How a solenoid valve works is by controlling the flow of liquids or gases in a positive, fully-closed or fully-open mode. They are often used to replace manual valves or for remote control. Solenoid valve function involves either opening or closing an orifice in a valve body, which either allows or prevents flow through the valve. A plunger opens or closes the orifice by raising or lowering within a sleeve tube by energising the coil.

Solenoid valves consist of a coil, plunger and sleeve assembly. In normally closed valves, a plunger return spring holds the plunger against the orifice and prevents flow. Once the solenoid coil is energised, the resulting magnetic field raises the plunger, enabling flow. When the solenoid coil is energised in a normally open valve, the plunger seals off the orifice, which in turn prevents flow.