model IOOS-RS Only:
If Unit is Purchased With On-Board Zero Air Source Option:
Ten (10) Refill Packages (.3 lbs/pkg) S-0189
For Model IOOS-RS, 220 Volt, Only:
One (1) U.V. Lamp Assembly
One (1) Ozone Generator Lamp Assembly'
For Model IOOS-HC Only:
A-0204-RS
C-0120-RS
One (1) O-Ring for Optics Bench s-0370
One (1) O-Ring for Optics Bench S-0369
Seven (7) Internal Filter Refill (.5 lbs/pkg) S-0189
If Unit is Purchased With Reference Measurement Charcoal Filter:
Seven (7) Refill Packages (.3 lbs/pkg) S-0189
7-2

TM920805DASIBI ENVIRONMENTAL CORP.
If Unit is Purchased With Internal Pump:
One (1) Photometer Pump Repair Kit R-0089
7.5 Replacement ComponentiAssembly Stock Numbers*
Descriation
Mechanical Parts/Assemblies:
For All 1008 Configurations:
Power cord
Function Switch Assembly
Flowmeter Assembly (O-3 LPM)
Photometer Valve Assembly
Replacement Diaphragm
Back Panel Fan
Particulate Filter Holder (W/Filter Inside)
For ModelsIOOS-AH, lOOS-PC, lOOS-PS 81 100%RS Only:
Optics Bench Assembly (Does Not Include Lamp)
Relay Block Assembly
Light Source Block Assembly
Absorption Tube Assembly (One)
Optics Bench Mirror
Optics Bench Window
O-Ring (Inlet Block)
O-Ring (Detector Block)
Optics Cleaning Rod Handle
Optics Cleaning End Rod
Optics Cleaning Middle Rod
Optics Cleaning Rod Assembly Holding Clips
Maintenance Tool: l/16" Allen Wrench
For Models 1008-AH, 1008-PC & IOOS-RS Only:
Ozone Scrubber Assembly
For Models IOOS-PC, 1008-PS & 1008-RS Only:
Thumbwheel (Manual 03 Adj.)
Analog Output Potentiometer
Flowmeter Assembly (O-6 LPM)
ForModels 1008-AH & 1008-HC Only:
Fuse
Power Switch Assembly
Pump Switch Assembly (Photometer)
110 Volt 220 Volt
A-0224 Same as 1lOV
S-0396-A II
A-0271-1 fl
S-0438-A II
R-0092 II
D-0114
I
II
B-0104-A II
Z-0022-08/09 Same as 11OV
Z-0125-A II
Z-0032-A II
Z-0378-A II
A-0210 II
A-0209 II
A-0212 II
A-0205 II
S-0366 II
S-0367 II
S-0368 II
S-0382 II
s-0415 II
Z-0284-A
A-0460
A-0175
A-0271-2
A-0220
B-0098-B
A-0173-A
Same as 11OV
Same as 1lOV
II
II
A-0109
B-0098-B-220V
II
7-3

Description 110 Volt
Mechanical Parts/Assemblies (Continued):
220 Volt
For ModelslOOS-PC & 1008-PS Only:
Power Switch Assembly B-0098 Specify 220V
Thumbwheel Assembly (Auto 03 Adj.) A-0443-B Same as 1lOV
0, Generator Pump Assembly A-0218K-1lOV A-0218K-220V
Photometer Pump Assembly A-0218-A Same as 1lOV
Elbow Fitting R-0003 II
Tee Fitting R-0004 II
Ozone Generator Assembly (W/O Lamp) Z-0271-PC II
Ozonator Lamp O-Ring A-0213 tt
Side Blower Assembly A-0226-A . A-0319-A
For Model IOOS-AH:
Photometer Pump Assembly A-0218J-1lOV A-0218J-220V
For Model 1008-RS Only:
Power Switch Assembly
Pump Switch Assembly (Photometer)
lfRemotelf Valve Assembly
Replacement O-Ring
Replacement Upper Diaphragm
Replacement Lower Diaphragm
Photometer Pump Assembly
0, Generator Pump Assembly
Ozone Generator Assembly (DoesNot Include Lamp)
Ozone Generator O-Ring
B-0098-A B-0098-RS
A-0173-A A-0173-RS
A-02Oj-S A-0203-R
R-0006 Same as 1lOV
R-0013 II
R-0014 II
A-0218J-1lOV A-0218J-RS
A-0218K-1lOV A-0218K-RS
Z-0271-A Same as 1lOV
A-0213 II
Optics Bench Assembly (Does Not Include Lamp)
Optics Cell Spacing Shim
Light Source Block Assembly
Optics Bench Window
Internal Filter Assembly
Z-0100-B Same as 1lOV
S-0423 I1
Z-0032-A II
A-0209 II
Z-0109-D 11
Pneumatic Parts/Assemblies:
l/4@' Teflon Tubing (Price/Foot)
l/4" Tygon Tubing (Price/Foot)
N-0034
s-0021
7-4
Same as.llOV
I(

DescriDtion
Electronic Parts/Assemblies:
TM920805
110 Volt 220 Volt
CPU/Memory Board Assembly
LED
I.C. (Ul)
I.C. (U2)
RAM (U3)
I.C. (U4)
I.C. (U5)
I.C. (U6)
Crystal (U7)
I.C. (U8)
I.C. (U9)
I.C. (UlO)
I.C. (Ull)
I.C. (U12)
I.C. (U13)
I.C. (U14)
D/A Board Assembly
I.C. (Ul &I U2)
I.C. (U3)
I.C. (U4)
Converter (U5)
1-C. (U6)
I.C. (U9)
Display Board Assembly
LED
I.C. (Ul & U2)
I.C. (U3)
I.C. (U4)
I.C. (U5)
Counter Board Assembly
I.C. (Ul & U2)
I.C. (U3)
I.C. (U4)
I.C. (U5)
I.C. (U6 & U7)
I.C. (U8 thru U19)
I.C. (U20)
LDHC Board Assembly
Transformer (Tl)
Transistor (42 & Q3)
Regulator (VR2)
I.C. (Ul)
I.C. (U2)
I.C. (U3)
7-5
S-0372-A
A-0177
A-0058
S-0325
s-0400
A-0057
S-0218
A-0276
s-0373
s-0371
N-0071
A-0159
A-0155
A-0165
A-0281
A-0287
A-0428-A
A-0063
A-0283
A-0281
B-0067
A-0437
A-0159
A-0430-A
A-0177
A-0063
A-0283
A-0281
A-0159
A-0429-A
A-0063
A.-0283
A-0281
A-0159
A-0276
A-0285
A-0282
A-0432-B
A-0148
A-0129
T-0442 '
A-0159
A-0154
A-0168
Same as 1lOV
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
11
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II

Electronic Parts/Assemblies (Continued):
Valve/Regulator Board
~~- Regulator (VRl)
Regulator. (VR2)
Regulator (VR3)
1-c. (Ul)
Pressure Sensor Board Assembly
Switch
I.C. (Ul)
Temperature Sensor Board Assembly
CP AmP
Electrometer Adapter Board Assembly
RIN Tester Assembly
Sample Channel Electrometer Board
Op-Amp (Ul)
I.C. (U2)
1-c. (U3)
1-c. (U4)
I.C.(US)
I.C.(UG)
Control Channel Electrometer Board Assembly
I.C.
Detector Assembly Only
Detector (Specify Sample or Control Channel)
S-0444-A
A-0531
A-0138
T-0442
c-0041
A-0435-A
A-0475
A-0483
S-0238-A
S-0247
S-0265-A
S-0263-A
S-0266-A
A-0530
A-0340
A-0155
A-0168
S-0245
S-0246
S-0260-A
A-0168
A-0263-B
A-0263
Same as 1lOV
II
II
II
II
II
II
II
II
II
II
II
II
II
II
I1
II
II
11
II
II
II
II
For ModelslOO&AH, 1008-PC, lOOS-PS & 1008-RS Only:
Temperature Sensor Assembly A-0370-A II
For Modelsloo&AH, 1008-RS & 1008-HC Only:
I/O Board Assembly
1-c. (U2)
I.C. (U3)
I.C. (U4)
I.C. (U5)
I.C. (U6)
Converter (U7)
I.C. (U9)
For Models1008-AH 4% 1008-HC Only:
S-0025-A
A-0409
A-0283
A-0281
A-0159
A-0030
A-0406
B-0035
Same as 1lOV
II
II
II
II
II
II
II
Mother Board Assembly A-0433-A A-0433-A-220VL- ~.
Main Transformer s-0022 S-0022A
Potentiometer A-0175 Same as 1lOV
~. 7-6

Electronic Parts/Assemblies (Continued):
For Models 1008-PC & 1008-PS Only:
e
Mother Board Assembly
Main Transformer
Potentiometer
I/O Board Assembly
I.C. (Ul & U2)
1-c. (U3)
1-c. (U4)
I.C. (U5)
I.C. (U6)
Converter (U7)
Converter (UB)
I.C. (U9)
Ozone Control Board Assembly
Transformer (Tl)
Transistor (Ql)
Transistor (42)
I.C. (ICl)
1-c. (IC2)
I.C. (IC3)
A-0433-P
S-ob22
A-0175
S-0025-B
A-0409
A-0283
A-0281
A-0159
A-0030
A-0406
B-0067
B-0035
A-0431-A
A-0148
B-0050
B-0049
A-0418
A-0159
A-0154
B-0042
For Model IOOS-RS Only:
Mother Board Assembly
Main Transformer
Potentiometer
Relay(RY1)
Ozone Control Board Assembly
Transformer
Transistor (Ql)
Transistor (42)
Regulator (URl)
Regulator (UR2)
Regulator (UR3)
1-c. (Ul)
1-c. (U2)
I.C. (U3)
A-0433-R
s-0022
A-0175
A-0217
A-0099-A
A-0148
B-0050
B-0049
A-0129
A-0151
A-0347
A-0082
A-0159
A-0154
B-0042
Temperature Sensor Assembly A-0370-C
220 Volt
A-0433-P-220V
S-0022A
Same as 1lOV
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
II
A-0433-R-220V
S-0022A
Same as 1lOV
II
II
If
II
II
II
II
II
II
II
II
II
Same as 1lOV
7-7

Descriotion
Components For Options:
4-20 mA Output Board Module (U2)
Isolated Analog Output Board I.C.(Ul)
Detector Block Assembly (Retrofit)
RS232 Board Driver I.C.
Dual Detector Control Channel Electrometer Board
I.C.(AD652)
CP-AmP
Dual Detector Assembly (Pair)
Control Detector Assembly (Only)
Temperature Sensor Circuit (Used with Blue Box)
Temperature Sensor Assembly (Used with Blue Box)
110 Volt
S-0228
S-0227
Z-0119-A
T-0156
S-0287-A
S-0289
A-0530
A-0263-C
A-0263-D
S-0345-A
A-0370-B
* Please consult factory for additional stock numbers.
7-8
TM920805
220 Volt
Same as 11OV
II
II
II
II
II
II
II
II
II
II

TM920805
APPENDIX A
MODEL 1008-HC INFORMATION
A-l

A.1 General
The information in this appendix applies only to Model 1008-
HC, which measures much higher ozone concentrations than Models
1008~AH, 1008-PC, and 1008-RS. The normal range of Model 1008-HC
is from 0 to 10 percent by weight (O-60,350 ppm by volume). Even
though it is electronically identical to the other models, there
are some pneumatic and optical differences the user should be aware
of:
1. Model 1008-HC usually does not contain a sample pump.
2. Model 1008-HC does not use a built-in ozone scrubber as its
zero reference; it uses some of the air or oxygen (or ambient
air) used to generate ozone. For this reason there is an
inlet port on the rear of the instrument labelled "zeroIt.
3. The length of the optical cell in Model 1008-HC is 0.076 cm.
instead of 71 cm. For this reason the flow rate need not be
2.0 l/min, but a flow rate of 0.5-1.0 l/min is sufficient.
4. Because most large scale ozone generators operate with
positive pressure, the absolute pressure sensor in Model 1008-
HC measures up to 30 psig, with the same voltage range.
NOTE
If the ozone sample and the zero air (carrier gas) are
not under positive pressure, a pump can be used to pull
in the sample and reference gases. The suction side of
the pump must be connected to the port labelled
tlexhaustll. In order to protect the pump from high ozone
levels (usually 1% or more) a molecular sieve cartridge
(300-400 cc volume) must be connected between the exhaust
port of the analyzer and the suction side of the pump.
If a molecular sieve cartridge is not necessary because
the pump is resistant to high ozone, then the exhaust of
the pump must be vented safelv. Figure A-l shows a
typical connection of Model 1008-HC to the gas stream of
an ozone generator.
A.2 Assembly of Sample Cell
Under conditions of normal operation, the sample cell windows
will eventually become contaminated with dirt and particulate from
the sample gas and must be cleaned periodically. The schedule for
such cleaning has been described under Section 6.0, Maintenance.
Here, the disassembly of the sample cell, the cleaning of windows,
and the reassembly of the cell are described.
A-2

To remove the cell from the instrument, disconnect the inlet
and outlet lines at the Swagelock fittings on the cell block.
Loosen the detector set screws and remove the detectors. Remove
the two screws holding the cell block to the cell base.
Figure A-2 shows the components that are contained in the
sample cell. Remove the four screws holding the window plate. All
of the components in the cell are now free to be removed.
Carefully allow them to slide out of the cell onto a cloth placed
on the workbench.
Wipe all of the components clean with a lint-free cloth.
Cleanthe quartz windows with alcohol, being careful to hold them
only by their edges after cleaning to avoid contamination with
fingerprints. It is advised to wash your hands before the actual
cleaning and reassembly of the cell are performed.
After cleaning, the components are replaced in the sample cell
in the order shown in Figure A-2. The only critical item here is
that the path length spacer must be properly aligned so that the
sample flow may pass freely through the sample cell. Figure/A-2
shows the sample flow as a heavy dotted line. After reassembly,
the notch, on the gap between the two .0298" shims (for the L =
,0298@@ path length instrument) must be aligned with the flow path
direction as indicated on the figure.
When all of the components are in place in the sample cell,
visually check through the sample inlet port that the path length
spacer gap is properly aligned. Screw the window plate back down
onto the cell block for a tight sealing of the o-rings.
Leak check the re-assembled unit by attaching a 10 psi source
of gas to the exhaust fitting. Hold your finger over the sample
gas inlet port and using ltsnooplt or other substance, ensure that
the unit does not leak at this pressure. If it does, visually
check the status of the o-rings to verify that they are worn out.
After a successful leak check, the unit is ready for
replacement in the instrument. Replace the sample gas inlet, and
attach the optics block to the cell base with the two screws. Re-
attach the exhaust line to the Swagelock fitting and install the
detectors and tighten in place with the set screws. The instrument
is now ready for operation. After the unit has warmed up it may be
necessary to readjust the sample frequency.
A-3

01
02
03
04
05
06
07
0a
OZONE
07 CLEAN
SUPPLY
Pressure regulator (2-5 PSI)
Pressure regulator (2-5 PSI)
Zero air inlet
Ozone sample inlet
Flowmeter (5-l LPM)
Particulate filter
Charcoal filter (optional) l
Monitor outlet
PROCESS
VENT
,
l Item for this point is only required when the clean dry air supply is not available.
All fittings and lines (possibly l/4” OD) should be either teflon or stainless steel or
combination of both.
Figure A-l Connection of Model 1008-HC to Ozone Generator
A-4

6-32 x I
FLAT HE40
2 x
HC CELL
(Z-0317)
DETECTOK BLOCK
(Z-Or29)
7 /-
Z”d;‘,‘,%2
URCE
_--- .-sm0w
LOCK WASHER
- tic CELL BASE
(Z-036)
Figure A-2 Model 1008-HC Sample Cell Components
A-5

APPENDIX B
INSTRUMENT CALIBRATION
TM920805
B-l

B.l General (New W Calibration Procedure)
The new W calibration procedure is quite simple. After
generating a stable, ozone concentration with an ozone generator,
the operator assays it by passing all or a portion of the gas flow
through the cell of a W photometer. The photometer readings are
then used in a formula to calculate the ozone concentration, which
is effectivelv a orimarv ozone standard. Most commercially
available photometers do the photometric calculations
automatically, and some may also make temperature and pressure
corrections automatically. The primary burden on the operator is
to insure that:
1) The photometer is operating correctly.
2) The apparatus is set up properly, is clean and leak-free.
3) The calculations are complete and accurate.
While none of these is particularly difficult, EPA has
prepared a Technical Assistance Document which explains these tasks
and provides other detailed information about the procedure
(Reference #9 in Appendix D). The photometer is obviously of
critical importance to the procedure and must have a precision
within 0.005 ppm or 3% of the concentration, whichever is greater.
While a calibration photometer can be assembled from laboratory
components, EPA recommends the purchase of a commercial photometer
which is either designed specifically for this calibration
procedure or which can be readily adapted to it. Such a photometer
and ozone generator system is the Dasibi Model 1008-PC (Fig. B-l).
W Photometers of the type used in ambient ozone analyzers are
likely to be suitable as calibration photometers. Conversion of an
ambient UV analyzer to a calibration photometer is covered in the
Technical Assistance Document. However, it is important to
differentiate between the use of a UV photometer as an ambient
analyzer and its use as a calibration photometer. This distinction
is predicated more on operational differences than on any specific
physical differences. The new calibration procedure requires that
a photometer used for calibration must be:
1) Dedicated exclusivelv to such use.
2) Must be maintained under meticulous conditions.
3) Must be used only with clean calibration gases.
W analyzers used for ambient monitoring should always be
calibrated with an independent calibration photometer or a
certified transfer standard. A W analyzer should not be
considered to be llself-calibratedl' even though it contains a UV
photometer which meets the specifications of the W calibration
procedure.
B-2

B.2 Calibration Procedure
The calibration procedure is based on the photometer's assay
of ozone (OS) concentrations in a dynamic flow system. The
concentration of 0, in an absorption cell is determined from a
measurement of the amount of 254 nm light absorbed by the sample.
This determination requires knowledge of:
1) The absorption coefficient (A) of 0, at 253.7 nm.
2) The optical path length (L) through the sample.
3) The transmittance of the sample at a wavelength of 253.7
nm.
4) The temperature (T) and pressure (P) of the sample.
The transmittance is defined as the ratio I/I,, where I is the
intensity of light which passes through the cell and is sensed by
the detector when the cell contains an 0, sample, and I, is the
intensity of light which passes through the cell and is sensed by
the detector when the cell contains zero air. It is assumed that
all conditions of the system, except for the contents of the
absorption cell, are identical during measurement of I and I,. The
quantities defined above are related by the Beer-Lambert absorption
iaw as presented next:
Transmittance = $ = e - (ALC) ,
0
where,
A = absorption coefficient of 0, at 253.7 nm
(308.3 atm" cm-' at 0' C and 760 mm Hg)
C = 0, concentration in atmospheres
L = optical path length in cm
In practice, a stable 0, generator is used to produce 03
isconcentrat .ions over the reguired range. Each 0, concentration
determined from the measurement of the transmittance (I/I ) of the
samole at 253.7 nm with a photometer of path length L and
calculated from the equation:
(1)
1
Uatm) = ( rLIC Lnl
10
I’)
(2a)
or,
6
10
C(ppm) = (
xPLn*
IO
I "
(2b)
B-3

The calculated OS concentrations must be corrected for o3
losses which may occur in the photometer and for the temperature
and pressure of the sample. This procedure is applicable to the
calibration of ambient air 0, analyzers, either directly or by
means of a transfer standard certified by this procedure. Transfer
standards must meet the requirements and specifications set forth
in Reference 8, as provided in Appendix D.
A complete W calibration system consists of an ozone
generator, an appropriate source of zero air, and other components
as necessary. The configuration must provide a stable ozone
Concentration at the system output and allow the photometer to
accurately assay the output concentration to the precision
specified for the photometer.
Figure B-2 shows a commonly used configuration and serves to
illustrate the calibration procedure which follows. Other
configurations may require appropriate variations in the procedural
steps. All connections between components in the calibration
system downstream of the 0 generator should be of glass, Teflon,
or other relatively inerlz materials. Additional information
regarding the assembly of a W photometer calibrating apparatus is
given in Reference 9 (Appendix D).
For certification of transfer standards which provide their
own source of 0,, the transfer standard may replace the 0, generator
and possibly other components shown in Figure B-2 (refer Reference
8 of Appendix D).
The photometer consists of a low-pressure mercury discharge
lamp, (optional) collimation optics, an absorption cell, a
detector, and signal-processing electronics, as illustrated in
Figure B-2. It must be capable of measuring the transmittance,
I/I at a wavelength of 253.7 nm with sufficient precision that the
stakdard deviation of the concentration measurements does not
exceed 0.005 ppm or 3% of the concentration.
Because the low-pressure mercury lamp radiates at several
wavelengths, the photometer must incorporate suitable means to
ensure that no O, is generated in the cell by the lamp, and that at
least 99.5% of the radiation sensed by the detector is 253.7 nm
radiation. (This can be readily achieved by prudent Selection of
optical filter and detector response characteristics). The length
of the light path through the absorption cell must be known with an
accuracy of at least 99.5%. In addition, the cell and associated
plumbing must be designed to minimize loss of O, from contact with
cell walls and gas handling components. See Reference 9 in
Appendix D for additional information.
Air Flow controllers: Devices capable of regulating air flows
as necessary to meet the output stability
and photometer precision requirements.
Ozone Generator: Device capable of generating stable levels of
0, over the required concentration range.
B-4

Outout manifold: The output manifold should be constructed of
glass, Teflon, or other relatively inert
material, and should be of sufficient diameter
to ensure a negligible pressure drop at the
photometer connection and other output ports.
The system must have a vent designed to insure
atmospheric pressure in the manifold and to
prevent ambient air from entering the
manifold.
Two-wav valve: Manual or automatic valve, or other means to switch
the photometer flow between zero air and the 0,
concentration.
Temoerature indicator: Accurate to +l" C.
Barometer or pressure indicator: Accurate to 22 torr.
Zero air: The zero air must be free of contaminants which would
cause a detectable response from the 0, analyzer, and it
should be free of NO, C2H4, and other species which react
with 0,.
A procedure for generating suitable zero air is given in
Reference 9 (Appendix D). As shown in Figure B-2, the zero air
supplied to the photometer cell for the I, reference measurement
must be derived from the same source as zero air used for
generation of the ozone concentration to be assayed (I
measurement). When using the photometer to certify a transfer
standard having its own source of ozone (Reference 8, Appendix D).
B-2.1 Procedure
General Operation: The calibration photometer must be
dedicated exclusively to use as calibration standard. It should
always be used with clean, filtered calibration gases, and never
used for ambient air samnlinq. Consideration should be given to
locating the calibration photometer in a clean laboratory where it
can be stationary, protected from physical shock, operated by a
responsible analyst, and used for a common standard for all field
calibrations via transfer standards.
Preparation: Proper operation of the photometer is of
critical importance to the accuracy of this procedure. The
following steps will help to verify the proper operation. The
steps are not necessarily required prior to each use of the
photometer. Upon initial operation of the photometer, these steps
should be carried out frequently, with all quantitative results or
indications recorded in a chronological record either in tabular
form or plotted on a graphical chart. As the performance and
stability record of the photometer is established, the frequency of
these steps may be reduced, consistent with the documented
stability of the photometer.
B-5

Instruction manual: Carry out all set-up and adjustment
procedures or checks as described in the operation or instruction
manual associated with the photometer.
System Check: Check the photometer system for integrity,
leaks, cleanliness, proper flow rates, etc. Service or replace
filters and zero air scrubbers or other consumable materials, as
necessary.
Linearity: Verify that the photometer manufacturer has
adequately established that the linearity error of the photometer
is less than 3%, or test the linearity by dilution as follows:
Generate and assay an 0, concentration near the upper range
limit of the system (0.5 or 1.0 ppm), then accurately dilute that
concentration with zero air and reassay it. Repeat at several
different dilution ratios. Compare the assay of the diluted
concentration divided by the dilution ratio, as follows:
E = ( *IL -*2/R
A.
) x 100% (3)
I
where,
E = linearity error, percent
Al = assay of the original concentration
A2 = assay of the undiluted concentration
R = dilution ratio (i.e., flow of original concentration
divided by the total flow).
The linearity error must be less than 5%. Since the accuracy
of the measured flowrates will affect the linearity error as
measured this way I the test is not necessarily conclusive.
Additional information on verifying linearity is contained in
Reference 9, Appendix D.
Intercomnarison: When possible, the photometer should be
occasionally intercompared, either directly or via transfer
standards, with calibration photometers used by other agencies or
laboratories.
Ozone losses: Some portion of the O3 may be lost upon contact
with the photometer cell walls and gas handling components. The
magnitude of this loss must be determined and used to correct the
calculated 0, concentration. This loss must not exceed 5%. Some
guidelines for quantitatively determining this loss are discussed
in Reference 9, Appendix D.
B.2.2 Assay of 0, Concentrations
1. Allow the photometer to warm up and stabilize.
2. Verify that the flowrate through the photometer absorption
cell, F, allows the cell to be flushed in a reasonably short
period of time (2 liter/min is a typical flow). The precision
of the measurements is inversely related to the time required
for flushing, since the photometer drift error increases with
time.
B-6

3.
4.
5.
6.
7.
8.
9.
10.
Ensure that the flowrate into the output manifold is at least
1 liter/min greater than the flowrate required by the
photometer and any other flow demand connected to the
manifold.
Ensure that the flowrate of zero air, F, is at least 1
liter/min greater than the flowrate required by the
photometer. ,* .
With zero air flowing in the output manifold, actuate the two-
way valve to allow the photometer to sample first the manifold
zero air, then F. The two photometer readings must be equal
(1 = IJ.
NOTE
In some commercially available photometers, such as the
Dasibi Model 1008-PC, the operation of the two-way valve
and various other operations are carried out
automatically by the photometer.
Adjust the 0, generator to produce an 0, concentration as
needed.
Actuate the two-way valve to allow the photometer to sample
the ozone concentration until the absorption cell is
thoroughly flushed and record the stable measured value of I,,.
Actuate the two-way valve to allow the photometer to sample
the ozone concentration until the absorption cell is
thoroughly flushed and record the stable measured value of I.
Record the temperature and pressure of the sample in the
photometer absorption cell. (See Reference 9 for guidance).
Calculate the 0, concentration from Equation (B-l). An
average of several determinations will provide better
precision.
fi
where:
(03LdJT
10-i 7 6 0 x T
('3'OUT= (ALPD x 273.15
IO
'(tncI' )
= 0, concentration, ppm
(B-1)
A = absorption coefficient of 0, at 253.7 4nm
(308.3 atm-' cm-' at 0' C and 760 mm Hg)
L = optical path length, cm
T = sample temperature, O K
P = sample pressure, mm Hg
D = correction factor for 0, losses = (1 - fraction 0,
lost).
B-7

NOTE
Some commercial photometers, such as DasibiModel1008-PC
automatically evaluate Equation (B-l), except for D. It
is the operator's responsibility to verify that the
information required for Equation (B-l) is obtained,
either automatically by the photometer or manually. For
llautomatic" photometers which evaluate the logarithmic
term of Equation (B-l) based on a linear approximation,
a manual correction may be required, particularly at
higher 0, levels. See the photometer instruction manual
and Reference 9, Appendix D for guidance.
11. Obtain additional 0, concentration standards as necessary by
repeating steps 6 to 10.
Certification of transfer standards: A transfer is certified
by relating the output of the transfer standard to one or more
ozone standards as determined according to Section B.2.2. The
exact procedure varies depending on the nature and design of the
transfer standard. Consult Reference 8, Appendix D for guidance.
B.2.3 Calibration of the Analyzer
Models 1008-AH, -PC, -RS are calibrated using ozone standards
obtained directly according to Section B.2.2 or by means of a
certified transfer standard.
1. Analyzer's controls (refer to Figure 5-1)
i:
POWER Switch (1) - ON
MODE SELECTOR Switch (4) - OPERATE position
2
T/P Switch(s) - OFF
VALVE Switch (6) - OFF
e. PUMP Switch (7) - OFF
Allow sufficient time (20-30 minutes) for the 0, analyzer and
the photometer or transfer standard to warm-up and stabilize.
Connect the analyzer inlet port to the manifold of your
calibration system (see Figure B-3) via l/4 Teflon tubing.
2. Offset the analyzer to +9 ppb in order to observe negative
readings. This can be done via the right hand side thumbwheel
switch on the D/A board (see Figure 3-12). Observe the
readings on the display for 3-5 minutes. The average reading
should be 9 ppb + l-2 ppb. This verifies that the optical-
electronic system is working well; we call this "no flow
zero". Turn on the valve and the pump (see Figure 5-l),
adjust the flow meter to 2 l/min, and allow the analyzer to
sample zero air until a stable response is obtained on the
recorder. Record the stable zero air response as IIZ1'.
B-8

3.
4.
5.
6.
7.
Generate an 0, concentration standard of approximately 80% of
the desired upper range limit (URL) of the 0, analyzer (400 or
800 ppb). Allow the 0 analyzer to sample this O3 concentration
standard until a sta i3le response is obtained on recorder.
Adjust the 0, analyzer's span control (see No. 2, Figure 5-1)
to obtain a recorder response as indicated in the following
equation:
Recorder Response (% Scale) = (
"3'OUT
URL
x 100%) + 2
where,
URL = upper range limit of the 0, analyzer, ppm
z = recorder response with zero air, percent scale. Record
the 0, concentration and the corresponding analyzer
response. If substantial adjustment of the span control
is necessary, recheck the zero and span adjustments by
repeating steps 2 to 4.
Generate several other 0, concentration standards (at least 5
others are recommended) over the scale range of the O3
analyzer by adjusting the 0, source. For each concentration
standard, record the 0, and the corresponding analyzer
response.
Plot the 0, analyzer responses versus the corresponding 0,
concentrations and draw the 0, analyzer's calibration curve or
calculate the appropriate response factor (see Figures B-3 and
B-4).
The various C+ concentrations required in step 5 may be
obtained by dilution of the 0, concentrations generated in
steps 3 and 5. With this option, accurate flow measurements
are required. The dynamic calibration system may be modified
as shown as Figure B-3 to allow for dilution air to be metered
downstream of the 0, generator. A mixing chamber between the
0 generator and the output manifold is also required. The
ffowrate through the 0, generator (F,) and the dilution air
flowrate (F,) are measured with a reliable flow or volume
standard traceable to NBS. Each 0, concentration generated by
dilution is calculated from:
('3' OUT = '"2 OUTX (F
fO
0
+ F,'
where,
q)fJuT = diluted concentration, ppm
F, = flowrate through the 0 generator,
F, = diluent air flowrate, I/
l/min
min.
B-9

DASIBI ENVIRONMENTALCORP.
.
Figure B-l Ozone Generator and Photometer System Schematic
B-10

fO
OUTPUT
amMANIFOLD
I’
fLcwOa-VENT
CONTROLLERGENERATOR
*.
ZERO
AIR
I
-u-
EXTRAOUTLETSCAPPED
WHENNOTINUSE
ct
I
10INLETOFANALYZER
UNDERCALIBRATION
FLOWTWO.WAY
CONTROLLERVALVE
VENT
UVP~~OTOMETERII
------------------------I--------------
r-
1
DETECTOR
52SIGNAL
PROCESSING
ELECTRONICS
IFD-
jFLOWMETER121COELER
III
-F--EXHAUST/
I
i
L------------------------1-------------I

DASIBI ENVIRONEENTAL CORP. TM901101
500
400
300
>
E
.
3
200
100
0 (
PPM =
DM - 1.1333----------m-e
1000.7619
, ,
0.10 0.20 0.30 0.40 0.50
OZONE, PPM
Figure B-3 Typical Calibration Curve, 0 - 0.5 ppm Range
B-12

DASIBIENVIRONMENTALCORP. TM901101
1000
8 0 0
6 0 0
4 0 0
2 0 0
0
OZONE, PPM
Figure B-4 Typical Calibration Curve, 0 - 1.0 ppm Range
B-13

APPENDIX C
MANUAL UPDATE INFORMATION
TM920805
C-l

c.1 RIN Tester Description
This assembly is stored on a connector that is located near
the bottom of the electrometer adapter board (refer to Figure 3-
4al). Its purpose is to aid in troubleshooting a noisy photometer
after the noise has been determined not to be in the optics.
This tool functionally separates the lamp/lamp drive circuit
from the electrometer section. Therefore, if the analyzer remains
noisy using the RIN tester, the problem can be traced to the
electrometer/logic circuitry. On the other hand, if the noise
disappears (which is usually the case), then the lamp/lamp drive
circuitry should be checked.
NOTE
Certain kinds of dirt (such as lint)
in the optics can cause noise even
with the pump and valve turned off.
Therefore, we recommend thoroughly
cleaning the optics section before
using the RIN tester.
c.1.2 RIN Tester Check
If the analyzer is exhibiting noise levels outside the
specified parameters, first clean the optics section (see Section
6.7). If the noise persists after performing this procedure, turn
off the power to the analyzer and unplug the detector assembly from
the sample channel electrometer.
. .
However, if your unit also contains a control detector
assembly (a specified option), then a determination of which
electrometer is most likely at fault, must be made first. This can
be accomplished by switching the front panel mode switch to "SAMP
FREQ" for a few minutes and recording the values indicated on the
front panel. Next, switch to the "CONT FREQ" mode for a few
minutes and record these values. If one frequency is substantially
more unstable than the other, then that channel's electrometer
becomes the suspected f@faulty" electrometer and its detector
assembly would be disconnected. If not, then start out by
disconnecting the sample electrometer detector.
After the detector assembly has been disconnected, unplug the
RIN tester from its holder on the adapter board and install it in
place of the removed detector assembly. Apply power to the
analyzer, turn the front panel switch to the appropriate frequency
mode and adjust the potentiometer on the RIN tester until the
desired frequency is obtained.
If the noise persists, this indicates that a check of the
electrometer/logic circuitry should be made. If the noise
disappears, then check the lamp/lamp drive circuitry
c-2

NOTE
The RIN tester is, by nature,
slightly more noisy than the
lamp/detector combination when they
are functioning properly. Thus, the
noise level observed when the RIN
tester is in place is not
necessarily a completely accurate
indication- of the
noise level.
c.2 Flow Restrictor Option
The end user has the option
restrictor to stabilize the flow
electrometer's
of requesting use of a flow
through the photometer. The
outlet of the photometer flowrestrictor would be located at the
meter. The restrictor in this instrument is designed to provide
approximately 2 liters per minute through the photometer. The use
of different pumps with time may vary this exact flow, but as long
as the flow rate falls between 1.5 LPM and 3.5 LPM, there will be
no problems.
The end user should be cautioned that use of such a flow
restrictor requires periodic maintenance to prevent "clogging".
Such an occurrence will result in too low of a flow rate if proper
maintenance is not performed. Dasibi recommends the use of the
particulate filter holder that comes standard on the unit's sample
port. This will reduce the amount of particulate matter flowing
through the instrument. Dasibi also recommends cleaning the
restrictor whenever cleaning of the optics bench absorption tubes
occurs.
To do this, simply pull the tygon tubing off of the flow
restrictor, and unscrew the nut holding the restrictor. Once
freed, run a piece of wire through the restrictor to loosen any
matter that may have collected. Then reverse the process to
replace the restictor. Make sure you perform a leak check every
time this is performed.
c.3 Rapid Response Software Option
The unit may be fitted with a special E-Prom containing
software that does not perform any averaging. This increases the
response time of the unit from 50 seconds to 20 seconds. The unit,
however, would be quality-controlled to insure the noise level of
the unit would still be well within Dasibi specifications.
c.4 CPU/Memory Board (Figures C-l and C-2)
The CPU/Memory Board consists of four (4) main sections, the
Central Processing Unit (CPU), the Counter/Timer Circuit, the
Memory, and the Watchdog Timer circuitry. Each of these sections
is described next.
c-3

The Central Processing Unit (CPU) is a 280A, running at 1.0
MHZ. It controls the operation of the entire instrument including
reading the switch settings, controlling the valve, reading the
temperature, pressure and light sensors, computing the
concentration, and outputing the results.
The Counter/Timer Circuit (CTC), is used for all non-critical
timing in the system. These include flush time, "count up" time,
and time between successive measurements. After the preset time
expires, the CTC generates an interrupt, signaling the CPU to
proceed with the next operation(s).
The Memory, consists of 8K Bytes of EPROM and 2K Bytes of RAM.
The program is stored in ROM, along with all constants required for
the calculations and unit conversions. The RAM is used to store
sensor readings, and intermediate results during calculations.
The Watchdog Timer is designed to expire and reset the unit.
In normal operation, the CPU repeatedly restarts the timer,
preventing it from expiring and resetting the CPU. If an error
occurs that causes the CPU to become stuck, the Watchdog timer will
expire, resetting the unit. In the ttSPANtt mode, the CPU does not
restart this.timer, allowing verification of the watchdog timer and
reset circuitry.
c.5 Optional RS232 Board (Figures C-5, C-6 & C-16)
The optional RS232 Board allows the communication between a
1008 ozone analyzer and an external computer, terminal, or
datalogger. This board contains all the circuitry required to
provide a Full-Duplex interface and is intended to be used to
display and/or capture ozone measurements, as well as provide
internal diagnostic information from the analyzer.
Because of the vast amount of confusion about RS232 interface,
Dasibi would like to present a brief overview on the subject. Put
simply, RS232 is an interface specification that defines signal
voltage levels, signal slew rates, line capacitance and so forth.
It is extremely important not to spell out exactly what the RS232
standard does specify, but rather what it does not specify. The
RS232 specification does not stipulate how many signals are
required, nor what signals are to appear on what lines (i.e. the
simplest RS232 interface could contain as few as 2 wires, one for
the signal and one for ground).
With RS232, one can only transmit about 50 feet on the best
coax and remain within the specifications due to the line
capacitance. But since communications are taking place daily over
vastly greater distances, some of what RS232 does provide, may be
misunderstood by some end users. Since every different
manufacturer has had a different version of what RS232 consists of,
or which signals other than Txd, Rxd, and Gnd, should appear on
what signal lines (Pin Numbers), Dasibi has opted to comply with
the most standard RS23 2 interface in existence today; that of the
IBM AT personal computer.
c-4

The 1008 monitor is pin-to-pin compatible with the IBM AT 9-
pin interface; there is no need to switch any wires at all,
including Rxd & Txd (simply connect Pin 1 to Pin 1, Pin 2 to Pin 2,
etc.). There are only 2 signals, (i.e. 3 wires), that are
W'requiredtl to interface to the 1008 monitor (it is conceivable that
one could skip the signal line Rxd, Pin 2, if satisfied with half-
duplex operation). The required wires are Pins 2, 3, and 5. The
addition of any extra signals/wires provides no benefit to the end
user and Dasibi recommends not using them unless the configuration
and/or software requires them. The following list defines the
Dasibi-to-IBM g-pin interface:
Dasibi Sisnal Name: $Pin
No Connection - l-
TxD Transmitted Data - 2 -
RxD Received Data - 3 -
DSR Data Set Ready - 4 -
Signal Ground - 5 -
DCD Data Carrier Detect - 6 -
CTS Clear To Send - 7 -
RTS Request To Send - 8 -
No Connection - 9 -
IBM AT Sisnal Name:
Received Line Signal Detect
RxD Received Data
TxD Transmitted Data
DTR Data Terminal Ready
Signal Ground /
DSR Data Set Ready
RTS Request To Send
CTS Clear To Send
Ring Indicator
NOTE
Both 1008 input pins numbers 7 and 4 have pull-up
resistors on them so the operator can leave them
floating. If not used, the 1008 monitor will stop
transmitting when either of them becomes false. If one
of them is held in the false state for any appreciable
time, the 1008 monitor will skip transmission of that
data packet and resume data transmission on the next
update that both lines are free.
If a 25 pin connector is going to be used, the following table
lists the most common 9-pin-to-25-pin adapter wiring:
9pin 1 8 DCD 25pin
2 3 RxD
3 2 TxD
4 20 DTR
5 7 Gnd
6 6 DSR
7 4 RTS
8 5 CTS
9 22
The RS232 section of this board (there are other features
available on this multi-functional board) consists of a 2.5 Mhz
crystal oscillator for generation of the baud rate, a serial I/O
unit (USART) for communicating with the CPU, and level shifters for
converting the TTL level signals into the RS232 levels.
c-5

To avoid affecting the ozone monitor's main task (that of
measuring ozone), the board is used in a polled fashion, where the
CPU periodically checks the port for input (which may cause a
slight delay in responding to keyboard inputs). The set up for the
RS232 is as follows:
Data Bits
Parity
Stop Bits
Baud Rate
7 bits - ASCII format
None
1
9600
The Baud Rate is set to 9600 bps, 7 data bits, no parity, 1
stop bit. The unit will probably work, however, with either even
or odd parity, and 1.5 or 2 stop bits depending on the software the
computer uses. The 1008 powers-up in the log mode. Typing a llD'@
(either upper or lower case), will put the unit into the
"diagnostic display mode". Typing any other key will return the
unit-to the log-mode. Only 2 of
(plus ground). These are Rxd and
The computers line labeled
The computers line labeled
Signal Gnd is wired to pin
the RS232 signals are mandatory
Txd:
llRxdlfi is wired to pin 2
llTxdll is wired to pin 3
5
The commands available via RS232 are as follows:
F Turns off RS232 display.
D Full system display as shown next:
Dasibi 1008 Ozone Monitor
009 ppm
FAULT: 0 MODE: 5 SPAN: 308
OFFSET:+gPPB
TEMP: 31.7 C
PRESS: 0.979 ATM
CONT FREQ: 500000 Hz
SAMP FREQ: 480000 Hz
Typing any other key produces the "Log Mode". This mode
displays the front panel readings and the error code if it is not
zero (no error). For example:
13.567 ppm 02
-1.678 ppm 02
0.008 ppm 07
0.009 ppm
0.008 ppm
C-6

The following are the error codes currently implemented. The
column labeled CPU refers to the error code(s) found on the
CPU/Memory Board error display which are described in Section
C.16.1.
CPU RS232
0 00
1 01
2 02
04
08
10
20
40
80
No Fault
Not currently used.
Sample frequency is above 481,250 Hz less than
300,000 Hz.
Control frequency is less than 300,000 Hz.
CPU Reset occurrence.
Not currently used.
Not currently used.
Heater Voltage below 4.10 Vdc.
User error - either the front panel mode
switch is not in the operate position, or the
T/P switch is in the off position.
In the case of a single error, the value in the table above
will be displayed. In the case of multiple errors, the lllowest'l
error will be displayed on the CPU/Memory Board's display (since
the lower the number, the more significant the error), and the
'Isurn" of the errors will be displayed in hexadecimal format in the
RS232 data. For example, the sum of the errors 2, 3, and 7 will
result in a Hexadecimal display of " 4 6 " . The calculated
concentration will be displayed though, even if errors are present.
C.6 Internal Timer (Optional)
An internal timer may be procured for the instrument to allow
automatic zero or span functions. Once the selected time is
achieved on the internal clock, the unit will automatically allow
itself to sample zero air, and then generate ozone for an internal
span check for a user-selectable duration.
The internal timer on the angle plate of the U.V. photometer.
To set the time, or adjust for changes in time due to daylight
savings, follow these procedures:
1) Open the hinged touch sensor door. Before setting, or
whenever the timer is without power for more than one
minute, the clock display will show 12:00 a.m..
2) Slide the function switch to the "SET CLOCK" position.
3) Press the IIHRS" button until the display shows the
carrect hour. Push and hold the button for rapid
advance. Make sure that the AM/PM indicator on the
display is correct.
4) Press llMINll button until the display shows the proper
minutes.
c-7

5; 'Wl-.;Y. you have t?le currer'L corre,.;. time, press the "ENTER"
1'lt-t~~ to begin !:,.me k.+!@i"g. The displ dy should blink
CJ!lCL, when the "EWER': button is pushed.
To set the program for internal automatic zero and span,
follow theqe steps:
2)
3)
4)
5)
6)
Slide the function switch to the "Program" position. The
number 0.001 should appear on the display.
Push the "Event" button until the number "1" appears
tibcx, r? - Jvent O:I Lild display.
Push the on/off button until the arrow at the right side
of the display points to the "ON" setting.
Push the "HRS" button until the hour you want the event
to happen appears. Make sure that the AM/PM indicator on
the left side of the display shows the correct setting.
Push the "MIN" button until the exact time you want the
event to occur appears.
Push the "ENTER" button to store the event you have just
programmed in the Timer's memory.
Slide the function switch to one of the "AUTOMATIC
FIXED".
Now, the duration of the zero and span must be set on the two
potentiometers on the RS232 Board the board furthest back on the
Mother Board Bus directly behind the Electrometer Board
configuration. To do this follow these steps:
1) Locate the *'zero" potentiometer on the RS232 Board.
Looking at the front of the board, it is the
potentiometer on the left.
2) The time must be set according to the "blinking"
frequency of the LED located to the left of the
potentiometer. This LED is set to blink l/128 of the
duration of the zeroing event. Thus, to find out how
long the zero will last, use the following formula:
LED Frequency = X min * 60(seconds) / 128
Thus, if the LE3 blinks a:-C'it once every 7 seconds, then
the zero check will iast for approximately 15 minutes.
To increase the zer? duration, turn the potentiometer
clockwise, to decrease the time, turn it counter-
clockwise.
C-8

4) To set the span duration, simply follow step number two
for the right side potentiometer.
REMOTE ELECTRICAL INSTALLATION NOTES:
When installing a Model 1008 with internal timer, the user
must be sure not to hook up more than one timing.device. In other
words, if the internal timer is to used, do not hook up an external
datalogger to perform remote zero and span functions.
All connections should be made at the rear panel, which
contains a terminal block with several screws for different
functions. For connections involving external dataloggers, use of
the three right-hand side screws (looking at the terminal block) is
necessary. To activate a function, simply "closeI' the contact
between the +5V screw and the desired function (szerl' for zero
check and IIcallU for span check).
NOTE
The contact closure should be
q*floatingll in relationship to the
other equipment's power.
If the internal timer is to be used for. the automatic
zero/span checks, then the connection should be made between the
"Z" on the terminal block and the IIzerlU and between the lfiCIU and the
U'cal@l . There should be no connections to the +5V.
TUBING CONNECTIONS FOR INSTALLATION:
On the back panel, there are two nylon fittings. These should
be exhausted safely. One kynar outlet port labelled "vent" is for
the connection between the unit to be calibrated and the
calibrator. The "zero" inlet port should be connected to an
appropriate zero air source.
c.7 Optics Cleaning Rod Assembly
A maintenance tool has been added to the standard 1008 unit to
aid in the cleaning of absorption tubes in the optics cell for
prevention of particulate matter build up. This tool is
particularly helpful in the field where teflon tubing (which can
also be used) may not be available.
The cleaning rod assembly components are clipped to the angle
of the optics bench. The first rod on top of the other, includes
a tip with a hole in the middle of it. This hole is provided for
a Kim Wipe (or other such material) to be run through the tubes for
dislodging all particulate matter. The bottom rod is provided to
connect to the end of the top rod in order to create a length long
enough to easily pass through the absorption tubes.
c-9

To use, simply disconnect both rods, screw the bottom rod into
the top rod, slide a Kim Wipe into the tip of the top rod and push
it through the absorption tubes. Reverse these instructions when
the cleaning is completed.
C-8 Dual Ozone Output Option For Model 1008-RS (Figure C-4)
This option allows the unit to create two levels of ozone upon
remote or manual command (referred to as "precision" for the lower
ozone output and "span" for the higher level). This. option
requires additional components on the Ozone Generator Board and
special labels on the back panel terminal block.
To activate any desired function from the back panel while in
the remote mode, short between the screw labeled %+5v" and
desired function. The two different levels of ozone generated
determined by the voltage divider combination of either the
labeled R16 or the pot labeled R17 on the Ozone Generator Board
the digital front panel pot.
When the screws labeled "+5v" and "PRE" (precision)
the
are
Pot
and
are
shorted between them, pot R17 is switched into the circuit by a
relay regardless of the status of any of the other controls
(including the remote/local switch on the front panel). When this
short is removed, pot R16 is switched into the circuit: again,
regardless of the status of any of the other controls.
To actually generate ozone in the remote mode, however, you
must also short between "+Sv" and ttZEROft to activate the pump and
valve, and also short between "+5v" and ItSPANng to enable the lamp.
With both of these terminals activated, you then select either the
ntSPAN1t or IvPREtt concentration by the status of the "PRE" terminal.
In the local mode, the "PRE" terminal functions the same way
as in the remote mode. The "SPAN" and the "ZERO" terminals,
however, are now replaced by the front panel toggle switches.
c.9 l/16" Allen Wrenches
Dasibi is in the process of adding a l/16" allen wrench into
the Model 1008 unit as a tool to aid in standard unit maintenance
procedures. The wrench would be housed inside of the optic bench's
detector block in a slot, covered by a screw.
The tool can be removed by simply loosening the screw so that
the head of the wrench is loosened, and pulling the wrench out.
This wrench is used primarily for tightening, or loosening, the set
screws in the detector block for the sample detector (and/or
control detector, if present in the analyzer - it is also used for
adjusting the control detector's aperture in cases where the
control detector is being saturated by too much light hitting its
surface). The wrench can be used for the removal of the front
panel function switch's knob (required when removing the function
switch for servicing).
c-10

c. 10 On-Board Zero Air Filter For Models 1008-RS, PC & HC
The Models 1008-RS, 1008-PC & 1008-HC can be purchased with an
on-board zero air filter assembly to allow automatic self-zero
checks for the RS's, on-board zero air capabilities for use in the
ozone generating sub-section of the Model 1008-PC and for the
reference measurement air flow for the Model 1008-HC. This
assembly (Z-0109-E) contains approximately .3 lbs of activated
charcoal and should last for between 12-20 hours of use. The life
of this charcoal can be maximized by setting the flow rate used
through the azone generator to 3.5 LPM, as this is the minimum flow
rate required.
c-11 "KNF" 5-Liter Pumps Replace "ASF" Pumps
For many years, Dasibi Environmental has utilized 5-liter
pumps manufactured by a company called "ASF". In an effort to
increase the quality of the 5-liter pumps utilized in the "PC" or
"RS" versions of the 1008 ozone analyzers, a switch has been made _
to pumps manufactured by a company called "KNF".
One side effect of this change has been the required use of a
charcoal filter up-stream of the internal ozone generator. In all
new units sold utilizing the KNF 5-liter pump, this charcoal filter
is located at the outlet port of the ozone generator's flowmeter.
All 5-liter KNF pumps purchased as replacement pumps will be
shipped with these charcoal filters. The charcoal filter may or
may not require replacement whenever a pump is replaced, though.
The life expectancy of the charcoal filter will be dependent upon
the characteristics of the zero air flowing through it. If the
zero air contains pollutants (such as NO, or SO,), then the filter
will become consumed much faster. If pure zero air is utilized
through the ozone generating subsystem, then the filter could
conceivably last forever.
To replace a charcoal filter already installed, simply loosen
and disconnect the nut located on the outlet side of the filter and
which extends from the tubing attached to the inlet port of the
ozone generator. Pull the filter free and install a new one. Once
the connection of the tubing is made, perform a leak check.
c-12 Pyrex Optics Tubes Changed to Stainless Steel Tubes
Dasibi is in the process of switching from the use of Pyrex
"absorption" tubes in the optics cell to stainless steel tubes in
Models 1008-AH, PC and RS. These new tubes are completely
retrofittable into any older 1008 analyzer without any
modifications necessary. The new tubes are stock number Z-0378-A
for each assembly (two per optics cell). The optics tube cleaning
procedure described within this manual remains exactly the same and
cleaning should be performed as regularly as with the Pyrex tubes.
c-11

c.13 Dual Analog Output Option (Figure C-3)
There is an option available for the Model 1008 in which a
second analog output range is added to the unit. The option
consists of adding another potentiometer to the front panel,
additional wiring to the terminal strip located on the back panel
and slight modifications to the unit's D/A Board (refer to Figure
C-3). Standard unit analog output is 1 volt; if the requested
range(s) are different, the front panel potentiometers will be
marked accordingly, as will the back panel terminal strip.
c.14 Changing the Unit's Analog Output Range
The analog output range of the 1008 can be modified very
easily. Simply change resistor R14 on the unit's D/A Board to
establish any of the following ranges:
Ranse R14 Resistor Value Dasibi Stock # For Resistor
1 PPM = .1 V 510 ohm A-0059
1 PPM = .5 V 3 K A-0410
1 PPM = 1.0 V 5.5 K D-0015
1 PPM = 2.0 V 10 K A-0010
1 PPM = 5.0 V 27 K A-0012
1 PPM = 10.0 V 50 K A-0005
c.15 New "Latching " Photometer Valve (Figs.C-7, 8, 9, 10 & 11)
Dasibi has changed the type of valve used in conjunction with
the U.V. photometer in the 1008 series (but not the "remote" valve
used in the Model 1008-RS) to a "latching" valve as opposed to the
"energized/de-energized" (on/off) valve used since the introduction
of the 1008 series. What is meant by "latching" is that the valve
receives a "momentary" electrical pulse to change state. Once
toggled into the appropriate state, the electrical signal is
removed and the valve then stays in that state (rather than being
either on or off depending on whether voltage is applied).
Therefore the terms "on" and "Off" no longer have any
relevance when discussing the state of this valve. Instead,
reference will now be made to either "Sample" or "Reference"
pulses. After receiving one of these pulses, the valve will then
be in a position that allows that particular gas to enter the
optics bench. Thus, after receiving a "Sample Pulse", the valve
will be in such a state that the sample gas will be fed directly
into the optics cell (without going through the scrubber first):
obviously, the "Reference Pulse" is when the valve diverts the air
flow through the scrubber before it enters the optics cell.
This modification does not affect the principles/theory of
operation in any way. It simply takes advantage of new '*state-of-
the-art" components that have only recently been introduced to the
market. The benefits of this new valve are two-fold:
c-12

1)
2)
First, and perhaps foremost, this new valve totally eliminates
the "magnetic offset" present in use of the previous valve
design. Since there is absolutely no magnetic field present
when the monitor performs either its sample or reference
frequency measurements, there will be absolutely no difference
between those frequency measurements resulting from the
magnetic field of the valve. Thus, the laborious task of
rotating the lamp and/or detector(s) to find their l'nulllfi
points is no longer necessary.
Secondly, the design of this new valve is such, that the
restriction to air flow is dramatically reduced over that of
the previous design to the point where, at 2 LPM, it is
virtually non-existent. What this means is that the user can
now rebuild/recondition the valve without the need to spend
hours of time l'balancingll the port restrictions, nor the need
for expensive flow test equipment used to perform such tasks.
The only expendable/replaceable part of this valve, is the
Viton diaphragm. To repair this valve, it is not necessary to
remove the entire valve body from the instrument. Simply remove
the top four screws holding the solenoid to the valve body and lift
the solenoid off. Then either clean the body and/or replace the
Viton diaphragm and replace the solenoid. (To clean the valve,
however, it is very advantageous to remove the body).
For cleaning, first remove the solenoid as described above and
then clean it using a small nylon bottle brush and isopropyl alco-
hol. After re-assembly, run the valve on about 800 ppb of ozone
for about two hours to cleanse any residual alcohol and/or other
substances.
Due to the change in operation of this valve, a design change
has had to be made to certain circuitry inside the unit. Used in
conjunction with this new valve, is a "Valve/Regulator Board".
This board is attached to the side of the optics cell (directly
beneath the optics cleaning tools) and serves two functions:
1) The new valve plugs directly into this board instead of
plugging into the Mother Board.
2) The regulators that used to be mounted on the unit's LDHC
Board are now mounted on this board. The reason for this
modification is that this moves the regulators (which need to
be l@cooledlt) closer to the air flow of the instrument. The
result is increased stability of the regulators, which in
turn, increases the stability of the lamp output, which in
turn increases the stability of the unit itself.
The diagram and schematics for the Valve/Regulator Board are
provided at the end of this section. Since the regulators have
been detached from the LDHC Board, this board has been essentially
tlstripped-downlt. In place of the regulators is a wiring connection
c-13

that extends from the LDHC to the Valve/Regulator Board. A diagram
and schematic for the stripped-down version of the LDHC Board is
also provided at the end of this section.
C.16 New Features of the CPU/Memory Board
One of the primary reasons for the introduction of the
CPU/Memory Board was to increase the memory space of the 1008
series of analyzer in order to allow new software features to be
added to the instrument. These additions will occur over
throughout the year of 1993 and will be carried in Appendix B until
the next version of the 1008 manual is written.
The following sections will describe the first three new
features added to the CPU/Memory Board since its inception.
C.16.1 "Diagnostic LED":
There is a single LED on top of the board, which will display
a number continuously, depending upon the operational status of the
unit, as well as the importance of the fault. If, for instance,
two faults are present in the unit, only the more important of the
two will be displayed. The lower the number, the higher the
importance of the fault. Descriptions of the fault numbers that
can be displayed are provided here:
0 =
1 =
2 =
3 =
4 =
5 =
6 =
7 =
8 ZZ
No faults.
Not used yet.
Sample Frequency is not above 300 Khz, or is not
below 480 Khz.
Control Frequency is not above 300 Khz, or is not
below 480 Khz.
Lamp heater voltage is incorrect.
Not used yet.
Not used yet.
CPU reset occurrence.
Displayed whenever any front panel switch not in
the correct position for proper operation.
These fault displays can be very useful in determining the
cause of problems that may occur in the unit. They are not
designed to diagnose the problem completely, but rather, save the
end user time and effort in determining the tlpossiblell causes. The
fault numbers not currently being utilized should be available by
the end of 1993.
C.16.2 "Selectable Averaging Switch":
This switch is mounted next to the LED display and allows the
end user to change the number of readings being averaged every
cycle. Currently, there are only two possible averaging
possibilities:
c-14

0 = No averaging occurs; the cycle time of the
instrument is 20 seconds.
1-9 = Averaging of five consecutive readings occurs; the
cycle time of the instrument is 50 seconds.
a
C.16.3 "Mode SwitchI':
This switch is mounted below the LED displ'iy and allows the
end user to change the output range of the display. Currently,
there are only six mode possibilities:
0 = Parts Per Billion (PPB)
1 = mg/m3
2 = % Weight in Oxygen Stream (For Model
3 = % Weight in Air Stream (For Model 1008-Hc
1008-HC only)
2 only)
4 = Parts-Per Ten-Thousand (For Model 1008-HC only)
5 = g/m3 (For Model 1008-HC only)
C.17 DasibiNet Interface (Figures C-12, C-13, C-14 & C-15)
Dasibi has introduced a new concept for use in its Ambient Air
Monitoring System, Model 1000. It is called "DasibiNet" and it
essentially allows the end user to obtain valuable diagnostic
information from each of the system's internally-mounted air
monitoring instruments. Since the Model 1008-AH is the unit that
provides ozone measurements for the System 1000, it has had the
capability added to its list of available options.
DasibiNet is a multi-drop network in which diagnostic signals
from ~more than one Dasibi instrument may be lllinkedll together
utiliking just one telephone line: this line can then be attached
to a hodem for remote accessibility of a central computer system
(as opposed to having several telephone lines connected to a site
for such information).
bhis feature affects the configuration of the Model 1008-AH in
two WAYS. First of all, there is an additional P.C. Board attached
to the unit's back panel. This board, the Network Interface Board,
allows the 1008 to be linked to the single network line and
contains ltInll and ItOut" ports for connection of two telephone
jacks'. There is another P.C. Board located in the Mother Board Bus
where' the RS232 Board would usually be located. This board, the
DasibiNet Board, attaches to the Network Interface Board on the
back panel via cable connection. Diagram and schematics for these
boards are provided at the end of this section.
C.18 New Back Panel Design For Models 1008-PC & -PS (Fig.C-17)
Dasibi has re-designed the back panel for Models 1008-PC and
lOOS-PS. This new design allows use of a fan on the back panel for
either of these units in order to decrease internal instrument
temperature.
c-15

Before this re-design, the only air flow inside the monitor
was provided by a blower located on the side of the chassis next to
the ozone generator's pump. In order to increase air flow
throughout the interior of the unit (and consequently reduce the
temperature inside), it was determined that a fan mounted in the
same manner as on the other 1008 models, would be much more
efficient. This modification does not affect the functionality of
either models: it will only affect the location of the ports on the
back panel. A diagram of this new design is provide in Figure C-
17.
c.19 Error Code rt3ff Removed From Front Panel Display
The error code number W311 (which was a diagnostic code that
indicated whenever the sample frequency was below 400 Khz) has been
removed from the front panel display since this diagnostic code (as
well as several others) is now indicated by an LED located on the
unit's CPU/Memory Board (refer to Sections C.4 and C.16).
c.20 Special Application Note for Model 1008-PS
The unit purchased with this manual is referred to as the
"Model 1008-PS" in order to distinguish it from the from the Dasibi
transfer standard, referred to as the "Model 1008-PC1t. The front
panel is labelled 111008-PCtt for both units because end users many
times wish to re-configure a primary standard into a transfer
standard at a later date, or vice-versa; modification of one type
to another is performed by simply removing the zero air manifold
(or adding it), adding an internal ozone l'scrubberl' (or removing
it) and modifying the plumbing accordingly.
Purchasers of the Model 1008-PS will notice a 3' piece of l/4"
O.D. Teflon tubing provided in the plastic bag containing the
unit's manual. This tubing is provided to help balance the air
pressure of the sample inlet and zero reference inlet air streams.
Since primary standards utilize a customer-selected external zero
air source for the W1referencell half of the measurement cycle, a
pressure imbalance may occur in which a negative offset is created
in the unit. Consequently, Dasibi provides a piece of Teflon
tubing that will be connected to the l'Vent" port of the zero air
manifold to prevent this occurrence. Please follow the
instructions provided next:
1) After the unit has been checked-in and installed per the
instructions in Sections 1 & 2 in this manual, simply
connect the tubing to the llVentlt port of the zero air
manifold located on the unit's back panel by removing the
port's nut, sliding the tube through it and then re-
connecting the nut back onto the fitting.
2) Attach a flow meter with a range of up to at least 6 LPM
to the other end of this tubing.
C-16

3) Referring to the operational instructions provided in
Section 5 of this manual, operate the unit so that it is
sampling zero air.
4) Adjust the zero air supply until it provides a minimum of
3 LPM on the external flow meter whenever the
photometer's valve is providing the reference half of the
measurement cycle.
5) Remove the flow meter, but leave the tubing in place for
continued pressure balancing.
c-21 Design Modification to the Model 1008-HC
Dasibi has modified the design of the Model 1008-HC High
Concentration Ozone Analyzer in an effort to increase the longevity
of several components utilized inside this 1008 configuration. The
longevity of such components has been affected by the continual
stream of high concentrations of ozone flowing through the
instrument. The design modifications are described next:
Addition of Ozone Scrubber Filter:
An 0
insta led1
scrubber filter assembly has been
directly downstream of the optics
cell. This filter has been added to remove
most of the 0, in the air stream as it exists
the measurement cell in order to protect the
components located downstream of the cell.
The materials contained inside of the assembly
(Dasibi "ozone scrubber refill" stock number
S-0134A-B) should be replaced periodically;
how often will depend upon the flow rate, the
frequency of analyzer usage and the level of 0,
flowing through it. Dasibi recommends
replacing it every 300 hours of use until such
time as an average replacement time period can
be determined by the end user. Figure C-18
shows how the assembly is constructed.
Addition of Mounting Plate For Pressure Sensor:
A mounting plate has been installed into the
Model 1008-HC in order to locate it closer to
the outlet of the charcoal filter assembly.
This sensor was previously located upstream of
the optics cell and was exposed to the high
concentrations of ozone flowing through the
instrument. BY locating it directly
downstream of the charcoal filter outlet port,
the sensor's measurements are still accurate,
while being protected from the harsh air flow.
c-17

Addition of Back Panel Fan:
A fan has been added to the Model 1008-HC's
back panel in order to improve air circulation
inside of the unit. This feature was not
provided before because there was no real heat
generation inside of the chassis that required
improved air circulation. However,- by both
adding a charcoal filter and moving the
pressure sensor closer to the optics cell, an
internal pump may be purchased (optionally)
for use in the Model 1008-HC.
Change in Components' Materials:
All of the fittings utilized on the back panel
of the Model 1008-HC have been changed from
Kynar material, to longer-lasting stainless
steel fittings. In addition, since the
charcoal filter assembly has been added, use
of tygon tubing replaces the use of Teflon.
Tygon tubing is much easier to work with than
is Teflon tubing (due to its increased
flexibility).
TM920805
C-18

Figure C-l CPU/Memory
CD-l
Diagram

DASIBI TM901101
Figure C-2 CPU/Memory Board Schematics
CD-2

TO us-15
us-18
C/A BOARD
1 0 6 5 3
3 ; T O B E U S E D WlTr- DA981 PQINTED clQcurT
BOARD I=/A 10658.
2. CAFACITCR VALUES ARE IN ~‘~ILROF~GACS.
1. GESISTORS V A L U E S A R E 1k-l OUMS.
NOTES:
Figure C-3 D/A Board Dual Analog Schematics Modification
CD-3

;o 0
D L!!i
0
0
0
00
00
1 0
Figure C-5 Optional RS232 Interface Board Diagram
CD-5

’ “‘I ii’lirr
Figure C-6 Optional RS232 Interface Board Schematics (A)
CD-6

TM920805
1008-PC .
HOLE FITTING
Figure C-7 New tfLatchingll Valve Diagram
CD-7

TM920805
Figure C-8 New Valve/Regulator Board Diagram
CD-8

a
4,
S$
Y
1‘
Figure C-9 New Valve/Regulator Board Schematics
CD-9

0
GRN/YLW
PIN I - BLACK
PIN 2 - GREEN/YELLOW ( 18 GAUGE )
PIN 3 - WHITE / RED
PIN 4 - VIOLET (22 GAUGE)
Figure C-10 Stripped-Down LDHC Board Diagram
CD-10

+-
-Q--r
P
Figure C-11 Stripped-Down LDHC Board Schematics
CD-11

Board # 11454 REV. X
tf
P2
TM920805
Figure C-12 Network Interface Board Diagram
CD-12
.

IN
fiul!l-d~op
I
Figure C-13 Network Interface Board Schematics
TM920805
Serial
R;02r3t2
(t O-pin rbbon
orblc herder)
P2
CD-13
.

.
Board f WS3 REY, X
Silk-screen White component side only
0
co
a+
00’ es
EBI
00,
a
u
onaI
E3.
+
cc0
a
c2
‘~ II3
,nal 4
cl0
0 PI
Board # 11453 REV
Figure C-14 DasibiNet Board Diagram
CD-14
4

ClZ
8MHr =PF
TM920805
P A 4
PA3
PO5
TP2
,15R
)r
Pb2
PA0 1.
PO4 #
PE6
PES
A2
PE4
PEZ
WR-
F
f4HC84
Ul
+
TPP
St-
‘V
rirq-
t :t
cc
‘rh
‘rl
2:
n d
-ADDRESB
AFAD
$01 - 200 rtrd status roglrkl
07-O drtr buffer full
-1 d&a buffer empty
(D7- rignrl “rtrb-” roth rt
HCfll wrtte todrtr
rtglster C; ohred by 280
mad)
$00 - 280 rord/wrlte to drtr
rrgts trr
(rtrobrr signal “rtrr-“1
ii
46
.“.ama.
f
Edge oonneotor pin out
COMPONENT SIDE
.l pF filter aaprottors
Cl 0,Cll ,Cl 4,ClS,Cl6
Figure C-15 Dasib'iNet Board Schematics
CD-15
*

ALARM t
1llllllI
Figure C-16 RS232 Board Schematics (B)
CD-16

O Z O N E O U T P U T S
I
3 AMP FtiSE
POWER
PARTICULATE
FILTER
Figure C-17 New Back Panel Design For Models 1008-PC & 1008-PS
CD-17

RETAINER RING
FILTER WAFER
-
--
I
Figure C-18 Construction of 1008-HC Ozone Scrubber Assembly
CD-18

DA!3IJ31 ENVIRONMENTAL CORP. TM901101
APPENDIX D
REFERENCES
D-l

DASIBIENVIROr4MEdTALCORP. m901101
D.l
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
References
E.C.Y. Inn and Y. Tanaka, "Absorption Coefficient of Ozone in the
Ultraviolet and Visible Regions,' J. Opt. Sot. Am., 43, 870 (1953).
A.G. Gearn, "Absorption of Ozone in the Ultraviolet and Visible Regions
of the Spectrum," Proc. Phys. Sot. (London) 78, 932 (1961).
W.B. Demore and 0. Raper, "Hartley Band Extinction Coefficients of Ozone
in the Gas Phase and in Liquid Nitrogen, Carbon Monoxide, and Argon," J.
Phys. Chem. 68, 412 (1964).
M. Griggs, 'Absorption Coefficients of Ozone in the Ultraviolet and
Visible Regions,' J. Chem. Phys. 49, 857 (1968).
K.H. Becker U. Schurath and H. Seitz, "Ozone Olefin Reactions in the Gas
Phase."
M.A.A. Clyne and J.A. Coxom, "Kinetic Studies of Oxy-halogen Radical
System," Proc. Roy. Sot. 303, 207 (1968).
J.W. Simons, R.J. Paur H.A. Webster, and E.J. Blair, 'Ozone Ultraviolet
Spectrum," J. Chem. Phys. 59, 1203 (1973).
Transfer standards for Calibration of Ambient Air Monitoring Analyzers
for Ozone, EPA Publication available from Nat. Tech. Inf. Svcs., 5265
Royal Rd., Springfield, VA 22161, Tel. (703) 457-4650, Stock No. PB 80-
146871.
Technical Assistance Document for the Calibration of Ambient Ozone
Monitors, EPA 600/4-79-057, September 1979, available from National
Technical Information Service (NITS).
Rate Constants and Activation Energies, Intl. Jour. of Chem. Kinetics VI
725 (1974).
40 CFR Part 50, National Primary and Secondary Ambient Air Quality
Standards, Appendix D (44 FR 8221).
40 CFR Part 58, Ambient Air Quality Surveillance, Appendix A and B
(44 FR 27574).
Quality Assurance Handbook for Air Pollution Measurement Systems, Volume
II, Ambient Air Specific Methods, EPA 600/4-77-027a, May 1977.
Pecsok, Robert L., and L. Donald Shields, "Modern Methods of Chemical
Analysis," John Wiley & Sons, Inc. (1968).
Handbook of Chemistry and Physics, 60th Ed., CRC Press (1979).
***** End of Manual *'#***
D-2

Dasibi 1008 Ozone Monitor Manual

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Dasibi 1008 Ozone Monitor Manual