Atm1122 Pneumatics Module-1

8/9/2019 Atm1122 Pneumatics Module-1

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Basic Hydraulics and

Pneumatics

Module 1: Introduction to Pneumatics

PREPARED BY

IAT Curriculum Unit

March 2011

Institute of Applied Technology, 2011


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ATM 1122 Basic Hydraulics and Pneumatics

Module 1: Introduction to Pneumatics

Module Objectives

After the completion of this module, the student will be able to:

Identify the common uses of pneumatic systems.

Identify the main parts of a pneumatic system.

Identify the main components of the pneumatic work station TP 101.

Understand how to to construct a pneumatic circuit

Explain the structure and signal flow of a pneumatic system.

List the main parts in the compressed air preparation stage.

Identify the symbol of air compressor and its function.

Identify the symbol of air tank and its function.

Explain the purpose of using the cooling and drying unit

Identify the main parts of the air service unit.

Identify the symbol of air filter and its function.

Identify the symbol of air pressure regulator and its function.

Identify the symbol of lubricator and its function.

Identify some important pneumatic accessories.


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Module 1: Introduction to pneumatics

Module Contents

1 Introduction.. ..............................................................................3

1.1 What does pneumatic mean................................................ 31.2 Defentition of pneumatics ..................................................... 3

1.3 What is the fluid power......................................................... 3

2 Applications of pneumatics ......................................................5

2.1 industrial applications ........................................................ 52.2 Industrial processes ............................................................ 5

2.3 Some of the pneumatic applications in our life ........................ 6

3 Advantages and disadvantages of pneumatics ...........................8

3.1 Advantages................................................................................. 8

3.2 Disadvantages............................................................................. 8

4 Structure and signal flow of pneumatic systems ........................9

4.1 Primary levels of the pneumatic system ...................................... 9

5 Air generation and distribution .................................................11

5.1 Preparation the compressed air.. ................................................. 11

5.2 Main parts in the compressed air preparation................................... 12

5.2.1 Air compressor ................................................................. 12

5.2.2 Air Tank (reservoir)............................................................ 135.2.3 Cooling and drying unit....................................................... 145.2.4 Piping............................................................................... 155.2.5 Air service unit .................................................................. 17

6 Pneumatic accessories ................................................................. 20

6.1 Manifold (distributor) ...................................................... 206.2 Shut-off valves ................................................................. 206.3 Tubes and fittings ............................................................. 206.4 Pressure gauges ............................................................... 21

References.........................................................................................22


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Module 1: Introduction to pneumatics 3

1 Introduction

1.1 What Does Pneumatic Mean?

Pneumatics comes from the Greek word pneuma, which means 'breath or

wind'. It is basically the use of under pressure gas that helps in performing a

certain work in science and technology.

1.2 Definition of pneumatics

Pneumatics is the transmission and control of forces and movements by means

of compressed air. (The use of compressed air as a medium to do work).

1.3 What is the fluid power?

Fluid power is the energy transmitted and controlled by means of a

pressurized fluid, either liquid or gas. The term fluid power applies to both

hydraulics and pneumatics. Hydraulics (oil or water) use liquids under pressure

while pneumatics use compressed air or other neutral gases.

Pneumatics technology has for some considerable time been used in carrying

out the simplest mechanical tasks, but nowadays has played a vital and

important role in automation and development of sophisticated technologies.


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2 Applications of pneumatics:

2.1 industrial applications

Pneumatic systems are used in many industrial applications such as:

Material handling

Clamping

Shifting

Positioning

Branching of material flow

Packaging

Filling

Transfer of materials

Sorting of parts

Stamping and embossing of components

2.2 Industrial processes

Pneumatic systems are used in carrying out machining and some industrial

processes such as:

Drilling Turning

Milling

Sawing

Finishing

Forming


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2.3 Some of the pneumatic applications in our life:

A Pneumatic machine is used todismantle an automobile tire

A pneumatic machine is used in an

automobile painting

A heavy duty pneumatic jackhammer

A pneumatic filling machine


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A dental drill is one of the uses of the

pneumatic technology

A pneumatic device is used to fill the

tire with compressed air to adjust the

tire pressure.


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3 Advantages and disadvantages of pneumatics:

3.1 Advantages:

1-Availability: Air is available everywhere in unlimited quantities.

2-Transport: Air can be easily transported in pipelines, even over large

distances.

3-Storage: Compressed air can be stored in a reservoir/tankand removed

as required.

4-Temperature: Compressed air is relatively insensitive to temperature

fluctuations.

5-Cleanliness: Unubricated exhaust air is clean.

6-The running cost is relatively inexpensive

7-Speed: Compressed air is a very fast working medium. This enables high

working speeds to be attained.

8-Overload safe: Pneumatic tools and operating components can be loaded

to the point of stopping and are therefore overload safe.

3.2 Disadvantages:

1-Preparation: Compressed air requires good preparation. Dirt and

condensates should be removed.

2-Speed: As air is compressible; it is difficult to achieve uniform and

constant piston speed.

3-Force requirement: Compressed air is economical only up to a certain

force requirement. Under the normal working pressure of 600 to 700 kPa

(6 to 7 bar).

4-Noise level: The exhaust air is loud (noise). This problem has now,

however been largely solved due to the development of sound

absorption material and silencers.


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4 Structure and signal flow of pneumatic systems

Pneumatic systems consist of an interconnection of different groups of

elements. This group of elements forms a control path for signal flow,

starting from the signal section (input) through to the actuating section

(output). Control elements control the actuating elements in accordance

with the signals received from the processing elements.

4.1 Primary levels of the pneumatic system:

Figure 1.1: Pneumatic signal flow and the coreesponding control elements


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0Z

Figure 1.2 : Examples of pneumatic control elements shoen in a practical

circuit


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5 Air generation and distribution

The main function of the air generation and distribution is to provide the

system with compressed air which is dry, clean, and at the required pressure

The compressed air supply for a pneumatic system should be adequately

calculated and made available in the appropriate quality.

Air is compressed by the air compressor and delivered to an air distribution

system in the factory. To ensure that the quality of the air is acceptable, air

service unit is utilized to prepare the air before being supplied to the control

system.

Malfunctions can be considerably reduced in the system if the compressed air

is correctly prepared. A number of aspects must be considered

5.1 Preparation of the compressed air:

The following points should be considered in preparing compressed air plants:

1. Quantity of air required to meet the demand of the system

2. Type of compressor to be used to produce the quantity required

3. Pressure requirements

4. Storage requirements

5. Requirements for air cleanliness

6. Acceptable humidity levels to reduce corrosion and sticky operation

7. Lubrication requirements, if necessary

8. Temperature of the air and effects on the system

9. Line sizes and valve sizes to meet demand

10.Material selection to meet environmental and system requirements

11.Drainage points and exhaust outlets in the distribution system

12.Layout of the distribution system to meet demand.


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5.2 Main parts in the compressed air preparation

5.2.1 Air compressor:

Air compressor is used to produce the

compressed air for the system by therequired volume and pressure.

As a rule, pneumatic components are

designed for a maximum operating

pressure of 800-1000 kPa (8 - 10 bar)

but in practice it is recommended to

operate at between 500-600 kPa (5

and 6 bar) for economic and safe use.

Due to the pressure losses in the

distribution system, the compressor

should be delivered between 650-700

kPa (6.5 and 7) bar to attain these

figures. Figure 1.3.a and figure 1.3.b

are examples of air compressors while

figure 1.3.c shows the ISO symbol of

the air compressor.

(a) Air compressor

(b) Air compressor

(c) ISO symbol of air compressor

Figure 1.3: (a) and (b) are examplesof some practical air compressors.(c) ISO symbol of air compressor.


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5.2.2 Air Tank (reservoir)

An air reservoir should be fitted to:

Store and stabilizes the

compressed air.

Compensate the pressure

fluctuation.

Cool the air.

Figure 1.4 (a) shows a real air tank

while the figure 1.4 (b) shows the

ISO symbol of an air reservoir.

(a) Air reservoir

(b) ISO symbol of air reservoir

Figure 1.4: (a) air reservoir. (b) ISO

symbol of an air reservoir.


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5.2.3 Cooling and drying unit

As the air comes out from the

compressor very hot and humid;

The cooling and drying unit is used

to:

Condensate the water vapor

(humidity) from the compressed

air.

Reduce the compressed air

temperature.

The accumulation of condensate

depends largely on the relative air

humidity. The relative air humidity

is dependent on the air

temperature and the weather

situation. To remove the humidity,

we use many types of air dryers,

the very common and practical one

is by using a cooling unit which

cool the air and at the same time

remove the water vapor. Figure 1.5

(a) and (b) show some examples of

real air dryers, while figure 1.5.c

represents an ISO symbol of air

dryer.

(a)

(b)

(c)

Figure 1.5: (a): and (b) are someexamples of real air dryers.

(c) ISO symbol of air dryer.


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5.2.4 Piping

The pipe diameter of the air distribution system should be selected in such a

way that the pressure loss from the pressurized reservoir to the consuming

device ideally does not exceed approx. 10 kPa (0.1 bar).

5.2.4.1 Selection of the pipe diameter:

1. Flow rate

2. Line length

3. Permissible pressure loss

4. Operating pressure

5. Number of flow control points in the line

5.2.4.2 Piping layout

Ring circuits (figure 1.6.a) are most frequently used as main lines. This

method of installing pressure lines also achieves a constant supply in the case

of high air consumption. In pipe-run layout, the pipe lines must be installed in

the direction of flow with a gradient of 1 to 2% as shown in figure 1.6 b. This

is particularly important in the case of branch lines. Condensate can be

removed from the lines at the lowest point. Any branching of air consumption

points where lines run horizontally should always be installed on the upper

side of the main line. Branching for condensate removal is installed on the

underside of the main line. Shut-off valves can be used to block sections of

compressed air lines if these are not required or need to be closed down for

repair or maintenance purposes.


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(a) Ring (loop) pneumatic distribution system

(b) pipe-run pneumatic distribution system

Figure 1.6 : (a) shows the ring or loop distribution system. (b) shows the pipe-

run distribution system


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5.2.5 .1 Air filter

Compressed air filter (Figure 1.8a)

has the job of removing all

contaminants from the compressed air

flowing through it as well as water

which has already condensed. The

compressed air enters the filter bowl

through guide slots. Liquid particles

and larger particles of dirt are

separated centrifugally collecting in

the lower part of the filter bowl. The

collected condensate must be drained

before the level exceeds the

maximum condensate mark, as it will

otherwise be re-entrained in the air

stream.

(a)a picture of a real air filter

(b) ISO symbol of the air filter

Figure 1.8: (a) air filter.(b) The ISO

symbol of an air filter


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5.2.5 .2 Pressure regulator

(Reduce/regulate the pressure).

The purpose of the regulator (figure1.9.a) is to keep the operating

pressure of the system (secondary

pressure) virtually constant regardless

of fluctuations in the line pressure

(primary pressure) and the air

consumption. Figure 1.9.b represents

the ISO symbol of the air regulator.

5.2.5 .3 Air lubricator

(Lubricate the moving parts)

Most moving parts require some type

of lubrication. The efficiency of

cylinders, valves and air motors can

be greatly improved if they are

supplied with adequate lubrication.

Pneumatic components can be

lubricated by using an air line

lubricator (figure 1.9.c), a device for

adding lubricating oil in aerosol form

into a compressed air line. The air

passing through the lubricator

transports the lubricant to air tools,

cylinders or other air operated

equipment. Figure 1.9.d represents an

ISO symbol of the air lubricator

(a) real pressure regulator

(b) ISO symbol of the pressure

regulator.

(c) air lubricator

(d) ISO symbol of the air lubricator.

Figure 1.9: (a) pressure regulator.(b)

ISO symbol of the pressure regulator.(c) Air lubricator. (d)ISO symbol of

the air lubricator.


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6.4 Pressure gauge

It used to display the actual

amount of the pressure in two

main units Pascal and bar

1 bar= 14.5 p.s.i

Figure 1.10g shows a real

pressure gauge. Figure 1.10h

represents the ISO symbol of the

pressure gauge.

(f) different fittings

(g) pneumatic pressure gauge

(h) ISO symbol of a pressure gauge

Figure 1.10

Activity:

Compare between hydraulics and pneumatics.


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References

1. Festo Didactic pneumatic basic level textbook TP 101.

2. Introduction to fluid power by James L. Johnson

3. http://www.omega.com/auto/pdf/CompressedAirTips.pdf


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Student notes

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Atm1122 Pneumatics Module-1

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