A multi-sensor fire alarm device

Abstract

A multi-sensor fire alarm device has a core (9) with a base (20) for engaging a ceiling and having a longitudinal axis. A cover (2) surrounds some of the core, and has vents (4, 204, 5, 205) to allow flow of ambient air radially inwardly into a first level (AF1) closest to the base and to flow (AF2) into a second level above the first level. An optical smoke chamber (160) is mounted centrally in the first level, and there are only two thermal probes on diametrically opposed sides near the vents in the second level. Air entering the second level is either directly incident on a thermal probe (50) or is deflected circumferentially towards it by a deflector (55) in the second level, and so there is only need for two probes. Guides provide air flow paths (150, 151, 152) from the first level to the smoke chamber Vents (204) for the first level have an insect-blocking mesh(204(a)) and vents (205) for the second level do not have such a mesh so that there is an open space for inflowing air without obstructions to affect temperature of the air.

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