Liquid level switch for temperatures as low as -80degC

Echotel 961 switches utilise pulsed ultrasound technology to detect the presence or absence of liquid. The system operates on a two-crystal pulsed - or transmit-receive - principle that applies a 2MHz high-frequency electronic burst to the receiving crystal. The speed of propagation determines the presence or absence of liquid.

By applying pulsed-wave technology, the unit is claimed to be less sensitive to buildup, aeration, foam and turbulence than most of its competitors. The 961 typically has a response time of 90 per cent, it can easily be integrated in SIL 1,2 and 3 loops, depending on the user's safety system and historical experience with the technology.

Dual-point version

A dual-point unit also exists with two selectable switch points on the same sensor (Echotel 962) for High and High/High Level alarm, Low and Low/Low level alarm or pump control.

The innovative features of the 961/962 sensors include adjustable time delay, 'on-demand' test buttons for the output signal (alarm and error), LED indication for alarm status, reliability condition and, in case of malfunction, identification of the malfunction and separate error signal.

The 961/962 is designed for use in ATEX intrinsically safe and explosion proof areas as well as CIP/SIP clean environments. The construction of the device conforms to PED (Pressure Equipment Directive) regulations.

Magnetrol says the 961/962 sensors are not sensitive to changing density or other liquid variables and therefore do not require any calibration. The units can be used on almost any liquid with a maximum viscosity of 10,000cP, resisting temperatures from –80 up to +165degC and pressures from full vacuum service up to 138bar. The 961/962 sensors are also available with relay or current shift output.