Often used to control single-acting, spring-return air cylinders, these valves have a third threaded port to exhaust media. They operate on electricity to automatically start and stop flow.

Valves require a minimum pressure drop between the inlet and the outlet for operation; the upstream pressure must be greater than the downstream pressure. The actuator is directly mounted to the valve body to minimize movement and reduce wear. Valves' enclosures meet NEMA 4X for resistance to washdowns, splashing water, corrosive liquid, and dust.

Normally closed valves exhaust media unless actuated; when actuated, they close the exhaust port and reverse the direction of flow to send media to equipment. Normally open valves send media to equipment unless actuated; when actuated, they open the exhaust port and reverse the direction of flow to exhaust media.

Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.