A solenoid valve, otherwise known as an electrically-operated valve is an automatic valve which serves the purpose of removing the need for an engineer to operate a valve manually.
Solenoids operate using an electromagnetic solenoid coil to change the state of a valve from open to closed, or vice-versa. If the solenoid valve is 'normally closed', when the coil is energized, the valve gets lifted open by the electromagnetic force produced by the coil.
There are 3 main different technologies; Direct acting, In-direct acting and Forced-lift piston type.
Any application where a clean (non-viscous) process media, such as very clean liquids/gases/light oils need to be controlled.
Simple on/off valves are the most popular as many process lines only need flow or no flow. Solenoid valves can be used in factories/plants where compressed air is not available. They can also be used in place of larger valves such as electrically actuated ball valves, but without taking up anywhere near as much space. Operation is also much quicker than other valve technologies.
Other solenoid operated valves use a more advanced technology meaning they can be used to proportionally control flow or pressure depending on a varying input signal. This is where another component further downstream needs a specific pressure or flow to maintain the correct working conditions.
Most common input signal used would be a 4-20mA loop signal which most factories will have at their disposal usually controlled by a PLC or similar system.
Many different valve body and seal materials are available, ranging from Brass, Cast Steel, Aluminium and Stainless Steel. Standard seals are usually NBR (Buna Nitrile) but EPDM and PTFE available for more corrosive environments.
Material choice all depends on the media going through the valve. If you are unsure on the optimum material for your application, it is always best to talk it through with a Norgren technical specialist first.
The illustration below depicts the basic components of a solenoid valve. The valve shown in the picture is a normally-closed, direct-acting valve. This type of solenoid valve has the most simple and easy to understand principle of operation.
1 Valve Body
2 Inlet Port
3 Outlet Port
5 Coil Windings
6 Lead Wires