This paper is an abridged version of NISTIR 6319. The design, construction, demonstration, and operation of a bench-scale device capable of screening the fire suppression efficiency of liquid agents are described in detail in this report. The apparatus is based on a well-characterized flame, a means to facilitate the introduction of liquid agents, and a way to generate liquid droplets. A Tsuji-type burner, a porous cylinder used in a counterflow diffusion configuration, is used. Both wake and enveloped flames can be maintained over a wide range of fuel and oxidizer flows. The flame is easily observed, and critical stages such as the blow-off limit (abrupt transition from an enveloped flame to a wake flame) can be ascertained with ease and high reproducibility. A small-scale vertical wind tunnel, which allows for the delivery of a uniform flow of oxidizer to the burner at a low turbulence intensity and also assists in the delivery of liquid agent droplets to the flame, is used for the flow facility. Two techniques of generating droplets have been examined: (1) a piezoelectric droplet generator and (2) a small glass nebulizer. The piezoelectric droplet generator was found incapable of handling fluids with high loading of dissolved solid due to frequent clogging of the orifice opening. The nebulizer is used in the current liquid screen apparatus.
Citation: Fire Safety Journal
Issue: No. 1
Pub Type: Journals
fire suppression, diffusion flames, droplets, water additives, sprays, equipment