ultrasonic level switch / for liquids / stainless steel / for hygienic applications

Echotel? Model 961 Ultrasonic Level Switches use pulsed signal technology for superior performance in difficult process conditions, and to provide excellent immunity from sources of electrical noise interference. Extensive self-testing of the electronics and transducer make this advanced switch suitable for a wide variety of hygienic level switch applications.

Model 961 is offered with either a 5-amp relay or a current shift electronics. The relay output electronics has a DPDT relay for level detection, and a SPDT malfunction relay. The current shift version indicates 8 mA during normal operation, 16 mA as a level alarm condition and a user-selectable 3.6 or 22 mA malfunction indication.

The Model 961 switches are designed for the stringent requirements of hygienic applications. These switches are offered with a deep-drawn 304 stainless steel housing that is favorable to CIP and SIP procedures. A 20 Ra surface finish is featured with hygienic Model 961 transducers. These transducers are available with 11?2" and 2" Tri-Clamp? fittings, and DN65 Varivent? Type N flanges.

Operating Principle

Model 961 switches use pulsed signal technology to detect the presence or absence of liquid in an ultrasonic transducer gap. The transducer uses a pair of piezoelectric crystals that vibrate at a given frequency when subjected to an applied voltage. The transmit crystal converts the applied voltage from the electronics into an ultrasonic signal. When liquid is present in the gap, the receive crystal senses the ultrasonic signal and converts it back into an electrical signal.