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Particulate Entry Lag in Smoke Detectors.

pdf icon Particulate Entry Lag in Smoke Detectors. (235 K)
Cleary, T. G.; Chernovsky, A.; Grosshandler, W. L.; Anderson, M.

NISTIR 6242; October 1998.

National Institute of Standards and Technology. Annual Conference on Fire Research: Book of Abstracts. November 2-5, 1998, Gaithersburg, MD, Beall, K. A., Editor(s), 11-12 pp, 1998.

Available from:

National Technical Information Service
Order number: PB99-102519


fire research; fire science; fire suppression; smoke detectors; time lag; sensors; signals


It is well known that smoke detectors do not instantaneously respond to smoke concentration directly outside the detector. The smoke must be transported through the detector housing to a sensing location inside the detector. The sensing time lag is a function of the free stream velocity of the smoke laden air as it approaches the detector. Previous work correlated the detector time lag as a first-order response with a characteristic time defined as L/V, where L is a characteristic length and V is the characteristic velocity (ceiling jet velocity of free stream velocity).