Along
side the technical specification of functional pneumatic
components ( eg valves) is found the schematic for that
component.
These schematics are used in the drafting of pneumatic system
drawings and are a shorthand, symbolic description of the
functional action of that component
The basic schematic has two windows each depicting the state
of the valve in each mode of operation.
In the drawing shown here the left window shows the state
when the coil of the activating solenoid is energised
The right window shows the de-energised state when the return
spring has acted and the valve is in its rest state.
In this case the rest state is for the output port to be
vented to atmosphere and the input port closed.
When active the input port is connected to the output port
and the vent is closed.
Some
variations on this theme are shown below
As in
the diagram above, the activated side is in the left window
Two way normally CLOSED valve
Energised - OPEN
De-energised - CLOSED
Two
way normally OPEN valve
Energised - CLOSED
De-energised - OPEN
A
3/2-way outlet - A normally vented valve
Energised - P connected to A - R closed
De-energised - P Closed - A exhausts to R
A
3/2-way - B pressurised valve - (ie vent normally closed)
Energised - outlet B vents to R - P closed
De-energised - input P open to B - R closed
A
3/2 Mixer Valve with P2 normally open
Energised P1 is connected to A - P2 closed
De-energised - P1 Closed - P2 connected to A
Diverter
Valve
Energised - P1 connected to A
De-energised P connected to B - A closed
A
3/2 - way valve - Direct Active - Universal Function
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The
SMC Micro Mechanical Valve ( Micro Switch Style)
This is a 3/2 way valve - press button activated.
You will notice that the energised state is in the right
window not the left as above
This is because the return spring is on the left and the
energising push button is on the right thus directly linking
the energising mechanism with the function diagram
Note that although there are 3 ports only 2 can be seen
(A + P) - Port R exhausts inside the case
The
designation 3/2 - way is 3 ports with 2 modes of operation
normally a 2/2 - way valve is refered to as a 2 way.
NOTE
-2
Port
designations - A, B, P, P1, P2, + R are used in schematics
and are marked on valve bodies
3/2 way valves are marked for a particular valve function
but can often be used for different functions.
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