3/2 Way Valve

3/2-Way Valve:

A 3/2-way valve has three ports and two positions that can be driven pneumatically, mechanically, manually or electrically via a solenoid valve. They are used, for example, to control a single-action cylinder, driving pneumatic actuators, blow-off, pressure release and vacuum applications. A valve is used to fill the cylinder, and also to exhaust it afterwards, so that a new working stroke can be realized. Therefore, a valve with two ports would not be adequate. Venting requires a third port. There are two kinds of 3/2 valves: mono-stable and bi-stable. Mono-stable 3/2-way valves can also be normally closed or normally open, just like 2/2-way valves.

The valve closes or opens by moving the spool or poppet. Mono-stable valves return to their default position, which is accomplished by spring force. In case of indirect operation, the spool is not directly actuated by the solenoid.The valve uses the system pressure to move the spool. In order to do this an additional pilot valve is used. This pilot valve is a small direct operated 3/2-way valve. The pilot valve delivers compressed air to a small air cylinder inside the valve. The compressed air in this cylinder pushes against the piston and actuates the solenoid to switch the valve. This way, a relatively small solenoid can be used to switch the valve.Mono-stable valves are built with one coil, bi-stable valves with two coils. With a NAMUR housing (housing with standardized footprint), the valve can be fixed directly to an actuator which also meets the NAMUR standard. Manifolds can be used to save space and to group valves. Not only can several 3/2-way valves be built up into one manifold, there is a possibility to mix valves. For example, you can mount a 5/2-way valve next to a 3/2-way valve. The possible combinations depend on the type and design of the manifold.