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Basic Pneumatic Circuitry
For control and automation
Contents
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

Introduction
Symbols
Circuit layout
Actuator control 2/2 Valve
Actuator control 3/2 Valve
Actuator control 5/2 Valve








Sequential control
Sequence solution
5/3 Valves
Poppet/spool logic
Balanced spool logic
Feedback

Click the section to advance directly to it
Introduction






This module shows the
methods of application of
pneumatic valves and
components for control
and automation
The methods of pure
pneumatic sequential
control are confined to
simple examples
The majority of modern
systems are controlled
electronically and is the
subject of electropneumatic modules



A message to pneumatic
circuit designers:







Use proven and reliable
design techniques
Produce circuits and
documentation that are
clear to read
Design for safety
Do not try to be too
clever, the circuit will be
difficult for others to
read and maintain
Symbols







The standard for fluid power symbols is ISO 1219-1. This
is a set of basic shapes and rules for the construction of
fluid power symbols
Cylinders can be drawn to show their extreme or
intermediate positions of stroke and any length above
their width
Valves show all states in the one symbol. The prevailing
state is shown with the port connections
Other components are single state symbols
Symbols single acting actuators





Single acting, sprung
instroked
Single acting, sprung
outstroked
Single acting, sprung
instroked, magnetic
Single acting, sprung
outstroked, magnetic
Symbols double acting actuators






Double acting, noncushioned
Double acting, adjustable
cushions
Double acting, through
rod, adjustable cushions
Double acting, magnetic,
adjustable cushions
Double acting, rodless,
magnetic, adjustable
cushions
Symbols rotary actuators




Semi-rotary double acting
Rotary motor single
direction of rotation
Rotary motor bidirectional
Symbols valves


2/2 Valve push button /
spring



3/2 Valve detented lever
operated

1

3/2 Valve push button /
spring



2
10

12

2
10

12
3
2
10
12
3

1

1
Symbols valves






3/2 Valve differential
pressure operated

2

12
3

10

1

5/2 Valve push button /
spring
5/3 Valve double pressure
operated spring centre

14

4

5
4

2

5

1 3

2
12
1 3
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
12

10
3

1
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
12

10
3

1
Symbols valves






This example is for a 5/2
valve
This 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)

4

2

14

12
5

1 3
Symbols valves






This example is for a 5/2
valve
This 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)

4

2

14

12
5

1 3
Symbols operators manual
General manual

Lever

Push button

Pedal

Pull button

Treadle

Push/pull button

Rotary knob
Symbols operators mechanical
Plunger

Pressure

Spring normally
as a return

Pilot pressure

Roller

Differential pressure

Uni-direction
or one way trip

Detent in 3 positions
Symbols 5/3 valves


All valves types shown in the normal position



Type 1. All ports blocked



Type 2. Outlets to exhaust



Type 3. Supply to outlets
Symbols function components



Non-return valve
Flow regulator unidirectional
Flow regulator bidirectional
Two pressure ‘AND’



Shuttle valve ‘OR’



Silencer



Quick exhaust valve with
silencer



Pressure to electric
switch adjustable





* Note:

Traditional symbol in
extensive use (preferred)

*
ISO 1219-1

Old
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
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
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
a0

a1

A

12
a0 3

2
1

10

2
10

12
a1

3

1
Example circuit
a0

a1

b0

A

b1

c0

B

c1

C

Sequence
Run/End
A+
B+
BC+
CARepeat
Run/End

a0
10 bar max

b1

a1
6 bar

To all inlet ports marked

b0

c1

c0
Actuator control 2/2 valve
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

12

OUT

2
10
1

12

IN

1
10
2
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

12

OUT

2
1

10

12

IN

1
10
2
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

12

OUT

2
10
1

12

IN

1
10
2
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

12

OUT

2
10
1

12

IN

1
2

10
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
12

OUT

2
10
1

12

IN

1
10
2
2/2 Valve actuator control




To control the speed of
the piston rod, flow
restrictors are placed in
the pipes close to each of
the valves.
Adjustment of the
restrictors will slow down
the flow rate thereby
giving independent
outstroke and instroke
speed control

2
10

12

OUT

1

1
10

12

IN

2
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

2
10

12

OUT

1

1
10

12

IN

2
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
pressure

2
10

12

OUT

1

1
10

12

IN

2
Actuator control 3/2 valve
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

2
10

12
3

1
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

12
3

2
1

10
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

2
10

12
3

1
3/2 valve actuator control




To generally slow the
cylinder speed an
adjustable
bi-directional flow
regulator or fixed
restrictor 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

2
10

12
3

1
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 restrictor
the outstroke speed of
the cylinder can be set

2
10

12
3

1
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

2
10

12
3

1
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

2
10

12
3

1
Actuator control 5/2 valve
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

-

14

+

4

2

5

1 3

12
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

-

14

+

4

2

5

1 3

12
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

-

14

+

4

2

5

1 3

12
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

-

14

+

4

2

5

1 3

12
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

-

+

4

2

5

12
1 3

14
Manual control







Remote manual control of
a double acting cylinder
Valve marked + will cause
the cylinder to outstroke
or move plus
Valve marked - will cause
the cylinder to instroke or
move minus
The 5/2 double pilot valve
is bi-stable therefore the
push button valves only
need to be pulsed

-

+

4

2

14

12
5

2
10

12

+

1 3

3

1

2
10

12

-

3

1
Manual control







Remote manual control of
a double acting cylinder
Valve marked + will cause
the cylinder to outstroke
or move plus
Valve marked - will cause
the cylinder to instroke or
move minus
The 5/2 double pilot valve
is bi-stable therefore the
push button valves only
need to be pulsed

-

+

4

2

14

12
5

12

+

3

2
1

1 3

2
10

12

10

-

3

1
Manual control







Remote manual control of
a double acting cylinder
Valve marked + will cause
the cylinder to outstroke
or move plus
Valve marked - will cause
the cylinder to instroke or
move minus
The 5/2 double pilot valve
is bi-stable therefore the
push button valves only
need to be pulsed

-

+

4

2

14

12
5

2
10

12

+

1 3

3

1

2
10

12

-

3

1
Manual control







Remote manual control of
a double acting cylinder
Valve marked + will cause
the cylinder to outstroke
or move plus
Valve marked - will cause
the cylinder to instroke or
move minus
The 5/2 double pilot valve
is bi-stable therefore the
push button valves only
need to be pulsed

-

+

4

2

14

12
5

2
10

12

+

1 3

3

1

2

12

-

3

1

10
Manual control







Remote manual control of
a double acting cylinder
Valve marked + will cause
the cylinder to outstroke
or move plus
Valve marked - will cause
the cylinder to instroke or
move minus
The 5/2 double pilot valve
is bi-stable therefore the
push button valves only
need to be pulsed

-

+

4

2

14

12
5

2
10

12

+

1 3

3

1

2
10

12

-

3

1
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”

+

a1

A

4

2

14

12
5

2
10

12

+

1 3

3

1

2
10

12

-

a1

3

1
Fully-automatic control
-

+

a0

a1



A


4
14

2



12
5

1 3

2
10
12
Run/End

3
12
a0 3



1
2
1

10

2
10

12
a1

3

1

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
Sequential control
Circuit building blocks
a0

A

a1

b0

b1

B

Run/End





These circuits can be considered as building blocks for
larger sequential circuits consisting of two or more
cylinders
Each actuator will have a power valve and two associated
feedback valves. The first actuator to move also has
a Run/End valve
Repeat pattern sequence






A repeat pattern
sequence is one where
the order of the
movements in the first
half of the sequence is
repeated in the second
half
Each actuator may have
one Out and In stroke
only in the sequence
There may be any number
of actuators in the
sequence









The signal starting the
first movement must pass
through the Run/End
valve
Needs only the basic
building blocks to solve
Examples of repeat
pattern sequences:
A+ B+ C+ D+ A- B- C- DA- B+ C- A+ B- C+
C+ A+ B- C- A- B+
Repeat pattern sequence
a0

a1

b0

A

b1

B

Run/End

b0





b1

a1

a0

The two cylinders A and B are to perform a simple repeat
pattern sequence as follows: A+ B+ A- BApply the rule “The signal given by the completion of each
movement will initiate the next movement”
In this way the roller valves can be
identified and labelled
Repeat pattern sequence
a0

a1

b0

A

b1

c0

B

C

Run/End

c0




c1

a1

a0

b1

b0

For three cylinders A, B and C also to perform a simple
repeat pattern sequence as follows: A+ B+ C+ A- B- CApply the rule “The signal given by the completion of each
movement will initiate the next movement”

c1
Non-repeat pattern sequence
a0

a1

b0

A

b1

B

Run/End

a0






b0

a1

b1

If the rule applied to a repeat pattern sequence is applied
to any other sequence there will be opposed signals on
one or more of the 5/2 valves preventing operation
This circuit demonstrates the problem
The sequence is A+ B+ B- A-
Opposed signals
a0

a1

b0

A

b1

B

Run/End

a0






b0

a1

b1

When the valve is set to Run, cylinder A 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 similar problem will occur for the
5/2 valve of B once it was +
The sequence is A+ B+ B- A-
Mechanical solution
a0

a1

b0

A

b1

B

Run/End

a0




b0

a1

b1

The problem was caused by valves b0 and a1 being
operated at the time the new opposing instruction is given
If these two valves were “one way trip” types and over
tripped at the last movement of stroke, only a pulse would
be obtained instead of a continuous signal
Sequence solution methods


The main solutions to
solving sequences are:








Cascade (pneumatic)
Shift register
(pneumatic)
Electro-pneumatic
PLC (Programmable
logic controller)

Cascade circuits provide
a standard method of
solving any sequence. It
uses a minimum of
additional logic hardware
(one logic valve per group
of sequential steps)







Shift register circuits are
similar to cascade but
use one logic valve for
every step
Electro-pneumatic
circuits use solenoid
valves and electromechanical relays
PLC. The standard
solution for medium to
complex sequential
systems (except where
electrical equipment
cannot be used)
Cascade two group








The A+ B+ B- A- circuit is
solved by the two group
cascade method
The sequence is divided
at the point where B
immediately returns
The two parts are
allocated groups l and ll
Gp l A+ B+ / Gp ll B- ATwo signal supplies are
provided from a 5/2 valve
one is available only in
group l the other is
available only in group ll





Because only one group
output is available at a
time it is not possible to
have opposed signals
A standard 5/2 double
pressure operated valve
is the cascade valve
Group l
14

Select l

Group ll
4

5

2
12
1 3

Select ll
Cascade (two group)
a0

a1

b0

A

b1

B

b0
a1

Gp l
Gp ll

Sequence
Gp l A+ B+ Gp ll B- ARun/End

a0

b1
Cascade (two group)
a0

a1

b0

A

b1

B

b0
a1

Gp l
Gp ll

Sequence
Gp l A+ B+ Gp ll B- ARun/End

a0

b1
Cascade (two group)
a0

a1

b0

A

b1

B

b0
a1

Gp l
Gp ll

Sequence
Gp l A+ B+ Gp ll B- ARun/End

a0

b1
Cascade (two group)
a0

a1

b0

A

b1

B

b0
a1

Gp l
Gp ll

Sequence
Gp l A+ B+ Gp ll B- ARun/End

a0

b1
Cascade (two group)
a0

a1

b0

A

b1

B

b0
a1

Gp l
Gp ll

Sequence
Gp l A+ B+ Gp ll B- ARun/End

a0

b1
Cascade (two group)
a0

a1

b0

A

b1

B

b0
a1

Gp l
Gp ll

Sequence
Gp l A+ B+ Gp ll B- ARun/End

a0

b1
Cascade building blocks




A two group building
block consists of a lever
valve to run and end the
sequence plus the 5/2
double pilot operated
cascade valve
For a two group system
consisting of any number
of cylinders this building
block and the cylinder
building blocks are all
that is required to solve
the sequence

Gp l

4
14

2
10
12

Sel l

12
5

Run/End

3

1

Gp ll

2

1 3

Sel ll
Cascade building blocks


This three group
building block
establishes an
interconnecting
pattern that can
be extended to
any number of
groups

Gp l
Run/End

Gp ll
Sel l
Sel ll
Gp lll
Sel lll
Dual trip building blocks






When a sequence has a
cylinder operating twice
in one overall sequence a
dual trip building block
may be required for each
of the two feedback
valves
The supply will be from
different groups and the
output go to different
destinations
Example is for feedback
valve a1 of cylinder A
when A is sent + both in
Group x and Group y

Send A+
a1 in x
a1 in y

A+ in
Group x

A+ in
Group y

a1

Note: can often be rationalised to less
than these three components
Cascade rules







Establish the correct
sequence
Divide the sequence in to
groups. Always start a
sequence with the
Run/End valve selecting
group l e.g.
R/E | A+ B+ | B- C+ | C- ASelect the cylinder
building blocks
Select the cascade
building block
Select dual trip building
blocks if required










Interconnect the blocks as
follows:
The first function in each group
is signalled directly by that
group supply
The last trip valve operated in
each group is supplied with
main supply air and selects the
next group
The remaining trip valves are
supplied with air from their
respective groups and initiate
the next function
The “run/end” valve will control
the signal from the last trip valve
to be operated
Three position valves
5/3 Valve





5/3 valves have a third
mid position
The valve can be tristable e.g. a detented
lever operator or monostable e.g. a double air or
double solenoid with
spring centre
There are three common
configurations for the mid
position:




All ports blocked
Centre open exhaust
Centre open pressure



The majority of
applications are actuator
positioning and safety
4

2

14
5 1 3
14

4

2

12
12

5 1 3
14

4

2

5 1 3

12
5/3 Valve actuator control








The valve illustrated has
“all ports blocked” in the
mid position
Whenever the mid
position is selected the
pressure conditions in
the cylinder will be frozen
This can be used to stop
the piston at part stroke
in some positioning
applications
Flow regulators mounted
close to the cylinder to
minimise creep

4

14

2

5

1 3

12
5/3 Valve actuator control








The valve illustrated has
“all ports blocked” in the
mid position
Whenever the mid
position is selected the
pressure conditions in
the cylinder will be frozen
This can be used to stop
the piston at part stroke
in some positioning
applications
Flow regulators mounted
close to the cylinder to
minimise creep

4

14

2

5

1 3

12
5/3 Valve actuator control








The valve illustrated has
“all ports blocked” in the
mid position
Whenever the mid
position is selected the
pressure conditions in
the cylinder will be frozen
This can be used to stop
the piston at part stroke
in some positioning
applications
Flow regulators mounted
close to the cylinder to
minimise creep

4

14

2

5

1 3

12
5/3 Valve actuator control








The valve illustrated has
“all ports blocked” in the
mid position
Whenever the mid
position is selected the
pressure conditions in
the cylinder will be frozen
This can be used to stop
the piston at part stroke
in some positioning
applications
Flow regulators mounted
close to the cylinder to
minimise creep

4

14

2

5

12
1 3
5/3 Valve actuator control








The valve illustrated has
“all ports blocked” in the
mid position
Whenever the mid
position is selected the
pressure conditions in
the cylinder will be frozen
This can be used to stop
the piston at part stroke
in some positioning
applications
Flow regulators mounted
close to the cylinder to
minimise creep

4

14

2

5

1 3

12
5/3 Valve actuator control







This version of a 5/3 valve
is “centre open exhaust”
The supply at port 1 is
isolated and the cylinder
has power exhausted
when this centre position
is selected
The version illustrated
shows a mono-stable
version double pilot
operated spring centre
The cylinder will be preexhausted when
changing from the mid
position

14

4

2

5

1 3

12
5/3 Valve actuator control







This version of a 5/3 valve
is “centre open pressure”
The supply at port 1 is
connected to both sides
of the cylinder and the
exhaust ports isolated
when this centre position
is selected
Can be used to balance
pressures in positioning
applications
The version illustrated is
mono-stable, double
solenoid, spring centre

14

4

2

5

1 3

12
Logic functions for poppet and
spool valves
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

Z
2
10

12

Y

3

2
10

12

X

1

3

1
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

Z
2
10

12

Y

3

12

X

3

1

2
1

10
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

Z
2
10

12

Y

3

2
10

12

X

1

3

1
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

Z
12

Y

3

1

2
10

12

X

2

3

1

10
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

Z
12

Y

3

12

X

3

2

10

1

2
1

10
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

Z
12

Y

3

1

2
10

12

X

2

3

1

10
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

Z
2
10

12

Y

3

2
10

12

X

1

3

1
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

Z
2
10

12

Y

3

2
10

12

X

1

3

1
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

Z

2
10

12

Y
2
10

12

X

3

1

3

1
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

Z

2
10

12

Y
2

12

X

3

1

10

3

1
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

Z

2
10

12

Y
2
10

12

X

3

1

3

1
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

Z

2

12

Y
2
10

12

X

3

1

3

1

10
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

Z

2
10

12

Y
2
10

12

X

3

1

3

1
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 (inlet
port numbered 1)
When the signal X is
present there is NOT
output Z
When X is removed
output Z is given

Z
2
10

12

X

1

3
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 (inlet
port numbered 1)
When the signal X is
present there is NOT
output Z
When X is removed
output Z is given

Z
2

12

X

1

3

10
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 (inlet
port numbered 1)
When the signal X is
present there is NOT
output Z
When X is removed
output Z is given

Z
2
10

12

X

1

3
Logic MEMORY





A logic MEMORY allows
the output signal state
(ON or OFF) to be
maintained after the input
signal has been removed
Any bi-stable valve is a
logic MEMORY
With this lever detented
valve, once the lever has
been moved X direction
or Y direction it can be
released and will stay in
that position

Z
X
12

Y

3

10
1
Logic MEMORY


A logic MEMORY allows
the output signal state
(ON or OFF) to be
maintained after the
signal that set it has been
removed

Z
X

12

10
3

1

Y
Logic MEMORY


A bi-stable double pilot
valve can be set or reset
simply by a pulse (push
and release) on buttons X
or Y

Z
12

10
3

1

2
10

12

Y
2
10

12

X

3

1

3

1
Logic MEMORY


A bi-stable double pilot
valve can be set or reset
simply by a pulse (push
and release) on buttons X
or Y

Z
12

10

3

1

2
10

12

Y
2

12

X

3

1

10

3

1
Logic MEMORY


A bi-stable double pilot
valve can be set or reset
simply by a pulse (push
and release) on buttons X
or Y

Z
12

10

3

1

2
10

12

Y
2
10

12

X

3

1

3

1
Logic MEMORY


A bi-stable double pilot
valve can be set or reset
simply by a pulse (push
and release) on buttons X
or Y

Z
12

10
3

1

12

Y
2
10

12

X

3

1

3

2
1

10
Logic MEMORY


A bi-stable double pilot
valve can be set or reset
simply by a pulse (push
and release) on buttons X
or Y

Z
12

10
3

1

2
10

12

Y
2
10

12

X

3

1

3

1
Logic MEMORY (latch)








A popular memory circuit
is the latch
Will not re-make after
pneumatic power failure
A pulse on X operates the
pilot / spring valve to give
output Z
A feedback from Z runs
through the normally
open valve Y to latch the
operation of Z when X is
released
A pulse on Y breaks the
latch and Z is exhausted

Z
Y

1

3
10
2

12

12

10
3

X

2
10

12
3

1

1
Logic MEMORY (latch)








A popular memory circuit
is the latch
Will not re-make after
pneumatic power failure
A pulse on X operates the
pilot / spring valve to give
output Z
A feedback from Z runs
through the normally
open valve Y to latch the
operation of Z when X is
released
A pulse on Y breaks the
latch and Z is exhausted

Z
Y

1

3
10
2

12

12

10
3

X

12
3

2
1

10

1
Logic MEMORY (latch)








A popular memory circuit
is the latch
Will not re-make after
pneumatic power failure
A pulse on X operates the
pilot / spring valve to give
output Z
A feedback from Z runs
through the normally
open valve Y to latch the
operation of Z when X is
released
A pulse on Y breaks the
latch and Z is exhausted

Z
Y

1

3
10
2

12

12

10
3

X

2
10

12
3

1

1
Logic MEMORY (latch)








A popular memory circuit
is the latch
Will not re-make after
pneumatic power failure
A pulse on X operates the
pilot / spring valve to give
output Z
A feedback from Z runs
through the normally
open valve Y to latch the
operation of Z when X is
released
A pulse on Y breaks the
latch and Z is exhausted

Z
1

Y

12

3
2

10
12

10
3

X

2
10

12
3

1

1
Logic MEMORY (latch)








A popular memory circuit
is the latch
Will not re-make after
pneumatic power failure
A pulse on X operates the
pilot / spring valve to give
output Z
A feedback from Z runs
through the normally
open valve Y to latch the
operation of Z when X is
released
A pulse on Y breaks the
latch and Z is exhausted

Z
Y

1

3
10
2

12

12

10
3

X

2
10

12
3

1

1
Logic arrangements for fully
balanced spool valves
Logic circuits (spool valves)








NO / NC
Selection / Diversion
Latch
OR, AND, NOT
Single pulse maker
Slow pressure build
Pre-select







5/2 OR
Single pulse control
Air conservation
Double flow
Counting

Click the section to advance directly to it
3/2 NO / NC








A fully balanced valve
allows pressure on any
pot or combination of
ports
A single valve can be
used normally open or
normally closed
For normally open the
supply pressure is
connected to port 1
For normally closed the
supply pressure is
connected to port 3

2
10

12
3

1

2
10

12
3

1
3/2 NO / NC








A fully balanced valve
allows pressure on any
pot or combination of
ports
A single valve can be
used normally open or
normally closed
For normally open the
supply pressure is
connected to port 1
For normally closed the
supply pressure is
connected to port 3

12
3

12
3

2

10

1

2
1

10
3/2 Valve selection / diversion





Selection of one of two
supplies connected to
ports 1 and 3 can be
different pressures
Diversion of one supply
to one of two outlets
If it is required to exhaust
the downstream air a 5/2
valve is required

2
10

12
3

3
12

1

1
10
2
3/2 Valve selection / diversion





Selection of one of two
supplies connected to
ports 1 and 3 can be
different pressures
Diversion of one supply
to one of two outlets
If it is required to exhaust
the downstream air a 5/2
valve is required

12

2

3

1

3

10

1

12

2

10
Latch with controls




In this version of a latch
the push button valves
are connected to perform
‘OR’ and ‘NOT’ functions
The ‘OFF’ valve must be
placed last in the signal
chain so that if both
valves are operated
together the ‘OFF’
command will dominate
over the ‘ON’ command

Out
2
10

12
3

ON

2
10

12
3

1
2
10

OFF 12
3

1

1
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

OR

z
12
3

x
AND

1

y
z

12
3

y
z

12
3

x

2
10
1

x
NOT

2
10

2
10
1
Single pulse maker






Converts a prolonged
signal x into a single
pulse z
Signal z must be removed
to allow the valve to reset
then x can be applied
again
The duration of the pulse
can be adjusted with the
flow regulator

z
2
10

12
3

x

1
Slow initial pressure build up






Choose a 3/2 pilot spring
valve with a relatively
high operating force e.g.
3 to 4 bar
When the quick connect
coupling is made, the
output at port 2 is
controlled at the rate of
the flow regulator setting
When the pressure is
high enough to operate
the valve full flow will
take over

2
10

12
3

1
Pre-select






The lever valve can preselect the movement of
the cylinder OUT or IN
The movement will occur
the next time the plunger
valve is operated
The plunger valve can be
released immediately and
subsequently operated
and released any number
of times

2
10

12
3
2
10

12
3

1
2
10

12
OUT/IN
pre-select

3

1

1
5/2 OR function




The valve at position ‘a’ is
reversed connected and
supplied from the valve
conventionally connected
at position ‘b’
The cylinder can be
controlled from either
position ‘a’ ‘OR’ position
‘b’

4

5

b

1 3

4

a

2

2

5

1 3

14

14

12

12
Single pulse control








Each time the foot
operated valve is
pressed the cylinder
will single stroke +
and - alternately
First foot operation
the cylinder moves
out
Second foot
operation the
cylinder moves in
Third….. out and so
on

4

2

14
5
2
10

12
3

2
10

12
3

1

1

12

1
2

12
3

1

10
Air conservation







Power stroke in the
instroke direction only
Differential area of the
piston gives an outstroke
force when the pressure
is balanced
Air used to outstroke is
equivalent to a cylinder
with only the same bore
as the rod diameter
Assumes the cylinder is
not loaded on the plus
stroke and low friction

4

2

14
5

1

12
Air conservation







Power stroke in the
instroke direction only
Differential area of the
piston gives an outstroke
force when the pressure
is balanced
Air used to outstroke is
equivalent to a cylinder
with only the same bore
as the rod diameter
Assumes the cylinder is
not loaded on the plus
stroke and low friction

4

2

14
5

1

12
Double flow





Where a larger 3/2 valve
is not available
Two flow paths in a 5/2
valve each with a
separate supply can be
arranged to give double
flow or supply separate
devices
Ensure the tube size to
the cylinder is large
enough to take the double
flow

4

2

14

12
5 1

3
Double flow





Where a larger 3/2 valve
is not available
Two flow paths in a 5/2
valve each with a
separate supply can be
arranged to give double
flow or supply separate
devices
Ensure the tube size to
the cylinder is large
enough to take the double
flow

4
14
5 1

2
12
3
Counting







Counting applications are
best achieved with
electro-mechanical or
programmable electronic
counters
Pneumatic counting
circuits use large
numbers of logic valves
and can be slow
The counting chain
shown will count to 4
Red and blue are nonoverlapping alternate
pulses, purple is the reset
line

4

3

2

1
Counting application
a0










The counting circuit is
applied to count 4 strokes
of a cylinder
At rest all counting valves
are held reset by the start
valve
Start outstrokes ‘A’
Alternate signals from
‘a1’ and ‘a0’ progresses
operation of the counting
valves up the chain
On the 4th operation of
‘a1’ the green signal
resets the start valve to
stop the cylinder

A

Start

a1

a0

a1
Feedback methods
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 unrestricted output is given
A reservoir provides
capacitance to allow less
fine and sensitive
settings on the flow
regulator making it easy
to adjust

Output
2

12
3 1

Signal
in

10
Time delay


-

Manual remote start of a
double acting cylinder
with a time delay in the
outstroked position
before automatic return

+

a1

A

4
14

2
12

5

1 3
2

12
3 1
2

12

10
3

1

2
10

12
a1

3

1

10
Pressure decay









Manual remote start of a
double acting cylinder
Uses a low pressure
operated valve connected
normally open
When the back pressure
in the front of the cylinder
falls below 0.1 bar the
return signal is given
Connection taken
between the cylinder and
flow regulator
Useful for pressing work
pieces of variable size

-

+

a1

A

4
14

2
12

5

1 3

2

12

10
3

1

10

2
1

12
3

0.1bar
Electro-pneumatic







The majority of systems
use electrical/electronic
control due to the high
degree of sophistication
and flexibility
Solenoid valves are used
to control cylinders
Feedback signals are
from reed switches,
sensors and electrical
limit switches
Logic is hard wired or
programmed in to a PLC
(programmable logic
controller)



Circuit building block for
each cylinder
a0

a1

4

2
12

A

14

5

a0

1 3

a1
End

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Pneumatic circuits

  • 1. Basic Pneumatic Circuitry For control and automation
  • 2. Contents       Introduction Symbols Circuit layout Actuator control 2/2 Valve Actuator control 3/2 Valve Actuator control 5/2 Valve       Sequential control Sequence solution 5/3 Valves Poppet/spool logic Balanced spool logic Feedback Click the section to advance directly to it
  • 3. Introduction    This module shows the methods of application of pneumatic valves and components for control and automation The methods of pure pneumatic sequential control are confined to simple examples The majority of modern systems are controlled electronically and is the subject of electropneumatic modules  A message to pneumatic circuit designers:     Use proven and reliable design techniques Produce circuits and documentation that are clear to read Design for safety Do not try to be too clever, the circuit will be difficult for others to read and maintain
  • 4. Symbols     The standard for fluid power symbols is ISO 1219-1. This is a set of basic shapes and rules for the construction of fluid power symbols Cylinders can be drawn to show their extreme or intermediate positions of stroke and any length above their width Valves show all states in the one symbol. The prevailing state is shown with the port connections Other components are single state symbols
  • 5. Symbols single acting actuators     Single acting, sprung instroked Single acting, sprung outstroked Single acting, sprung instroked, magnetic Single acting, sprung outstroked, magnetic
  • 6. Symbols double acting actuators      Double acting, noncushioned Double acting, adjustable cushions Double acting, through rod, adjustable cushions Double acting, magnetic, adjustable cushions Double acting, rodless, magnetic, adjustable cushions
  • 7. Symbols rotary actuators    Semi-rotary double acting Rotary motor single direction of rotation Rotary motor bidirectional
  • 8. Symbols valves  2/2 Valve push button / spring  3/2 Valve detented lever operated 1 3/2 Valve push button / spring  2 10 12 2 10 12 3 2 10 12 3 1 1
  • 9. Symbols valves    3/2 Valve differential pressure operated 2 12 3 10 1 5/2 Valve push button / spring 5/3 Valve double pressure operated spring centre 14 4 5 4 2 5 1 3 2 12 1 3
  • 10. 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 12 10 3 1
  • 11. 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 12 10 3 1
  • 12. Symbols valves     This example is for a 5/2 valve This 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) 4 2 14 12 5 1 3
  • 13. Symbols valves     This example is for a 5/2 valve This 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) 4 2 14 12 5 1 3
  • 14. Symbols operators manual General manual Lever Push button Pedal Pull button Treadle Push/pull button Rotary knob
  • 15. Symbols operators mechanical Plunger Pressure Spring normally as a return Pilot pressure Roller Differential pressure Uni-direction or one way trip Detent in 3 positions
  • 16. Symbols 5/3 valves  All valves types shown in the normal position  Type 1. All ports blocked  Type 2. Outlets to exhaust  Type 3. Supply to outlets
  • 17. Symbols function components  Non-return valve Flow regulator unidirectional Flow regulator bidirectional Two pressure ‘AND’  Shuttle valve ‘OR’  Silencer  Quick exhaust valve with silencer  Pressure to electric switch adjustable    * Note: Traditional symbol in extensive use (preferred) * ISO 1219-1 Old
  • 18. 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
  • 19. 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
  • 20. 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 a0 a1 A 12 a0 3 2 1 10 2 10 12 a1 3 1
  • 23. 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 12 OUT 2 10 1 12 IN 1 10 2
  • 24. 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 12 OUT 2 1 10 12 IN 1 10 2
  • 25. 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 12 OUT 2 10 1 12 IN 1 10 2
  • 26. 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 12 OUT 2 10 1 12 IN 1 2 10
  • 27. 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 12 OUT 2 10 1 12 IN 1 10 2
  • 28. 2/2 Valve actuator control   To control the speed of the piston rod, flow restrictors are placed in the pipes close to each of the valves. Adjustment of the restrictors will slow down the flow rate thereby giving independent outstroke and instroke speed control 2 10 12 OUT 1 1 10 12 IN 2
  • 29. 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 2 10 12 OUT 1 1 10 12 IN 2
  • 30. 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 pressure 2 10 12 OUT 1 1 10 12 IN 2
  • 32. 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 2 10 12 3 1
  • 33. 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 12 3 2 1 10
  • 34. 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 2 10 12 3 1
  • 35. 3/2 valve actuator control   To generally slow the cylinder speed an adjustable bi-directional flow regulator or fixed restrictor 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 2 10 12 3 1
  • 36. 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 restrictor the outstroke speed of the cylinder can be set 2 10 12 3 1
  • 37. 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 2 10 12 3 1
  • 38. 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 2 10 12 3 1
  • 40. 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 - 14 + 4 2 5 1 3 12
  • 41. 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 - 14 + 4 2 5 1 3 12
  • 42. 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 - 14 + 4 2 5 1 3 12
  • 43. 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 - 14 + 4 2 5 1 3 12
  • 44. 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 - + 4 2 5 12 1 3 14
  • 45. Manual control     Remote manual control of a double acting cylinder Valve marked + will cause the cylinder to outstroke or move plus Valve marked - will cause the cylinder to instroke or move minus The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed - + 4 2 14 12 5 2 10 12 + 1 3 3 1 2 10 12 - 3 1
  • 46. Manual control     Remote manual control of a double acting cylinder Valve marked + will cause the cylinder to outstroke or move plus Valve marked - will cause the cylinder to instroke or move minus The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed - + 4 2 14 12 5 12 + 3 2 1 1 3 2 10 12 10 - 3 1
  • 47. Manual control     Remote manual control of a double acting cylinder Valve marked + will cause the cylinder to outstroke or move plus Valve marked - will cause the cylinder to instroke or move minus The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed - + 4 2 14 12 5 2 10 12 + 1 3 3 1 2 10 12 - 3 1
  • 48. Manual control     Remote manual control of a double acting cylinder Valve marked + will cause the cylinder to outstroke or move plus Valve marked - will cause the cylinder to instroke or move minus The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed - + 4 2 14 12 5 2 10 12 + 1 3 3 1 2 12 - 3 1 10
  • 49. Manual control     Remote manual control of a double acting cylinder Valve marked + will cause the cylinder to outstroke or move plus Valve marked - will cause the cylinder to instroke or move minus The 5/2 double pilot valve is bi-stable therefore the push button valves only need to be pulsed - + 4 2 14 12 5 2 10 12 + 1 3 3 1 2 10 12 - 3 1
  • 50. 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” + a1 A 4 2 14 12 5 2 10 12 + 1 3 3 1 2 10 12 - a1 3 1
  • 51. Fully-automatic control - + a0 a1  A  4 14 2  12 5 1 3 2 10 12 Run/End 3 12 a0 3  1 2 1 10 2 10 12 a1 3 1 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
  • 53. Circuit building blocks a0 A a1 b0 b1 B Run/End   These circuits can be considered as building blocks for larger sequential circuits consisting of two or more cylinders Each actuator will have a power valve and two associated feedback valves. The first actuator to move also has a Run/End valve
  • 54. Repeat pattern sequence    A repeat pattern sequence is one where the order of the movements in the first half of the sequence is repeated in the second half Each actuator may have one Out and In stroke only in the sequence There may be any number of actuators in the sequence       The signal starting the first movement must pass through the Run/End valve Needs only the basic building blocks to solve Examples of repeat pattern sequences: A+ B+ C+ D+ A- B- C- DA- B+ C- A+ B- C+ C+ A+ B- C- A- B+
  • 55. Repeat pattern sequence a0 a1 b0 A b1 B Run/End b0    b1 a1 a0 The two cylinders A and B are to perform a simple repeat pattern sequence as follows: A+ B+ A- BApply the rule “The signal given by the completion of each movement will initiate the next movement” In this way the roller valves can be identified and labelled
  • 56. Repeat pattern sequence a0 a1 b0 A b1 c0 B C Run/End c0   c1 a1 a0 b1 b0 For three cylinders A, B and C also to perform a simple repeat pattern sequence as follows: A+ B+ C+ A- B- CApply the rule “The signal given by the completion of each movement will initiate the next movement” c1
  • 57. Non-repeat pattern sequence a0 a1 b0 A b1 B Run/End a0    b0 a1 b1 If the rule applied to a repeat pattern sequence is applied to any other sequence there will be opposed signals on one or more of the 5/2 valves preventing operation This circuit demonstrates the problem The sequence is A+ B+ B- A-
  • 58. Opposed signals a0 a1 b0 A b1 B Run/End a0    b0 a1 b1 When the valve is set to Run, cylinder A 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 similar problem will occur for the 5/2 valve of B once it was + The sequence is A+ B+ B- A-
  • 59. Mechanical solution a0 a1 b0 A b1 B Run/End a0   b0 a1 b1 The problem was caused by valves b0 and a1 being operated at the time the new opposing instruction is given If these two valves were “one way trip” types and over tripped at the last movement of stroke, only a pulse would be obtained instead of a continuous signal
  • 60. Sequence solution methods  The main solutions to solving sequences are:      Cascade (pneumatic) Shift register (pneumatic) Electro-pneumatic PLC (Programmable logic controller) Cascade circuits provide a standard method of solving any sequence. It uses a minimum of additional logic hardware (one logic valve per group of sequential steps)    Shift register circuits are similar to cascade but use one logic valve for every step Electro-pneumatic circuits use solenoid valves and electromechanical relays PLC. The standard solution for medium to complex sequential systems (except where electrical equipment cannot be used)
  • 61. Cascade two group      The A+ B+ B- A- circuit is solved by the two group cascade method The sequence is divided at the point where B immediately returns The two parts are allocated groups l and ll Gp l A+ B+ / Gp ll B- ATwo signal supplies are provided from a 5/2 valve one is available only in group l the other is available only in group ll   Because only one group output is available at a time it is not possible to have opposed signals A standard 5/2 double pressure operated valve is the cascade valve Group l 14 Select l Group ll 4 5 2 12 1 3 Select ll
  • 62. Cascade (two group) a0 a1 b0 A b1 B b0 a1 Gp l Gp ll Sequence Gp l A+ B+ Gp ll B- ARun/End a0 b1
  • 63. Cascade (two group) a0 a1 b0 A b1 B b0 a1 Gp l Gp ll Sequence Gp l A+ B+ Gp ll B- ARun/End a0 b1
  • 64. Cascade (two group) a0 a1 b0 A b1 B b0 a1 Gp l Gp ll Sequence Gp l A+ B+ Gp ll B- ARun/End a0 b1
  • 65. Cascade (two group) a0 a1 b0 A b1 B b0 a1 Gp l Gp ll Sequence Gp l A+ B+ Gp ll B- ARun/End a0 b1
  • 66. Cascade (two group) a0 a1 b0 A b1 B b0 a1 Gp l Gp ll Sequence Gp l A+ B+ Gp ll B- ARun/End a0 b1
  • 67. Cascade (two group) a0 a1 b0 A b1 B b0 a1 Gp l Gp ll Sequence Gp l A+ B+ Gp ll B- ARun/End a0 b1
  • 68. Cascade building blocks   A two group building block consists of a lever valve to run and end the sequence plus the 5/2 double pilot operated cascade valve For a two group system consisting of any number of cylinders this building block and the cylinder building blocks are all that is required to solve the sequence Gp l 4 14 2 10 12 Sel l 12 5 Run/End 3 1 Gp ll 2 1 3 Sel ll
  • 69. Cascade building blocks  This three group building block establishes an interconnecting pattern that can be extended to any number of groups Gp l Run/End Gp ll Sel l Sel ll Gp lll Sel lll
  • 70. Dual trip building blocks    When a sequence has a cylinder operating twice in one overall sequence a dual trip building block may be required for each of the two feedback valves The supply will be from different groups and the output go to different destinations Example is for feedback valve a1 of cylinder A when A is sent + both in Group x and Group y Send A+ a1 in x a1 in y A+ in Group x A+ in Group y a1 Note: can often be rationalised to less than these three components
  • 71. Cascade rules      Establish the correct sequence Divide the sequence in to groups. Always start a sequence with the Run/End valve selecting group l e.g. R/E | A+ B+ | B- C+ | C- ASelect the cylinder building blocks Select the cascade building block Select dual trip building blocks if required      Interconnect the blocks as follows: The first function in each group is signalled directly by that group supply The last trip valve operated in each group is supplied with main supply air and selects the next group The remaining trip valves are supplied with air from their respective groups and initiate the next function The “run/end” valve will control the signal from the last trip valve to be operated
  • 73. 5/3 Valve    5/3 valves have a third mid position The valve can be tristable e.g. a detented lever operator or monostable e.g. a double air or double solenoid with spring centre There are three common configurations for the mid position:    All ports blocked Centre open exhaust Centre open pressure  The majority of applications are actuator positioning and safety 4 2 14 5 1 3 14 4 2 12 12 5 1 3 14 4 2 5 1 3 12
  • 74. 5/3 Valve actuator control     The valve illustrated has “all ports blocked” in the mid position Whenever the mid position is selected the pressure conditions in the cylinder will be frozen This can be used to stop the piston at part stroke in some positioning applications Flow regulators mounted close to the cylinder to minimise creep 4 14 2 5 1 3 12
  • 75. 5/3 Valve actuator control     The valve illustrated has “all ports blocked” in the mid position Whenever the mid position is selected the pressure conditions in the cylinder will be frozen This can be used to stop the piston at part stroke in some positioning applications Flow regulators mounted close to the cylinder to minimise creep 4 14 2 5 1 3 12
  • 76. 5/3 Valve actuator control     The valve illustrated has “all ports blocked” in the mid position Whenever the mid position is selected the pressure conditions in the cylinder will be frozen This can be used to stop the piston at part stroke in some positioning applications Flow regulators mounted close to the cylinder to minimise creep 4 14 2 5 1 3 12
  • 77. 5/3 Valve actuator control     The valve illustrated has “all ports blocked” in the mid position Whenever the mid position is selected the pressure conditions in the cylinder will be frozen This can be used to stop the piston at part stroke in some positioning applications Flow regulators mounted close to the cylinder to minimise creep 4 14 2 5 12 1 3
  • 78. 5/3 Valve actuator control     The valve illustrated has “all ports blocked” in the mid position Whenever the mid position is selected the pressure conditions in the cylinder will be frozen This can be used to stop the piston at part stroke in some positioning applications Flow regulators mounted close to the cylinder to minimise creep 4 14 2 5 1 3 12
  • 79. 5/3 Valve actuator control     This version of a 5/3 valve is “centre open exhaust” The supply at port 1 is isolated and the cylinder has power exhausted when this centre position is selected The version illustrated shows a mono-stable version double pilot operated spring centre The cylinder will be preexhausted when changing from the mid position 14 4 2 5 1 3 12
  • 80. 5/3 Valve actuator control     This version of a 5/3 valve is “centre open pressure” The supply at port 1 is connected to both sides of the cylinder and the exhaust ports isolated when this centre position is selected Can be used to balance pressures in positioning applications The version illustrated is mono-stable, double solenoid, spring centre 14 4 2 5 1 3 12
  • 81. Logic functions for poppet and spool valves
  • 82. 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 Z 2 10 12 Y 3 2 10 12 X 1 3 1
  • 83. 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 Z 2 10 12 Y 3 12 X 3 1 2 1 10
  • 84. 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 Z 2 10 12 Y 3 2 10 12 X 1 3 1
  • 85. 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 Z 12 Y 3 1 2 10 12 X 2 3 1 10
  • 86. 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 Z 12 Y 3 12 X 3 2 10 1 2 1 10
  • 87. 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 Z 12 Y 3 1 2 10 12 X 2 3 1 10
  • 88. 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 Z 2 10 12 Y 3 2 10 12 X 1 3 1
  • 89. 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 Z 2 10 12 Y 3 2 10 12 X 1 3 1
  • 90. 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 Z 2 10 12 Y 2 10 12 X 3 1 3 1
  • 91. 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 Z 2 10 12 Y 2 12 X 3 1 10 3 1
  • 92. 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 Z 2 10 12 Y 2 10 12 X 3 1 3 1
  • 93. 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 Z 2 12 Y 2 10 12 X 3 1 3 1 10
  • 94. 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 Z 2 10 12 Y 2 10 12 X 3 1 3 1
  • 95. 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 (inlet port numbered 1) When the signal X is present there is NOT output Z When X is removed output Z is given Z 2 10 12 X 1 3
  • 96. 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 (inlet port numbered 1) When the signal X is present there is NOT output Z When X is removed output Z is given Z 2 12 X 1 3 10
  • 97. 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 (inlet port numbered 1) When the signal X is present there is NOT output Z When X is removed output Z is given Z 2 10 12 X 1 3
  • 98. Logic MEMORY    A logic MEMORY allows the output signal state (ON or OFF) to be maintained after the input signal has been removed Any bi-stable valve is a logic MEMORY With this lever detented valve, once the lever has been moved X direction or Y direction it can be released and will stay in that position Z X 12 Y 3 10 1
  • 99. Logic MEMORY  A logic MEMORY allows the output signal state (ON or OFF) to be maintained after the signal that set it has been removed Z X 12 10 3 1 Y
  • 100. Logic MEMORY  A bi-stable double pilot valve can be set or reset simply by a pulse (push and release) on buttons X or Y Z 12 10 3 1 2 10 12 Y 2 10 12 X 3 1 3 1
  • 101. Logic MEMORY  A bi-stable double pilot valve can be set or reset simply by a pulse (push and release) on buttons X or Y Z 12 10 3 1 2 10 12 Y 2 12 X 3 1 10 3 1
  • 102. Logic MEMORY  A bi-stable double pilot valve can be set or reset simply by a pulse (push and release) on buttons X or Y Z 12 10 3 1 2 10 12 Y 2 10 12 X 3 1 3 1
  • 103. Logic MEMORY  A bi-stable double pilot valve can be set or reset simply by a pulse (push and release) on buttons X or Y Z 12 10 3 1 12 Y 2 10 12 X 3 1 3 2 1 10
  • 104. Logic MEMORY  A bi-stable double pilot valve can be set or reset simply by a pulse (push and release) on buttons X or Y Z 12 10 3 1 2 10 12 Y 2 10 12 X 3 1 3 1
  • 105. Logic MEMORY (latch)      A popular memory circuit is the latch Will not re-make after pneumatic power failure A pulse on X operates the pilot / spring valve to give output Z A feedback from Z runs through the normally open valve Y to latch the operation of Z when X is released A pulse on Y breaks the latch and Z is exhausted Z Y 1 3 10 2 12 12 10 3 X 2 10 12 3 1 1
  • 106. Logic MEMORY (latch)      A popular memory circuit is the latch Will not re-make after pneumatic power failure A pulse on X operates the pilot / spring valve to give output Z A feedback from Z runs through the normally open valve Y to latch the operation of Z when X is released A pulse on Y breaks the latch and Z is exhausted Z Y 1 3 10 2 12 12 10 3 X 12 3 2 1 10 1
  • 107. Logic MEMORY (latch)      A popular memory circuit is the latch Will not re-make after pneumatic power failure A pulse on X operates the pilot / spring valve to give output Z A feedback from Z runs through the normally open valve Y to latch the operation of Z when X is released A pulse on Y breaks the latch and Z is exhausted Z Y 1 3 10 2 12 12 10 3 X 2 10 12 3 1 1
  • 108. Logic MEMORY (latch)      A popular memory circuit is the latch Will not re-make after pneumatic power failure A pulse on X operates the pilot / spring valve to give output Z A feedback from Z runs through the normally open valve Y to latch the operation of Z when X is released A pulse on Y breaks the latch and Z is exhausted Z 1 Y 12 3 2 10 12 10 3 X 2 10 12 3 1 1
  • 109. Logic MEMORY (latch)      A popular memory circuit is the latch Will not re-make after pneumatic power failure A pulse on X operates the pilot / spring valve to give output Z A feedback from Z runs through the normally open valve Y to latch the operation of Z when X is released A pulse on Y breaks the latch and Z is exhausted Z Y 1 3 10 2 12 12 10 3 X 2 10 12 3 1 1
  • 110. Logic arrangements for fully balanced spool valves
  • 111. Logic circuits (spool valves)        NO / NC Selection / Diversion Latch OR, AND, NOT Single pulse maker Slow pressure build Pre-select      5/2 OR Single pulse control Air conservation Double flow Counting Click the section to advance directly to it
  • 112. 3/2 NO / NC     A fully balanced valve allows pressure on any pot or combination of ports A single valve can be used normally open or normally closed For normally open the supply pressure is connected to port 1 For normally closed the supply pressure is connected to port 3 2 10 12 3 1 2 10 12 3 1
  • 113. 3/2 NO / NC     A fully balanced valve allows pressure on any pot or combination of ports A single valve can be used normally open or normally closed For normally open the supply pressure is connected to port 1 For normally closed the supply pressure is connected to port 3 12 3 12 3 2 10 1 2 1 10
  • 114. 3/2 Valve selection / diversion    Selection of one of two supplies connected to ports 1 and 3 can be different pressures Diversion of one supply to one of two outlets If it is required to exhaust the downstream air a 5/2 valve is required 2 10 12 3 3 12 1 1 10 2
  • 115. 3/2 Valve selection / diversion    Selection of one of two supplies connected to ports 1 and 3 can be different pressures Diversion of one supply to one of two outlets If it is required to exhaust the downstream air a 5/2 valve is required 12 2 3 1 3 10 1 12 2 10
  • 116. Latch with controls   In this version of a latch the push button valves are connected to perform ‘OR’ and ‘NOT’ functions The ‘OFF’ valve must be placed last in the signal chain so that if both valves are operated together the ‘OFF’ command will dominate over the ‘ON’ command Out 2 10 12 3 ON 2 10 12 3 1 2 10 OFF 12 3 1 1
  • 117. 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 OR z 12 3 x AND 1 y z 12 3 y z 12 3 x 2 10 1 x NOT 2 10 2 10 1
  • 118. Single pulse maker    Converts a prolonged signal x into a single pulse z Signal z must be removed to allow the valve to reset then x can be applied again The duration of the pulse can be adjusted with the flow regulator z 2 10 12 3 x 1
  • 119. Slow initial pressure build up    Choose a 3/2 pilot spring valve with a relatively high operating force e.g. 3 to 4 bar When the quick connect coupling is made, the output at port 2 is controlled at the rate of the flow regulator setting When the pressure is high enough to operate the valve full flow will take over 2 10 12 3 1
  • 120. Pre-select    The lever valve can preselect the movement of the cylinder OUT or IN The movement will occur the next time the plunger valve is operated The plunger valve can be released immediately and subsequently operated and released any number of times 2 10 12 3 2 10 12 3 1 2 10 12 OUT/IN pre-select 3 1 1
  • 121. 5/2 OR function   The valve at position ‘a’ is reversed connected and supplied from the valve conventionally connected at position ‘b’ The cylinder can be controlled from either position ‘a’ ‘OR’ position ‘b’ 4 5 b 1 3 4 a 2 2 5 1 3 14 14 12 12
  • 122. Single pulse control     Each time the foot operated valve is pressed the cylinder will single stroke + and - alternately First foot operation the cylinder moves out Second foot operation the cylinder moves in Third….. out and so on 4 2 14 5 2 10 12 3 2 10 12 3 1 1 12 1 2 12 3 1 10
  • 123. Air conservation     Power stroke in the instroke direction only Differential area of the piston gives an outstroke force when the pressure is balanced Air used to outstroke is equivalent to a cylinder with only the same bore as the rod diameter Assumes the cylinder is not loaded on the plus stroke and low friction 4 2 14 5 1 12
  • 124. Air conservation     Power stroke in the instroke direction only Differential area of the piston gives an outstroke force when the pressure is balanced Air used to outstroke is equivalent to a cylinder with only the same bore as the rod diameter Assumes the cylinder is not loaded on the plus stroke and low friction 4 2 14 5 1 12
  • 125. Double flow    Where a larger 3/2 valve is not available Two flow paths in a 5/2 valve each with a separate supply can be arranged to give double flow or supply separate devices Ensure the tube size to the cylinder is large enough to take the double flow 4 2 14 12 5 1 3
  • 126. Double flow    Where a larger 3/2 valve is not available Two flow paths in a 5/2 valve each with a separate supply can be arranged to give double flow or supply separate devices Ensure the tube size to the cylinder is large enough to take the double flow 4 14 5 1 2 12 3
  • 127. Counting     Counting applications are best achieved with electro-mechanical or programmable electronic counters Pneumatic counting circuits use large numbers of logic valves and can be slow The counting chain shown will count to 4 Red and blue are nonoverlapping alternate pulses, purple is the reset line 4 3 2 1
  • 128. Counting application a0      The counting circuit is applied to count 4 strokes of a cylinder At rest all counting valves are held reset by the start valve Start outstrokes ‘A’ Alternate signals from ‘a1’ and ‘a0’ progresses operation of the counting valves up the chain On the 4th operation of ‘a1’ the green signal resets the start valve to stop the cylinder A Start a1 a0 a1
  • 130. 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 unrestricted output is given A reservoir provides capacitance to allow less fine and sensitive settings on the flow regulator making it easy to adjust Output 2 12 3 1 Signal in 10
  • 131. Time delay  - Manual remote start of a double acting cylinder with a time delay in the outstroked position before automatic return + a1 A 4 14 2 12 5 1 3 2 12 3 1 2 12 10 3 1 2 10 12 a1 3 1 10
  • 132. Pressure decay      Manual remote start of a double acting cylinder Uses a low pressure operated valve connected normally open When the back pressure in the front of the cylinder falls below 0.1 bar the return signal is given Connection taken between the cylinder and flow regulator Useful for pressing work pieces of variable size - + a1 A 4 14 2 12 5 1 3 2 12 10 3 1 10 2 1 12 3 0.1bar
  • 133. Electro-pneumatic     The majority of systems use electrical/electronic control due to the high degree of sophistication and flexibility Solenoid valves are used to control cylinders Feedback signals are from reed switches, sensors and electrical limit switches Logic is hard wired or programmed in to a PLC (programmable logic controller)  Circuit building block for each cylinder a0 a1 4 2 12 A 14 5 a0 1 3 a1
  • 134. End

Notas del editor

  1. The flow regulators should be close to the push button valves. The reason for this is the pipework and valve cavity volume between the push button valves and their flow regulators act as small reservoirs. This will cause the movement to overrun after releasing each button. If the flow regulators are placed the other side of the push button valves, the reservoir effect will cause a slight jump in the cylinder action when each button is first pushed.