Direct Acting solenoid valves utilise the armature movement as the direct means of the Open / Closed function of the solenoid valve.

With a direct acting solenoid valve, the solenoid plunger directly opens or closes the orifice, and the seal disc is attached to the plunger. In the case of a normally closed solenoid operator or valve, the orifice is closed by the seal when the solenoid coil is de-energized. When energized the orifice is open. The valve begins at its maximum rated pressure and is operated to close flow or zero (0) psi.

Direct Acting 2-way Valves.

Direct-Acting 2-way valves are shut-off valves with one inlet and one outlet port.

Direct Acting 3-way Valves.

Direct-Acting 3-way valves have three ports and two internal orifices one inside the valve body and one at the end of the armature tube. The moving armature has two seals one at each end, when one orifice is open the other is closed. When the solenoid coil is energized, the armature moves and the position reverses. Hence the description 2 position. The image below shows a 3-way, 2 position normally closed valve. With the coil de-energized, the armature spring holds the the lower armature seal tightly against the lower orifice, and shuts off flow. Port 2 is exhausted through Port 3. When the coil is energized, the armature is pulled into the coil and the orifice at Port 3 is sealed off by armature top seal. The media now flows from Port 1 to Port 2.

Benefits of Direct Acting Solenoid Valves.

Direct acting solenoid valves do not require any pressure differential to operate making them suitable for systems with low or no pressure. The lack of moving parts allows for very compact designs to be produced direct acting valves are available with Brass, Stainless Steel and Plastic bodied variants and a choice of seal materials making them suitable for most media types. Because they don't normally rely on the use of very small (<1mm) internal holes or passageways direct acting valves can be more tolerant of small amounts of dirt in the media than servo-assisted types.

Other names for Direct Acting Solenoid Valves.

Poppet solenoid Valves, Miniature Solenoid Valves, Direct operated solenoid valves, Zero Delta P solenoid valve, Plunger type solenoid valve.