Pneumatics Jr 01

7/28/2019 Pneumatics Jr 01

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Introduction to Pneumatics

The term PNEUMA is derived from the ancient Greek,

and meant breadth or wind.

PNEUMATIC is the study of air movement and air

phenomena.

Although the fundamentals of pneumatics rank amongstthe earliest perceptions of mankind, it was not until the

last century that the behavior and the fundamentals

were researched systematically.

Some earlier applications and areas of use ofpneumatics in the industry were; railways, mining and

construction.

Real practical industrial applications of pneumatics

dates back only to about 1950s.


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Properties of Air

78% Nitrogen

21% Oxygen

1% Other Gas (CO2, H, Ne, Krypton, Xenon,

Water, etc.)

Air is compressible.

Air is expandable.

Air when compressed produces a maximum

temperature of 200 to 300C. Air contains 40PPM of solid particles and

increases to 9 times when compressed.


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What is Pressure?

PRESSURE is defined as a force or

thrust acting on the surface of the body

in a uniform manner and at a right angle

to the surface.


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Pascals Law

Pascals Law states that when a force

is applied to a confined fluid, the force

will be transferred undiminished

throughout the fluid to all surfaces of thecontaining vessel or tank.


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Advantages of compressed air

AMOUNT Air is available practically everywhere for

compression, in unlimited quantities.

TEMPERATURE Compressed Air is insensitive to temperature

fluctuations. This ensures reliable operation, even

under extreme conditions of temperature.

TRANSPORT Air can be easily transported in pipelines, even

larger distances. It is not necessary to return the

compressed air.

STORABLE A compressor need not be in continuous operation.

Compressed Air can be stored in and removed from

a reservoir. In addition, transportation in the

reservoir is possible.


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Advantages of compressed air(continued)

EXPLOSION PROOF Compressed Air offers no risk of explosion or fire,

hence no expensive protection against explosion

is required.

CLEANLINESS Compressed Air is clean since any air which

escapes through leaking pipes or elements does

not cause contamination. This cleanness isnecessary, for example, in the food, wood, textile

and leather industries.

CONSTRUCTION The operating components are of simple

construction, and are therefore inexpensive.

SPEED Compressed Air is very fast working medium.

This enables high working speeds to be attained.

(Pneumatic cyl inders have a wo rking speed of 1 to

2 Meters/Second ).


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Advantages of compressed air(continued)

ADJUSTABLE With compressed air components, speeds and

forces are infinitely variable.

OVERLOAD SAFE Pneumatic tools and operating components can

be loaded to the point of stopping and they are

therefore overload safe.


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Disadvantages of compressed air

PREPARATION The Compressed Air needs good preparations.

Dirt and humidity may not be present. (Wear o f

Pneumatic Components).

COMPRESSIBLE It is not possible to achieve uniform and constant

piston speeds with compressed air.

FORCE REQUIREMENT Compressed Air is economical only up to a

certain force requirement. Under the normally

prevailing working pressure of 700 KPa (7 Bar /

101.5 PSI)and dependent on the travel and

speed. The limit is between 20,000 and 30,000 N

(2,000 and 3,000 Kg .f).


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Disadvantages of compressed air(continued)

EXHAUST AIR The exhaust air is loud. This problem has now,

however, been largely solved due to the

development of sound absorption material.

COSTS Compressed Air is a relatively expensive means

of conveying power. The high-energy costs are

partially compensated by inexpensive

components and higher performance. (Number

of cycles).


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Some applications of

Pneumatic Systems

Industrial robots (Automation)

Operation of bus doors

Operation of machine tools

Operation of work holding devices

Air tools


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Some applications of

Pneumatic Systems

Industrial robots (Automation)

Operation of bus doors

Operation of machine tools

Operation of work holding devices

Air tools


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Benefits of Compressed Air

Explosion proof

Fast

Easily transportable Easily stored

Overload safe

Variable speed

Variable pressure

Clean

Simple construction

Stroke setting No return lines

Wide operating

temperatures

Others(compact,light,repair)


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A Basic Pneumatics System

Intake air filter

Compressor

After cooler

Air separator

Pressure switch

Safety valve

Air Receiver

Air service unit

Directional valves

Actuators


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Summary of Energy Supply

Compressor

Plant

Service Unit

Piping System

Dryer

Receiver

Types of Compressor (Positive

displacement, Flow Compressor)

Flow Rate

Pressure

Service

To dampen pressure

fluctuation

Condensation of water vapor

Safety

Cooling (note: Dew Point)

Absorption

Adsorption

Ring Circuit

Gradient 1-2%

Tapping Outlets pointing upwards

Diameter

Filter Pressure Regulator

Lubricator


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Compressor

Plant

Service Unit

Piping System

Dryer

Receiver

Types of Compressor (Positive

displacement, Flow Compressor)

Flow Rate

Pressure

Service

Compressors are required to compressed

the gas to the desired working pressure

for transmission of power.


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Compressor

Plant

Service Unit

Piping System

Dryer

Receiver

To dampen pressure

fluctuation

Condensation of water vapor

Safety

Compressed Air Receiver serves to

stabilized the air supply and smoothens

pressure fluctuations in the network when

air is consumed.


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Compressor

Plant

Service Unit

Piping System

Dryer

Receiver

Cooling (note: Dew Point)

Absorption

Adsorption

Good preparation is important when using

compressed air. Water (moisture) is introduced

in the system by the compressor which should be

dealt with at the point of usage.


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Air outlet

Airinlet

Refrigerating unit Air to air-heat exchanger

Moisture

separato

r

Refrigerant

Moistureseparator

Refrigerationmachine

Air Drying

Refrigeration Drying

If the temperature is

lowered further, the

water vapor contained

in it begins to

condense.


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Dew Point Curve

Example:

At a dew point of

40C (313K), the

quantity of water in

1M air is 50 Grams.


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Absorption Drying

Desiccant

Condensate

Moist

air inletCondensate drain

Dry air outlet

Air Drying(continued)

Moisture, gases or dissolved

materials from the air combines

with the desiccant to form into a

solid or liquid state. It is a

chemical process and noexternal energy is required.

Simple installation but high

operating cost because the

desiccant have to be discarded.


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Shut-off valve (open)

Prefilter (oil filter)

Adsorber 1

Hot airHeater

Shut-off valve (open)

Dryair

Shut-off valve (closed)

Shut-off valve (closed)

Adsorber 2

Secondary filter

Blower

Adsorption Drying

Air Drying(continued)

Moisture, gases or

dissolved materials from

the air deposits on the

porous surface of thedesiccant. It is a

physical process and

regeneration is possible

through hot air flow.


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Compressor

Plant

Service Unit

Piping System

Dryer

Receiver

Gradient 1-2%

Tapping Outlets pointing upwards

Diameter

Ring Circuit

Condensation in the system should be

prevented. Condensate can be trapped in

pipelines at lowest points. Pipelines should

be installed with downward gradient,

measured in the direction of flow.

Piping diameter should be selected primarily

on the basis of flow volume, pipe length and

working pressure.


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Installation of Pipelines

Branch Line

Inter-connected System

Ring Circuit

Ring circuit are the commonly

used pipeline installation. Gas

can flow from two direction and a

uniform supply can be obtain

where there is heavy

consumption.


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Compressor

Plant

Service Unit

Piping System

Dryer

Receiver

Filter Pressure Regulator

Lubricator

Compressed air needs good preparation.Dirt and humidity should be prevented as

it may wear pneumatic components or

cause it to malfunction.


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Service Units

Compressed Air Filter

Combined Symbols - Air Service Units


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Inlet

Outlet

Water Trap

Drain

Filter Element

Baffles

Filter with Water Trap Manual ControlFilters remove contaminants, mainly

condensed water from compressed air.

Compressed air is conducted into the

filter bowl and is rotated at high speed.

Heavy particles of dirt and water

particles are centrifuged onto the wall

of the filter bowl and they remain there.

Condensed water accumulates in the

lower part of the filter bowl and is

drained through the drain plug when

the water reaches the maximum level

mark. Fine particles are retained by

the filter element through which the air

has to flow.


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Service Units

Pressure Regulating

Valve with Relief Port


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Valve Body

Inlet Outlet

Vent

Spring and

Adjusting screw

Pressure operation

Pressure Regulator with Relief Port


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6 Bar

The set screw permitsadjustment of the initial

tension in the diaphragmspring. The diaphragm liftsoff the push rod off its seat.The push rod shuts off theexhaust port in thediaphragm.

Operation of Pressure Regulator with Relief Port


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6 Bar

4.5 Bar

If the pressure in the volume

with the output port exceedsthe set value, the diaphragm

moves down first, shutting off

the input port and then

opening the exhaust ports to

relieve the excess pressure.

Operation of Pressure Regulator with Relief Port


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Compressed Air Lubricator

Service Units


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Lubricator

Air flows through the

lubricator from left to

right. Some of the air

flowing through thevalve is guided through

a nozzle.

Due to the resulting

pressure drop, oil isdrawn from an oil

reservoir through a feed

pipe.


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LubricatorThe air lubricator is usedwhen

-Extremely rapid oscillatingmotions are required

-With cylinders with largediameters(125mm)


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The Structure of Pneumatic Systems

Energy

supply

Signal input

Signal processing

Command Execution

Signal Output

Processing elements:

Directional control valves, Shuttle valves,

Dual-pressure valves, Sequencers,Pressure sequence valves

Input elements:

Push-button directional control valves

Roller lever valves, Proximity switches, Air barriers

Working elements:

CylindersMotors

Optical indicators

Control elements:

Directional control valves

Energy supply elements:

Compressor

Pneumatic reservoir

Pressure regulating valve, Service units


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Energy supply elements

1A 1S3

1V2 4 2

1V1 2

14 12

1 1(3)

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3

1S1 2 1S2 2 1S3 2

1 3 1 3 1 3

0Z

0S2

1 3

Input elements

Processing element

Control element

Working element

System Circuit Diagram

S b l f th P S l S ti


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Symbols for the Power Supply Section

Energy Supply: Compressor with constant

displacement volumePneumatic reservoirPressure

Source

Maintenance:

2

1 3

Filter Water separator withmanual actuation

Water separator withautomatic condensate drain

Pressure regulating valve

with relief port, adjustableLubricator

Combined Symbols:

Air Service Unit (consisting of: Compressed

air filter, Pressure regulating valve, Pressure

gauge and compressed air lubricator)

S b l f C t l El t


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Non-return,

Flow Control and

Pressure Control

Valves

Symbols for Control Elements

S b l f th P i i l W ki El t


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Symbols for the Principle Working Elements

Linear

Actuators:

Double-acting cylinder with single,

non-adjustable cushioning

Single-acting cylinder Double-acting cylinderDouble-acting cylinder

with through piston rod

Double-acting cylinder with

adjustable cushioning at both endsRodless cylinder with

magnetic coupling

Rotary Drives:

Air motor, constant displacement,

rotation in one direction

Air motor, variable displacement,

rotation in one directionAir motor, variable displacement,

rotation in both directions

Pneumatic rotary motor


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Poppet ValvesBall Seat Valve

Disc Seat Valve

Slide Valves

Longitudinal Slide Valve

Longitudinal Flat Slide Valve

Plate Slide Valve (Butterfly Valve)

Design Characteristics of Directional Valves

Valve designs are categorized as follows:

The design principle is a contributory factor with regards to

service life, actuating force, means of actuation, means of

connection, and size.


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3/2-Way Valve: Ball Bearing

Seat, Normally ClosedPosition

Ball Seat Poppet Valve


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3/2-Way Valve: with Disk Seat,

Normally Closed Position

Disk Seat Poppet Valve


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5/2-Way Double Pilot Valve, Pneumatically Actuated, Both Sides

5 Working ports, 2 switching positions

The valve has a memory function. A short signal (pulse) is sufficient foractuation.

Longitudinal Slide Valve


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4/3-Way Valve, Mid-Position Closed,

(flat slide valve)

4 Working ports, 3 switching positions

Flat slide valves are mostly actuated

manually as other types of actuation

can only be implemented with difficulty.

By rotating two disks, the flow

channels are connected with, or

isolated from each other.

Longitudinal Flat Slide Valve


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SWITCHING SYMBOLS FOR VALVES

The connecting lines for supply and exhaust air are drawn

outside the square.

The valve switching position is shown by a square.

The number of squares corresponds to the number of

switching positions.

Lines indicate the flow paths, arrows indicate the direction of

flow.

Closed ports are shown by two lines drawn at right angles to

one another.

Directional Control Valves:


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Directional Control Valves:

Ports and Switching Positions

2/2-way valve, normally open position

Number of ports

Number of switching positions

3/2-way valve, normally closed position

3/2-way valve, normally open position

4/2-way valve, flow from 1 to 2 and from 4 to 3

5/2-way valve, flow from 1 to 2 and from 4 to 5

5/3-way valve, mid-position closed

Valve Connections Labeling


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Connection Coding As per ISO 1219 As per ISO 5599

Working or Outlet ports A, B, C 2, 4, 6

Power Connection P 1

Drain, Exhaust Ports R, S, T 3, 5, 7...

Leakage Line L 9

Control Lines X, Y, Z 12, 14, 16

Valve Connections Labeling

PORT DESIGNATIONS


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PORT DESIGNATIONS

Port designation in accordance with DIN ISO 5599-3

"Fluid Technology Pneumatics, 5-Way Valves"

1 -Supply port

2, 4 -Working ports

3, 5 -Exhaust ports

10 -Signal applied blocks flow from 1 to 2

12 -Signal applied opens flow from 1 to 2

14 -Signal applied opens flow from 1 to 4

81, 91 -Auxiliary pilot air


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Pneumatics Jr 01

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