What Does a Three-Way Control Valve Do?

Three way valves are part of many familiar items.

Most valves control the flow of a single stream -- turning it on or off. Three-way valves redirect a stream between two different channels. Several different mechanisms are used to redirect the streams.

Piston Valves

In piston valves, a piston is moved between two different positions. In one position, the stream flows in one channel. In the other position, the stream flows in the other channel. In musical instruments, a spring holds the piston in one position. Pressing a key moves the piston to the other position.

Ball Valves

Ball valves have a rotating ball with holes drilled in it. Rotating the ball into one position allows the fluid to flow through the holes in the ball into one channel. Rotating the ball into the other position allows the fluid to flow through the holes in the ball into the other channel. Ball valves are used for small diameter pipes.

Butterfly Valves

Butterfly valves are used for large diameter pipes. The keys that operate butterfly valves turn a large disk that fits snugly inside the large pipe. In one position, the disk forces the flow into one channel. In the other position, the disk forces the flow into the other channel.

References

• Tpub: Three Way Valves
• DEP: Valve Basics

Resources

• ASCO: 3-Way Solenoid Valves