Pnuematic Note

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BEE1922Engineering Laboratory II

Pneumatic

By:

NAZRIYAH BINTI HAJI CHE ZAN


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1.0 Introduction to Pneumatic

1.1 Pneumatic in review

1.2 Structure & signal flow of pneumaticsystems

1.3 Product and preparation of compress air

1.3.1 Compressor 1.3.2 Reservoir

1.3.3 Air Dryer 1.3.4 Piping System

1.3.5 Service Unit

1.4 Safety and Operation


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2.0 Basic pneumatic system

component2.1 Pneumatic Actuator Linear -Single Acting Cylinder & Double

Acting Cylinder

Rotary -Pneumatic Motor

2.2 Pneumatic Valves Directional ctrl valve exercise 1

Non-return Valve - exercise 2 Flow Control Valve exercise 3

Pressure Control valve exercise 4

Combination valve exercise 5


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Practical Assessment 1

2.0 Basic pneumatic system

component


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3.0 Additional pneumatic system

component3.1 Timer Exercise 6

3.2 Counter

3.3 Sensor

Directional ctrl valve exercise 1

Non-return Valve - exercise 2


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Practical Assessment 2

Final Test

3.0 Additional pneumatic

system component


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Pneumatic Greek word Pneumos : breath, air

Actic : movement, action

Pneumatic : control action by air system


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Advantages

Availability practically everywhere inunlimited quantities

Easily transported in pipeline

Explosion Proof no risk of explosion orfire

Cleanliness Fast Action



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Disadvantages

Complicated preparation of compressedair-no dirt and condensate allowed!

Impossible to get constant piston speed

Economical only up to max. 7 bar pressure

Exhaust air is loud! (need silencers)



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Signal condition for pneumatic controlsystem

Regulatory control system

3 psig (0%) to 15 psig (100%)

Sequences system (ON/OFF)

Depend on equipment spec.

1.2 Structure & signal flow of

pneumatic systems


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1.2 Structure & signal flow of

pneumatic systems


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Pneumatic and Electrical


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1.3 Product and preparation of

compress air

Instrument air system


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As an source of air supply to the system.

Generate pressurized air to the system.

Varies type of compressor such as

Screw compressor

Reciprocating piston compressor

Radial flow compressor

Sliding vane compressor

Axial compressor

1.3.1 Compressor


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Air drawn in throughsuction nozzle moveaxially via two impeller

at high speed. Pressure up to 10 bar

Motor drive continuesrunning in idle mode.

1.3.1a Screw Compressor


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Draws air in through thesuction valve duringpiston stroked downward.

Compress during upwardand push out throughdischarge valve

Single stage up to 6 bar

Double stage up to 15 bar

1.3.1b Reciprocating piston

Compressor


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Through rapidlyrotating blades, theair is accelerated

radially.

Pressure: Withmulti-stage design

up to approx. 1000kPa (10 bar)

1.3.1c Radial flow Compressor


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Cylinder volume increase with rotor rotationcause air flow into the cylinder

Air is sealed within the cylinder vanes &

compress by rotation Discharged when compress air pressure

reaches outlet pressure.

Single stage up to 4bar ; two stage up to 8

bar

1.3.1d Sliding vane compressor


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Through rapidly rotatingblades, the air is acceleratedradially.

The kinetic energy of the airis converted into pressureenergy.

Pressure: Up to approx. 600kPa (6 bar)

1.3.1e Axial Compressor


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Configure at downstream (after)compressor to stabilize air.

To cool an air after compressed bycompressor

Separated the heavy moisture from air.

Some cases pressure control forcompressor (compress/idling) are takingfrom reservoir.

1.3.2 Reservoir


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Main purpose is to reduce watermoisture in the compressed air, call airhumidity.

Reduce pneumatic device service live ifcompress air is low humidity or highmoisture.

To increase humidity to 100, air need toreached dew point.

1.3.3 Air Dryer


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Water droplets and solidparticles are removedthrough a filter.

Filter finenessStandard filter: 5 to 40 m

Fine filter: 1 m

Micro filter: 0.01 m

1.3.4 Air Filter


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Do leak test for the system by using

Snooper liquid

Soap liquid Bubble exist at leak position

VDI (German Association of Engineer)

Design Guidelines for Machine Tool andother Product Equipment:-

1.4 Safety and operation


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VDI (German Association of Engineer)Design Guidelines for Machine Tool andother Product Equipment:-

P 4.5.1 Controller malfunction

In the even of controller malfunction or dis-connection of the system, operating staff

must be not endangered.



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P4.5.2 Emergency Stop Switch (ESS)

Pneumatic system using several forcecylinder must be equipped with an

emergency switch. ESS function is

To put sys into zero pressure status.

To reset all force cylinder into initial position

To inhibit cylinder in their current position.



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BASIC PNEUMATIC SYSTEM

COMPONENT ACTUATOR

VALVE


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An output device to apply control action.

Describe to 2 group

Linear motion Single Acting Cylinder / Actuator

Double Acting Cylinder / Actuator

Rotary motion

Air motor

Rotary Cylinder / Actuator

2.1 Actuator


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Applied air only oneside of cylinders piston

face or actuator

diaphragm. Return back by spring.

Force balance concept.

Stroke when Fin > Fspring Fin = Psupply X Apiston Fspring = Psupply X Apiston

Linear-Single Acting Cylinder


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Similar to singleacting cylinder.

Spring function

replace bypneumatic supply.

This two portsalternately assupply andexhaust ports.

Linear-Double Acting Cylinder


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Transformpneumatic energy tomechanical energy.

Pneumatic motor Piston motor

Sliding-vanemotor

Gear motor

Turbines

Rotary - Pneumatic motor


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Cylinder Symbols


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Cylinder Symbols


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Function is to control pressure or flowrate of pressure media

Divided to below categories: Directional Control Valve (DCV)

Non Return Valve / Checked valve

Flow Control Valve Pressure control valve

Combination valve

2.2 Valve


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Switching positions

2 switching port

Directional Control Valve


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Switching positions

2 switching port

Working Port



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Switching positions

2 switching port

Working Port

3 port

Flow direction



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Switching positions

2 switching port

Working Port

3 port

Flow direction

Flow barrier



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Switching positions

2 switching port

Working Port

3 port

Flow direction

Flow barrier


DCV name : Port / working pos.

: 3/2 way valve


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2/2 way valve

Also call as ON-OFF

valve Function is either ON

or OFF pneumaticflow.



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3/2 way valve


4/2 way valve


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5/2 way valve


5/3 way valve


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Type of actuator / control signal


Mechanicalsignal

Return byspring

Pneumatic signal

IndirectPneumatic, piloted


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Electrical signal/Solenoid

Solenoid, piloted,

with manual override

Type of actuator / control signal


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Pneumatic Flow atNormal condition /

Not energize (OFF)

Pneumatic Flow atActivated condition /

Energize (ON)

Plunger Valve condition


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Example 1 of DCV operation

Push pushbutton, single actingcylinder will extend. Releasepushbutton, cylinder will retractback.


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Push pushbutton, single actingcylinder will extend. Releasepushbutton, cylinder will retractback.


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START STOP

Push START pushbutton, double acting cylinder will extend. PushSTOP pushbutton, cylinder will retract back.


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Exercise 1

Training aims Operation of a single acting cylinder

Direct actuation of single-acting cylinder

Use of 3/2 way DCV

Application of a service unit with on-off

valve and manifold

Problem description The allocating device supplies aluminum

valve blanks to a machine station. Byoperated a START push button, the pistonrod of the single acting cylinder 1A, ismade to advance. By press STOP pushbutton, the piston rod is return.


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Exercise 1-solution

STARTSTOP


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Non Return Valve

Shuttle valve (ORValve)

Dual PressureValve (AND Valve)

Quick ExhaustValve

One way flowcontrol valve**.

Non Return Valve


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a) Non Return Valve

Allowed flow in one direction

Input pressure should higherthan downstream pressure.

Non return valve with springloaded release a flow when

force of input is larger thansprings pretension.

Non Return Valve

a) Non return Valve(check valve)

b) Non return Valve,Spring loaded


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Non Return Valve


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Non Return Valve


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b) Shuttle Valve (OR Valve)

Had 2 input and 1 output.

Logic OR connection

Air present at either 1 or bothinput will produce an outputsignal.

The output signal is followingthe higher pressure.

Non Return Valve

1

2

1(3)


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c) Dual-Pressure Valve(AND Valve)

Logic AND connection

Output produced whenboth input is present.

Diff. input, lower pressurereaches the output.

Non Return Valve

1

2

1(3)


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d) Quick Exhaust Valve

Used for quick venting ofwork elements

Become a buster for theactuator.

Non Return Valve

1

2

3


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Example of quickventing valve

Cylinder will expandin normal speed, buthigh speed (buster)when to retract.

Non Return Valve


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Exercise 2

Training aims Indirect actuation of a double acting cylinder Operation of a 5/2 way single pilot valve with

spring return Application of a dual-pressure valve Learning a final control element can be

influenced via an AND connection

Problem description Operating of 2 identical valve by push button

cause the forming tool of an edge foldingdevice to thrust downward and fold over theedge of a flat sheet of cross section area 40X 5.

If bothor even just one push button isreleased, double acting cylinder (1A) slowlyreturn to initial position. The cylinderpressure are indicated.


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Flow control Valve


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Exercise 3

Training aims Direct actuation of a single acting cylinder Operation of a 3/2 way push button Valve with

flow in normal position Realizing that DCV exist both in the normally

close and normally open position Setting one way flow control valve

Problem description The parcel separating device feeds parcel post

from a sloping conveyor slide to an X-rayapplication.

Operating a push button cause very rapidretraction of the single acting cylinder (1A) with

the attached parcel tray. After release the valveactuator, the piston rod advances.

Forward motion time = 0.9 s. a pressure gaugeis fitted before and after the one way flowcontrol valve.


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a) Pressure RegulatingValve with Relief Port

Holds working pressure,

independent of pressurefluctuations in the network andthe air consumption

The inlet pressure must higherthan working pressure

If the working pressureincreases, compressed air

escape through a vent hole

Pressure control Valve


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a) Pressure SequenceValve

As a pneumatic relay.

Set when pilot port exceeds atadjusted pressure value.

Reset back if the pilot pot is

less than preset value.

Pressure control Valve


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Exercise 4

Training aims Indirect actuation of a double acting cylinder Operating a 5/2 way double pilot valve Use of a 3/2 way push button valve Connecting up pressure gauge

Problem description A plastic component is embossed using a

die driven by a double acting cylinder. The die is to advanced and emboss the

plastic when a push button is operated. The return of the die is to be effected when

a preset pressure is reached. The embossing pressure is to be adjustable.


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ADDITIONAL PNEUMATIC

SYSTEM COMPONENT TIMER

COUNTER

SENSORBASIC SEQUENCE

IDLE ROLLER

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