ms4.18 Basic Pneumatic System/Tieh SF1 Basic Pneumatics.

ms4.18 Basic Pneumatic System/Tieh SF 1

Basic Pneumatics


Introduction

Air has existed since the beginning of time. Man has harnessed the power of the wind to power many devices. Only in the last century has man used air as power transmission medium


Pneumatics System

Use air under pressureIs a low power systemTransmitting medium is compressibleLeaks are cleanComponents are lighter and less

expensiveAir is cheap


Applications of Pneumatic System

Industrial robots (Automation)Operation of bus doorsOperation of machine toolsOperation of work holding devicesAir tools


Benefits of Compressed Air

Explosion proofFast Easily

transportableEasily storedOverload safeVariable speedVariable pressure

CleanSimple

constructionStroke settingNo return linesWide operating

temperaturesOthers

(compact,light,repair)


A Basic Pneumatics System

Intake air filter

Compressor

After cooler

Air separator

Pressure switch

Safety valve

Air Receiver

Air service unit

Directional valves

Actuators


Filter element

Drain

FILTER

Pneumatic components

Air filter with water separatorTo filter dirt and moisture from the

air line


Air Compressor

It takes in atmospheric air.

Compresses the air so as to increase the air pressure.

Transfers the compressed air into an air receiver.


Simplified representation


Air Service UnitAir filter with water

separatorPressure regulator

with pressure gaugeOil mist lubricator

Detailed representation

Pressure regulating valve

LubricatorFilter

Pressure gauge



Pressure Regulator To reduce the air supply pressure. To keep the outlet pressure constant

even if the outlet air supply pressure fluctuates.

Input (Inlet) pressure must be greater than the output pressure.



Pressure Regulator



Oil mist

DrainVenturi tube

Oil

LUBRICATOR

Oil mist lubricator (Lubricator ) To provide oil mist in

the compressed air so as to lubricate the pneumatic components

Reduce wear of component

Protect from corrosion



Pressure Limiting Valve ( Safety Valve ) To prevent the maximum permissible

pressure in a system from being exceeded

System pressure

Outlet to Atmosphere

System pressure

To atmosphere

Pressure relief valve adjustable


Pneumatic Valves

Flow control valve (throttle relief valve) air flow is throttled in one direction only check valve blocks the flow in one

direction and the air can only pass through the restricted passage

check valve allow the reversed air to by pass the restricted passage

use for speed regulation


Pneumatic Valves

Throttle relief valveAir blocked this direction must go through restriction

1 2 3

4

5

8

76

p

1

p

2

7

Symbol to ISO 1219


Pneumatic Valves

Two pressure valves (AND element) compressed air flows through only if

signals are applied to both inlets the signal which is last applied passes to

the outlet for 2 different input pressure, the smaller

pressure will pass to the outlet for interlocking and safety control, check

function or logic operation


Pneumatic Valves

Check valve stop flow completely in one direction allow full flow in another direction blocking element can be cones, balls,

plates or diaphragms


1 2

3

4

1

Symbol to ISO 1219

Pneumatic Valves

Variable flow control valve (adjustable designed by arrow)


Pneumatic Valves

Shuttle valve (OR element) this is called double control valve or

double check valve air flows to the outlet if pressure is

applied to any of the 2 inlet the pressure which is first applied will

flow to the outlet


Pneumatic Valves

Quick exhaust valve used to increase the piston speeds in

cylinders particularly useful for single acting

cylinder


Pneumatic Valves

Sequence Valve acts as pressure switch where a specific

pressure is required for a switching operation.


Pneumatic Valves

Time Delay Valve

ZZ

P P

R

A

R

A

Normally closed time delay


Pneumatic Valves

Directional Control Valves Examples : 2/2, 3/2, 4/3 way valves To control start, stop, and directional of

air flow so that the cylinder’s movement can be controlled

Start or stop, forward or reduce stroke, clockwise or anti-clockwise rotation of an air motor


Examples:

A) Simplest valve: shut-off valve 2 connections 2 positions ( squares )produces a 2/2 way directional control valve.

B) 3 connections 2 positions ( squares )produces a 3/2 way directional control valve.

P

A

a b

A

P

a b

R


C) 4 connections 2 positions ( squares )produces a 4/2 way directional control valve.

D) 5 connections 2 positions ( squares )produces a 5/2 way directional control valve.

P

a b

R

A B

P

a b

R

A B

R


Pneumatic Lines & Fittings

Transfer the compressed air to different components

Flexible hoses and quick-disconnect couplings are more suitable for equipment which require couple or un-coupled frequently


Pneumatic Lines & Fittings

Things to look into when installing correct dimension of pipes regular maintenance and checking pipelines are installed at a downward

gradient of 1 to 2 % main line should be installed as a ring

circuit where space is available should be easy to install, resistant to

corrosion and inexpensive


Advantages of Pneumatic System

Availability air is practically available every where

in unlimited quantityTransportation

can be easily transported in pipe lines not necessary to return the compress

air



Storage compressor need not be in continuous

operation can be stored in and remove from a

reservoir or cylinder Temperature

insensitive to temperature fluctuation ensure reliable operation



Explosion proof no risk of explosion or fire expensive protection against explosion is

not required Cleanliness

leaking air does not cause contamination suitable for food, wood, textile and

leather industries



Construction simple construction inexpensive

Speed very fast working medium cylinders have working speed of 1 ~ 2

m/s


Disadvantages of Pneumatic System

Preparation require to remove dirt and humidity

Compressible Not possible to achieve uniform and

constant piston speeds.



Force requirement low working loads the require output force is economical

only up to about 20 KN to 30 KN commonly used working pressure of 7

barCost

Expensive to produce



Exhaust air noisy the oil mist with compressed air

escapes with the exhaust to the atmosphere


1 3 2

Symbol to ISO 1219

Silencer


Muffler

Symbol to ISO 1219

Cutaway of a muffler

ms4.18 Basic Pneumatic System/Tieh SF1 Basic Pneumatics.

Documents

air pressure

basic pneumatic systemtieh

air line slide

reversed air

atmospheric air

outlet air supply pressure

system pressure outlet

atmosphere system pressure