FIRE ALARM WITH A LIGHT SCATTERING ASSEMBLY IN THE REGION OF A SMOKE ENTRY OPENING FOR CONTAMINATION MONITORING

摘要

The invention relates to a fire detector (M), in particular a smoke detector, which has a detector housing (3) with a smoke inlet (OF), a detection unit (DET) for fire characteristics, an evaluation unit (7) for a fire alarm (AL), and a detector having connected light transmitter (1) and light receiver (2) for monitoring the smoke inlet opening to an inadmissible contamination (V) out. According to the invention, the light emitter and the light receiver are arranged in a scattered light arrangement. A specified by this scattered light volume (SV) is located in a pollution (V) tending region of the smoke inlet opening. The light emitter is aligned and aligned in such a way that a first part (D) of an emitted light bundle (L) traverses the area of the smoke inlet opening without tangent to adjacent housing parts (4, 5, 8, N). Alternatively or additionally, the light transmitter is aligned and aligned such that a second part (A) impinges on a housing part adjacent to the smoke inlet opening. In this case, the surface of the housing part is designed and aligned such that the incident there second part is deflected away from the light receiver. By means of the evaluation unit, a service message (WARN) can be output if the scattered light (S) detected by the light receiver exceeds a minimum value.