Page 52 - PNEUMATIC SYSTEM INSTRUMENT

TWO-WAY, TWO-POSITION VALVES

Two-way, two-position valves consist of two ports connected with a

passage that can be opened or blocked to control flow through the

valve. Usually, an electrically activated solenoid shifts the valve spool

or poppet to direct flow. The valve provides an easy on-off function,

which many systems use to interlock, isolate, and connect various

system parts.

A two-way valve has a pressure port 1(P) and an outlet port 2(A). The

pressure port is connected to the compressed air source and the

outlet port is connected to the actuator. Pushing the valve button

opens the valve to allow air to pass through. The spring causes the

parts to be closed to air flow when the valve button is not pushed.

Two-way valves are commonly used to START and STOP flow in

particular line.

2(A)

1(P)

Figure 7.3: Two-way valve schematic symbol

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