The LRS01 Ex operates on the light scattering principle. A light source and a light sensor are arranged inside the sensing chamber, such that the light normally does not fall on the sensor.

It is only when airborne particles (smoke, soot particles) enter the chamber that light is scattered / deflected on the light sensor. LRS01 Ex electronic circuitry also monitors the smoke detection system for slight contamination (dust and dirt build up), heavy contamination and faults (sensing chamber failure).

The evaluation electronics in the LRS01-EX monitors the smoke component of the sensor for mild contamination, serious fouling and for faults (eg. failure of the measuring chamber).

A long term compensation function automatically maintains a constant difference between the quiescent signal and the alarm threshold, until a set limit indicating heavy contamination is reached.

A relay contact switches opens in case of an alarm or a fault condition or on power failure.

Environmental Conditions
In places where there is a likelihood of interference from steam, dust, dew formation, or smoke or fumes from plant operation, optical smoke switches should not be employed.

Note: On hold-open installations in places where there is an explosion hazard:

• All components of the system must be certified for us in the relevant Ex-zone.

• The operation of hold-open installations in places where there is an explosion hazard, is only permissible in conjunction with a gas warning system certified for use in Ex-zones.