Introduction to Pneumatics

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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 amongst the 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 of pneumatics 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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Advantages of compressed air
AMOUNT Air is available practically everywhere
for compression, in unlimited quantities.
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.
TEMPERATURE Compressed Air is insensitive to
temperature fluctuations. This ensures reliable
operation, even under extreme conditions of
temperature.
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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 is
necessary, 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 cylinders have a working
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 of 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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Summary of Energy Supply
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Summary of Energy Supply
Plant
Compressors are required to compressed the gas to
the desired working pressure for transmission of
power.
Compressor
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Summary of Energy Supply
Plant
Compressed Air Receiver serves to stabilized the
air supply and smoothens pressure fluctuations in
the network when air is consumed.
Receiver
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Summary of Energy Supply
Plant
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.
Service Unit
Piping System
Dryer
Receiver
Compressor
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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 1M³ air is 50 Grams.
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Air Drying (continued)
Absorption Drying
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 no external energy is required. Simple
installation but high operating cost because the
desiccant have to be discarded.
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Air Drying (continued)
Adsorption Drying
Moisture, gases or dissolved materials from the
air deposits on the porous surface of the
desiccant. It is a physical process and
regeneration is possible through hot air flow.
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Summary of Energy Supply
Plant
Service Unit
Piping System
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.
Dryer
Receiver
Compressor
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Installation of Pipelines
Branch Line
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.
Inter-connected System
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Summary of Energy Supply
Plant
Service Unit
Piping System
Compressed air needs good preparation. Dirt and
humidity should be prevented as it may wear
pneumatic components or cause it to malfunction.
Dryer
Receiver
Compressor
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Service Units
Compressed Air Filter
Combined Symbols - Air Service Units
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Filter with Water Trap Manual Control
Outlet
Filters 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.
Inlet
Baffles
Filter Element
Water Trap
Drain
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Service Units
Pressure Regulating Valve with Relief Port
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Pressure Regulator with Relief Port
Outlet
Inlet
Pressure operation
Valve Body
Vent
Spring and Adjusting screw
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Operation of Pressure Regulator with Relief Port
The set screw permits adjustment of the initial
tension in the diaphragm spring. The diaphragm
lifts off the push rod off its seat. The push rod
shuts off the exhaust port in the diaphragm.
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Operation of Pressure Regulator with Relief Port
If the pressure in the volume with the output
port exceeds the set value, the diaphragm moves
down first, shutting off the input port and then
opening the exhaust ports to relieve the excess
pressure.
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Service Units
Compressed Air Lubricator
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Lubricator
Air flows through the lubricator from left to
right. Some of the air flowing through the valve
is guided through a nozzle. Due to the
resulting pressure drop, oil is drawn from an oil
reservoir through a feed pipe.
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Lubricator
The air lubricator is used when -Extremely rapid
oscillating motions are required -With cylinders
with large diameters(?125mm)
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The Structure of Pneumatic Systems
Working elements Cylinders Motors Optical
indicators
Control elements Directional control valves
Processing elements Directional control valves,
Shuttle valves, Dual-pressure valves,
Sequencers, Pressure sequence valves
Signal processing
Input elements Push-button directional control
valves Roller lever valves, Proximity switches,
Air barriers
Signal input
Energy supply elements Compressor Pneumatic
reservoir Pressure regulating valve, Service
units
Energy supply
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System Circuit Diagram
Working element
Control element
Processing element
Input elements
Energy supply elements
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Symbols for the Power Supply Section
Energy Supply
Maintenance
Combined Symbols
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Symbols for Control Elements
Non-return, Flow Control and Pressure Control
Valves
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Symbols for the Principle Working Elements
Linear Actuators
Rotary Drives
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Design Characteristics of Directional Valves
The design principle is a contributory factor
with regards to service life, actuating force,
means of actuation, means of connection, and size.
Valve designs are categorized as follows
Poppet Valves Ball Seat Valve
Poppet Valves Disc Seat Valve
Slide Valves Longitudinal Slide Valve
Slide Valves Longitudinal Flat Slide Valve
Slide Valves Plate Slide Valve (Butterfly Valve)
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Ball Seat Poppet Valve
3/2-Way Valve Ball Bearing Seat, Normally Closed
Position
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Disk Seat Poppet Valve
3/2-Way Valve with Disk Seat, Normally Closed
Position
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Longitudinal Slide Valve
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
for actuation.
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Longitudinal Flat Slide Valve
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.
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SWITCHING SYMBOLS FOR VALVES
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Directional Control Valves Ports and 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
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Valve Connections Labeling
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
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PORT DESIGNATIONS
Port designation in accordance with DIN ISO
5599-3 "Fluid Technology Pneumatics, 5-Way
Valves"
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
1 -Supply port 2, 4 -Working ports 3, 5 -Exhaust
ports
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End of Presentation