Determining the elongation of T-type pressure fire hoses based on full-scale experiments

Abstract

The phenomenon of changing the geometric parameters of pressure fire hoses is manifested when they transport extinguishing liquids. Although the extension of pressure fire hoses does not have a significant impact on the fire extinguishing process, the energy costs associated with such changes should be taken into account. In fact, part of the power of the fire pump is spent not on transporting liquids and forming extinguishing jets but on the «optional» lengthening of pressure fire hoses. Latex pressure fire hoses with diameters of 51 mm and 77 mm and fire pressure hoses with double-sided polymer coating of 51 mm (all of type T) were randomly selected for the experiments. The temperature was 263 K and 298 K, the fluid flow rate was constant, the pressure values at the inlet of the Protek 366 fire barrel had fixed values. No significant changes in the diameters (expansion or narrowing) of pressure fire hoses were recorded during water transportation. An elongation of 79 cm with a hose length of 1960 cm (73 cm with a hose length of 1790 cm) was recorded when transporting water in the case of using hoses with a diameter of 77 mm, a pressure at their inlet of 0.8 MPa, a temperature of 263 K, and a water flow rate of 0 l/s. The force that provided such a stretch was 2.04 kN. When extinguishing liquid was supplied by pressure fire hoses with a diameter of 77 mm in the temperature range of 263–298 K, the elongation decreased slightly with decreasing temperature. A slight unevenness of stretching of pressure fire hoses along the length was found when stretching increased closer to their middle. The results indicate the dependence of the amount of stretching on the materials from which pressure fire hoses are made, as well as their diameter. The values of dynamic forces that cause stretching of pressure fire hoses established in the study can be used in practice when taking into account the forced energy losses for fluid transportation