Citation

Heskestad G. Fire Safety J. 1986; 11(1-2): 77-83.

Copyright

(Copyright © 1986, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

This paper is a contribution in support of NFPA 204M-1982, Guide for Smoke and Heat Venting, focusing on the fundamentals of techniques of designing smoke and heat venting systems for single compartments. Effective venting systems require roof vents large enough (or exhaust systems of sufficient capacity in the case of mechanical ventilation) to extract fire gases at the rate injected into the smoke layer by the fire plume. They also require sufficiently large, low-level inlet openings in the compartment for make-up air. Roof vent areas can be calculated using available formulas and specification of the design fire size. Individual vents must be limited in size to prevent air from the clear layer below from being extracted together with the fire gases, reducing the effectiveness of the vents. The calculation methods are illustrated in a number of examples. Reference is made to NFPA 204M for a number of practical venting recommendations relative to vent spacing, draft curtains, and limiting fire sizes.