Raspberry pi based liquid flow monitoring and control

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 07 | Jul-2014, Available @ http://www.ijret.org 122
RASPBERRY PI BASED LIQUID FLOW MONITORING AND
CONTROL
N.Suresh1
, E.Balaji2
, K.Jeffry Anto3
, J.Jenith4
1
Assistant Professor, Dept of EIE, Sathyabama University, Tamilnadu, India
2
Student, Dept of EIE, Sathyabama University, Tamil Nadu, India
3
4
Abstract
In industries there will be many big pipelines carrying various types of liquids, including the flammable liquids and corrosive
liquids. It is necessary to control the flow rate of the liquid for enhancing the processes and to prevent the accidents. The paper
proposes a methodology to monitor and control the liquid flow in the pipeline of industries through web server. There are many
systems to do the same, but this is about to monitor and control the flow of liquid using Internet with the help of Raspberry pi and
Arduino. The flow rate of the liquid is measured by Hall Effect sensor based flow meter. Arduino, a microcontroller development
board reads the pulses from the flow meter and sends it to Raspberry pi, a microcomputer to control the electro valve which is
connected to the pipeline. Server was setup by means of Raspberry pi..
Keywords: Arduino, Raspberry pi, Flow meter, Hall Effect sensor, electro valve.
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1. INTRODUCTION
Measuring the flow of liquids is a critical need in many
industrial plants. In some operations, the ability to conduct
accurate flow measurements is so important that it can make
the difference between making a profit or taking a loss. In
other cases, inaccurate flow measurements or failure to take
measurements can cause serious or even disastrous results.
With most liquid flow measurement instruments, the flow
rate is determined inferentially by measuring the liquid's
velocity or the change in kinetic energy. Velocity depends
on the pressure differential that is forcing the liquid through
a pipe or conduit. Because the pipe's cross-sectional area is
known and remains constant, the average velocity is an
indication of the flow rate.
It is very important to know what a flow meter can do as
well cannot do. Each type has both advantages and
disadvantages. Technological improvements of flow meter
must also be considered. It is always considered about the
needs of the flow meter. The satisfaction received with the
product depends on the care used in selecting and installing
the device. Mistakes when installing the device is common.
Every design has some tolerance to variable velocity
conditions in the pipe. Without it accuracy and performance
will not be correct. The biggest problem is with metering.
The values may not be clearly understood that is they may
be in different parameters. Regularly the meters have to be
calibrated. All the flow meters require initial calibration.
The recalibration depends on how well the meter fits the
application. There are number of factors influence
maintenance requirements and the life expectancy of flow
meters. The major factor is matching the right instrument to
the particular application. There are many other flow meters
used in various places. They are monitored using the wired
computer systems. The person can notice the flow only he is
in the computer system and using the particular application
to monitor the flow. So that for monitoring only the person
needs an individual computer. The person cannot know the
flow when he was not in the place of monitoring. The
proposed system helps to monitor and control the flow of
liquid through internet by mobile or computer.
2. PROPOSED SYSTEM
The proposed system to monitor the flow of liquid basically
consists of electro-valve, flow meter, microcontroller
microcomputer and web server. The block diagram of the
system is shown in the fig.1. To measure the flow rate of the
liquid, Hall Effect sensor based flow meter is used. Arduino
and Raspberry Pi will act as a microcontroller and
microcomputer respectively. The electro valve is physically
connected to the pipeline in which the flow to be controlled.
The electro valve is connected with the flow meter / flow
sensor. The flow sensor measures the flow and generates
analog pulse. The flow sensor/ flow meter is connected with
arduino in order to read the pulses from the flow sensor. The
arduino reads the analog pulse from the flow sensor and
sends the signal to the raspberry pi which is the main
component to control the electro valve. The Electro valve is
electrically connected to the raspberry pi, by which is to be
energized to open or close the valve. The raspberry pi is
programmed to read the arduino signal and to control the
electro valve. The raspberry Pi is also programmed to act as
a Web server by which the electro valve is controlled using
the LAN (Local Area Network), or internet connection.
Arduino is responsible for collecting the data from the flow
meter and sends it to the raspberry pi. Flow meter is
interfaced with Arduino directly.

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Fig-1: Block diagram of the proposed system to control the
flow of liquid.
The flow meter works on the principle of Hall Effect sensor.
The Hall Effect sensor is a transducer whosw output voltage
varies in response to a magnetic field. As the liquid flows
through the flow meter, Hall Effect sensor senses the liquid
flow and sends the corresponding data to Arduino through
the interface. The next part involves the uploading of data
that has been received from the arduino to raspberry pi.
Raspberry Pi is a microcomputer which is of light weight
that runs on Linux Operating System capable of handling
various hardware interfaces. Arduino is directly connected
to the Universal Serial Bus port that is available in raspberry
pi. The python is used as a primary coding language by the
raspberry pi to receive the data from the serial port and
uploading it to the server and also running the server. The
flow rate of the liquid can be controlled by electro valve
activated by the raspberry pi through the internet. Raspberry
pi is capable of controlling hardware using the GPIO pins
(General Purpose Input/output pins) it has. The electro-valve
is connected to the GPIO pins and is accessed through
internet. The GPIO pins in raspberry pi are capable of
supplying power. The electro-valve is a solenoid valve. This
electro-valve will interrupt the liquid flow until 12v power
supply is given. The power supply to the solenoid valve is
given by means of GPIO pins from raspberry pi and controls
it from the web server.
3. HARDWARE
The major components used in the proposed have been
discussed briefly.
3.1 Hall Effect Flow Sensor
The flow rate of the liquid is measured with the help of Hall
Effect sensor type flow meter. Hall Effect type flow sensor
is shown in the fig.2.A Hall Effect sensor is a transducer that
varies its output voltage in response to a magnetic field. The
Hall Effect is the production of a voltage difference across
an electrical conductor, transverse to an electric current in
the conductor and a magnetic field perpendicular to the
current Hall Effect sensors are used for proximity switching,
positioning, speed detection, and current sensing
applications. The flow meter is capable of measuring 1-30
Liters per minute. It can withstand the pressure of water less
than or equal to 2.0 Mpa. The flow sensor is connected to a
½ inch pipe. It senses the flow of liquid in the pipe and
sends the corresponding analog signal to arduino.
Fig-2: Flow meter sensor
3.2 Solenoid Electro-valve
A solenoid valve is an electromechanically operated valve.
The valve is controlled by an electric current through a
solenoid. Raspberry Pi controls the operation of the electro-
valve. The picture of the electro-valve to control the flow of
liquid is shown in the fig.3. The operating voltage of the
electro-valve is 12V. The solenoid valve operates at a
minimum of around 3 psi and allows around 3 L/min of
flow, and it needs enough pressure to operate. It will
interrupt the flow until 12V is applied to the fast-on
connectors on the solenoid.
Fig-3: Solenoid Electro-valve
The electro valve is connected to the ON – OFF switches.
The valve is connected to the electrical circuit which
energizes the valve to open or close whenever necessary.
When the OPEN switch is activated the valve gets de
energized and lets the liquid to flow and when the close
switch is pressed the valve gets energized by the electrical
circuit and it gets closed and does not allow the liquid to
flow.
3.3 Arduino
Arduino is a single board micro controller intended to make
the application of interactive objects or environments more
accessible. There are many types of Arduino available. The
ARDUINO UNO REV3 model. has been used. It is shown
in the fig.4. The Arduino Uno is a micro controller board
based on the ATmega328. It has 14 digital input/output pins
(of which 6 can be used as PWM outputs), 6 analog inputs, a
16 MHz ceramic resonator, a USB connection, a power jack,

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an ICSP header, and a reset button. It contains everything
needed to support the micro controller; simply connect it to
a computer with a USB cable or power it with an AC-to-DC
adapter or battery to get started.
Fig-4: Arduino board
In order to program Arduino, arduino IDE (i.e.) arduino
programming platform is installed in a Windows Pc. The
program is written in the arduino ide and then uploaded to
the arduino with the help of a serial cable Universal Serial
Bus directly connected to the pc. The arduino will read the
data from the flow meter and convert it as it is programmed.
The data that is received from the flow meter in the form of
analog data is converted to digital pulses by arduino so that
raspberry pi can read it.
3.4 Raspberry Pi
Raspberry pi is a credit card sized single board computer
which is capable of doing the entire job that an average
desktop computer does Like spread sheets, word processing,
Internet, Programming, Games etc .It consist of 512mb
RAM, ARM v6 Processor,2 USB and an ethernet port,
HDMI & RCA ports for display,3.5mm Audio jack,SD card
slot (bootable), General purpose I/O pins, runs on 5v. The
Raspberry Pi model is shown in fig.5.
Fig.5: Rasperry Pi model
Raspberry pi runs on Linux kernel based operating systems.
It boots and runs from the SD card. It does not have any
internal memory other than the ROM. It has an SD card slot
which is capable of reading up to 32 GB. The GPIO pins of
the raspberry pi are programmed using Python programming
language. The Electro-valve is connected to GPIO pins with
the help of transistor and relay so that we can switch on
switch off it whenever needed.
4. RESULTS AND DISCUSSION
The prototype model to control the flow of liquid through
server is shown in fig.6.Water is used as the liquid to test the
setup.
Fig-6: Prototype Model
Snapshot of the water flow setup is shown in fig.7.
According to flow meter sensor’s data sheet 5600 pulses = 1
litres. The program is written to send the data every second.
First of all, a small tank with low pressure was used. The
data was like this (The liquid used here is water) 258
L/hour,321 L/hour,278 L/hour,345 L/hour etc. The water
flow was very slow. But even when the water is turned OFF
there were some reading like 20L/hour, 31L/hour, etc.
indicating zero error. All the components were checked
carefully, It was found to be loose connection between the
interrupt pins in arduino, sending blank pulses to the serial
port and has been rectified. Now the connections are
checked again and the water flow is switched ON. Now
there is no error and the data it shows is perfect when the
water is switched OFF it correctly shows 0 L/hour
Fig-7: Snapshot of Water flow setup.

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The fig.8 shows the monitoring of the liquid flow through
the Smart phone. The electro-valve needs minimum of 12-
15 PSI to work. Initially, the electro-valve was connected to
the small tank (low pressure), when triggered it does not
open properly. Small tank that we used for flow meter did
not suffice. So overhead tank has been used. After doing the
plumbing connections, the electro-valve was triggered and it
worked fine
Fig-8: Liquid Flow Monitoring using Smart phone
In order to open the server in any browser the IP (internet
protocol) address of the server need to be known.. The
HTML page designed uses java script, so whatever the
browser is used, it must be installed with java plugin or else
the data will not be displayed properly. For security reasons
we have assigned username and password for the user to
monitor the data, to enter the website. When the web page
opens, there will be two options Flow data and Control. The
required option shall be selected
5. CONCLUSION
The Liquid flow can be monitored and controlled from
anywhere in the world using internet through personal
computer or Smartphone. The system has been tested for
water as a flowing liquid successfully. The work can be
extended to liquids that are used in various industries with
careful considerations of parameters like pressure,
temperature, corrosion, etc with appropriate use of flow
sensors and electro-valve.
REFERENCES
[1]. Design of networking liquid flow measurement and
management control system based on .NET, Ya-Ping Shi et
al, IEEE Conference Publications,2011.
[2]. Remote Measuring of Flow Meters for Petroleum
Engineering and Other Industrial Applications ,
Abdelgawad, A. et al, IEEE Conference Publications, 2007.
[3]. A Hall Effect sensor based syringe injection rate
detector , Mukherjee, B et al, IEEE Conference
Publications, 2012
[4]. Data acquisition and control using Arduino-Android
platform: Smart plug , Shajahan, A.H et al, IEEE
Conference Publications,2013
[5]. An arduino based system provided with GPS/GPRS
shield for real time monitoring of traffic flows, Costanzo, A.
IEEE Conference Publications,2013
[6]. Control and monitoring system of small water and wind
power plant , Kovalcik, M. et al, IEEE Conference
Publications,2013.
[7]. Bluetooth communication using a touchscreen interface
with the Raspberry Pi , Sundaram, G.S et al, IEEE
Conference Publications, 2013.
[8]. Raspberry Pi based interactive home automation system
through E-mail , Jain, S. et al, IEEE Conference
Publications,2014
[9]. Automated electric meter reading and monitoring
system using ZigBee-integrated raspberry Pi single board
computer via Modbus , Bonganay, A.C.D. et al, IEEE
Conference Publications, 2014.
[10]. Precise dosage system for controlled liquid delivery
based on fast MEMS based flow sensor , Goetz, M. et al,
IEEE Conference Publications, 2009.
[11]. www.raspberrypi.org
[12]. www.arduino.cc

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