Accession Number : ADD003139

Title :   Ultraviolet Wavelength Smoke Detector.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON D C

Personal Author(s) : Trumble,Terry M

Report Date : 21 Sep 1976

Pagination or Media Count : 6

Abstract : Collimated ultraviolet light radiation at wavelengths of 2537A and 3129A is alternately directed across the space to be monitored for smoke indicative of a fire. A 'cats eye' mirror at the far side of the monitored space returns the ultraviolet rays to a photomultiplier detector adjacent the light source. Smoke, for example pine smoke having a particle mean diameter of 1.4 to 3.0 micrometers, will attenuate the shorter wavelength beam much more than the longer wavelength beam. Approximately 1.3 times greater attenuation is inflicted on the 2537A beam than on the 3129A by the pine smoke. Thus, returning beam signals having this ratio of signal levels will provide an indication of a pine fire. Particles of a different diameter intercepting the beam will produce a different ratio of attenuated signals.

Descriptors :   *Fire detectors, *Smoke, *Ultraviolet detectors, *Patents, Optical equipment, Mirrors, Particle size, Photomultiplier tubes

Subject Categories : Safety Engineering
      Ultraviolet Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE