Smoke detector system with self-diagnostic capabilities and replaceable smoke intake canopy

A self-diagnostic smoke detector system, comprising:

• a signal sampler cooperating with a radiation sensor to produce signal samples indicative of periodic measurements of a smoke obscuration level in a spatial region;
• and
• a processor receiving and processing the signal samples, the processor comparing the signal samples to multiple threshold values, one of the threshold values representing a smoke obscuration alarm level and another of the threshold values representing a tolerance limit for the radiation sensor, and the processor determining from the signal samples corresponding to smoke obscuration levels that exceed the alarm level and from signal samples corresponding to smoke observation levels that exceed the tolerance limit whether the signal samples are indicative of an alarm condition or an out-of-calibration condition of the system.

In a smoke detector canopy including a side structure having multiple passages through which smoke particles can pass and a top structure in contact with the side structure, the side and top structures forming an open-ended enclosure having an interior, the interior having a central portion, an improvement comprising:

• an array of pegs positioned in the interior of the enclosure, the pegs being shaped and arranged within the interior to form a labyrinth that permits low impedance passage of smoke particles flowing to the interior, and the pegs having first surfaces facing but not parallel to the side structure and of sufficient area to block external light infiltrating through the passages, and the pegs having second surfaces facing the central portion of the interior and angled to minimize spurious reflections of light within the interior.

A field replaceable optical block for a smoke detector system comprising a radiation emitter and a radiation detector positioned within the interior of a housing so that radiation emitted by the radiation emitter does not propagate directly toward the radiation detector, the housing having a central region and a periphery including multiple apertures in a periphery through which smoke particles can flow into the interior and intersect radiation propagating from the radiation emitter, the optical block comprising:

• multiple spaced-apart elements positionable within the housing to block external light infiltrating through the apertures and having multi-faceted surfaces designed to direct away from the radiation detector spurious radiation reflections occurring within the interior of the housing, each of the multi-faceted surfaces having a portion that includes a pair of facets joined at an apex that is positioned closest to the central region than any other portion of the multi-faceted surface.