How do Solenoid Valves Work?

by Mike Hansen | ©Dultmeier Sales

Solenoid Valves are used for controlling the flow of air, water or chemicals. Generally, this is done using a small coil of wire wrapped around a piston, called a solenoid. When electricity is moved through the solenoid, it generates a magnetic field, which will then move the piston linearly. When electricity is cut off, the piston returns to its starting position and closes the valve. Solenoid valves are so widely used because of their ability to be toggled on or off, allowing for full automation.

Available in a wide variety of styles and configurations, solenoid valves typically have brass, stainless or plastic bodies with internal sealing options of Buna, Viton, EPDM or Teflon and are available as valves only or with strainer/valve or adjusting combinations.

Solenoid Valve Coils are available in 24 Volt, 110 Volt, 12 Volt or 240 Volt options. These coils are available in normally open or normally closed types. Normally open coils open flow when the coil is off or not energized and close flow when the coil is energized. Normally closed coils close flow when not energized and open flow when the coil is energized. Solenoid valve coils are available with lead wires, spade coils or Din coils.

There are a number of different solenoid valves, including direct acting valves, pilot-operated valves, two-way, three-way, and four-way valves. Of those, pilot valves and diaphragm valves (two-way valves) are the most popular. Pilot style solenoid valves operate using electromagnetism to raise and lower a piston, opening or closing flow accordingly. Diaphragm valves operate largely the same, but utilize a rubber diaphragm to stop flow.

Typical sizes for solenoid valves range from 1/8" to 2" ports.

Flow Adjusting Solenoid Valves have a needle stem feature that allows for regulating the amount of product that passes through the valve. Built-in strainers are also available for some models to ensure that clean products are entering the valve chamber. Combination solenoid valve/manifold blocks are also popular for a single input product and multiple control of output flows.

Solenoid valves have pressure ratings that are based on minimum and maximum "operating pressure differential" or ODP. This ODP rating can range from 0 psi to 1200 psi and higher. ODP is the difference in pressure from the inlet side of the solenoid valve to the outlet or discharge side of the valve or system.

Most solenoid valves are easy to repair. Pistons, seals and diaphragms are usually inexpensive and easy to change out.

Common Solenoid valve manufacturers include Dema Engineering, Kip Inc., GC Valves, Suntec, Texas Industrial Remcor, Kingston, GinSan, Morrison Bros, TeeJet and more.