ms4.18 basic pneumatic system/tieh sf1 basic pneumatics
TRANSCRIPT
ms4.18 Basic Pneumatic System/Tieh SF 2
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
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Pneumatics System
Use air under pressureIs a low power systemTransmitting medium is compressibleLeaks are cleanComponents are lighter and less
expensiveAir is cheap
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Applications of Pneumatic System
Industrial robots (Automation)Operation of bus doorsOperation of machine toolsOperation of work holding devicesAir tools
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Benefits of Compressed Air
Explosion proofFast Easily
transportableEasily storedOverload safeVariable speedVariable pressure
CleanSimple
constructionStroke settingNo return linesWide operating
temperaturesOthers
(compact,light,repair)
ms4.18 Basic Pneumatic System/Tieh SF 6
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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Filter element
Drain
FILTER
Pneumatic components
Air filter with water separatorTo filter dirt and moisture from the
air line
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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.
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Simplified representation
Pneumatic components
Air Service UnitAir filter with water
separatorPressure regulator
with pressure gaugeOil mist lubricator
Detailed representation
Pressure regulating valve
LubricatorFilter
Pressure gauge
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Pneumatic components
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.
ms4.18 Basic Pneumatic System/Tieh SF 12
Pneumatic components
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
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Pneumatic components
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
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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
ms4.18 Basic Pneumatic System/Tieh SF 15
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
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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
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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
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1 2
3
4
1
Symbol to ISO 1219
Pneumatic Valves
Variable flow control valve (adjustable designed by arrow)
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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
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Pneumatic Valves
Quick exhaust valve used to increase the piston speeds in
cylinders particularly useful for single acting
cylinder
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Pneumatic Valves
Sequence Valve acts as pressure switch where a specific
pressure is required for a switching operation.
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Pneumatic Valves
Time Delay Valve
ZZ
P P
R
A
R
A
Normally closed time delay
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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
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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
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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
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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
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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
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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
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Advantages of Pneumatic System
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
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Advantages of Pneumatic System
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
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Advantages of Pneumatic System
Construction simple construction inexpensive
Speed very fast working medium cylinders have working speed of 1 ~ 2
m/s
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Disadvantages of Pneumatic System
Preparation require to remove dirt and humidity
Compressible Not possible to achieve uniform and
constant piston speeds.
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Disadvantages of Pneumatic System
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
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Disadvantages of Pneumatic System
Exhaust air noisy the oil mist with compressed air
escapes with the exhaust to the atmosphere