The accuracy and reliability of comparative efficiency assessment of portable fire extinguishers used in the process of fire extinguishing of structural components of motor vehicles and automotive finishing

Introduction. The relevance of this work resides in the need to perform an unbiased comparative assessment of fire extinguishers. The focus must be placed on the efficiency of a fire-fighting agent, as it has a major impact on the process of fire extinguishing. The purpose of this work is to confirm the applicability of a dimensionless efficiency indicator of portable fire extinguishers, assess the measurement accuracy (correctness and precision) and their statistical values. Materials and methods. The co-authors used the methodology specified in GOST R 51057–2001 applicable to the fire extinguishing of class A model fire seats. The model fire seat had samples of materials attached to its upper edge at the angles whose values were obtained using a specialized test bed. A specialized test bed was used to perform the testing and identify the sample's inclination angles that prevented the fire extinguishing agent, applied to their surface, from streaming down or crumbling. The accuracy (correctness and precision) was assessed pursuant to the methodologies specified in GOST R ISO 5725-1–2002, GOST R ISO 5725-6–2002. The statistical significance of measurements was assessed using Student's t-test. Results and discussion. The co-authors offer the results of the experiments aimed at the identification of an inclination angle of the fire seat surface that prevents the fire extinguishing agent from streaming down or crumbling. The results of comparative fire testing of fire extinguishers that contain quick setting foam and powder are provided. The formula of a dimensionless efficiency indicator, applicable to portable fire extinguishers, is provided, and its applicability is proven. Conclusions. The measurement accuracy assessment, performed pursuant to the methodologies, specified in the regulations, has shown the effectiveness of mean arithmetic values of all indicators applied to calculate Peo efficiency indicator. The assessment of the statistical significance of experimentally obtained values of all indicators, performed with the help of Student's t-test, has demonstrated that the discrepancy of their mean arithmetic values is reliable and it doesn't have a random nature. The superiority of the quick setting foam extinguisher over the powder one was proven in an experiment. The value of its Peo efficiency indicator exceeds the one of a powder extinguisher 50-fold due to the comprehensive impact made by the extinguishing agent and the construction of a fire extinguisher.