Development of a Flow Modifier for Reducing the Reaction Force of Firefighting Nozzles
Technical rept. 21 Mar 1990-7 May 1991
RISK AND INDUSTRIAL SAFETY CONSULTANTS INC DES PLAINES IL
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The purpose of this study was to develop a device that can be inserted upstream of conventional water firefighting nozzles in order to reduct their reaction force. The device was intended to create a resistance to flow that may be controlled by the firefighter holding the nozzle. Earlier laboratory tests carried out under Phase I of this study had shown that a flow modifier with two drag generators spaced a short distance apart could produce a significant reduction in the nozzle reaction force provided that adequate water pressure was available at the pump. The reduction in reaction force could be achieved without destroying the stream solidity or throw range. A laboratory test program was first carried out in order to examine the effects of modifier design variables on the reaction force. By using the results of these tests, a Model I prototype of the flow modifier was then constructed out of brass and tested successfully at Underwriters Laboratories hydraulic laboratory. A Model II prototype was then constructed out of a much lighter polymeric material. Only the drag generators were made of brass. This model was demonstrated successfully at Tyndall AFB using Tyndalls fire pumper and fire department personnel. Difficulty in adjusting the spacing between the drag generators at water pressures above 90 psi was encountered. A Model III prototype was then fabricated and delivered to Tyndall AFB with minor changes in the design in order to alleviate this problem.
- Safety Engineering