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Particulate Entry Lag in Smoke Detectors (NISTIR 6242)



Thomas G. Cleary, Artur A. Chernovsky, William L. Grosshandler, Michael D. Anderson


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).
NIST Interagency/Internal Report (NISTIR) - 6242
Report Number


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


Cleary, T. , Chernovsky, A. , Grosshandler, W. and Anderson, M. (1998), Particulate Entry Lag in Smoke Detectors (NISTIR 6242), NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 21, 2024)


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Created October 1, 1998, Updated November 10, 2018