Pneumatic directional valves

Valves which are used to control and change in direction of flow of a air are called - pneumatic directional valves.

The designation of a directional valve refers to the number of ways and the number of spool position.

Directional valves are used to control single acting or double acting pneumatic cylinders.

A directional valve with 5 service ports and 3 spool positions is this designated as a 5/3 directional valve.

Types of pneumatic valves

There are three types of directional valves:

• spool valves;
• popper valves;
• rotery valves;

Actuating methods

• mechanical (manual);
• spring;
• electrical;
• pneumatic;
• hydraulic.

Directional spool valves design

Directional spool valves in which a moving spool is situated in the valve housing.

In fig. 1 is a pneumatic spool valve with three spool positions (pneumatic actuation method).

On the left (and right) hand side is an wet pin solenoid.

The springs are supported on the solenoid housings and sentere the spool in neutral position.

The air flow path, when solenoid 1 is activated, is from port P to port A and from port B to port R2. When solenoid 2 is activated, the flow path is from port P to port B and from port A to port R1.

2/2 directional valve with mechanical (manual) operation

The spool is fixed to the operating mechanism and follows its movement.