Technical information

Action - Operating mechanism
Direct acting
The magnetic plunger (orange) is acting directly on the valve seal to open or close the valve orifice depending upon whether the solenoid is energized or de-energized. The pressure and flow of this type of solenoid valve depend directly on the orifice size and the coil (yellow) power. Its function is not dependent upon line pressure or flow rate.

Example of 2/2 way normally closed solenoid valve

Example: 3/2 way normally closed solenoid valve

Pilot operated
This type is designed to permit a high flow rate at high pressure not depending directly upon the coil power. The plunger is acting on a pilot orifice to close or open it, depending upon whether the solenoid is energized or de-energized, thus permitting to pressurize or to release pressure in the pilot chamber.

A 2/2 way solenoid valve is equipped with a diaphragm (3) in which there is one bleed orifice (4), and one pilot orifice (1). When the solenoid is energized, it opens the pilot orifice and releases pressure from the pilot chamber (2). This results in overpressure in the bottom of the diaphragm which is lifted by the line pressure opening the main orifice.

When the solenoid is de-energized, the pilot orifice (1) is closed and full line pressure is applied in the pilot chamber (2) through the bleed orifice (4) , thereby providing a seating force for tight closure. This type of solenoid valve requires a minimum operating differential pressure. We also produce pilot operated solenoid valves with a diaphragm mechanically connected to the plunger which may operate from zero up to its maximum pressure service. See all figures showing the various designs of solenoid valves direct and pilot operated as well as the different types of connections in order to obtain the functions as described above.

Example: 2/2 way normally closed pilot operated solenoid valve