The magnetic field exerts a force on the plunger. As a result, the plunger is pulled toward the centre of the coil so that the orifice opens. This is the basic principle that is used to open and close solenoid valves. “A solenoid valve is an electromechanical actuated valve to control the flow of liquids and gases.”

A solenoid is a set of coiled wire which acts as an electromagnet when current is passed through it. … Solenoids are commonly used as the switch or valves which are entirely automated. The magnetic field of solenoid also has a south and a north pole like other magnets.