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A vent valve solenoid is an electromagnetic actuator used to remotely or automatically open and close vent valves used as pressure relief devices. The solenoid is a widely used actuator type consisting of a wire wound coil and a ferrous metal plunger. When the solenoid is activated, a suitably-rated electric current is passed through the coil creating a strong magnetic field around it. This field attracts the metal plunger causing it to move rapidly towards the coil, the movement being harnessed to open the valve. When the current is cut, the valve spring closes the valve mechanism and returns the plunger to its neutral position.
Vent valves are often included in pipe systems and pressure vessels as a means of relieving the internal pressure in the system. When the system is subject to working pressure, the valve remains closed, only being opened when the vessel or pipe system require venting to release the pressure. Many vent valves are manually-operated by means of a cammed lever or screw down mechanism. In applications where the valve is situated a long way from operator stations or where the environment around the valve or the contents of the system are hazardous, a remote solution such as a vent valve solenoid is required for obvious reasons. The same is true of unmanned applications or valves situated in small, closed spaces where the valve is inaccessible and required to open and close automatically.
One of the most viable methods of achieving this remote activation is the vent valve solenoid. Simple, effective, and reliable, solenoids are the obvious choice for a wide range of similar applications. Consisting of little more than a wire coil and a ferrous metal plunger, the solenoid is simplicity itself while producing reliable and surprisingly powerful activation motion.
In the case of a typical vent valve solenoid, the plunger will attach to the spring-loaded valve stem via a series of linkages. When an operator or an automated system sends an electric current to the solenoid coil, a powerful magnetic field is produced around it that attracts the metal plunger. This causes the plunger to move rapidly towards the coil, the movement being transferred via the linkage to the valve stem, opening it in the process. When the pressure in the system has dropped to the required level, the coil current is cut, allowing the valve spring to pull the plunger and valve mechanism back to the closed position. This resets the vent valve solenoid in readiness for the next pressure cycle.