Offered in general purpose and intrinsically safe versions, the ultrasonic level sensor provides reliable level measurement of non-foaming chemical, water, wastewater and petroleum based liquids in ambient tank or sump applications from 1-12 meters. How does an ultrasonic level sensor work? The ultrasonic level sensor emits a high frequency acoustic pulse from its transducer. The pulse travels through the air gap, reflects against the liquid surface and returns to the transducer. The ultrasonic level sensor measures the pulse time of flight and converts this into level height or distance.