Plastic Solenoid Valves
First developed around 1910, solenoid valves are electromechanical devices designed to control gas or liquid flow and thereby adjust, switch, actuate or otherwise manage movement within other devices. Plastic solenoid valves are a type of solenoid valve that is enclosed in a plastic material casing. They are ideal for applications in which the valve encounters or is surrounded by moisture because, unlike metal or metal alloy valves, they will not degrade or malfunction because of it. Likewise, they are perfect for use in any environment in which the threats of corrosion or electric shock are present, as they are not susceptible to these dangers. Examples of machines in which they may be found include dishwashers, washing machines, sprinkler systems, vacuum cleaners and a variety of water systems.
Most plastic solenoid valves consist of the following: a plastic casing/body, an inlet port, an outlet port, a coil/solenoid, coil windings, a plunger, a spring and an orifice. Note that, while the most common valve design calls for just two ports, other, more advanced designs may call for several ports. Plungers, or seals, are typically made from nitrile rubber, Ethylene Propylene Diene Monomer (EPDM) rubber, Viton or polytetrafluoroethylene (PTFE), more commonly known as Teflon. Each rubber offers different types of resistance and work better with some substances than others. Nitrile rubber, for example, is most commonly used to seal air, water and fuels, oils and gases. Viton plungers, on the other hand, perform best with media including acid, alkali, hot water, hydrocarbon and salt solutions.
For plastic solenoid valves to work, fluid flows through the inlet port of the solenoid valve and then continues on through the orifice and out the outlet port. However, this flow is only allowed when the orifice is open. Whether an orifice is opened or closed depends on the plunger, which seals it when pressed by the spring and opens when released by the spring. This spring is controlled by the displacement caused by a magnetic field, caused by the flow of an electric current run through the coil. Plastic solenoid valves that are open unless acted upon are called normally open (NO); at a state of rest, they allow fluids to flow through. Valves that are closed unless acted upon are called normally closed (NC); while at rest, they do not allow fluid to flow through.
In addition to being corrosion and moisture resistant and offering a longer service life, plastic solenoid valves are valued for their light weight, their ability to be operated remotely and their low production costs. Because they are virtually the same as other solenoid valves, aside from their plastic casing, they are also available in potentially endless sizes and configurations, appropriate for nearly any application. For a comprehensive look at your options and to learn how to best care for your plastic solenoid valves, contact a valve manufacturer today.
Plastic Solenoid Valves - International Polymer Solutions