The Echotel 915 P/W from Magnetrol International is a 2-wire level switch that can detect the high or low level of almost any liquid without calibration.

After FMEDA analysis, Exida - one of the world's leading agencies to verify suitability of equipment for SIL certified loops - has issued a report of the Echotel 915 P/W into a SIL 2 loop as a standalone installation or in a SIL 3 loop, installed as a redundant set up.
Customers have the benefit of a SIL 2 / SIL 3 compliant device at no extra cost. The Echotel 915P/W is the second Magnetrol product to obtain SIL compliance, following the Eclipse Guided Wave Radar (TDR) level transmitter.
Echotel 915 P/W ultrasonic level switches are 2-wire, loop powered units, which utilize pulsed signal technology.
The principle behind contact ultrasonic switches is that high frequency sound waves are easily transmitted across a transducer gap in the presence of liquid, but are attenuated when the gap is dry.
Pulsed signal technology is used for superior performance in difficult process conditions, and to provide excellent immunity from sources of electrical noise interference. As per its NAMUR NE 21 testing, the unit can safely be used without shielded instrumentation cable - although the appliance of shielded cable is a manufacturer recommendation.
The Echotel 915P/W provides at all times a live signal : 18mA (safe condition) / 8mA (process alarm). The device's performance is monitored by a continuous self test procedure that will report an instrument failure with 5 mA. By using a standard mA signal, the unit can be connnected directly to an analog I/O, or to a digital I/O via a commercially available trip amplifier card.
Contact: Martine De Permentier, Magnetrol, Tel: +32 52 45 11 11; Fax: +32 52 45 09 93; E-mail: mdepermentier@magnetrol.be; website: www.magnetrol