HP UNIT 4 PPT

 Pneumatic Components:
 Properties of air. Compressors.
 FRL Unit –
 Air control valves,
 Quick exhaust valves
 pneumatic actuators- cylinders, air motors.

 Branch of engineering science which deals
with the study of the behaviour and
application of compressed air.
 It is abundantly available.
 It is safe to use.
 It is very cheaper
 Easier maintenance and easy handling.
 It can be exhausted easily.

 Density is lesser
 Viscosity is lesser
 Reduce the requirement of special designs
 Comparatively cheaper in cost
 Provide better operational
 Lesser in weight
 Leakage will not affect the system
performance

 Cannot provide precise actuator control and
precise positioning control
 It can be used for low pressure applications.
Applications
 Stamping Material handling
 Drilling hammering
 Hoisting
 Punching
 Assembling
 Clamping
 Riveting

 Air is a mixture of gas
 Air is invisible, colourless, odourless and
tastless.
Composition:
 Main constituents of air by volume are
 78% of nitrogen
 21% of oxygen
 1% of other gases (argon and carbon dioxide)

Atmospheric Pressure:
The air surrounding the earth exerts a pressure on the
earth’s surface. The pressure prevailing directly on
the earth’s surface is known as atmospheric pressure.
The atmospheric pressure is also reference to as
reference pressure. Normally it considers the sea
level as its reference point.
The atmospheric pressure may be calculated by
barometer which states that the barometer reads the
pressure due to the height of mercury (Hg) in the
tube and its weight

 Atmospheric pressure = ρ g h
 ρ = Density of Hg = 13600kg/m2
 g = Acceleration due to gravity = 9.81m/s2
 h = Height of Hg column = 760 mm of Hg at
normal sea level.
Atmospheric pressure = 13600 x 9.81 x 0.76
= 101396 N/m2
= 1.01 bar

Pressure and Volume: Boyle’s Law
How is the pressure applied to a gas related to its volume?
Piston
Gas molecules
Piston
Gas molecules
Volume is inversely proportional to applied pressure.
Boyle’s Law: P1V1 = P2V2

How is the volume of a gas related to its temperature?
moveable mass (constant pressure)
gas molecules
The volume of a gas is directly
proportional to its Temperature
(temperature must be in Kelvin)
Charles’s Law: V1/T1 = V2/T2

1. Volume held CONSTANT
2. Found direct relationship
between temperature & pressure
3. P1 = P2
T1 T2

Combined Gas Law (Boyle and Charles):
T must be in Kelvin
Can be rearranged to:
P1V1T2 = P2V2T1
A combined gas law problem can be recognized by
having two sets of conditions.
Note: if one set of parameters is unchanged that term
will cancel on each side.

1. Contains ALL variables
2. P V = n R T
3. Where
P = pressure (depends on R)
V = volume (liters)
n = amount of gas (moles)
R = ideal gas constant (depends on
pressure) T = temperature (Kelvin)

 Positive displacement types
 Working on the principles of increasing the
pressure of a definite volume of air by reducing
that volume in an enclosed chamber
 Dynamic compressor or turbo compressor
 Employs rotating vanes or impellers to increase
the pressure of the air

 Fig shows single-acting piston actions in the cylinder of a
reciprocating compressor.
 The piston is driven by a crank shaft via a connecting rod.
 At the top of the cylinder are a suction valve and a discharge valve.
 A reciprocating compressor usually has two, three, four, or six
cylinders in it.

 Staging
 Dividing the total pressure among two or more
cylinders by allowing the outlet from one
cylinder into the inlet of the next cylinder and so
on.
 In single stage compressor gives the compressed
air of about 5 bar, the compressed air
temperature can rise over to 200⁰C.
 effective cooling of compressor is necessary.
 When used multistage compressor effective cooling
can be implemented between stages.
 Reduces input power requirements
 Increase the efficiency of the compressor.

 Pressure has been developed in the
compressor piping. The pressure will push
back against the compressor. This makes
starting the compressor more difficult when
required.
 Starting unloader valve is required to start
compressor whenever desired .This
arrangement releases the pressure in the
piping to the atmosphere and now the
compressor is free to start.

 Screw compressors are also belong to the positive
displacement compressor family.
 In screw compressors, the compression is
accomplished by the enmeshing of two mating
helically grooved rotors suitably housed in a
cylinder equipped with appropriated inlet and
discharge ports

 The rotor shaft is mounted eccentrically in a
steel cylinder so that the rotor nearly touches
the cylinder wall on one side, the two being
separated only by an oil film at this point.
 Directly opposite this point the clearance
between the rotor and the cylinder wall is
maximum.
 Heads or end-plates are installed on the ends
of the cylinder and to hold the rotor shaft.

 The vanes move back and forth radially in the rotor slots as
they follow the contour of the cylinder wall when the rotor is
turning.
 The vanes are held firmly against the cylinder wall by action
of the centrifugal force developed by the rotating rotor.
 In some instances, the blades are spring-loaded to obtain a
more positive seal against the cylinder wall.

Definition:
• Valve are defined as devices to control or regulate the
commencement, termination and direction and also the pressure
or rate of flow of a fluid under pressure which is delivered by a
compressor or vacuum pump or is stored in a vessel.
Functions:
• They control the supply of air to power units, example
cylinders .
• They provide signal which govern the sequence of
operation .
• They act as interlock and safety devices .

• Direction control valve
• Flow control valve
• Pressure control valve

• Directional valves control the way the air passes
and are used principally for controlling
commencement, termination and direction of air
flow. The different classification scheme of the
pneumatic cylinders are given below
1. Based on construction
• i) Poppet or seat valves
- Ball seat valve
- Disc seat valve
- Diaphragm Valves

• 2. Based on the Number of ports
I. Two way valves
II. Three way valves
III.Four way valves
• 3. Based on methods of actuation
I. Manual
II. Mechanical
III.
IV.
V.
Electrical
Pneumatic
Combined action
• 4. Based on mounting styles
I. Manifold
II. In-line

• Pressure control valves control the
pressure of the air flowing through the
valve or confined in the system controlled
by the valve.
There are three types of pressure control
valves
1. Pressure limiting valve
2. Pressure regulator or pressure reducing
valve

For sequencing operations, the pneumatic
circuits can be designed in various methods
follows:
Classic method
Cascade method
Step-counter method
Logic design method
Combinational circuit design

 Step-I: Given sequence letters
Ex: A+ B+ B– A– C+ C–
+: Represents extension stroke of the cylinder
–: Represents retraction stroke of the cylinder
Step-II: Grouping
Group minimal, C– can be assigned to group I
Step-III: No. of pressure lines = No. of groups=2
Step-IV: Selection of valves
(i).No. of 4/2 DC Valves = No. of Cylinders=2
(ii). No. of limit valves = 2 x No. of cylinders = 2x2 = 4
(iii).No. of cascade valves = No. of groups-1 = 2-1 = 1
Step-IV: The cascade circuit and their valve connections for the
sequence A+ B+ B– A– C+ C–

Ex: A+ B+ B– A–
Step-II: Grouping
Step-IV: The cascade circuit and their valve connections for
the sequence A+ B+ B– A–

Ex: A+ B+ B– C– C+ A–
Step-II: Grouping
Step-V: The cascade circuit and their valve connections for
the sequence A+ B+ B– C– C+ A–

 Port 2 is connected directly
to the end cover of a
cylinder
 Port 1 receives air from the
control valve
 Air flows past the lips of the
seal to drive the cylinder
 When the control valve is
exhausted, the seal flips to
the right opening the large
direct flow path
 Air is exhausted very rapidly
from the cylinder for
increased speed
1
2
1
2
1
2

 Fluidics – Introduction to fluidic devices,
simple circuits Introduction to Electro
Hydraulic Pneumatic logic circuits, PLC
applications in fluid power control, ladder
diagrams
 Fluid Power Circuit Design: Sequential circuit
design for simple applications using classic,
cascade, step counter, logic with Karnaugh-
Veitch Mapping and combinational circuit
design methods.

 Reduced speed of travel of machine tool
elements.
 Slow response to control.
 Excessive leakage in the system.
 Excessive loss of system pressure.
 Rise in the oil temperature.
 Non-uniform or jerky movement of tables,
carriages at low feed rate.
 Increased noise in the system.
 No supply or less supply from pump.
 Cavitation of seal failure.
 Poor oil life

 Inadequate supply of oil in the reservoir.
 Clogged or dirty oil filters.
 Leaking seals.
 Loose inlet lines the cause the pump to take
in air.
 Incorrect type of oil.
 Excessive oil temperature.
 Excessive oil pressure.

 Quality improvement and repeatability in
quality.
 Cost reduction.
 Improved sustainability.
 Improved safety.
 Reduced rejection

 Low cost automation is defined as a technology
that creates some degree of automation around the
existing equipment, tools, methods and people,
using mostly standard components available in the
market.
Low Cost Automation main used:
 To reduce machine investment cost.
 To reduce the process time.
 To increase productivity.
 To have consistent quality.

 Material movement/ handling operations.
 Loading
 Feeding
 Pick and place functions
 Clamping
 Welding
 Forming
 Machining operations like drilling, riveting, broaching,
shaping etc.
 Painting
 Measurement and inspection functions such as
marking, checking, gauging etc.
 Assembly and packing

 Using gravitational force
 Using leverage systems
 Using hydraulic systems
 Using pneumatic systems
 Using electromagnetic systems

 Hydraulic circuit for a drilling machine
 Hydraulic circuit for a shaping machine
 Hydraulic circuit for a planning machine
 Hydraulic circuit for a surface grinding machine
 Hydraulic circuit for a milling machine
 Hydraulic circuit for a punching machine
 Hydraulic circuit for a forging machine
 Hydraulic circuit for a forklift machine
 Hydraulic circuit for a drilling machine
 Hydraulic power steering
 Hydraulic braking for automobiles
 Hydraulic circuit used in construction,
agricultural, mining industries.

 Pneumatic drills
 Pneumatic press and power press
 Air brakes for automobiles and trains
 Air suspension system
 Pneumatic conveyor systems
 Pneumatic adjustable tables
 Pneumatic clamps and fixtures
 Pneumatic jacks
 Pneumatic work piece clamping in hacksaw cutting
machine
 Door opening and closing mechanism using air cylinder
 Pneumatic circuit for LCA in drilling machine
 Pneumatic circuit for line feeding automation
 Pneumatic circuit for pick and place robot gripper
actuation
 Pneumatic circuit for tool handling in CNC machine tools.

 A hydraulic power pack is a self contained unit that is used
instead of a built in power supply for hydraulic machinery.
 It works to apply the hydraulic pressure needed to drive
motors, cylinders and other complementary parts of given
hydraulic system.
 The hydraulic power pack is also called as hydraulic power
unit.

 A hydraulic reservoir (or) tank
 Regulator
 Pressure supply lines and pressure relief line
 Electrical motor
 Pump
 Other components:
(i). Filters
(ii). Pressure control valves
(iii).Directional control valves
(iv). Flow control valves
(v). Accumulators
(vi). Coolers and heaters
(vii). Power unit controllers

 A pneumatic power pack is self contained unit that is used
instead of a built in power supply for pneumatic machinery.
 It work apply the air pressure needed to drive motors,
cylinders, and other complementary parts of a given
pneumatic system.
 The pneumatic power pack is also called as pneumatic
power unit.

 Electric motor
 Compressor
 reservoir
 Air cooler
 Air dryer/separator
 Valves (flow, pressure and DC valves)
 FRL unit

HP UNIT 4 PPT

More Related Content

What's hot (20)

Similar to HP UNIT 4 PPT (20)

More from gopalkrishnan202 (8)

Recently uploaded (20)

HP UNIT 4 PPT