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Author
Fischer, G. | Leonard, J. T.
Title
Effectiveness of Fire Extinguishing Powders Based on Small Scale Suppression Tests. June 1983-June 1984.
Coporate
Wehrwissenshaftliche Dienstelle der Bundeswehr fur ABC-Schutz Naval Research Laboratory, Washington, DC
Sponsor
Naval Sea Systems Command, Washington, DC
Report
NRL/MR/6180-95-7778, October 19, 1995, 22 p.
Keywords
powders | fire suppression | fire extinguishment | dry chemicals | effectiveness | fire extinguishing agents | particle size | fire fighting | extinguishment
Identifiers
dry chemical agents; commercial powders; apparatus for studying the effectiveness of dry chemicals as fire extinguishing agents
Abstract
A simple laboratory test method was developed for evaluating the fire extinguishing power of dry chemical agents. The apparatus consisted of a Bunsen burner which was modified by the addition of a delivery tube to permit the dry chemical powder to be injected into the methane/air stream about 4 cm below the burner tip. The powder concentration was increased until the test flame was extinguished. A total of 21 commercial extinguishing powders were tested in this apparatus. It was found that the fire extinguishing effectiveness of a given powder is primarily determined by its particle size rather than its chemical composition. For four of the agents tested (KHCO₃, NH₄H₂PO₄, KCI and NaHCO₃), it was found that the fire extinguishing performance could be divided into three regions: (1) a very effective range up to 25 µm, (2) a transition range with a steep effectiveness slope in the 25-50 µm particle size range, and (3) relatively ineffective range above 50 µm. The same type of behavior was found for Monnex™ except that very effective range extended to about 40 µm and the transition range was 40-60 µm.