Experimental determination of the Class B fire extinguishing efficiency using low-expansion foam generated by deflector type sprinklers
DOI:
https://doi.org/10.33408/2519-237X.2020.4-3.251Keywords:
foam expansion rate, foam stability, foam dispersion, extinguishing efficiency, extinguishing time, extinguishing agent discharge, automatic extinguishing system, sprinkler, field testsAbstract
Purpose. To establish the relationship between the foam expansion rate and stability of low-expansion air-mechanical foam generated in deflector type sprinklers for automatic extinguishing systems. To develop a methodology and carry out field tests of foam and foam-water sprinklers. To compare the extinguishing efficiency of the tested sprinklers basing on the results of field tests.
Methods. The method of regression analysis was used to establish the dependence of the foam stability on its expansion rate. The assessment of the extinguishing efficiency of the sprinklers was carried out experimentally, and the processing of the obtained experimental data was carried out using the method of estimation and expression of measurement uncertainty.
Findings. A linear relationship has been established between the expansion rate K and stability C of the low-expansion air-mechanical foam: C = γ·K, where γ is an empirical coefficient depending on the physicochemical properties of the foaming agent. The empirical dependences C = f(K) were obtained for brand of the foaming agents PO-6RZ (6 %). The methodology was developed and field tests of four deflector type sprinklers (V2 sprinkler with optimized geometry on the foam expansion rate, TY 3251 (USA), DPU-15 (Russia) and DVN-11 (Belarus)) were carried out. To compare the extinguishing efficiency of the sprinklers, the extinguishing efficiency indicator Et was used. This indicator takes into account the extinguishing time of the model fire site and the discharge rate of the extinguishing agent. In the result of field tests, it was found that the V2 sprinkler has at least 2.5 times better extinguishing efficiency compared to other tested sprinklers.
Application field of research. The obtained empirical dependence C = γ·K can be used to predict the stability of the foam based on its expansion rate value and vice versa. The developed methods of field testing and evaluating the extinguishing efficiency of foam and foam-water deflector type sprinklers can be implemented for the development of standards, as well as for the study of other sprinklers in conditions close to a real fire.
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Copyright (c) 2020 Kamlyuk A.N., Likhomanov A.O., Grachulin A.V.
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