A solenoidrnvalve is an electro-mechanical controlled valve. The valve features a solenoid,rnwhich is an electric coil with a movable ferromagnetic core in its center. Thisrncore is called the plunger. In rest position, the plunger closes off a smallrnorifice. An electric current through the coil creates a magnetic field. Thernmagnetic field exerts a force on the plunger. As a result, the plunger isrnpulled toward the center of the coil so that the orifice opens.