Working Principle: ultrasonic level detector works on the principle of SONAR. It consists of a ultrasonic transmitter-receiver set mounted on the top of the tank. The beam is projected downward by the transmitter and is reflected back by the surface of the material inside the tank. The time ‘t’ taken between the transmitting and receiving a pressure pulse is proportional to the distance between the ultrasonic set and the surface of the content inside the tank.
where, l - level inside the tank. H - height of tank d - distance from the top of the tank upto the surface of content inside the tank.
Advantages: 1) They have no moving parts. 2) Used for both solid and liquid level measurement. 3) It is a non-disturbance technique.
Disadvantages: 1) Complicated design 2) Temperature compensation is required 3) The dirt affects the accuracy of the measurement.