What is a solenoid valve and what are they used for? Solenoid valve talk is always a hot topic here at Zoedale - They're some of our most popular products. They come in various formats and sizes and are suitable for many different industries and applications - there are lots of uses you may have never considered before....
A solenoid valve is a valve that is electromechanically operated by an electric current. When an electric current is passed through a solenoid coil it energises the coil which then creates a magnetic field. This magnetic field causes a plunger inside the coil to move which can make the valve open or close. The common voltages for a solenoid valve are AC 12V, 24V, 110V, 220V, and DC 24V, 48V. A solenoid valve that remains open when the coil is de-energised is called a normally open solenoid valve and a valve that remains closed when the coil is de-energised is called a normally closed solenoid valve. 2-Way solenoid valves have one inlet and one outlet which allow the flow of media or shut off the flow of media. 3 way solenoid valves can have options of being normally open, normally closed or universal function. They are commonly used to alternately apply pressure to and exhaust pressure from a valve actuator or a single-acting cylinder.
What is a solenoid valve that is pilot-operated or one that is direct acting? The main difference being that direct acting valves directly control the opening and closing function of the valve, however pilot operated valves use the process media to assist in piloting the valve. Pilot operated valves often have a higher tolerance of pressure than direct acting.
The media and environment the solenoid valve will be placed in will determine the body type and seal type of the solenoid valve. The most common types of seal are Ethylene Propylene Elastomer (EPDM), Polytrafluoroethylene (PTFE), Nitrile Rubber / Buna (NBR) and Flourinated Elastomer/Perfluoro Elastomer (Viton / FKM). EPDM is one of the more popular seals and mainly used for water in WRAS approved applications and air applications although has a resistance to acids, alkalis and salts. It does not however, work with oils, petrochemicals or highly concentrated acids. PTFE is chemically inert and can withstand high temperatures and is mainly used in applications that require a big resistance to chemicals. NBR also has a high chemical resistance and is ideal for use with oils and petrochemicals. FKM is used where high temperature and chemical resistance is required - with an ability to handle over 200°C. Often used for hot water, acid, salts, hydrocarbons and oils.
Hopefully this will help explain what is a solenoid valve in very basic terms. For further reading on solenoid valves read some of our other popular blog posts we wrote on maintenance tips for solenoid valves and 5 cool uses for solenoid valves.