pneumatic system
AA-
15FMCE220PneumaticandHydraulicsystemspart112.pptxPneumatics has long since played an important role as a technology in the performance of mechanical work. It is also used in the development of automation solutions.
Pneumatic components can perform the following types of motion:
1-Linear
2-Rotary
1
Note here that it is important to talk about the importance of pneumatic systems and the wide use of this system in industry. Also Talk about how long have humans used pneumatic system way before the industrial revolution, by citing the examples of sailing and wind mill as the most primitive pneumatic system
1
2
In this slide we talk about the diversity of the pneumatic system application and also the different way to classify these systems
2
Pneumatic Tools
3
Pneumatic systems is not limited to heavy equipment but also can be used in small tools
3
Pneumatic Tools
4
Disadvantage's
5
It is important to mention that every system has advantages and disadvantages and based on the importance of this two, we will choose whether to use this system or not.
5
Symbols single acting actuators
Single acting actuator, spring in stroked
Single acting actuator, spring outstroke
Single acting actuator, spring in stroked, magnetic
Single acting actuator, spring outstroked, magnetic
6
It is important for students to learn the different components used in pneumatic systems ( full name of the components and their symbole)
6
Symbols double acting actuators
Double acting actuator, non-cushioned
Double acting actuator, adjustable cushions
Double acting actuator, through rod, adjustable cushions
Double acting actuator, magnetic, adjustable cushions
Double acting actuator, rodless, magnetic, adjustable cushions
7
Symbols rotary actuators
Semi-rotary double acting actuator
Rotary motor single direction of rotation
Rotary motor bi-directional
8
8
Symbols valves
2/2 Valve push button / spring
3/2 Valve push button / spring
3/2 Valve detented lever operated
2
3
1
12
10
2
10
12
1
1
2
3
12
10
9
This symbol for the
exhaust port
This symbol for the
pressurized air from the compressor
The valve in pneumatic system are governed by specific standard. Valves are represented by both full names and symbols which contains standard number. In this slide, just mention the difference between the compressor and the exhaust in symbol and function. Also mention that the exhaust is not a physical component but just a symbolic representation of it is function.
9
Symbols valves
3/2 Valve differential pressure operated
5/2 Valve push button / spring
5/3 Valve double pressure operated spring centre
1
2
4
5
3
14
12
1
2
4
5
3
1
2
3
12
10
10
As standard:
Port 1 : for the compressor
Ports 3 & 5 : for the exhaust (odd No.)
Ports 2 & 4 : for the cylinder (even No.)
Ports 10 ,12 ,14 ,…etc : for the control signals
In this slide we will talk about the number used in the valve symbol and what they mean
10
Directional control valves can be classified according to:
Number of ports
Number of positions
Actuating methods (later on)
Example: A 3/2 directional control valve would have three ports and two spool positions. Ports No. / Position No.
Number of Ports
According to total number of entries or exits connected to the valve through which fluid can enter the valve or leave the valve there are types like two way, three way, four way valves.
Number of Positions
Including the normal and working positions which a valve spool can take there are types like two position, three position and proportional valves.
11
In this slide we talk about how do we name the valves. Make sure to insist that we can only use one position at a time not both, so either we connect the pipeline to the right position or to the left position but we can not mix.
11
Test
12
2/2 DCV
4/3 DCV
3/2 DCV
4/2 Roller/Spring DCV
Use this slide to test whether the students understood the naming standard or not.
12
Interaction of components (Animation)
13
13
This slide though it is taken from hydraulic system but the principle is still the same. Use this slide to explain how the valve work from the inside and why it is important to understand how many port and how many position do we have access to in each valve. The few slides coming forth are animation to this slide
Interaction of components (Animation)
14
14
Interaction of components (Animation)
15
15
Interaction of components (Animation)
16
16
Interaction of components (Animation)
17
17
Interaction of components (Animation)
18
18
Interaction of components (Animation)
19
19
Interaction of components (Animation)
20
20
Symbols valves
A valve function is known by a pair of numbers e.g. 3/2. This indicates the valve has 3 main ports and 2 states
The valve symbol shows both of the states
Port numbering is to CETOP RP68P and shows:
when the valve is operated at the 12 end port 1 is connected to port 2
when reset to the normal state at the 10 end port 1 is connected to nothing (0)
2
3
1
12
10
21
Insist on Port numbering is following standard CETOP RP68P
21
Symbols valves
A valve function is known by a pair of numbers e.g. 3/2. This indicates the valve has 3 main ports and 2 states
The valve symbol shows both of the states
Port numbering is to CETOP RP68P and shows:
when the valve is operated at the 12 end port 1 is connected to port 2
when reset to the normal state at the 10 end port 1 is connected to nothing (0)
2
3
1
12
10
22
Symbols valves
This example is for a 5/2 valve
It has 5 main ports and 2 states
When the valve is operated at the 14 end port 1 is connected to port 4 (also port 2 is connected to port 3)
When reset to the normal state at the 12 end port 1 is connected to port 2 (also port 4 is connected to port 5)
1
2
4
5
3
14
12
23
Symbols valves
This example is for a 5/2 valve
It has 5 main ports and 2 states
When the valve is operated at the 14 end port 1 is connected to port 4 (also port 2 is connected to port 3)
When reset to the normal state at the 12 end port 1 is connected to port 2 (also port 4 is connected to port 5)
1
2
4
5
3
14
12
24
Symbols operators manual
General manual
Push button
Pull button
Push/pull button
Lever
Pedal
Treadle
Rotary knob
25
25
27
Go through the different type of valve activation mechanism
Symbols operators mechanical
Plunger
Spring normally as a return
Roller
Uni-direction or one way trip
Pressure
Pilot pressure
Differential pressure
Detent in 3 positions
26
26
27
OR / Shuttle Valve
Activated when any of its sides activated
27
A shuttle valve permits the combination of two signals into OR function. An output signal is generated , if pressure is applied at one of two inputs.
AND/Dual Pressure Line
28
A Dual valve permits the combination of two signals into AND function. An output signal is generated , if pressure is applied at the two inputs in the same time.
X
Y
Symbols function components
Non-return valve
Flow regulator bi-directional
Flow regulator uni-directional
Silencer
Quick exhaust valve with silencer
Pressure to electric switch adjustable
29
Symbols air line equipment
Water separator with automatic drain
Filter with manual drain
Filter with automatic drain
Filter with automatic drain and service indicator
Lubricator
Pressure regulator with gauge
F.R.L. filter, regulator, lubricator simplified symbol
30
Circuit layout
The standard for circuit diagrams is ISO 1219-2
A4 format or A3 folded to A4 height for inclusion in a manual with other A4 documentation
To be on several sheets if necessary with line identification code
Minimum crossing lines
Limit valves position of operation by actuators shown by a marker with reference code to symbol
Circuits should be drawn with all actuators at the top of the page in order of sequential operation
Other components to be drawn in sequential order from the bottom up and from left to right
Circuit should show the system with pressure applied and ready to start
31
Make sure you mention the standard use in circuit diagram ISO 1219-2. Here we need to talk about the information that we can extract from the circuit diagram even if we don’t know anything about the circuit, like the working order of the actuator.
31
Example of Circuit
32
No need for the students to understand the circuit or how it works but it is important that they see the standard rules applied to this circuit, like actuators naming, markers, rollers naming and the sequence order.
32
Component identification
The ISO suggested component numbering system is suited for large circuits and those drawn on several pages
For this presentation a simple code is used
For cylinders: A,B,C etc.
For associated feedback valves: alpha-numeric code ‘a0’ for proof of instroke, ‘a1’ for proof of outstroke
For cylinder B: b0 and b1
Note: the a0 valve symbol is drawn in the operated position because the actuator A is instroked
A
a0
a1
1
2
3
12
10
a0
2
1
3
12
10
a1
33
It is important here to mention that every roller has a unique name and that the marker existence and the roller existence are strongly related. It is either they exist or don’t, as need of course
33
34
Example of automatic System
35
Animation, not clear on printed version
a0
a1
Actuator control 2/2 valve
36
2/2 Valve actuator control
A pair of the most basic of all valve types the 2/2 can be used to control a single acting cylinder
The normally closed position of the valve is produced by the spring
The operated position is produced by the push button
One valve admits air the other valve exhausts it
2
10
12
1
1
10
12
2
OUT
IN
37
2/2 Valve actuator control
The button marked OUT is pushed to operate the valve
Air is connected to the cylinder and it outstrokes
Air cannot escape to atmosphere through the valve marked IN as this is closed
The air at atmospheric pressure in the front of the cylinder vents through the breather port
2
10
1
12
1
10
12
2
OUT
IN
38
2/2 Valve actuator control
The push button of the valve marked OUT is released and it returns to a normal closed position
Air is now trapped in the system and provided there are no leaks the piston rod will stay in the outstroked position
If the load increases beyond the force exerted by the air the piston rod will start to move in
2
10
1
12
1
10
12
2
OUT
IN
39
2/2 Valve actuator control
The button marked IN is pushed to operate the valve
Air escapes and the piston rod moves to the instroked position
The push button must be held operated until the piston rod is fully in
Atmospheric air will be drawn in to the front of the cylinder through the vent port
2
10
1
12
1
2
10
12
OUT
IN
40
2/2 Valve actuator control
If the button marked IN is released the piston rod will remain in the instroked position
Any leaks in the installation can cause the piston rod to creep
2
10
1
12
1
2
10
12
OUT
IN
41
2/2 Valve actuator control
Adjustment of the flow regulator will slow down the flow rate thereby giving independent outstroke and instroke speed control
10
12
10
12
OUT
IN
2
1
1
2
42
42
Here talk about the different way to control the speed of the actuator in instroke and outstroke.
2/2 Valve actuator control
By repeated operation of either button during movement the piston rod can be moved in small steps for approximate positioning
This will only be successful under slow speeds
10
12
10
12
OUT
IN
2
1
1
2
43
2/2 Valve actuator control
With any compressed air system that intentionally traps air, the potential hazard of this must be recognised
Unintended release or application of pressure can give rise to unexpected movement of the piston rod
A pressure indicator or gauge must be fitted to warn of the presence of high pressure
2
10
1
12
1
2
10
12
OUT
IN
44
For any reason we might not be able to see if there is a high pressure in the system or not. Example, actuator blocked by load or by friction or by any other reason. For safety reason, we need to be able to see it. Pressure indicator will tell us if there is a high pressure or not.
44
Actuator control 3/2 valve
45
3/2 valve actuator control
A 3 port valve provides the inlet and exhaust path and is the normal choice for the control of a single acting cylinder
In the normal position produced by the spring, the valve is closed
In the operated position produced by the push button the valve is open
The push button must be held down for as long as the cylinder is outstroked
1
2
3
12
10
46
Mention that 3/2 has two direction of air flow, which makes it easier to control actuators. Also mention that 3/2 and 2/2 are only used with single acting actuators
46
3/2 valve actuator control
A 3 port valve provides the inlet and exhaust path and is the normal choice for the control of a single acting cylinder
In the normal position produced by the spring, the valve is closed
In the operated position produced by the push button the valve is open
The push button must be held down for as long as the cylinder is outstroked
1
2
3
12
10
47
3/2 valve actuator control
A 3 port valve provides the inlet and exhaust path and is the normal choice for the control of a single acting cylinder
In the normal position produced by the spring, the valve is closed
In the operated position produced by the push button the valve is open
The push button must be held down for as long as the cylinder is outstroked
1
2
3
12
10
48
3/2 valve actuator control
To generally slow the cylinder speed an adjustable or fixed bi-directional flow regulator can be used
The flow regulator setting will be a compromise as the ideal outstroke speed may not produce the desired results for the instroke speed
1
2
3
12
10
49
3/2 valve actuator control
To control the outstroke speed of a single acting cylinder without controlling the instroke speed, a uni-directional flow regulator is used
The flow into the cylinder closes the non return valve and can only pass through the adjustable restrictor
By adjusting the flow regulator, the outstroke speed of the cylinder can be set
1
2
3
12
10
50
3/2 valve actuator control
For independent speed control in each direction two flow regulators are required
Installed in opposite directions to each other
Upper regulator controls the outstroke speed
Lower regulator controls the instroking speed
1
2
3
12
10
51
Actuator control 5/2 valve
52
5/2 Valve actuator control
For a double acting cylinder the power and exhaust paths are switched simultaneously
When the button is pushed the supply at port 1 is connected to port 4 and the outlet port 2 connected to exhaust port 3. The cylinder moves plus
When the button is released port 1 is connected to port 2 and port 4 connected to port 5. Cylinder minus
1
2
4
5
3
14
12
+
-
53
5/2 valve has two line, one for the outstroke and another one for the instroke. Also it can not be used with single acting actuator.
53
5/2 Valve actuator control
For a double acting cylinder the power and exhaust paths are switched simultaneously
When the button is pushed the supply at port 1 is connected to port 4 and the outlet port 2 connected to exhaust port 3. The cylinder moves plus
When the button is released port 1 is connected to port 2 and port 4 connected to port 5. Cylinder minus
1
2
4
5
3
14
12
+
-
54
5/2 Valve actuator control
Independent speed control of the plus and minus movements
In most applications speed is controlled by restricting air out of a cylinder
Full power is developed to drive the piston with speed controlled by restricting the back pressure
1
2
4
5
3
14
12
+
-
55
It is important for students to recognize which flow regulator control the instroke and the outstroke. The picture here show a reverse logic control. The flow regulator located on the outstroke line actually control the instroke speed, and vice versa. If we want to use the direct logic, all what we have to do is to flip the two flow regulators vertically. It is important to insist that the students draw the flow regulator in every single circuit unless they are asked specifically to control one direction and also the danger of drawing the flow regulator in the wrong way.
55
5/2 Valve actuator control
Independent speed control of the plus and minus movements
In most applications speed is controlled by restricting air out of a cylinder
Full power is developed to drive the piston with speed controlled by restricting the back pressure
1
2
4
5
3
14
12
+
-
56
5/2 Valve actuator control
Valves with a spring return are mono-stable and need the operator to be held all the time that the cylinder is required in the plus position
Bi-stable valves will stay in the position they were last set
The lever valve example illustrated indicates a detent mechanism. The lever need not be held once the new position has been established
1
2
4
5
3
14
12
+
-
57
Manual control
Remote manual control of a double acting cylinder
Valve marked + will cause the cylinder to outstroke or move plus (A+)
Valve marked - will cause the cylinder to instroke or move minus (A-)
The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed
1
2
4
5
3
14
12
1
2
3
12
10
1
2
3
12
10
+
-
+
-
58
Give an example for this: door opening, manual open the door, manual close the door using pneumatic actuator. Mention that once the signal is sent, it can not be retracted.
58
Manual control
Remote manual control of a double acting cylinder
Valve marked + will cause the cylinder to outstroke or move plus (A+)
Valve marked - will cause the cylinder to instroke or move minus (A-)
The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed
1
2
4
5
3
1
2
3
12
10
1
2
3
12
10
14
12
+
-
+
-
59
Manual control
Remote manual control of a double acting cylinder
Valve marked + will cause the cylinder to outstroke or move plus (A+)
Valve marked - will cause the cylinder to instroke or move minus (A-)
The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed
1
2
4
5
3
1
2
3
12
10
1
2
3
12
10
14
12
+
-
+
-
60
Manual control
Remote manual control of a double acting cylinder
Valve marked + will cause the cylinder to outstroke or move plus (A+)
Valve marked - will cause the cylinder to instroke or move minus (A-)
The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed
1
2
4
5
3
14
12
1
2
3
12
10
1
2
3
12
10
+
-
+
-
61
Manual control
Remote manual control of a double acting cylinder
Valve marked + will cause the cylinder to outstroke or move plus (A+)
Valve marked - will cause the cylinder to instroke or move minus (A-)
The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed
1
2
4
5
3
14
12
1
2
3
12
10
1
2
3
12
10
+
-
+
-
62
Semi-automatic control
Manual remote start of a double acting cylinder with automatic return
Cylinder identified as “A”
Trip valve operated at the completion of the plus stroke identified as “a1”
1
2
4
5
3
14
12
1
2
3
12
10
1
2
3
12
10
+
-
+
-
A
a1
a1
63
Here mention that at least one action should be executed manually, and the number of roller required will depends on how many automatic action should be executed.
63
Fully-automatic control
Continuous automatic cycling from roller operated trip valves
Manual Run and End of the automatic cycling
Cylinder will come to rest in the instroked position regardless of when the valve is put to End
Tags for the roller feedback valves a0 and a1 show their relative positions
1
2
4
5
3
14
12
2
1
3
12
10
1
2
3
12
10
1
2
3
12
10
Run/End
+
-
A
a0
a1
a0
a1
64
In fully automatic, all the action are executed automatically, and the existence or the manual valve is only to start the cycle not to execute one of the actions. Also give the example of A-A+ here
64
Logic functions
65
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
12
10
1
2
3
12
10
X
Y
Z
66
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
12
10
1
2
3
X
Y
Z
12
10
67
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
12
10
1
2
3
12
10
X
Y
Z
68
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
1
2
3
12
10
X
Y
Z
12
10
69
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
1
2
3
X
Y
Z
12
10
12
10
70
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
1
2
3
12
10
X
Y
Z
12
10
71
Logic AND
To obtain the output Z both plungers X AND Y must be operated and held
If X only is operated the air will be blocked at port 1 in valve Y
If Y only is operated there will be no pressure available at port 1
If either X or Y is released the output signal Z will be lost
1
2
3
12
10
1
2
3
12
10
X
Y
Z
72
Logic AND
This method must not be used as a two handed safety control
It is too easy to abuse. e.g. one of the buttons could be permanently fixed down and the system operated from the other button only
Use the purpose designed two handed safety control unit
1
2
3
12
10
1
2
3
12
10
X
Y
Z
73
Logic OR
Use of an ‘OR’ function shuttle valve
Source X and Y can be remote from each other and remote from the destination of Z
When X or Y is operated the shuttle valve seal moves across to prevent the signal Z from being lost through the exhaust of the other valve
X
Y
Z
1
2
3
12
10
1
2
3
12
10
74
Give the truth table for everyone of this logic functions
74
Logic OR
Use of an ‘OR’ function shuttle valve
Source X and Y can be remote from each other and remote from the destination of Z
When X or Y is operated the shuttle valve seal moves across to prevent the signal Z from being lost through the exhaust of the other valve
X
Y
Z
1
2
3
12
10
1
2
3
12
10
75
Logic OR
Use of an ‘OR’ function shuttle valve
Source X and Y can be remote from each other and remote from the destination of Z
When X or Y is operated the shuttle valve seal moves across to prevent the signal Z from being lost through the exhaust of the other valve
X
Y
Z
1
2
3
12
10
1
2
3
12
10
76
Logic OR
Use of an ‘OR’ function shuttle valve
Source X and Y can be remote from each other and remote from the destination of Z
When X or Y is operated the shuttle valve seal moves across to prevent the signal Z from being lost through the exhaust of the other valve
X
Y
Z
1
2
3
12
10
1
2
3
12
10
77
Logic OR
Use of an ‘OR’ function shuttle valve
Source X and Y can be remote from each other and remote from the destination of Z
When X or Y is operated the shuttle valve seal moves across to prevent the signal Z from being lost through the exhaust of the other valve
X
Y
Z
1
2
3
12
10
1
2
3
12
10
78
Logic NOT
A logic NOT applies to the state of the output when the operating signal is present (the output is simply an inversion of the operating signal)
The valve shown is a normally open type
When the signal X is present there is NOT output Z
When X is removed output Z is given
2
3
1
12
10
Z
X
79
Logic NOT
A logic NOT applies to the state of the output when the operating signal is present (the output is simply an inversion of the operating signal)
The valve shown is a normally open type
When the signal X is present there is NOT output Z
When X is removed output Z is given
2
3
1
12
10
Z
X
80
Logic NOT
A logic NOT applies to the state of the output when the operating signal is present (the output is simply an inversion of the operating signal)
The valve shown is a normally open type
When the signal X is present there is NOT output Z
When X is removed output Z is given
2
3
1
12
10
Z
X
81
Give the truth table for the NOT function. Notice that the 3/2 valve used in the NOT function is different then the regular 3/2 valve. This will be presented in the next slide
81
82
3/2 NO / NC
A single valve can be used normally open or normally closed
For normally open the air flows naturally without any action from the operator
For normally closed the the pressure can not flow unless the operator activate the valve.
1
2
3
12
10
2
3
1
12
10
83
3/2 NO / NC
A single valve can be used normally open or normally closed
For normally open the air flows naturally without any action from the operator
For normally closed the the pressure can not flow unless the operator activate the valve.
1
2
3
12
10
2
3
1
12
10
84
3/2 Valve selection / diversion
Selection of one of two supplies connected to ports 1 and 3. It can be different pressures or different flow rate.
Diversion of one supply to one of two outlets. It can be for different process or different circuits.
2
1
3
12
10
1
2
3
12
10
85
3/2 Valve selection / diversion
Selection of one of two supplies connected to ports 1 and 3. It can be different pressures or different flow rate.
Diversion of one supply to one of two outlets. It can be for different process or different circuits.
2
1
3
12
10
1
2
3
12
10
OR, AND, NOT
A single 3/2 pilot operated spring return valve can be use for any of these logic functions
x OR y gives output z
x AND y gives output z
x gives NOT z
1
2
3
12
10
1
2
3
12
10
3
2
1
12
10
AND
OR
NOT
x
y
z
x
y
z
x
z
86
Notice that the OR function use a selection valve connected in the right way. OR function can not be called a selection valve and vice versa
86
Time delay
A signal is restricted to slow the rate of pressure build up on a pressure switch (3/2 differential pressure operated valve)
When the pressure switch operates a strong un-restricted output is given
A reservoir provides capacitance to allow less fine and sensitive settings on the flow regulator making it easy to adjust
1
2
3
12
10
Signal
in
Output
87
Time delay calculation conducted in classroom
Signal is slowed down by the flow regulator then it takes some time to fill the reservoir then it will also takes some time to activate the 3/2 valve differential pressure.
87
Time delay
Manual remote start of a double acting cylinder with a time delay in the outstroked position before automatic return
2
1
2
4
5
3
14
12
1
3
12
10
+
-
A
a1
1
2
3
12
10
a1
1
2
3
12
10
88
Explain how the circuit work and give the example of A-(Time delay)A+
88
89
Notes:
Always follow the standard when drawing a circuit
Always use the right valve with the right actuator
Never forget to add compressor and exhaust whenever it is needed
Always add flow regulator to the circuit to reduce the speed in both stroke direction unless if you are required to control a specific direction
Rollers are always used as NC valve
Manual valves are always used NC and initially deactivated
Sequential control
