Chapter 1 - Introduction to Pneumatic System

KEMENTERIAN PENGAJIAN TINGGI

M

P

I

MECHANICAL ENGINEERING
DEPARTMENT

PNEUMATIC & HYDRAULICS

Introduction to Pneumatic System

Uma Devi Nadarajah
Norasyidah binti Mohd. Noh

Introduction to Pneumatic System by:
Uma Devi Nadarajah
Norasyidah Binti Mohd Noh

Published by:
Politeknik Banting Selangor
Persiaran Ilmu
Jalan Sultan Abdul Samad
42700 Banting, Selangor

https://pbs.mypolycc.edu.my

Copyright © 2021

Editor
M Maniyarasi Munusamy

Cover book by Uma Devi Nadarajah

Pictures by Uma Devi Nadarajah

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ISBN:

UCTION TO PNEUMATIC SYSTEM

Acknowledgement

We are grateful to Politeknik Banting Selangor to give us a w
like to appreciate everyone who gave us chance to explore t
might be left deep within us without knowing to this world.
Our heartiest gratitude to e-Learning Unit of PBS, who alwa
and being our companion in the discussion of e-book writing
We would like to express our appreciation to our colleagues
have directly or indirectly inspired us in completing this e-bo
A very special thanks to our beloved family for being there t
book. Last but not the least, thank you to the God for keepin

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wonderful opportunity to write this e-book. We would
the hidden talent inside us to become authors which
.

ays share knowledge on e-book writing, encourage us
g.

s, contributors, authors of sources of information who
ook.

to support and provide us some space to write this e-
ng us positive and hopeful in writing this e-book.

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Abstract

This e-book contains subtopic which relates to Chapter
content discussed is related to basic knowledge, a
pneumatic system. Besides that, this e-book also
reciprocating piston and rotary compressor. This e-bo
pneumatic system. The advantage of using this book
subtopic where students can use this book as a referen
that, students may opt to answer questions online bec
were developed using Google form platform to enable
they answered the questions. For the types of compr
compressor works. This would give better understandin
use this book for self-study or revision. This interactive
prefer to use gadget instead of old book style for their t

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r 1 of syllabus DJJ40153 Pneumatic & Hydraulics. The
application, advantages and disadvantages of the
has explained on types of compressor such as
ook also covers types of valve and actuator used in
k is, it comes with exercise and answers for each
nce for DJJ40153 Pneumatic & Hydraulics. Other than
cause each exercise has its link where the questions
e the students to know their result immediately after
ressor, video link is also given to watch on how the
ng and learning experience especially when students
e-book would attract the Y generation students who
teaching and learning activity.

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Table of Content

Content

Acknowledgement
Abstract
Table of contents
Introduction to pneumatic system

Diagram of structural block and pneumatic system signa
ISO standard symbol of components in pneumatic
Air generation system and air distribution system
Types of air compressor
Air dehydration
Air treatment
Valve
Directional control valve
Non-return valve
Flow control valve
Pressure control valve
Types of actuator
Linear actuator
Rotary actuator
Sizing a cylinder
Cushioning
References
Tutorial questions and answers

al flow Page Number

i iii
ii
iii
1
5

6
8
14
21
28
32
33
38
42
43
44
45
47
48
49
50
51

Introduction to Pneumatic

1. A pneumatic system is a system that uses compres
control energy. Compressed air is used as a mediu

2. Pneumatic systems are used in controlling train do
clamps, etc.

3. The term Pneumatics comes from the Greek word
basically the use of under pressure gas that helps
technology.

4. Pneumatics is the science of mechanical propertie
transmit and control energy through by means of

5. In pneumatics, the power is air where the volume
compression, thus increasing its pressure.

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System

ssed air to perform useful work by transmit and
um to do work.
oors, automatic production lines, mechanical,

d “pneuma”, which means 'breathe or wind'. It is
in performing a certain work in science and

es of elastic fluids.Fluid power system is one that
pressurized liquid or gas.
e of the atmospheric air is reduced by

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Application of Pneumatic Sy

1. Pneumatic system that used widely in industrial is
compressed inert gases.

Some of the pneumatic applications in industry:

A
Pneumatic
machine is

used to
dismantle

an
automobile

tire

(Images courtesy of Compressed Air & Gas Institute)

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ystem

s commonly powered by compressed air or

A Pneumatic
pneumatic system in
machine is
used in an food
automobile industry

painting

(Image courtesy of pxfuel.com)

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Advantages of pneumatics

1. Availability: Air is available everywhere abundantl
2. Transport: Air can flow easily in pipelines regardle
3. Storage: Air can be stored and removed easily from
4. Temperature: Compressed air does not influenced

operation, even under extreme conditions.
5. Cleanliness: Exhaust air without lubrication is clea
6. Economy: Installation cost for pneumatic system i

cost. Furthermore, maintenance cost is also low d
also relatively inexpensive.
7. Speed: High working speed is able to achieved bec
8. Overload safe: Pneumatic tools and operating com
actuators also free from producing heat except for
9. Explosion proof: Compressed air has a very low ris
expensive protection against explosion.

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ly and it is free.
ess of the distance.
m the storage.
d by temperature fluctuations, thus ensures reliable

an.
is relatively low cost because of modest component
due to long life without service. The running cost is

cause compressed air is a very fast working medium.
mponents is unaffected by overloaded. Pneumatic
r friction.
sk of explosion or fire, hence it does not require any

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Disadvantages of pneumati

1. Preparation: Compressed air requires good prepa
stages to remove dirt and condensates.

2. Speed: It is difficult to achieve uniform and consta
3. Force requirement: Compressed air is only econo

600 to 700 kPa (6 to 7 bar).
4. Noise level: The exhaust air is loud (noise). Howe

by the development of sound absorption materia

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ics:

aration where air has to be filtered in many
ant piston speed because air is compressible.
omical under the normal working pressure of
ever, this problem has now been largely solved
al and silencers.

Portable compressor
(Image courtesy of pixelsquid)

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Structural block and pneum

Air generation system

(Images courtesy of NPTEL Module 6)

Compressor Air Receiver Dryer
(Tank)
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matic system signal flow

Air distribution system

Air Service Directional Actuator)
unit Valve
55
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ISO standard symbol of compo

Symbols for the power supply section

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onents in pneumatic

Symbols for actuators

(Images courtesy of FESTO)

TION TO PNEUMATIC SYSTEM 6

Symbols for rotary motions Symbols for fl
valve

Symbols for
relay

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low control Symbols for non return valves
es and derivatives

r time delay
y NO

(Images courtesy of FESTO)

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Pneumatic system

Air generation system

Air dis
sy

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m with elements

stribution Image courtesy of SMC
ystem basic pneumatic manual

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1. Compressor is a mechanical device where it produces high
pressurized air by reducing its volume. Temperature of a gas nat
increases when compression occurs. Air enters to the compress
atmospheric pressure and compressed at a higher pressure and
delivered to the pneumatic system. During compression, mecha
energy is transformed into pneumatic energy.

2. Electrical motor is used to supply mechanical power to the
compressor by transforming electrical energy into mechanical e

3. Pressure switch is a device that controls the operation of electri
motor. This switch is set to a maximum pressure so that it stops
motor when pressure in the tank reach its maximum limit and s
the motor when minimum pressure is detected in the tank.

4. Check valve is used to ensure air from the compressor into the t
in one way and prevents the air leaking back when the compres
stop works.

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Air Generation System

turally Air generation system
sor at
d
anical

energy.

ic
the
starts

tank is
ssor

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5. Tank or reservoir is a compartment used to store the
compressed air. Besides that, tank also helps to stabilize
the pressurized air. When the compressed air is taken from
the system, the tank compensates the pressure
fluctuations. As the pressure in the tank drops to a certain
value, the compressor starts to compensate until the set
maximum value is reached. This cause the compressor to
operate when required only.

6. Pressure Gauge is used to indicate the pressure of the
reservoir.

7. Auto Drain is used to drain out the water deposited in the
tank due to condensation automatically.

8. Safety Valve blows compressed air off when pressure in
the tank rise above the allowed pressure.

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Air Generation System

m Air generation system
n

e

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9. Refrigerated Air Dryer helps to cool the compressed air
to a few degrees above freezing point and condenses
most of the air humidity. By doing this, water in the
downstream system can be avoided.

10. Line Filter helps to keep the line free from dust, water
and oil. This filter must be able to minimize pressure
drop and remove oil mist.

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Air Generation System

Air generation system

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Air Distribution System

Air distribution 1. Air Take-off: Air is re
system off for distribution. T
ensure condensate r
beneath the pipe will
will be removed when

2. Auto Drain helps to
condensation and mu
from remaining in the

3. Air Service Unit is a
Lubricator (FRL). A
compressed air to e
pressure and if requir
life of those pneumat
air service unit to be
can be FRL or FR type.

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eceived from generation system through air take-
The air take-off is at the top of the main pipe to
remains in the main pipe, water take off from
l flow into an automatic drain and the condensate
n it reaches a low point .

drain out the remaining water produced from
ust be placed at its lowest point to prevent water
e tube.

combination of Filter – Regulator –
Air service unit conditions the
ensure the air is clean at optimum
red, lubricant is added to extend the
tic system components. The type of
used is depending on application, it
.

Air service unit

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Air Distribution System

4. Directiona
alternately
valves con
cancelling

5. Actuator i
energy of
shown her
or an air to

Air distribution 6. Speed Con
system

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al Valve pressurizes and exhausts the cylinder ports
y to control the direction of movement. This type of
ntrols the direction of air signals by generating,
or redirecting signals.

is a power component which converts the potential
the compressed air into mechanical energy. Actuator
re is a linear cylinder; it can also be a rotary actuator
ool etc.

ntrollers allows to adjust the speed of the actuator.

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Types of Air Compressors

Reciprocating single Diaphragm
stage piston compressor
compressors
3
1

2
Reciprocating double

stage piston
compressor

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Screw
compressor

5

4 Click here to watch
Sliding vane how does an air
compressor work?

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Types o

Reciprocating Piston Rotary
Compressor

Piston Compressor Diaphragm
( 1 Stage & 2 Stage Piston) Compressor

Sliding Vane Rotary Two Ax
Compressor Com

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Types of air compressors

of Compressor

y Compressor Flow Compressor

Radial-flow Axial-flow
Compressor Compressor

xial Screw Screw Compressor
mpressor

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Reciprocating A

1.

One of the main parts that convert
mechanical to pneumatic energy in

piston compressors is the piston.
The piston performs linear
reversible motion in the
compressor cylinder.

3.

Major types of reciprocating
compressors include reciprocating

single stage piston compressor,
reciprocating double stage piston

compressor, and reciprocating
diaphragm.

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Air Compressors

2.

Reciprocating air compressors
are positive
displacement machines, where
they increase the pressure of the
air by reducing its volume.

Click here to watch how a
single stage reciprocating
compressor works.

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Reciprocating single sta

Working principle of a single stage piston compressor
(Image courtesy of Bright Hub Engineering)

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age piston compressors

For a single-stage compressor, air from atmosphere is
drawn and compressed to final pressure in one stroke.

The downward movement of the piston increases
the volume to produce a pressure lower than
atmospheric pressure, thereby allowing air to
enter the cylinder through the intake valve.

At the end of the stroke, the piston moves upward,
as the air is compressed, the intake valve closes,
forcing the exhaust valve to open, and the air is
discharged into the receiving tank.

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Reciprocating double

The air sucked in at atmospheric pressure is
compressed to the final pressure in two stages.

The compressed air enters the secondary cylinder after
passing through the intercooler, and the temperature is

greatly reduced. Compared with the single-stage unit,
the efficiency is improved. The final delivering
temperature can be around 120°C.

Single-stage and two-stage reciprocating compressors
are often used in car and truck repair shops, body

repair shops, service companies, and industrial plants.
Although this type of compressor is usually oil-

lubricated, hospitals and laboratories can purchase oil-
free compressors

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e stage piston compressor

Working principle of a double stage piston compressor
(Image courtesy of SMC basic pneumatic manual)

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Sliding vane

1. When the rotor rotates, the blades slide out against th
As the rotor rotates in an eccentric cylinder, air co
occurs when the volume of the space between the sli
decreases.

2. This type of compressor may or may not be lubricated
to high operating temperature and difficult sealing, oil
vane compressors are limited to low-pressure applic
oil-lubricated version can obtain higher pressures.

3. Some of the advantages of rotary sliding vane comp
smooth and pulse-free air output, compact size, low n
and low vibration levels.

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he housing.
ompression
ding blades

d by oil. Due Working principle of a vane compressor
l-free rotary (Image courtesy of SMC basic pneumatic manual)
cations. The

pressors are Click here to watch how a
noise levels, rotary compressor works

UCTION TO PNEUMATIC SYSTEM 1199

Screw compressor

1. When the rotor is unmesh at the intake e
cylinder, air is drawn into the cavity betw
rotor blades and the secondary rotor gro

Working prin
(Image co

2. A
t
t

Parts in a screw compressor
(Image courtesy of Compressed Air & Gas Institute)

3. As further rotation causes the main ro
to roll into the secondary rotor groove
compression begins, reducing the volu
increasing the unit pressure.

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end of the
ween the main
ooves.

nciple of a screw compressor
ourtesy of SMC basic pneumatic

manual)

As the rotation continues, the tip of the rotor passes through
the edge of the air inlet, trapping air in the cell formed by
the rotor cavity and the cylinder wall.

otor blades Click here to
es, watch how a
ume and
screw
compressor

works

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