Tony,

We have investigated many fires with similar circumstances and decided to conduct a study that is presented in the following paper:

Holton, M. M.; Olenick, S. M.; Klassen, M. S.; Roby, R. J., "Study of the Effectivnesss of Passive Infrared Burglar Alarms to Detect Fires and Smoke," Combustion Science and Engineering, Inc., Columbia, MD, Research and Practice: Bridging the Gap. Fire Suppression and Detection Research Application Symposium. Proceedings. Fire Protection Research Foundation. January 23-25, 2002, Tampa, FL, 355-371 pp, 2002.

Both bench-scale and full-scale tests were conducted to determine the conditions necessary for activation of passive infared (PIR) motion sensors. Tests were also conducted to determine the visual range of these types of sensors. It was determined that PIR sensors will activate when a flame is within thier visual range, and will also activate in the absence of a flame when smoke satisfies certain criteria. A buoyant gas plume generated by a hot plate also satisfies the activation criteria, indicating that radiation from the hot gases rather than smoke density was responsible for activation. It was determined that the gas plume must have a sufficient velocity and radiative intensity, which varies for different heat sources, within the visual range of the detector in order to cause activation of the PIR sensor.

I hope this is helpful to you.

Sincerely,

Doug Carpenter

Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
www.csefire.com