Choosing the right solenoid valve

Solenoid valves are devices that use a solenoid to control valve activation. They are considered electromechanical control devices used to regulate liquid or gas flow. An electrical current runs through a coil to control the valve by moving a plunger. If the solenoid receives an electrical signal (energized), it channels the air supply directly to the plunger. When the electrical signal is removed (de-energized) the valve returns to its normal condition.

Solenoid valves are being used to open and close something. The media enters through the inlet port and flows through the orifice before it continues to the outlet port. This port is closed and available by the plunger.

Direct-acting: Solenoid valves can be viewed as direct-acting, which means that the plunger directly opens and closes the orifice inside the valve.

Pilot-operated: Solenoid valves can also be considered pilot-operated, which means the plunger opens and closes a pilot orifice. The inlet pressure opens and closes the valve seal. This kind of valve is also called a servo-type valve.


Solenoid valves are being used in a wide variety of industries. They are being used in machinery, devices, and equipment such as refrigerators and computerized faucets. Solenoid valves are commonly found in central heating systems to control the thermostat to modify the flow of heated water to the heating element. Fortunately they are used in programmed irrigation sprinkler systems, air control, fluid control, and in pharmacology experiments.


Solenoid valves generally have two ports: an inlet and an outlet port. There are several types of solenoid valves including three or even more ports.

Three-way solenoids are being used to use single-acting actuators, such as diaphragm actuators. They are designed to only send air to one chamber of an actuator. Three way solenoids are used to interrupt or override a musical instrument signal for double-acting actuators with a pneumatic positioner.  Visit this website to get more insight Solenoid Valve Manufacturers

Four-way solenoids provide a positive two directional action. They could be used instead of positioners to provide on-off procedure of double-acting valves. When the solenoid is de-energized, it sends the entire air supply to one side of the actuator and exhausts the other side to the atmosphere.

The effective size of a solenoid valve can be increased by servo or pilot operation. The word servo-operated is applicable to solenoid valves to indicate the key valve is fluid-powered and actuated by a little valve in a servo or pilot circuit.

Valve State

Powered states include normally open and normally closed.

Normally closed — Normally closed solenoid valves use a spring to press the plunger tip resistant to the opening of the orifice. This keeps the media from entering the orifice before plunger is lifted by the electromagnetic field created by the coil.

Normally open — Normally open valves close when the coil is energized, allowing the media to flow through the system. This valve state is most beneficial used for water, air, and noncorrosive liquids.

Solenoid Valve Components

Solenoid valves come in a variety of sizes and materials to be able to integrate within many fluid management systems. The body of the valve should be produced of a material that is compatible with the system media to prevent premature failure of the valve, or contamination of the media. The main components to consider when deciding on a solenoid valve will be the seal, coil, and the ports of the valve.


In general, seals will be the most limiting factor when selecting a solenoid valve. When choosing the material for the seal it is important to consider the chemical properties of the media, and temperature and pressure of the media and system. The most frequent seal material choices are nitrile rubber (NBR), ethylene propylene diene monomer rubber (EPDM)

Solenoid Valve Coils

The solenoid valve coil converts electrical energy into linear motion. It is usually made of copper or aluminum wire wound around a hollow form. A ferromagnetic core, called the valve plunger, is put inside the coil. As electric energy flows through the coil, the lines of magnetic flux turn the plunger into an electromagnet, setting up a magnetic field. The valve body orifice opens as the magnetic field pulls the plunger further up in to the coil.  Polarity of the coil does not matter because most coils with lead wires use the same color wire for both terminals and the positive terminal can be linked to either wire without affecting the procedure of the valve. You will find two types of coils you can use in a solenoid valve.

Tape wrap coil- Tape wrap coils are composed of conductor wire wrapped around a spool or bobbin. The conductor wire, also known as magnet wire, has a thin insulation layer around it and the completed winding is protected by another layer of insulation tape. Tape wrap coils are best found in applications which have mild environments. They could be used for smaller production runs, but they have a reduced tolerance for moisture.

Encapsulated coils- Encapsulated coils, also known as molded coils, are also consists of conductor wire wrapped around a spool or bobbin. The coil is then encapsulated in a suitable resin rather than a tape. Encapsulated coils can be used in environments with higher humidity levels and are created using stronger wires to safeguard against pull out.

Solenoid valve coils are available in several voltages and can be utilized with DC or AC electricity. It is possible to change coils out to be able to use a different voltage for the valve.

Solenoid Valve Ports

Solenoid valves generally have two ports. The ports can come with either inside or outside threaded ports. Within a tandem center solenoid valve, the pressure and tank ports are linked as the service ports are blanked. This allows system unloading while still providing isolation of the service lines. Within a float center solenoid valve, the supply pressure port is closed. All others ports are interconnected. This allows the supply to be turn off while enabling force to move or free wheel with flow open to other services.