A solenoid valve is a valve
that is operated by a solenoid
. These valves come in sizes from 1/8" NPS up to about 3" NPS although the larger the valve, the less pressure
it will be able to handle because of the limited amount of force
that can be generated.
There are 2 types: direct acting and pilot operated. The direct acting version uses the solenoid core movement directly to open and close an orifice that allows the media to flow through. The pilot operated versions open a much smaller hole which then, with the assistance of the differential pressure across the valve opens the main flow path.
Solenoid valves come in 2, 3, 4, and 5-way configurations and can be made from a variety of material such as brass and 316 grade stainless steel. They usually have threaded ends. A special application for the 3 and 4 way valves is for operation of pneumatic actuators. These are mounted using a NAMUR standard pad.