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Effect of an Obstructed Ceiling on the Activation Time of a Residential Sprinkler.

pdf icon Effect of an Obstructed Ceiling on the Activation Time of a Residential Sprinkler. (6815 K)
Vettori, R. L.

NISTIR 6253; 150 p. November 1998.


General Services Administration, Washington, DC

Available from:

National Technical Information Service
Order number: PB99-100042


sprinklers; residential sprinklers; sprinkler response; sprinkler systems; beams; ceiling jets; corners; fire growth; tenability limits; wall fires; sprinkler activation


A series of 45 experiments were conducted to compare the effects of two different ceiling configurations on the activation times of a quick response residential pendent sprinkler. The two ceiling configurations consisted of a smooth horizontal unobstructed ceiling and a horizontal ceiling obstructed by parallel beams measuring 0.038 m (1.5 in) wide by 0.24 m (9.5 in) deep and spaced 0.41 m (16 in) on center. For each of the two ceiling configurations, the fire source, a computer controlled methane gas burner, was placed in three different locations within the fire compartment and 2.1 m (7 ft) below the ceiling. Additionally, for each burner location, the flow of methane gas to the burner was supplied in such a way as to give three different fire growth scenarios. For the smooth horizontal unobstructed ceiling three experiments were performed for every burner position and fire growth rate. For the horizontal obstructed/beamed ceiling there were two experiments for everyburner position and fire growth rate. Measurements taken include the time to sprinkler activation, temperature and velocity of the ceiling jet at the sprinkler of activation, and temperatures and ceiling jet velocities at various other locations and elevations within the fire compartment. The horizontal obstructed/beamed ceiling increased sprinkler activation time by 57% to 137% depending on the experimental setup.