The KOBOLD ultrasonic level sensor, model NUS-4, is used for non- contact, continuous level and volume measurement in tanks or for flow measurement in open channels. Ultrasonic level measurement is especially suited for applications where no physical contact can be established with the media's surface, such as with corrosive, contaminating, or adhesive media. The ultrasonic level sensing technology is based on the principle of measuring the time required for the ultrasound pulses to make a round trip from the sensor to the level to be measured and back. The sensor emits an ultrasonic pulse train and receives the echoes reflected. The compact, integrated electronic evaluates the echo time of the pulses and determines the level.