INVESTIGATION OF CHARACTERISTICS OF WOVEN REINFORCING FRAMES OF PRESSURE FIRE HOSES AND THEIR INFLUENCE ON VALUES OF INTERNAL BURSTING PRESSURES

The article proposes a technique for experimental studies of contact zones between threads in woven reinforcing frames of pressure fire hoses using a JSM-6490LV scanning electron microscope and statistical methods, on the basis of which the coefficients of vertical crumpling of threads, coefficients characterizing the lengths of contact zones between threads in fractions of the diameters of the warp and weft threads, the account of which is necessary for a more accurate determination of the bursting pressures in the pressure head fire hoses. Burst pressure is regulated by GOST R 51049-97 and is an important strength parameter of a pressure head fire hose, characterizing its ability to resist destruction under the influence of the internal hydraulic pressure of a fire extinguishing fluid. The influence of such parameters of a woven reinforcing frame made of polyester threads based on polyethylene terephthalate (PET), as the breaking force of the weft threads (threads laid along the circumference of the sleeve), the radius of the sleeve, geometric densities along the warp and weft, the coefficients of vertical crumpling, has been studied. and the diameters of the warp and weft threads, the coefficients characterizing the lengths of the contact zones between the threads in fractions of the diameters of the warp and weft threads by the value of the bursting pressure in the latex pressure fire hose manufactured by BEREG, designed for a working pressure of 1.6 MPa. As a result of the study, it was established: the bursting pressure of the pressure head fire hose significantly depends on the geometric densities along the base and weft of the fabric of the reinforcing frame (with an increase (decrease) in geometric densities, the calculated bursting pressure of the hose falls (increases)); the bursting pressure of the sleeve is directly proportional to the bursting force of the weft threads and inversely proportional to the radius of the pressure head fire hose with all its other parameters constant, and the dependence of the bursting pressure on these parameters is significant; with an increase in such parameters of the woven reinforcing frame of the pressure head fire hose as the diameters of the warp and weft threads, their vertical crushing, the length of the contact zones between the threads, the bursting pressure increases, which indicates the need to take these parameters into account in the strength calculation of the woven reinforcing frames of the fire hoses . The results of the study must be taken into account when designing new types of these technical products.