A Normally Open (NO) Solenoid Valve is a vital component in many fluid and gas control systems, acting as a mechanical switch that either allows or blocks the flow of a medium based on the presence or absence of an electrical signal. In its default state, the valve remains open, allowing the passage of fluid or gas. When activated by an electrical current, the solenoid pulls or pushes a plunger to close the valve, stopping the flow. This simple yet effective mechanism plays an essential role in a variety of industrial and commercial applications.
Working Principle of Normally Open Solenoid Valves The operating principle of a Normally Open Solenoid Valve is relatively straightforward. In the absence of electrical power, the valve is open, allowing fluid or gas to flow freely. The “normally open” designation refers to this default state. When an electrical current is applied to the solenoid coil, the resulting magnetic field moves the valve’s internal mechanism—typically a plunger or diaphragm—towards a closed position, thus preventing the flow of the medium. In other words, when the solenoid valve is not energized, the system behaves as though the valve is fully open. However, once the electrical signal is received, the solenoid’s action alters the valve’s position to a closed state, cutting off the flow. This behavior is in stark contrast to the Normally Closed (NC) solenoid valve, which remains closed by default and opens when energized.