Gas solenoid valves control the flow of gasses through tubes as regular valves do, but unlike other valves, gas solenoid valves can be controlled remotely. Most often pneumatic, additional actuation methods for these solenoid valves include electric and electro-pneumatic. Compared to actuation methods such as hydraulic power, pneumatic power is considered cleaner and lower maintenance.
Typical gaseous media that gas solenoid valves control include air, nitrogen, argon, oxygen, hydrogen, liquefied petroleum, and natural gas. Offering low control power, gas solenoid valves are used in a wide range of industries such as automotive, aerospace, oil and gas, commercial, agricultural, food processing, medical, semiconductor, and marine.
Gas solenoid valves can be made from either plastics or metallic elements and alloys, with the more common materials including brass, PVC, polypropylene, PTFE, aluminum, copper, bronze, steel, cast iron, ductile iron, and stainless steel. Gas solenoid valves come in a wide range of sizes, with a compact design that offers fewer moving parts than most regular valves. In addition, gas solenoid valves offer fast and safe switching, long service lives, high reliability, and good medium compatibility of the materials used.
Operated electromechanically by a solenoid, which is a magnetized coil activated by electrical charges, gas solenoid valves control the flow of gasses precisely through targeted electrical charges, sensor cues, or by hysteresis (device memory).
Gas solenoid valves can be either a normally closed (NC) valve or a normally open (NO) valve.
In an NC valve, a plunging pin or rod within the valve is held blocking the passage of air in a solenoid coil; the air pressure coming into the valve helps keep the valve shut as long as the pin blocks the passage. In order for gas 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.
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.
Gas solenoid valves also have two additional distinctions based on how the valve performs its function: direct-acting and pilot-operated.
Direct-acting gas 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 gas solenoid valve works with a diaphragm rather than a plunger, using differential pressure to control the flow of gasses. In pilot-operated valves there is a solenoid-operated vent which is opened to allow the pressure to equalize, permitting gasses to flow through the diaphragm in the valve’s larger chamber.