Ultrasonic makes use of sound waves in the 20 – 200 kHz range (above the range for human hearing). A transducer mounted in the top of a tank transmits sound waves in bursts onto the surface of the material to be measured. Echoes are reflected back from the surface of the material to the transducer and the distance to the surface is calculated from the burst-echo timing.Ultrasonic level measurement is one of the modern level measuring techniques.
Principle Of Operation
The key points in applying an ultrasonic transducer are:
- The speed of sound varies with temperature. If the transducer does not use temperature compensation and the temperature of the air space in the vessel varies your level readings will not be correct.
- Heavy foam on the surface of the material can absorb the sound wave bursts resulting in no echo or an echo that is too weak to process.
- An irregular material surface can cause false echoes resulting in irregular readings.
- Heavy vapor in the air space can distort the sound waves resulting in false reading.