What is a Solenoid Valve and How Does it Work?

Solenoid valves are an electromechanically operated flow control unit that can restrict or enable liquid or gas flow, depending on the type of valve and whether it is in a currently activated (energised) state. They work by passing electrical signals through a coil to generate a magnetic field that moves a core, or plunger, within the valve body.

A solenoid valve is composed of a valve body, and a solenoid that is mounted in the valve body, around which there are various orifices, or ports. The solenoid is a coil of insulated copper wire wound tightly around a ferromagnetic core or plunger, which can be either spring-mounted or spool-mounted in some valve models.

The core or plunger is made of a soft, ferromagnetic metal that can easily be magnetized and demagnetized at low magnetic fields. When an electrical current is passed through the coil, a magnetic field is generated which causes the core to be attracted towards the center of the coil.

In the energized (energised) position, the core moves upwards towards the center of the coil to open the orifice for the medium. When the coil is de-energized, the core moves downwards to close the orifice.

Solenoid valves are available in a range of different types, and they can be used for many applications in a wide range of industries. These include direct acting and indirect operated, 2-way 'normally closed' and 3-way 'normally open', as well as bi-stable or latching. Some are also ATEX or gas approval certified, have options for manual overrides and media separation, and they can be used for mixing or diverting fluids.