LS 300 with LS 500

LS 300 with LS 500

Thermal limit and level Switch with ATEX approval

Knows if the limit has been reached

Our thermal limit switch, prevents the overfilling of tanks and process containers. It consists of a sensor (LS 300) installed inside the tank and a transducer (LS 500) with an output relays. For water-polluting liquids, this overfill prevention device is an indispensable component for environmental protection.

How it works

At the switching point of the sensor LS 300 an isolated PTC resistor is mounted. The PTC resistor is a variable resistor, with the resistance increasing with temperature. Since the liquid has a better heat conductivity than gas, the PTC resistor heats itself more readily in the air and vapor area. When immersed into a liquid, the PTC resistor is cooled down. The resistance value is evaluated by the transducer LS 500.

Level Detector LS 300

We offer a variety of special designs that are designed where space is limited or installation conditions are difficult and challenging. From laboratory bottles to rail wagons we find a suitable solution - challenge us!

  • Standard: - 25 °C to + 50 °C
  • High temperature: - 25 °C to + 80 °C
  • Low temperature: - 40 °C to + 50 °C (pressure-free)

Transducer LS 500

The transducer with alarm system and relay output not only recognizes an overfill situation but also constantly checks the functionality of the sensor (LS 300) with its scanner function. The transducer has a free relay output which can be connected to an acoustic alarm, actuators or PLC system. The LS 500 is available as wall mounting version and as LS 500 H for DIN rail mounting.


Equipment Type Overfill Prevention, Thermal Level Detector
Liquid Acids, Chemicals, Fuel, Solvents, Wastewater, Water
Vessel Bulk Tank, Intermediate Bulk Container (IBC), Laboratory Bottle, Road Tanker, Ship, Underground Storage Tank, Waste Container
Measuring range 10.00 mm up to 6 000.00 mm
Stem diameter 3.00 mm up to 24.00 mm
Process Connection Fitting, Flange, None
Temperature -40.00 °C up to 110.00 °C
Pressure 0.00 bar up to 25.00 bar
Certification ATEX, IECEx, WHG
Signal output Relay, RS-485 - MODBUS (ASCII)
Power Supply 115 VAC, 230 VAC, 24 VAC, 24 VDC
Additional criteria Dry run protection, Vibration resistant