The decisive parameter in the design of automatic fire extinguishing systems in the depots for storing oil and oil products, the organization of fire extinguishing in the tanks with mobile equipment is the standard (critical) foaming agent supply rate. The purpose of this work is to evaluate the influence of the scale of model fire centers and their design on the values of critical intensity of the foam solution supply.
The article presents the results of the analysis of the scientific studies of the process of oil products combustion and approaches to determining the standards for supplying a foaming agent solution to extinguish fires in the tanks. It is shown that the existing fire extinguishing modeling methods in the tanks do not fully take into account the effect on the extinguishing process of the following factors: the change in the rate of oil products burn-up depending on the tanks sizes, the transformation of the aerodynamic characteristics of the medium in the vicinity of the combustion zone, the scale and design of model combustion centers, means and methods of foam supply. The analysis of the work on estimating the burn-up rate of flammable liquids in the tanks of various diameters does not allow to conclude what the minimum size of the experimental tank should be, so that the results obtained for determining the critical intensity of the foam solution supply would not cause anyone doubts.
The paper presents the results of mathematical modeling of changes in the heat flux density on the surface of burning gasoline in the tanks with a diameter of 3 m, 5 m and 21 m. It is shown that combustion in small-diameter tanks does not simulate the thermal regime of a fire implemented on the large-diameter tanks. Consequently, the foaming agent solutions critical on intensity supply for small and large tanks differ from each other. The combustion source used in a number of documents do not simulate the conditions for heating the side of a real tank, which explains the failure to extinguish fires in the large tanks.
It is proposed to determine the intensity of the foaming solution supply, evaluate the efficiency of means and methods for producing foam in full-scale tanks or their mock-ups, which is economically justified and ensures the results reliability.