Experimental determination of pressure loss in main arms and their approximation to justify fire extinguishing tactics

One of the key tasks of fire tactics is to substantiate the parameters of pump-hose systems to ensure the required consumption of extinguishing agents. The effectiveness of tactical decisions directly depends on the accuracy of predicting pressure losses, which in real conditions can differ significantly from reference data. The article presents the results of a full-scale experiment to determine pressure losses in main hose lines with a diameter of 77 mm with varying their length from 2 to 20 hoses. An experimental setup, a measurement procedure and a procedure for processing the results have been developed and described. It has been experimentally established that relative pressure losses increase nonlinearly from 35.3% to 59.4%. The performed analysis of variance using the Fisher criterion confirmed the statistical significance of the effect of the main line length on the pressure at the nozzles (p < 0.05). A regression equation was obtained for the dependence of the pressure at the nozzles on the pressure at the pump and the number of hoses (R² = 0.89). For the first time, an inverse relationship between the pressure dispersion and the line length was recorded and quantitatively described. The necessity of mandatory consideration of pressure losses when designing pump-hose systems within the framework of the fundamentals of fire extinguishing tactics is shown.