Point Level Switch
By Design Engineering StaffGeneral sensors
Endress+Hauser Liquiphant FailSafe FTL8x suitable for monitoring Minimum and Maximum liquid levels in safety applications.
Endress+Hauser introduced its Liquiphant FailSafe FTL8x series of point level switches. The level switches have two relay outputs, a 4-20mA output that connects to a failsafe switching unit with a two-channel output, safety contacts and a safety locking function.
The 4-20mA output can be connected directly to a safety PLC or similar system for MIN and MAX safety applications up to SIL3. The 4-20mA signal jumps from high to low current when the MIN or MAX point level is reached for detection by the safety system. In addition, a permanent live signal of 0.25 Hz is superimposed on the sensor output to indicate the sensor is operating in the “good” state. The level switch meets SIL3 requirements in accordance with IEC 61508, IEC 61511-1, ISA 84-1 and DIN EN ISO 13849.
The switches can be used for minimum and maximum level detection in liquids from -76 to 536F (-60 to 280C), at pressures up to 1450 psi (100 bar), viscosity up to 10,000 mPa-s, and densities from 0.4 to 2.0 g/cm3. The FTL8x can also be used in highly corrosive media. Tuning fork sensors are available in 316L or 318L stainless steel with AlloyC22 plating, and the other wetted parts are available with Alloy22 plating or ECTFE or PFA coatings for use in aggressive liquids.