The Optical-Thermal Detector FI750/OT operates both by means of an optical sensing chamber based on the principle of scattered light as well as with a rate-of-rise thermal sensor according to EN 54-5, Class
A1R. The analysis of the analogue values of both detection units and the integrated comparison of characteristics of fire ensure safe fire detection.

The detector is designed for use on loops with Labor Strauss protocol. In the parameter settings of the control panel, one of 4 sensitivity levels of the smoke detection unit can be selected, thereby adapting the detector optimally to the respective application. A thermal-only operation is also possible.

Intelligent evaluation algorithms in the detector compensate for the impact of contamination of the optical sensing system. As a result, the response sensitivity of the detector is kept constant for a long time, thus constituting an effective measure for preventing false alarms. A fine-meshed protective grid protects the sensing chamber against ingress of dust and insects. In addition, the design of the housing makes it more difficult for dust to settle inside the sensing chamber.

The two multicoloured LED indicators with 360° visibility indicate the activated condition of the detector in red and the test condition in green. An output for the connection of a remote indicator is available. The integrated dual-isolator disconnects the loop at short circuit on the loop line.

By means of the Programming Unit FI750/PU, the address of the detector can be set in the range 1 to 240. In addition, the programming unit allows for the reading-out of parameters, such as the level of contamination of the optical chamber, the default analogue value or the production date. Furthermore, in case of connection to a compatible fire detection control panel, the detector can also be AUTO-addressed.

The detector is accommodated in a white housing and is designed for indoor mounting. In the thermal-only mode the room height is limited to 7.5m.