A fuel shutoff solenoid is an electromagnetically-operated valve used to remotely cut the fuel supply to an engine. The solenoid typically consists of a valve body with an integral solenoid assembly connected to the valve stem. When the solenoid is energized, the motion of its plunger retracts the spring-loaded valve poppet from its seat, allowing fuel to pass through the valve. When the solenoid is deactivated, the valve spring pulls the poppet back onto its seat effectively cutting the flow of fuel. The shutoff solenoid may be manually activated or be part of an automated engine management system.
Solenoid valves are among the most commonly-used remote fluid flow devices and are used in a wide variety of applications. The fuel shutoff solenoid is one such device used to remotely and, in some cases, automatically cut the fuel supply to an engine or burner. These valves are generally one piece units consisting of two separate devices. The first is the actual fuel shutoff valve that is, in most cases, a pretty conventional, brass poppet-style valve. The valve operating stem is connected to the plunger of a solenoid that generally mounts on the top of the valve body.
When a suitable electric current is passed to the solenoid coil, a strong magnetic field is created around it. This field attracts the solenoid plunger, pulling it rapidly towards the coil. Being connected to the valve stem, the moving solenoid plunger raises the valve poppet from its seat allowing fuel to pass through the valve. When the power is cut to the fuel shutoff solenoid, the valve spring pulls the poppet back to its seated position, closing the valve and resetting the solenoid in readiness for the next duty cycle.
The power that activates the fuel shutoff solenoid may be controlled manually or by an automated system, or both. In some cases, the shutoff solenoid may be used as an engine cut-out as is the case in many jet aircraft, or be used as part of an automated safety system. These valves generally open when the system start-up sequence is initiated and shut off if a dangerous condition is detected. This immediately cuts the flow of fuel to the burner or engine, effectively preventing any escalation of the hazard. The valves are also commonly used as part of several types of vehicle security system, cutting the fuel supply should the vehicle be stolen.