industrial pneumatic circuit basic

1. INDUSTRIAL PNEUMATIC CIRCUIT

2. Component identification
 The ISO suggested component
numbering system is suited for
largecircuitsand thosedrawn
on several pages
 Forthis presentationa simple
code is used
 Forcylinders: A,B,C etc.
 Forassociated feedback valves:
alpha-numericcode ‘a0’ for
proof of instroke, ‘a1’ forproof of
outstroke
 Forcylinder B: b0 and b1
 Note: the a0 valve symbol is
drawn in the operated
position because theactuator
A is instroked
A
a0 a1
1
2
12 10
a0 3
2
3 1
12 10
a1

3. Example circuit
Run/End
A
a0 a1
B
b0 b1
C
c0 c1
a0 a1 b0
b1 c0
c1
10 bar max 6 bar
To all inlet ports marked
Sequence
Run/End
A+
B+
B-
C+
C-
A-
Repeat

5. 2/2 Valve actuator control
 A pairof the most basicof all
valve types the 2/2 can be used
tocontrol a singleacting
cylinder
 The normallyclosed position
of thevalve is produced by the
spring
 The operated position is
produced by the push button
 Onevalveadmitsairtheother
valveexhausts it
2
10
12
1
1
10
12
2
OUT IN

6. 2/2 Valve actuator control
 The button marked OUT is
pushed tooperate thevalve
 Air is connected to the
cylinderand itoutstrokes
 Aircannotescape to
atmosphere through thevalve
marked IN as this is closed
 The air at atmospheric
pressure in the frontof the
cylindervents through the
breatherport
2
10
1
12
1
10
12
2
OUT IN

7. 2/2 Valve actuator control
 The push buttonof thevalve
marked OUT is released and it
returns toa normal closed
position
 Air is now trapped in the
system and provided thereare
no leaks the piston rod will
stay in theoutstroked position
 If the load increases beyond
the forceexerted by theair the
pistonrod will start to move in
2
10
1
12
1
10
12
2
OUT IN

8. 2/2 Valve actuator control
 The button marked IN is
pushed tooperate thevalve
 Airescapes and the piston rod
moves to the instroked
position
 The push button must be held
operated until the piston rod
is fully in
 Atmosphericairwill be drawn
in to the frontof thecylinder
through thevent port
2
10
1
12
1
2
10
12
OUT IN

9. 2/2 Valve actuator control
 If the button marked IN is
released the pistonrod 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

10. 2/2 Valve actuator control
 Tocontrol thespeed of the
piston rod, f low restrictorsare
placed in the pipes close to
each of thevalves.
 Adjustmentof the restrictors
will slow down the flow rate
therebygiving independent
outstrokeand instrokespeed
control
10
12 10
12
OUT IN
2
1
1
2

11. 2/2 Valve actuator control
 By repeated operation of
either buttonduring
movementthe piston rod can
be moved in small steps for
approximatepositioning
 Thiswill only be successful
underslow speeds
10
12 10
12
OUT IN
2
1
1
2

12. 2/2 Valve actuator control
 With anycompressed air
system that intentionallytraps
air, the potential hazard of
this must be recognised
 Unintended release or
application of pressurecan
give rise to unexpected
movementof the piston rod
 A pressure indicator or gauge
must be fitted to warn of the
presenceof pressure
2
10
1
12
1
2
10
12
OUT IN

14. 3/2 valve actuator control
 A 3 portvalve provides the
inletand 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
thevalve is open
 The push button must be
held down foras long as the
cylinder is outstroked
2
3 1
12 10

15. 3/2 valve actuator control
 A 3 portvalve provides the
inletand 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
thevalve is open
 The push button must be
held down foras long as the
cylinder is outstroked
2
3 1
12 10

16. 3/2 valve actuator control
 A 3 portvalve provides the
inletand 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
thevalve is open
 The push button must be
held down foras long as the
cylinder is outstroked
2
3 1
12 10

17. 3/2 valve actuator control
 Togenerally slow thecylinder
speed an adjustable
bi-directional flow regulator
or fixed restrictorcan be used
 The flow regulator setting will
beacompromiseas the ideal
outstroke speed may not
produce thedesired results for
the instrokespeed 2
3 1
12 10

18. 3/2 valve actuator control
 Tocontrol theoutstrokespeed
of a single acting cylinder
withoutcontrolling the
instrokespeed, a uni-
directional f low regulatoris
used
 The flow into the cylinder
closes the non returnvalve
and can only pass through the
adjustable restrictor
 Byadjusting the restrictorthe
outstroke speed of the
cylindercan be set
2
3 1
12 10

19. 3/2 valve actuator control
 For independentspeed control
in each direction two flow
regulatorsare required
 Installed in opposite
directions toeach other
 Upper regulatorcontrols the
outstrokespeed
 Lowerregulatorcontrolsthe
instroking speed
2
3 1
12 10

20. 3/2 valve actuator control
 A 3 portvalve provides the
inletand 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
thevalve is open
 The push button must be
held down foras long as the
cylinder is outstroked
2
3 1
12 10

22. 5/2 Valve actuator control
 Fora doubleacting cylinder
the powerand exhaust paths
areswitched simultaneously
 When the button is pushed
thesupplyat port 1 is
connected toport 4 and the
outlet port 2 connected to
exhaust port 3. Thecylinder
movesplus
 When the button is released
port 1 is connected to port 2
and port 4 connected toport
5. Cylinder minus
2
4
5 1 3
14 12
- +

23. 5/2 Valve actuator control
 Fora doubleacting cylinder
the powerand exhaust paths
areswitched simultaneously
 When the button is pushed
the supply at port 1 is
connected toport 4 and the
outlet port 2 connected to
exhaust port 3. Thecylinder
movesplus
 When the button is released
port 1 is connected to port 2
and port 4 connected toport
5. Cylinder minus
2
4
5 1 3
14 12
- +

24. 5/2 Valve actuator control
 Independentspeed control of
the plus and minus
movements
 In mostapplications speed is
controlled by restricting air
outof acylinder
 Full power is developed to
drive the piston with speed
controlled by restricting the
back pressure
2
4
5 1 3
14 12
- +

25. 5/2 Valve actuator control
 Independentspeed control of
the plus and minus
movements
 In mostapplications speed is
controlled by restricting air
outof acylinder
 Full power is developed to
drive the piston with speed
controlled by restricting the
back pressure
2
4
5 1 3
14 12
- +

26. 5/2 Valve actuator control
 Valveswith a spring returnare
mono-stableand need the
operator to be held all the
time that the cylinder is
required in the plus position
 Bi-stablevalves will stay in the
position theywere last set
 The levervalveexample
illustrated indicates a detent
mechanism. The lever need
not be held once the new
position has been established
2
4
5 1 3
14 12
- +

27. Manual control
 Remote manual control of a
doubleacting cylinder
 Valve marked + will cause the
cylinder to outstroke or move
plus
 Valve marked - will cause the
cylinder to instrokeor move
minus
 The 5/2 double pilotvalve is
bi-stable thereforethe push
buttonvalves only need to be
pulsed
2
4
5 1 3
14 12
2
3 1
12 10
2
3 1
12 10
+ -
- +

28. Manual control
 Remote manual control of a
doubleacting cylinder
 Valve marked + will cause the
cylinder to outstroke or move
plus
 Valve marked - will cause the
cylinder to instrokeor move
minus
 The 5/2 double pilotvalve is
bi-stable thereforethe push
buttonvalves only need to be
pulsed
2
4
5 1 3
2
3 1
12 10
2
3 1
12 10
14 12
+ -
- +

29. Manual control
 Remote manual control of a
doubleacting cylinder
 Valve marked + will cause the
cylinder to outstroke or move
plus
 Valve marked - will cause the
cylinder to instrokeor move
minus
 The 5/2 double pilotvalve is
bi-stable thereforethe push
buttonvalves only need to be
pulsed
2
4
5 1 3
2
3 1
12 10
2
3 1
12 10
14 12
+ -
- +

30. Manual control
 Remote manual control of a
doubleacting cylinder
 Valve marked + will cause the
cylinder to outstroke or move
plus
 Valve marked - will cause the
cylinder to instrokeor move
minus
 The 5/2 double pilotvalve is
bi-stable thereforethe push
buttonvalves only need to be
pulsed
2
4
5 1 3
14 12
2
3 1
12 10
2
3 1
12 10
+ -
- +

31. Manual control
 Remote manual control of a
doubleacting cylinder
 Valve marked + will cause the
cylinder to outstroke or move
plus
 Valve marked - will cause the
cylinder to instrokeor move
minus
 The 5/2 double pilotvalve is
bi-stable thereforethe push
buttonvalves only need to be
pulsed
2
4
5 1 3
14 12
2
3 1
12 10
2
3 1
12 10
+ -
- +

32. Semi-automatic control
 Manual remotestartof a
doubleacting cylinderwith
automaticreturn
 Cylinderidentified as “A”
 Tripvalveoperated at the
completionof the plus stroke
identified as “a1”
2
4
5 1 3
14 12
2
3 1
12 10
2
3 1
12 10
+ -
- +
A
a1
a1

33. Fully-automatic control
 Continuousautomaticcycling
from rolleroperated trip
valves
 Manual Run and End of the
automaticcycling
 Cylinderwill come torest in
the instroked position
regardlessof when thevalve is
put to End
 Tags for the roller feedback
valves a0 and a1 show their
relativepositions
2
4
5 1 3
14 12
2
3 1
12 10
1
2
12 10
2
3 1
12
10
Run/End
- +
A
a0 a1
a0 3 a1

35. Circuit building blocks
 Thesecircuitscan beconsidered as building blocks for larger
sequential circuitsconsisting of twoor morecylinders
 Each actuatorwill havea powervalveand twoassociated feedback
valves. The firstactuatorto movealso has
a Run/End valve
Run/End
A B
a0 a1 b0 b1

36. Repeat pattern sequence
 A repeat patternsequence is one
where theorderof the
movements in the first half of
the sequence is repeated in the
second half
 Each actuator may haveone Out
and In strokeonly in the
sequence
 There may beany numberof
actuators in the sequence
 The signal starting the first
movement must pass through
the Run/End valve
 Needsonly the basic building
blocks tosolve
 Examples of repeatpattern
sequences:
 A+ B+ C+ D+ A- B- C- D-
 A- B+ C- A+ B- C+
 C+ A+ B- C- A- B+

37. Repeat pattern sequence
Run/End
b0 b1 a1 a0
 The twocylinders A and B are to perform a simple repeat pattern
sequence as follows: A+ B+ A- B-
 Apply the rule “The signal given by the completion of each movement
will initiate the next movement”
 In this way the rollervalves can be
identified and labelled
a0 a1
A B
b0 b1

38. Repeat pattern sequence
 Forthreecylinders A, B and C also toperforma simple repeat
pattern sequenceas follows: A+ B+ C+ A- B- C-
 Apply the rule “The signal given by thecompletionof each
movementwill initiate the next movement”
Run/End
c0 c1 a0
a1
a0 a1 b0 b1
A B C
b0
b1
c0 c1

39. Non-repeat pattern sequence
 If the rule applied to a repeat pattern sequence is applied to any
othersequence therewill be opposed signalson oneor moreof the
5/2 valves preventing operation
 Thiscircuitdemonstrates the problem
 Thesequence is A+ B+ B- A-
Run/End
a1
a0 b0 b1
a0 a1 b0 b1
A B

40. Opposed signals
Run/End
A B
a0 b0 a1 b1
 When thevalve is set to Run, cylinderA will not move because the 5/2
valve has an opposed signal, it is still being signalled to hold position
by the feedback valve b0
 If A was able to move + a similarproblem will occur for the 5/2 valve of
B once it was +
 Thesequence is A+ B+ B- A-
a0 a1 b0 b1

41. Mechanical solution
 The problemwas caused byvalves b0 and a1 being operated at the
time the newopposing instruction is given
 If these twovalveswere “oneway trip” types and overtripped at the
last movementof stroke, onlya pulsewould
beobtained instead of acontinuoussignal
Run/End
A B
a1
a0
a0 a1 b0 b1
b0 b1