e-book pneumatic_3

Linear Actuator – double acting cylinder





air inlet cylinder rod
Double acting
cylinder


1. Double acting cylinder has two air inlets to create power strokes
in two directions which is extending and retracting as air
pressure is applied alternately to the air inlets.


2. Double acting cylinders are commonly used in the application
Double acting cylinder where larger stroke length is required.

3. One of the advantage of the double- acting cylinder is that the

cylinder is able to carry out work in both directions of motion.

4. For the forward stroke, the force transferred by the piston rod is
greater than for the return stroke because of effective piston
surface is reduced on the piston rod side by the cross-sectional
Symbol of double area of the piston rod. However this is only a consideration if the
acting cylinder cylinder is used to “pull” the same load in both directions.
Construction of double acting cylinder
Image courtesy of NPTEL-Module 6


46
INTRODUCTION TO PNEUMATIC SYSTEM 46

Linear Actuator – double acting cylinder





air inlet cylinder rod
Double acting
cylinder


1. Double acting cylinder has two air inlets to create power strokes
in two directions which is extending and retracting as air
pressure is applied alternately to the air inlets.


2. Double acting cylinders are commonly used in the application
Double acting cylinder where larger stroke length is required.

3. One of the advantage of the double- acting cylinder is that the

cylinder is able to carry out work in both directions of motion.

4. For the forward stroke, the force transferred by the piston rod is
greater than for the return stroke because of effective piston
surface is reduced on the piston rod side by the cross-sectional
Symbol of double area of the piston rod. However this is only a consideration if the
acting cylinder cylinder is used to “pull” the same load in both directions.
Construction of double acting cylinder
Image courtesy of NPTEL-Module 6


46
INTRODUCTION TO PNEUMATIC SYSTEM 46

Rotary actuators



b. Rack and pinion
Rotary Actuators
are used for applications required angular motion. This actuator is also referred to as limited rotation
This type of actuator produces high torque output and cylinders, of the single or multiple,
have a limited rotary movement. Standard rotations bidirectional piston are used for turning,
are 90○ , 180 ○ , and 270 ○ . Rotary actuators are positioning, steering, opening and
mainly available in three designs which are ram type, closing, swinging, or any other mechanical function
rack and pinion and air motor. involving restricted rotation.


c. Air motor
a. Ram type Air motors are widely used in
Compressed air enters to air industrial and automotive.
hole which is connected to the Example: Used as a screwdriver,
output shaft. The air openings drilling machine and grinding
is protected from leakage by machine.
using protective rubber or Air motor produces a continuous
elastomeric coating. output torque to move the shaft.








47
INTRODUCTION TO PNEUMATIC SYSTEM 47

Rotary actuators



b. Rack and pinion
Rotary Actuators
are used for applications required angular motion. This actuator is also referred to as limited rotation
This type of actuator produces high torque output and cylinders, of the single or multiple,
have a limited rotary movement. Standard rotations bidirectional piston are used for turning,
are 90○ , 180 ○ , and 270 ○ . Rotary actuators are positioning, steering, opening and
mainly available in three designs which are ram type, closing, swinging, or any other mechanical function
rack and pinion and air motor. involving restricted rotation.


c. Air motor
a. Ram type Air motors are widely used in
Compressed air enters to air industrial and automotive.
hole which is connected to the Example: Used as a screwdriver,
output shaft. The air openings drilling machine and grinding
is protected from leakage by machine.
using protective rubber or Air motor produces a continuous
elastomeric coating. output torque to move the shaft.








47
INTRODUCTION TO PNEUMATIC SYSTEM 47

Sizing a Cylinder




1. Linear cylinders have the following standard diameters as recommended in ISO:

8, 10, 12, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 140, 160, 200, 250, 320 mm


2. The force developed by a cylinder is a function of the piston diameter, the operating air pressure and the frictional resistance.
This, theoretical force, is calculated using the formulae:


Force (N) = Cross section area of Piston area (m2) X air pressure (N/m2)




Extending stroke for a double acting cylinder: X efficiency where, D = piston diameter,
P = Working (gauge) pressure
g



Retracting stroke for a double acting cylinder: X efficiency where, d = piston rod diameter






For a single acting cylinder, extending stroke: X efficiency where, F = spring force at the end of stroke
s

48
INTRODUCTION TO PNEUMATIC SYSTEM 48

Sizing a Cylinder




1. Linear cylinders have the following standard diameters as recommended in ISO:

8, 10, 12, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 140, 160, 200, 250, 320 mm


2. The force developed by a cylinder is a function of the piston diameter, the operating air pressure and the frictional resistance.
This, theoretical force, is calculated using the formulae:


Force (N) = Cross section area of Piston area (m2) X air pressure (N/m2)




Extending stroke for a double acting cylinder: X efficiency where, D = piston diameter,
P = Working (gauge) pressure
g



Retracting stroke for a double acting cylinder: X efficiency where, d = piston rod diameter






For a single acting cylinder, extending stroke: X efficiency where, F = spring force at the end of stroke
s

48
INTRODUCTION TO PNEUMATIC SYSTEM 48

Cushioning




1. High speed movement created by pneumatic cylinders result in
considerable development of shock forces on the end of the stroke
when the piston touching the cylinder cover or lid rod at the end of
each stroke. This impact force can damage the piston or piston rod. To Is used for large cylinders

avoid this, cushioning is required for cylinders.
larger cylinders, the impact
Types of cushioning effect can be absorbed by an air

cushion that decelerates the
piston over the last portion of
the stroke.
Is used for small cylinders Rubber buffer Air cushions
often have fixed cushioning i.e.
rubber buffers, to absorb the

shock and prevent internal
damage to the cylinder.








49
INTRODUCTION TO PNEUMATIC SYSTEM 49

Cushioning




1. High speed movement created by pneumatic cylinders result in
considerable development of shock forces on the end of the stroke
when the piston touching the cylinder cover or lid rod at the end of
each stroke. This impact force can damage the piston or piston rod. To Is used for large cylinders

avoid this, cushioning is required for cylinders.
larger cylinders, the impact
Types of cushioning effect can be absorbed by an air

cushion that decelerates the
piston over the last portion of
the stroke.
Is used for small cylinders Rubber buffer Air cushions
often have fixed cushioning i.e.
rubber buffers, to absorb the

shock and prevent internal
damage to the cylinder.








49
INTRODUCTION TO PNEUMATIC SYSTEM 49

References




1. SMC Pneumatics Inc. (1997). Basic pneumatics (Rev. 0100 ed.) [E-book].
2. FESTECH Factory Automation Expert Group. (2007). Practical pneumatics. FESTECH.
3. IAT Curriculum Unit, Institute of Applied Technology. (2011). Basic Hydraulics and Pneumatics Module 1: Introduction to Pneumatics. Silo. Tips.
https://silo.tips/download/basic-hydraulics-and-pneumatics#modals
4. NPTEL – Mechanical – Mechatronics and Manufacturing Automation. Lecture 1 pneumatic system, lecture 2 compressors, lecture 3 air treatment
and pressure regulation. In Joint initiative of IITs and IISc – Funded by MHRD (Ed.), Module 6: Pneumatic Systems (pp. 1–26).
5. Bright Hub Inc. (2010, February 11). Air compressor operation: Description of two stage and theory. Bright Hub Engineering.
https://www.brighthubengineering.com/hvac/63715-operation-of-an-air-compressor/https://www.brighthubengineering.com/hvac/63715-
operation-of-an-air-compressor
6. Tyler Currie. (2015, March 5). After-cooler for air-compressor– that ain’t a dryer! Van Air Systems. https://www.vanairsystems.com/after-cooler-for-
air-compressor-that-aint-a-dryer/

Videos:
1. How does an air compressor work video:
https://www.youtube.com/watch?v=bJluUxA7aaY&list=PLpA864g8WSUuIqmpbDdbyDeqg0fT4Hs_8&index=2
2. Single stage reciprocating video: https://www.youtube.com/watch?v=BeFEmIzZvEA
3. Rotary compressor video: https://www.youtube.com/watch?v=b93GSe-xgqI
4. Screw compressor video: https://youtu.be/YMFe7saE-_E?list=PLpA864g8WSUuIqmpbDdbyDeqg0fT4Hs_8
5. Air cooled cooler video: https://www.youtube.com/watch?v=Y1ibPUcj-Yg
6. Water cooled video: https://www.youtube.com/watch?v=ckXyj_wpyVc
7. Check valve video: https://www.youtube.com/watch?v=lwI9D_DRg_g&t=20s
8. Shuttle valve video: https://www.youtube.com/watch?app=desktop&v=tVghySXf8TU



50
INTRODUCTION TO PNEUMATIC SYSTEM 50

References




1. SMC Pneumatics Inc. (1997). Basic pneumatics (Rev. 0100 ed.) [E-book].
2. FESTECH Factory Automation Expert Group. (2007). Practical pneumatics. FESTECH.
3. IAT Curriculum Unit, Institute of Applied Technology. (2011). Basic Hydraulics and Pneumatics Module 1: Introduction to Pneumatics. Silo. Tips.
https://silo.tips/download/basic-hydraulics-and-pneumatics#modals
4. NPTEL – Mechanical – Mechatronics and Manufacturing Automation. Lecture 1 pneumatic system, lecture 2 compressors, lecture 3 air treatment
and pressure regulation. In Joint initiative of IITs and IISc – Funded by MHRD (Ed.), Module 6: Pneumatic Systems (pp. 1–26).
5. Bright Hub Inc. (2010, February 11). Air compressor operation: Description of two stage and theory. Bright Hub Engineering.
https://www.brighthubengineering.com/hvac/63715-operation-of-an-air-compressor/https://www.brighthubengineering.com/hvac/63715-
operation-of-an-air-compressor
6. Tyler Currie. (2015, March 5). After-cooler for air-compressor– that ain’t a dryer! Van Air Systems. https://www.vanairsystems.com/after-cooler-for-
air-compressor-that-aint-a-dryer/

Videos:
1. How does an air compressor work video:
https://www.youtube.com/watch?v=bJluUxA7aaY&list=PLpA864g8WSUuIqmpbDdbyDeqg0fT4Hs_8&index=2
2. Single stage reciprocating video: https://www.youtube.com/watch?v=BeFEmIzZvEA
3. Rotary compressor video: https://www.youtube.com/watch?v=b93GSe-xgqI
4. Screw compressor video: https://youtu.be/YMFe7saE-_E?list=PLpA864g8WSUuIqmpbDdbyDeqg0fT4Hs_8
5. Air cooled cooler video: https://www.youtube.com/watch?v=Y1ibPUcj-Yg
6. Water cooled video: https://www.youtube.com/watch?v=ckXyj_wpyVc
7. Check valve video: https://www.youtube.com/watch?v=lwI9D_DRg_g&t=20s
8. Shuttle valve video: https://www.youtube.com/watch?app=desktop&v=tVghySXf8TU



50
INTRODUCTION TO PNEUMATIC SYSTEM 50

Introduction to Pneumatic System



Chapter 1 – Introduction to Pneumatic System
Answer all the questions (Click here for online exercise)



1. What is pneumatic system?
A.a system that uses compressed air to transmit and control energy to perform useful work

B.a system that uses compressed air to control energy to perform useful work

C.a system that uses air to transmit and control energy to perform useful work


2. Which is the correct statement about the pressure developed in the air compressor?

A. The pressure generated is lower than atmosphere pressure.

B. The pressure generated is depending on the temperature during the compression
process
C. The air from the atmosphere is reduced in volume by compression, thus increasing its
pressure.



3. Pneumatic sytem is using ____________________as a working medium.
A. Oil

B. Compressed air
C. Water




4. What is X in the given figure?








Structural block of
pneumatic system

A. Air conditioning
B. Dryer

C. Air regulator




5. Pneumatic system is preferred in food industry because ________

A. the cost is low

B. it is using air as a medium which is available everywhere
C. it is using unlubricated air which is clean

Chapter 1 – Introduction to Pneumatic System







6. Picture below shows the ISO standard symbols for .









A. Flow control valve

B. Directional control valve

C. Pressure control valve



7. Why compressed air requires good preparation?

A. So that pneumatic system is clean
B. To protect the operator from dirt and dust

C. To maximize performance and extend the life of the components doing the work
in a pneumatic system



8. Name the component that is used to transform the potential energy of
the compressed air into mechanical work.

Answer: _______________________________________




9. Symbol shown in figure below is a combination of ______________








A. Air filter, regulator

B. Air filter, regulator, check valve
C. Regulator, lubricator

D. Air filter, regulator, lubricator





10. Which of the following components list belongs to air generation system?

A.Actuator, check valve, air service unit, compressor
B.Tank, actuator, pressure switch, electric motor

C.Pressure switch, electric motor, compressor, check valve
D.Directional control valve, line filter, compressor, auto drain

Introduction to Pneumatic System






Chapter 1 – Introduction to Pneumatic System – Air dehydration & Treatment

Answer all the questions (Click here for online exercise)






1. There are TWO (2) types of air dryer.

A. True B. False




2. Which process is the following statement refers to?


"After final compression the air will be hot, when it cools it will deposit water in
considerable quantities in the airline (pipe system) system which should be avoided.”


A. Water cool B. Aftercoolers
C. Absorption drying D. Adsorption drying






3. Diagram below shows

































A. Desiccant air dryers B. Refrigerant drying


C. Main line filter D. Deliquescent air dryers

Introduction to Pneumatic System








4. Which of the following statement describes best about the diagram shown below?




















A. air flows from the compressor to an aftercooler that lowers the temperature (within
10-15°C of the cooling medium), causes condensation and removes the majority
of water.

B. a steel shell housing tubes with water circulating on one side and air on the other,
usually arranged so that the flow is in opposite directions through the cooler.


C. The cold dry air return pipe passes through air heat exchanger and gains heat
from the incoming high temperature air.



5. What is the purpose of air treatment in air generation system?



A. Toremove heat after compression, the air should be further cooled as

near as possible to the point of use

B. To remove remaining moisture, contaminants such as fine particles of
carbonised oil, pipe scale and other foreign matter, the air should be further
cleaned as near as possible to the point of use



C. Toremove moisture from the air after air is cooled down by air dryers.

Introduction to Pneumatic System





Chapter 1 – Introduction to Pneumatic System - Valves

Answer all the questions



1. Which of the following is the function of directional control valve, DCV?


A. control flow of the air B. control the direction of the air
C. control the speed of the air D. control the pressure of the air






2. Which of the following is NOT the actuation method of

a pneumatic DCV?







A. mechanically B. manually

C. hydraulically D. combination




3. How many groups of pneumatic valve can be divided?
A. 4 B. 5

C. 3 D. 6




4. Which of the following does not belongs to non return valve?


A. shuttle valve B. dual pressure valve

C. quick exhaust valve D. sequence valve






5. Valves shown in figure can be categorized as
valve










A. non return valve B. directional control valve
C. flow control valve D. pressure control valve

Introduction to Pneumatic System


6.
Name the component shown in the figure.



A. one way flow control valve B. flow control valve

C. shuttle valve D. AND valve






7.
What is the name of the component shown in the figure?


A. 3/2 way single button DCV B. 3/2 way NC pushbutton DCV with
spring return
C. 3/2 way NO pushbutton DCV with D. 3/2 way double pilot with spring
spring return
return DCV





8.
What is the name of this component?



A. 5/2 way double pilot B. 4/2 way double pilot DCV with
spring return
C. 5/2 way single pilot DCV with
spring return D. 4/2 way single pilot DCV with
spring return




9.

What is the name of the component shown in the figure?


A. 5/3 way hand lever valve with B. 4/3 way hand lever valve with

closed mid position open mid position
C. 4/3 way hand lever valve with D. 5/3 way hand lever valve with
closed mid position closed mid position





10. What is the name of the component shown in the

figure?




A. dual pressure valve B. shuttle valve

C. check valve D. quick exhaust valve

Introduction to Pneumatic System




11. What is the component in the figure?




A. non return valve B. spring valve
C. check valve D. filter




12.


What is the name of the component in the
figure?


A. Drain B. Filter

C. Cooler D. Heat exchanger



13.


What is the name of this component?



A. AND Valve B. shuttle valve
C. quick exhaust valve D. NOT valve




14. How many control position does this valve has?



A. 5 B. 2

C. 3 D. 4





15. Which operating method of a directional control valve is
shown?



A. general B. push button

C. pedal D. detent lever




16. Which actuation method of a directional control valve

is shown?

A. roller B. spring centering

C. return spring D. idle return roller

Introduction to Pneumatic System




17.
What is the function of this component?








A. control flow of air in one direction B. control direction of the air in one
direction
C. control flow of air in both direction
D. allow flow of air in one direction only






18. How many port does this valve has?




A. 5 B. 2
C. 3 D. 4






19. What is the function of this valve?






A. allow flow of air to the outlet when there B. allow flow of air to the outlet when
are pressure at both inlets there is pressure at any of the inlet

C. exhaust the cylinder air quickly to D. unidirectional valve and permit the
atmosphere. free flow in one direction only







20. Which of the following statement is not correct about this
component?


A. this valve is a combination of a B. When air flows from Port 1 to 2, it will
flow control valve and a non choose the throttle path to flow since check
return valve valve is blocked. Thus, air flow is controlled.

C. controls air flow in both D. When air flows from Port 2 to 1, it will
direction which is through the air choose check valve path because it fully open.

throttle Thus air is free flow

Introduction to Pneumatic System

Chapter 1 – Introduction to Pneumatic System – Actuators
Answer all the questions (Click here for online exercise)


1. The pneumatic actuator can be categorized into two groups. Name the two groups.

Answer: ____________________________________________



2. Which cylinder is the following statement referring to?
'The cylinder uses the pressure imparted by compressed air to create a driving force in

one direction (usually out), and a spring or by external force from the load or spring to
return to the "home" position.'


Answer: ____________________________________________




3. Name the cylinder shown and label the parts in the Figure 1
















Figure 1


Answer: ____________________________________________




4. Which of the following statements describes best about double acting cylinder?

A. thrust is developed in extending direction only as air pressure is applied
alternately to opposite sides of a piston.
B. thrust available on the extending stroke is reduced due to the smaller effective

piston area, but is only a consideration if the cylinder is to “pull” the same load
in both directions
C. thrust available on the retracting stroke is reduced due to the smaller effective

piston area, but is only a consideration if the cylinder is to “pull” the same load
in both directions.

5. Name TWO (2) types of cushions in pneumatic cylinder.


Answer: ____________________________________________

Chapter 1: Introduction to Pneumatic System

Answer.

1. B - A system that uses compressed air to control energy to perform useful work.
2. C - The air from the atmosphere is reduce in volume by compression, thus increasing its
pressure.
3. B - Compressed air.
4. B - Dryer
5. C - It is using unlubricated air which is clean.
6. A - Flow control valve.
7. C - To maximize performance and extend the life of the components doing the work in a
pneumatic system
8. Actuator / cylinder
9. A – Air filter, regulator.
10. C - Pressure switch, electric motor, compressor, check valve



Chapter 1: Introduction to Pneumatic System – Air dehydration & Treatment

Answer.

1. B - False
2. B - Aftercoolers.
3. A – Desiccant air dryers.
4. B - A steel shell housing tubes with water circulating on one side and air on the other, usually
arranged so that the flow is in opposite directions through the cooler.
5. B - To remove remaining moisture, contaminants such as fine particles of carbonised oil,
pipe scale and other foreign matter, the air should be further cleaned as near as possible to
the point of use



Chapter 1: Introduction to Pneumatic System – Valves
Answer.

1. B - Control the direction of the air.
2. C – hydraulically.
3. B – 5.
4. D – sequence valve.
5. D – pressure control valve.
6. A – one way flow control valve.
7. B – 3/2 way NC pushbutton DCV with spring return.
8. D – 4/2 way single pilot DCV with spring return.
9. C – 4/3 way hand lever valve with closed mid position.
10. D – quick exhaust valve.
11. C – check valve.
12. B – filter.

13. B - shuttle valve.
14. C– 3.
15. C – pedal.
16. D – idle return roller.
17. C – control flow of air in both directions.
18. A – 5.
19. A – allow flow of air to the outlet when there is pressure at both inlets.
20. C – controls air flow in both direction which is through the air throttle.



Chapter 1: Introduction to Pneumatic System – Actuators.

Answer.
1. Linear, rotary
2. Single acting cylinder.
3. Single acting cylinder
A – pressure port.
B – vent.
C – rod.
D – piston seal.
E – spring.
4. C – thrust available on the retracting stroke is reduce due to smaller effective piston area,
but is only a consideration if the cylinder is to ‘pull’ the same load in both directions.
5. Air cushions, rubber buffer.

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