Pneumatic systems use compressed air to transmit and control energy. They are commonly used to control things like train doors and production lines. The document discusses the main components of pneumatic systems including compressors, filters, regulators, cylinders, valves and more. It covers the advantages like durability, safety and adaptability to harsh environments, as well as disadvantages like lower accuracy and load capacity compared to other systems. Pneumatic components work together to produce, transport, and use compressed air to generate motion or other effects.

1. PNEUMATIC SYSTEMS
By. Kelvin Elimada Ojango
1.Introduction
Pneumatic system is a system that uses compressed air to
transmit and control energy.
Pneumatic systems are used in controlling train doors,
automatic production lines, mechanical clamps etc
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2. 1.1. ADVANTAGES OF PNEUMATIC SYSTEM
 High effectiveness
 High durability and reliability; Pneumatic components are
extremely durable and can not be damaged easily. Compared to
electromotive components, pneumatic components are more
durable and reliable.
 Simple design ; The designs of pneumatic components are
relatively simple. They are thus more suitable for use in simple
automatic control systems.
 High adaptability to harsh environment; Compared to the
elements of other systems, compressed air is less affected by high
temperature, dust, corrosion, etc. 9/6/2022 2

3. 1.1. ADVANTAGES CONT……………..
 Safety; Pneumatic systems are safer than electromotive systems because
they can work in inflammable environment without causing fire or
explosion.
 Easy selection of speed and pressure; The speeds of rectilinear and
oscillating movement of pneumatic systems are easy to adjust and subject to
few limitations. The pressure and the volume of air can easily be adjusted
by a pressure regulator.
 Environmental friendly; The operation of pneumatic systems do not
produce pollutants. Therefore, pneumatic systems can work in environments
that demand high level of cleanliness.
 Economical; As pneumatic components are not expensive, the costs of
pneumatic systems are quite low. Also the cost of repair is significantly
lower than that of other systems. 9/6/2022
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4. 1.2. DISADVANTAGES OF PNEUMATIC SYSTEM
 Relatively low accuracy -As the volume of air may change when
compressed or heated, the supply of air to the system may not be
accurate, causing a decrease in the overall accuracy of the system.
 Low loading - As the cylinders of pneumatic components are not
very large, a pneumatic system cannot drive loads that are too
heavy.
 Processing required before use -Compressed air must be
processed before use to ensure the absence of water vapour or
dust. Otherwise, the moving parts of the pneumatic components
may wear out quickly due to friction.
 Uneven moving speed- As air can easily be compressed, the
moving speeds of the pistons are relatively uneven.
 Noise - Noise will be produced when compressed air is released
from the pneumatic components.
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5. 2.MAIN COMPONENTS OF PNEUMATIC SYSTEM
 Air filters: These are used to filter out the contaminants from the air.
 Compressor: Compressed air is generated by using air compressors. Air
compressors are either diesel or electrically operated. Based on the
requirement of compressed air, suitable capacity compressors may be used.
 Air cooler: During compression operation, air temperature increases.
Therefore coolers are used to reduce the temperature of the compressed air.
 Dryer: The water vapor or moisture in the air is separated from the air by
using a dryer.
 Control Valves: Control valves are used to regulate, control and monitor for
control of direction flow, pressure etc.
 Air Actuator: Air cylinders and motors are used to obtain the required
movements of mechanical elements of pneumatic system.
 Electric Motor: Transforms electrical energy into mechanical energy. It is
used to drive the compressor.
 Receiver tank: The compressed air coming from the compressor is stored in
the air receiver.
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6. Basic Components of Pneumatic System
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7. 2.1 Receiver tank
The air is compressed slowly in the compressor. But since the
pneumatic system needs continuous supply of air, this compressed
air has to be stored. The compressed air is stored in an air receiver as
shown in Figure below.
The air receiver smoothens the pulsating flow from the compressor.
It also helps the air to cool and condense the moisture present.
The air receiver should be large enough to hold all the air delivered
by the compressor. The pressure in the receiver is held higher than
the system operating pressure to compensate pressure loss in the
pipes. Also the large surface area of the receiver helps in dissipating
the heat from the compressed air.
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8. 2.1 Receiver tank
Generally the size of receiver depends on,
 Delivery volume of compressor.
 Air consumption.
 Pipeline network
 Type and nature of on-off regulation
 Permissible pressure difference in the pipelines
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9. 2.MAIN COMPONENTS OF PNEUMATIC SYSTEM
Pneumatic components can be divided into two categories:
 Components that produce and transport compressed air.
 Components that consume compressed air.
2.2. Components that produce and transport compressed air
Examples of components that produce and transport compressed air
include compressors and pressure regulating components ( Air service
unit)
2.2.1 Compressor- A compressor can compress air to the required
pressures. It can convert the mechanical energy from motors and engines
into the potential energy in compressed air. The compressor increases the
air pressure by reducing its volume which also increases the temperature
of the compressed air.
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10. 2.2.1 Compressor
The compressor is selected based on the pressure it needs to operate and
the delivery volume.
The compressor can be classified into two main types
 Positive displacement compressors and
 Dynamic displacement compressor
a) Positive displacement compressors
Positive displacement compressors include piston type, vane type,
diaphragm type and screw type.
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11. Piston compressors
Piston compressors are commonly used in pneumatic systems. The
simplest form is single cylinder compressor . It produces one pulse of air
per piston stroke. As the piston moves down during the inlet stroke the
inlet valve opens and air is drawn into the cylinder. As the piston moves
up the inlet valve closes and the exhaust valve opens which allows the air
to be expelled. The valves are spring loaded. The single cylinder
compressor gives significant amount of pressure pulses at the outlet port.
The pressure developed is about 3-40 bar.
Single Acting Piston compressor
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12. Double acting piston compressor
The pulsation of air can be reduced by using double acting compressor
as shown in in figure below. It has two sets of valves and a crosshead.
As the piston moves, the air is compressed on one side whilst on the
other side of the piston, the air is sucked in. Due to the reciprocating
action of the piston, the air is compressed and delivered twice in one
piston stroke. Pressure higher than 30bar can be produced.
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13. Multistage compressor
As the pressure of the air increases, its temperature rises. It is essential to reduce the air
temperature to avoid damage of compressor and other mechanical elements. The
multistage compressor with intercooler in-between is shown in below. It is used to
reduce the temperature of compressed air during the compression stages. The inter-
cooling reduces the volume of air which used to increase due to heat. The compressed
air from the first stage enters the intercooler where it is cooled. This air is given as input
to the second stage where it is compressed again. The multistage compressor can
develop a pressure of around 50bar.
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14. Combined two stage compressors
In this type, two-stage compression is carried out by using the same piston.
Initially when the piston moves down, air is sucked in through the inlet
valve. During the compression process, the air moves out of the exhaust
valve into the intercooler. As the piston moves further the stepped head
provided on the piston moves into the cavity thus causing the compression
of air. Then, this is let out by the exhaust port.
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15. Diaphragm compressor
These are small capacity compressors. In piston compressors the lubricating oil from the
pistons walls may contaminate the compressed air. The contamination is undesirable in
food, pharmaceutical and chemical industries. For such applications diaphragm type
compressor can be used. The piston reciprocates by a motor driven crankshaft. As the
piston moves down it pulls the hydraulic fluid down causing the diaphragm to move
along and the air is sucked in. When the piston moves up the fluid pushes the diaphragm
up causing the ejection of air from the outlet port. Since the flexible diaphragm is placed
in between the piston and the air no contamination takes place.
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16. Screw compressor
Piston compressors are used when high pressures and relatively low volume of air is
needed. The system is complex as it has many moving parts. For medium flow and
pressure applications, screw compressor can be used. It is simple in construction with
less number of moving parts. The air delivered is steady with no pressure pulsation. It
has two meshing screws. The air from the inlet is trapped between the meshing screws
and is compressed. The contact between the two meshing surface is minimum, hence no
cooling is required. These systems are quite in operation compared to piston type. The
screws are synchronized by using external timing gears.
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17. Rotary vane compressors
The principle of operation of vane compressor is similar to the hydraulic vane
pump. The unbalanced vane compressor consists of spring loaded vanes eating
in the slots of the rotor. The pumping action occurs due to movement of the
vanes along a cam ring. The rotor is eccentric to the cam ring. As the rotor
rotates, the vanes follow the inner surface of the cam ring. The space between
the vanes decreases near the outlet due to the eccentricity. This causes
compression of the air. These compressors are free from pulsation. If the
eccentricity is zero no flow takes place.
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18. Liquid ring vane compressor
The casing is filled with liquid up to rotor center. The air enters the compressor through
the distributor fixed to the compressor. During the impeller rotation, the liquid will be
centrifuged along the inner ring of the casing to form the liquid ring. There are two suction
and discharge ports provided in the distributor. During the first quarter of cycle, the air is
sucked in both suction chambers of the casing and during the second quarter of the cycle,
the air is compressed and pushed out through the two discharge ports. During the third and
fourth quarters of the cycle, the process is repeated. This type of compressor has no
leakage and has minimal friction. For smooth operation, the rotation speed should be about
3000 rpm. The delivery pressure is low (about 5 bar).
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19. Lobe compressor
The lobe compressor is used when high delivery volume but low pressure is
needed. It consists of two lobes with one being driven and the other driving.
Figure below shows the construction and working of Lobe compressor. It is
similar to the Lobe pump used in hydraulic systems. The operating pressure
is limited by leakage between rotors and housing. As the wear increases
during the operation, the efficiency falls rapidly.
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20. Dynamic compressors
When very large volume of compressed air is required in applications such as
ventilators, combustion system and pneumatic powder blower conveyors, the
dynamic compressor can be used. The pressure needed is very low in such
applications. Figure below shows a typical Centrifugal type blower. The impeller
rotates at a high speed. Large volume of low pressure air can be provided by blowers.
The blowers draw the air in and the impeller flings it out due to centrifugal force.
Positive displacement compressors need oil to lubricate the moving parts, whereas
the dynamic compressors have no such need. The efficiency of these compressors is
better than that of reciprocating types.
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21. 2.2.2 AIR SERVICE UNIT
The Air service unit is a combination of the following
 Filter (with water separator) – can remove impurities from
compressed air before it is fed to the pneumatic components.
 Pressure regulator – to stabilize the pressure and regulate the
operation of pneumatic components
 Lubricator – To provide lubrication for pneumatic components
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22. 2.3.Components that consume compressed air.
Examples of components that consume compressed air include
execution components (cylinders), directional control valves and
assistant valves.
2.3.1 Execution component
Pneumatic execution components provide rectilinear or rotary
movement. Examples of pneumatic execution components include
cylinder pistons, pneumatic motors, etc. Rectilinear motion is produced
by cylinder pistons, while pneumatic motors provide continuous
rotations.
There are many kinds of cylinders, such as single acting cylinders and
double acting cylinders.
Single acting Double acting
Cylinder cylinder 9/6/2022 22

23. 2.3.2 VALVES
The function of valve is to control the pressure or flow rate of pressure
media. Depending on design these can be divided into the following
categories;
 Directional control valves
 Non return valves
 Flow control valves
 Pressure control valves
 Shut off Valves
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24. Directional control Valves
Directional control valve controls the passage of air signals by
generating, cancelling or redirecting signals.
Directional control valves ensure the flow of air between air ports by
opening, closing and switching their internal connections. Their
classification is determined by the number of ports, the number of
switching positions, the normal position of the valve and its method of
operation. Common types of directional control valves include 2/2, 3/2,
5/2, etc.
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25. Directional control Valves symbols
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26. Non return valves
A non-return valve allows air to flow in one direction only. When air
flows in the opposite direction, the valve will close. Another name for
non-return valve is poppet valve.
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27. Flow control valves
Flow control valves restricts or throttles the air in a particular direction
to reduce the flow rate of the air and hence control the signal flow.
A flow control valve is formed by a non-return valve and a variable
throttle.
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28. Pressure control valves
There are three main group of Pressure control valves utilized in
pneumatic systems :-
 Pressure limiting valves
 Pressure regulating valves and
 Pressure sequence valves
Pressure limiting valves are utilized in upstream sides of the
compressor to ensure the receiver pressure is limited, for safety and
that the supply to the system is set to the correct pressure.
Pressure regulating valve keep the pressure constant irrespective of
any pressure fluctuations in the system. The valve regulate the
pressure via a built-in diaphragm. 9/6/2022 28

29. Pressure sequence valves
The Pressure sequence valve is used if a pressure – dependent signal
is required for the advancing of a control system.
When the applied control signal reaches the set pressure, 3/2 – Valve
incorporated at this point is actuated. Conversely, the valve reverses, if
the control signal falls below the set pressure.
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30. Combinations valves
The combined functions of various elements can produce a new
function. An example is the time delay valve which is the combinations
of one way flow control valve , a reservoir and a 3/2 –way directional
control valve.
Other combinational valves include the ; Two-hand start unit, pulse
generator, stepper modules and memory modules. 9/6/2022 30

31. Air Treatment stages.
For satisfactory operation of the pneumatic system the compressed air
needs to be cleaned and dried. Atmospheric air is contaminated with dust,
smoke and is humid. These particles can cause wear of the system
components and presence of moisture may cause corrosion. Hence it is
essential to treat the air to get rid of these impurities.
The air treatment can be divided into three stages as shown in Figure below
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32. Air Treatment stages.
In the first stage, the large sized particles are prevented from entering
the compressor by an intake filter. The air leaving the compressor may
be humid and may be at high temperature.
The air from the compressor is treated in the second stage. In this stage
temperature of the compressed air is lowered using a cooler and the air is
dried using a dryer. Also an inline filter is provided to remove any
contaminant particles present. This treatment is called primary air
treatment.
In the third stage which is the secondary air treatment process, further
filtering is carried out. A lubricator introduces a fine mist of oil into the
compressed air. This will help in lubrication of the moving components
of the system to which the compressed air will be applied.
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33. Pneumatics and control system development.
The product and development in pneumatics can be considered in a
number of areas:
 Actuators
 Sensors and input devices
 Processors
 Accessories
 Control systems.
Structure and Signal flow of pneumatic systems.
Pneumatic systems consist of an interconnection of different group of
elements. This group of elements forms a control path for signal flow,
from the signal section (input) through the actuating section (output)
Control elements control the actuating elements in accordance with the
signals received from the processing elements. 9/6/2022 33

34. Structure and signal flow of pneumatic systems.
The primary levels in pneumatic system are:
 Energy supply
 Input elements
 Processing elements(sensors)
 Control elements
 Power components (actuators).
The elements in the system are represented by symbols which indicate
the functional of the element.
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35. Structure and signal flow of pneumatic systems.
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36. Symbols and descriptions of components.
The symbols used in pneumatics are detailed in the standard DIN ISO
1219 “ Circuit symbols for fluidic equipment and systems.
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37. Symbols and descriptions of components.
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38. Development of single actuator circuit
1.A single-acting cylinder of 25mm diameter is to clamp a
component when a push button is pressed. As long as the push
button is activated, the cylinder is to remain in the clamped position.
If the push button is released, the clamp is to retract. Draw the
circuit diagram for the system, designate the valves and describe the
operations.
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39. Operation of the circuit
On operating the push button the air passes through the valve from
port 1 to 2 via the valve S1 into the piston chamber of the cylinder
1A. The pressure build up and advances the piston rod against the
force of the cylinder return spring. On release of the button, the
valve spring returns the 3/2 way valve to its initial position and the
cylinder retracts. The air returns from the cylinder via the exhaust
port 3.
NOTE
Components which are the only one of their type are designated
without 2 supplementary number since the cylinder is the only
working element in the circuit, it is designated 1A. The service unit
(0Z) and the start-up valve (0S).
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40. Control of Double Acting cylinder
2. A piston of a double-acting cylinder is to move out when a push
button is operated , when the push button is released, the cylinder is
to travel back into the end position.
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41. Control of Double Acting cylinder
Operation
The double acting cylinder can be reversed either by a 4/2-way or a
5/2-way valve.
In the normal position of the 4/2- way valve, P is connected with the
B and A is connected with R. By operating the push button, the
valve reverses, P is connected with A and B with R. The cylinder
piston travels from the rear to the front end position.
In the normal position of the 5/2- way valve, P is connected with the
B and A with R. By operating the push button, the valve reverses, P
is connected with A and B with S. The piston of the cylinder travels
from the rear to the front end position.
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42. Designation of Individual elements.
 Designation by numbers: with this type of designation, elements
are divided into groups. Group 0 contains the elements for the
power supply, groups 1,2….. Designate the individual control
chains. One group number is generally allocated for each cylinder.
 Designation by letters: This type of designation is used primarily
for a systematic development of the circuits diagrams. Here limit
switches are allocated to the cylinder ,which acknowledges them.
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43. Logic functions: AND,OR.
Describe the function using a circuit diagram. The pneumatic shuttle
valve and dual pressure valve have logic functions. Both have two
inputs and one output each. The shuttle valve has a characteristic of
an OR function, whereby at least either of two inputs 1 or 1(3) are
required to generate an output at port 2, of the valve. In the case of
the dual pressure valve, the characteristic is that of the AND
function, whereby both inputs 1 and 1(3) are required to initiate an
output 2.
The logic AND function: Another name for an AND function is
interlock control. This means control is possible only when two
conditions are satisfied. A classic example is a pneumatic system
that works only when its safety door is closed and its manual control
valve is operated. The flow passage will open only when both
control valves are operated. 9/6/2022 43

44. The logic AND function
1.The piston rod of a double acting cylinder is to advance when the 3/2
way roller lever valve is actuated and the push button of the 3/2 way
valve is actuated .If either of these are released then the cylinder is to
return to the initial position.
i. Draw the circuit diagram for the system
ii. Designate the valves
iii. Describe the operations of the system.
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45. The logic AND function
Circuit diagram
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46. The logic AND function
Operation of the system.
From figure above, the input 1 and 1(3) of the dual-pressure valve 1V1 are
connected to the working ports 2 of the valves 1S1 and 1S2. The 3/2 way roller
lever valve 1S2 is actuated by the insertion of a work piece and then creates a
signal at one input of the dual-pressure valve. Since only one input is actuated,
the AND condition has not been fulfilled and the output of the dual-pressure
valve remains closed.
If the push button of the 3/2 way valve 1S1 is now also actuated, a signal will
also be applied at the second input. The AND condition is now fulfilled and a
signal is generated at the output 2 of the dual-pressure valve. The 5/2 way
pneumatic valve 1V2 switches, the piston side of the cylinder is pressurized
and the piston rod advance.
If one of the two valves 1S1 or 1S2 is no longer actuated, then the AND
condition will no longer be fulfilled and the signal at output of the dual-
pressure valve will be reset. The signal pressure at the control port 14 of the
control element 1V2 switches back. The pressure building up on the piston rod
side ensures the retraction of the piston rod 9/6/2022 46

47. The logic AND function
An alternative solution to using the dual pressure valve is to use two 3/2-way
valves in series. Here the signal is passed from the push button valve 1S1 to the
roller lever valve 1S2 and then on to the control element 1V2 but only if both
valves IS1 and 1S2 are operated, i.e. when the AND condition is met. When a
valve is released ,the signal at the control element is reset and the piston rod
retracts.
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48. The logic OR function
1.A double acting is to advance if one of two push button is operated.
If the push button is then released ,the cylinder is to retract.
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49. The logic OR function
Operation
The inputs 1 and 1(3) of the shuttle valve 1V1 are connected to the
working connections of the valves 1S1 and 1S2 .Upon operation of one
of the push buttons, the corresponding valve 1S1 or IS2 is actuated and
a signal is generated at the 1 or 1(3) side of the shuttle valve . The OR
condition is fulfilled and signal passes through the shuttle valve and is
emitted at port 2. The signal pressure is prevented from escaping via
exhaust of the unactuated valve by closing the line in the shuttle valve
.The signal effects the switching of the control element via 1V2. The
piston side of the cylinder is pressurized and the piston rod advances.
When the actuated push button is released, the signal pressure is
relieved via the valves 1S1 and 1S2 and the control element is switched
back to its initial position. The pressure now building up on the piston
rod side ensures the retraction of the piston rod.
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50. The logic OR function
2. The piston rod of a double acting pneumatic cylinder travels out if
either push button or a foot pedal is operated. The cylinder return to its
starting position after fully extending. The piston rod will return
provided the manual actuators have been released.
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51. The logic OR function
3.A cylinder is used to transfer parts from a magazine. If either a
pushbutton or a foot pedal is operated, then the cylinder is to extend.
Once the cylinder is fully extended, it is to retract to the initial position. A
3/2 way roller lever is to be used to detect the full extensions of the
cylinder.
i. Draw the circuit diagram for the system
ii. Designate the valves
iii. Describe the operations of the system.
Solution.
The pneumatic components which can be used to implement the
mentioned task are as follows:
Double acting cylinder ,3/2 push button valve ,3/2 roller valve shuttle
valve ,3/2 foot pedal actuated valve ,5/3 pneumatic actuated direction
control valve and compressed air source and connecting piping
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52. The logic OR function
Circuit diagram
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53. The logic OR function
Operation
Figure above shows the proposed circuit diagram. As the problem stated,
upon actuation of either the push button of valve (S1) or the foot pedal
valve (S2), a signal is generated at 1 or 1(3) side of the shuttle valve. The
OR condition is met and the signal is passed to the control port 14 of the
direction control valve (V2). Due to this signal, the left position of V2 is
actuated and the flow of air starts. Pressure is applied on the piston side
of the cylinder (A) and the cylinder extends. If the push button or pedal
valve is released, the signal at the direction control valve (V2) port is
reset. Since DCV (V2) is a double pilot valve, it has a memory function
which doesn’t allow switching of positions. As the piston reaches the rod
end position, the roller valve (S3) is actuated and a signal is applied to
port 12 of the DCV (V2). This causes actuation of right side of DCV
(V2). Due to this actuation, the flow enters at the rod-end side of the
cylinder, which pushes the piston towards left and thus the cylinder
retracts. 9/6/2022 53

54. Memory Circuit and Speed control of a cylinder.
Memory is a common basic function. It can keep a component at a
certain state permanently until there is a change of signals. Fig. below
shows a memory function circuit. When control valve (1) is operated
momentarily (that is, pressed for a short time), the output signal of the
5/2 directional control valve (3) will be set to ON. The signal will stay
that way until control valve (2) is operated momentarily and generates
another signal to replace it, causing it to stay permanently at OFF.
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55. Memory Circuit and Speed control of a cylinder.
1.The piston rod of a double acting cylinder is to advance when a 3/2 way push button
valve is actuated manually . The cylinder is to remain advanced until a second valve is
actuated. The signal of the second valve can only take effect after the first valve has been
released. The cylinder is to then return to the initial position. The cylinder is to remain in
the initial position until a new start signal is given. The speed of the cylinder is to be
adjustable in both directions.
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56. Memory Circuit and Speed control of a cylinder.
Solution.
4/2-way or 5/2-way double pilot valves posses the required memory
function. The valve retains its last switched position until an opposing
signal is received. This characteristics is independent of the line period, for
which the signal is applied to the switching valve.
The one way flow control valves control the cylinder speed in both
directions and are independently adjustable. Since the displaced air flow is
restricted in each case , this is an exhaust air flow control.
In the initial position ,the control element 1V1 is switched in such a way
that the piston rod side of the cylinder is pressurized and the cylinder is in
the retracted state.
Upon operation of the push button, the valve 1S1 is actuated ,so that a
signal is generated at the pilot port 14 of the control element 1V1. The
control element 1V1 switches, the piston side of the cylinder is pressurized
and the piston rod advances. Whilst the supply air flows unrestricted
through the one way flow control valve 1V2,the air displaced via the one-
way flow control valve 1V3 on the piston side is restricted. The advancing
speed of the piston rod is therefore reduced.
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57. Memory Circuit and Speed control of a cylinder.
The switching status of the valve 1V1 is maintained, if the valve 1S1 is
released, since this is a memory valve. If the valve 1S2 is actuated, a
signal is generated at the control port 12 of the control element. The valve
switches, pressure is applied at the piston rod side of the cylinder and the
piston rod retracts. Exhaust air flow control is effected via the one way
flow control valve 1V2. If the valve 1S2 is released, the switching
position of the control element 1V1 is maintained due to its memory
function.
The supply air is transferred through the by-pass check valve of the flow
control valves, giving unrestricted supply to the cylinder. The flow
control influences the volumetric flow rate of the exhaust air and as such
the piston speed. Due to the different volumes of air to be displaced on
the piston side and on the piston rod side, the restrictors must be set at
different levels to obtain the same retracting and advancing speed.
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58. Pressure dependent control
1. A plastic component is embossed using a die driven by a double-
acting cylinder. The die is to advance 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.
Positional sketch
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59. Pressure dependent control
Circuit diagram
9/6/2022 59

60. Pressure dependent control
Operation of the circuit
If the piston rod is not in its initial position, the circuit must be reset
by operating the manual override on the 5/2-way double pilot valve.
All valves are unactuated in the initial position, pressure is applied at
the piston rod side of the cylinder and the piston rod remains in the
retracted state.
Actuation of the push button switches the valve 1S to flow and a
signal is applied at the control port 14 of the double pilot valve 1V2.
The valve 1V2 switches, pressure is applied at the piston side of the
cylinder and the piston rod advances. The switching status of the
double pilot valve 1V2 remains intact if the push button 1S is released.
When the piston rod reaches the workpiece, travel is stopped and
pressure starts to build up on the piston side. The increasing pressure
causes the force of the die to increase. 9/6/2022 60

61. Pressure dependent control
The control port 12 of the pressure sequence valve 1V1 is connected to
the pressure line on the piston side of the cylinder 1A. When the
pressure in the cylinder reaches the value set on the pressure sequence
valve, the 3/2-way valve switches. A signal is now applied at the
control port 12 of the valve 1V2. The valve 1V2 switches, pressure is
applied at the piston rod side of the cylinder and the piston rod retracts.
During retraction, the response pressure set on the pressure sequence
valve is not met and the pressure sequence valve returns to its initial
position.
The response pressure set on the pressure sequence valve must be lower
than the system pressure in order to ensure reliable switching.
Should the advancing piston rod meet an obstacle ,then it will retract
again before reaching the embossing position.
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62. Delay function (The time delay valve)
A pneumatic delay circuit can delay the operating time of the next control
valve. Its principle of operation involves the use of an orifice to slow down
the flow of air and control the time of pneumatic operation.
Delay functions can be divided into two classes: ON-signal delay and OFF-
signal delay.
1. A double acting cylinder is used to press together glued components.
Upon operation of a push button, the clamping cylinder extends. Once
the fully advanced position is reached, the cylinder is to remain for a time
of T= 6 seconds and then immediately retract to the initial position . The
cylinder retraction is to be adjustable. A new start cycle is only possible
after the cylinder has fully retracted.
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63. Delay function (The time delay valve)
Circuit diagram
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64. Delay function (The time delay valve)
Solution
In the initial position, all valves with the exceptional of the roller lever
valve 1S2 (limit switch) are unactuated. Pressure is applied at the
piston rod side of the cylinder and the piston rod remains in the
retracted state.
Valve 1S1 and the limit switch 1S2 must be actuated as a start
condition. The limit switch 1S2 is not actuated unless the piston rod is
in its initial position. If the start condition is fulfilled, the dual pressure
valve 1V1 is switched to flow and a signal is applied at the control port
14 of the double pilot valve 1V3. The valve 1V3 reverses, pressure is
applied at the piston side of the cylinder and the piston rod advances.
The advancing speed is dependent on the setting of the one- way flow
control valve 1V5 (exhaust air control). After a short advancing travel,
the piston rod releases the limit switch 1S2. 9/6/2022 64

65. Delay function (The time delay valve)
Following this, the AND condition at the dual pressure valve 1V1 is no longer
met and the signal at the control port 14 of the double pilot valve 1V3 is reset,
whilst its switching position ( stored) does not change. A renewed actuation of
the valve 1S1 is now ineffective until the system has reached its initial status
again. When the embossing position is reached, the limit switch 1S3 is
actuated. The air reservoir in the time delay valve 1V2 starts filling up via the
integrated one- way flow control valve. The rate of pressure increase is
dependent on the setting of the integrated restrictor. When the pressure is
sufficiently high, the 3/2- way valve switches and a signal is applied at the
control port 12 of the double pilot valve 1V3. The valve 1V3 reverses, pressure
is applied at the piston rod side of the cylinder and the piston rod retracts. The
retracting speed is dependent on the setting of the one-way flow control valve
1V4.
When retracting, the limit switch 1S3 reverses and the air reservoir of the time
delay valve 1V2 is exhausted to atmosphere via the non- return valve and the
limit switch 1S3. As result of this, the 3/2-way valve of the time delay valve
switches into its initial position. The signal at the control port 12 of the double
pilot valve 1V3 is then reset. When the piston rod reaches its initial position,
the limit switch 1S2 is actuated and a new cycle can be started.
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66. T-piece
 A T-piece or T-connector is a very simple component
that lets us split or divide airflow. It can be very useful if
you want two cylinders to operate at the same time.
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67. Safety in pneumatic systems.
Environmental pollution
Two forms of environmental pollution may occur in pneumatic
systems :
 Noise: caused by the escape of compressed air.
 Oil mist: caused by lubricants which have been introduced at the
compressor or via a service unit and which are discharged into the
atmosphere during the exhaust cycles.
Exhaust noise: Measure must be taken against excessive noise. This
can be achieved by means of:
Exhaust silencers and fit manifolds with connections to the exhaust
ports of the power valves
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68. Exhaust silencers
 Exhaust silencers: silencers are used to reduce the noise at the
exhaust ports of valve. They operate on the principle of exhaust air
flow control by creating a greater or less flow resistance. Normal
silencers have only limited in influence on the speed of the piston rod
while in case of throttle silencers, however the flow resistance is
adjustable .These silencers are used to control the speed of the cylinder
piston rod.
In the case of throttle silencers, however the flow resistance is
adjustable. These silencers are used to control the speed of the cylinder
piston rod.
 Another method of noise reduction is to fit manifolds with
connections to the exhaust ports of the power valves and thus to
discharge the air via a large common silencer.
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