Estimate of nozzle pressure for firefighting nozzles from static pressure measurement

Abstract

Performance evaluations of a firefighting pump are important for inspection of fire equipment. A standard protocol established by the Ministry of Internal Affairs and Communications is generally employed to measure the firefighting pump performance using the static pressure of a standard straightening pipe to calculate a nozzle pressure without any direct measurements at the core of the jet of the firefighting nozzle. This standard protocol is a convenient method to evaluate nozzle pressure using the standard firefighting nozzle designed for the standard straightening pipe which has diameter 65 mm. In late years, there are some opportunities for a large-capacity firefighting pump performance evaluations using a large diameter straightening pipe (75 mm). However, it is not applicable to the straightening pipe (75 mm), because the protocol is based on the empirical table for 65 mm pipe. In this study, a new estimated expression was devised for the nozzle pressure to evaluate for performance of the large-capacity firefighting pump. Empirical standard protocol, experimental value and ideal value calculated by Bernoulli's theorem were compared and discussed. Results was shown that the estimated expression was expansion of the empirical standard protocol and the validity was shown. By comparison with experimental values, the estimated expression was proven to be applicable to flow straightening pipe diameter 75 mm.

Keywords

• nozzle
• high reynolds number
• jet
• straightening pipe