Ningbo Kaiven Pneumatic Cylinders Co.,Ltd >> Solenoid Valves

Solenoid valves control the flow of gases or liquids through tubes, as regular valves do, but unlike other valves, solenoid valves can be controlled remotely. Operated electromechanically by a solenoid, which is a magnetized coil activated by electrical charges, solenoid valves control the flow of gases or liquids precisely through targeted electrical charges, sensor cue or by hysteresis (device memory). In many valves – such as pneumatic and diaphragm valves – liquid or gas pressure changes help to close and activate the valve. In a normally closed (NC) valve, a plunging pin or rod within the valve is held blocking the passage of air or fluid by a solenoid coil; the air or fluid pressure coming into the valve helps keep the valve shut as long as the pin blocks the passage. In order for gas or fluid to flow through the valve, an electromagnetic charge is run through the solenoid coil, which becomes active and lifts the plunger out of the passage and allows flow through the entire valve. Normally open (NO) valves are the opposite; they remain open until the solenoid is activated and pushes down the plunger, blocking flow and creating pressure to keep the valve closed.

Solenoid valve manufacturers make two general types of valves: direct-acting and pilot-operated. Direct-acting solenoid valves have a plunger that is in direct contact with the in-flow opening in the valve body, or orifice. This plunger is used to open and close the orifice, which permits or hinders flow. The pilot-operated solenoid valve, which is actually a combination of a pneumatic or hydraulic valve and a smaller solenoid valve, works with a diaphragm rather than a plunger, using differential pressure to control the flow of gases or fluids. In pilot-operated valves, often the same as diaphragm valves, there is a solenoid-operated vent which is opened to allow the pressure to equalize, permitting fluids or gases to flow through the diaphragm in the valve’s larger chamber. Both direct-acting and pilot-operated valves use solenoid coils to move parts and create flow. Direct-acting solenoid valves need more power to be activated initially, but they can remain open (or closed, in a NC valve) with relatively little power and respond much more quickly to activation than pilot-operated valves.