Citation

Theobald CR. Fire Safety J. 1984; 7(2): 177-190.

Copyright

(Copyright © 1984, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The results of research into the factors governing the performance of water jets from hand-held equipment are presented with the aim of incorporating an optimised jet-forming section into a general purpose jet and spray branch. Maximum effort was concentrated on deriving optimum performance from prototype nozzles having lower contraction ratios because these could perform efficiently when fitted to a supply pipe or branch of reduced diameter. This feature would allow an independent spray-forming section to be added without prejudicing the basic requirement that all hand-held equipment should be as light and as compact as possible.Performance figures for jets were derived by measuring water flow rates both at the nozzles and at a target positioned downrange in wind-free conditions. The effective performance of fire-fighting equipment is most critical when large jets need to be used at or near the limits of their useful ranges. In these circumstances up to 84% of the water leaving a conventional nozzle may be lost in the form of spray before the jet reaches the target. An improved nozzle was made which reduced this wastage to 79% representing an increase of about 30% of the nozzle discharge being effectively used.The significant profiles for the improved nozzle-branch system are dimensionless and may therefore be of interest to people involved in larger-scale operations such as offshore work.