The Ultrasonic Level Switch emits a short burst of ultrasonic energy. The energy is coupled through a rubber membrane to the tank causing the tank to vibrate. The tank vibrations are detected and analysed by the Switch. Based on the vibration patterns the Switch is able to detect the presence or absence of liquid inside the tank, and directly opposite the Switch.

When the liquid inside the tank is below the switch point of the Switch, the Switch’s relay will be in the energized state referred to as the Normally Open (N.O) state (connecting the relay common to the relay normally open connector). When the liquid inside the tank is above the detection zone of the Switch, the relay will be in the non-energized state referred to as the Normally Closed (N.C) state (connecting the relay common to the relay normally closed connector).