Ultrasonic waves detect an object in the same way as Radar does it. Ultrasonic uses the sound waves, and Radar uses radio waves. When ultrasonic pulse signal is targeted towards an object, it is reflected by the object and echo returns to the sender. The time travelled by the ultrasonic pulse is calculated, and the distance of the object is found. Bats use well known method to measure the distance while travelling. Ultrasonic level measurement principle is also used to find out fish positions in ocean, locate submarines below water level, also the position of a scuba diver in sea.
The level height is calculated from the time it takes for ultrasonic pulses to travel from the sensor to the surface of the medium and back. Chemical and physical properties of the medium do not influence the measurement result. Therefore, aggressive and abrasive, viscous and adhesive media can be measured without problems.
This continuous level measurement is based on the travel time of ultrasonic pulses to the surface of the medium and back.
When installing the sensor, the typical block distance has to be considered. Rough liquid surfaces and the changed angle during filling and emptying granulated solids influence the reflection of the ultrasonic pulses and may impact measurement