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The level of detail for the equipment relates to the type of schematic being produced.   A Process Flow Sheet will only show the basic level of information sufficient to show the essential process flowpaths.   An Engineering Line Diagram of P & ID drawing will show a much more detailed representation.

Reading Pneumatic Schematic Symbols

5/2 Valve has 5 ports and 2 possible conditions

1.)    B is pressurized and A is exhausted.

2.)    A is pressurized and B is exhausted.

When the solenoid is NOT energized the B port is pressurized. The spring symbol defines the valve position at rest. 

The Block

The block symbolizes the possible valve functions orpositions. Example: A 5/2 valve schematic will be illustrated with 2 blocksdescribing two valve functions or positions/ A 5/3 valve schematic will show threeblocks describing 3 possible valve functions.

The Actuator.

(Solenoid) Symbol

Pneumatic valves can be operated in several ways. Handoperated (including levers and push and or push pull buttons) : Air piloted(operated remotely by pneumatic signals) : Solenoid (directly actuated withelectronic signals)

Exhaust Port Symbol

The inverted triangle symbol Denotes an exhaust port.The letters EA indicate this is the exhaust port for the A circuit. Ebin turnindicated the exhaust port for the B circuit.

The Arrows

The arrow symbols illustrate the direction of gassesflowing into and out of the valve ports. Gas pressure is supplied from port P.Depending on which of the valve blocks is in function, the gas is directed toport A or B as shown by the arrows.

The return spring

The spring symbol defines the “at Rest” position ofthe solenoid valve. The spring “pushes” from the side it is drawn on and placesthe right side block diagram of the valve in function. 

The T Symbol

This symbol indicates that a port is closed and isneither passing or exhausting gas.

Pressure of air supply symbol

This symbol indicates the air supply port, in addition tothis the letter P or the number 1 also indicated the air supply port.