Optical smoke detector inlet screen - consists of wire mesh extending between offset ports on outside and inside walls of dark chamber to bar insects

摘要

An optical smoke detector has a housing which forms a dark chamber into which light is directed on a path viewed by a photocell. Light scattered from the path by smoke causes the cell to trigger an alarm. The housing includes an interior wall around the dark chamber and an exterior wall exposed to ambient light. A wire mesh extending between offset ports in the exterior and interior walls screens insects from the chamber and obstructs light from passing directly to the interior part. A typical mesh screen is of dull black coated aluminum wire cloth with wire 0.011 inch in diameter and 18 openings per square inch.