Echotel® Ultrasonic Contact Switches make use of a pair of piezoelectric crystals that are mounted inside a transducer (sensor) to perform level measurement in a wide variety of applications. The crystals are normally made from a lead zirconate or barium titanate compound, and they convert electrical energy to mechanical energy and vice versa.
A transmit crystal is mounted on one side of the transducer gap, and a receive crystal is mounted on the opposite side. An electrical signal is generated by the ultrasonic switch electronics, and forwarded to the transmit crystal. This causes the crystal to vibrate at a specific frequency. If there is liquid in the gap, the receive crystal will sense the vibrations from the transmit crystal. If the gap is dry, the receive crystal cannot sense the vibrations from the transmit crystal.
The ultrasonic transducer continuously monitors the gap to determine if the gap is wet or dry. When used as a high level switch, the electronics will immediately actuate a relay or shift a current when it detects a wet gap. When used as a low level switch, it continuously checks for a dry gap condition.
