Changing the geometric parameters of fire hoses when they transport water

Abstract

Main hose lines are usually laid to transport water and working solutions of foaming agents to the centre of the fire when extinguishing large fires or fires with remote water sources. Their components are separate pressure fire hoses, they come in different diameters. As a result of their operation during the transportation of fire-extinguishing substances, fire hoses can change their geometric parameters, first of all, their length. For different types of hoses and their different diameters, it was revealed that their elongation occurs under hydrodynamic pressure. In some cases, when using a plug at the end of a fire hose, the coefficient of relative elongation of fire hoses was 1.04. 3 types of hoses were used for the research: latex pressure hoses with diameters of 51 mm 77 mm type T and fire hoses with doublesided polymer coating with 51 mm type T. All hoses were previously used during the real work of fire calculations. The results presented in the paper are an average of each of the three hose types. The experiments were carried out under typical conditions in the open air using a Protek 366 fire barrel under constant fluid flow and different pressure values at its entrance. Fire hoses were placed on a horizontal surface. The amount of fire hoses elongation when transporting water depended on the physical and mechanical properties of the materials from which they are made, the pressure of the liquid at their entrance, and the flow rate. The maximum elongation (62 cm with a hose length of 1960 cm, the relative extension was 0.032) was recorded when transporting water with a fire hose with a diameter of 77 mm at a pressure at its entrance of 1.0 MPa and a flow rate of 1.9 l/s, the issue of changes in head loss along the length were not considered. There were no significant changes in the diameters of fire hoses.