Analysis of the Impact of Selected Parameters of the Hybrid Extinguishing System on the Fire Environment in a Closed Room

Jerzy Gałaj,Tomasz Drzymała,Paweł Wolny

doi:10.3390/su11236867

Abstract

The main purpose of this study was to analyze the impact of some parameters (water mist flow rate and type of gas used) of the hybrid extinguishing system on the fire environment (temperature as well as carbon monoxide and oxygen concentrations) in a closed room. Hybrid fire-extinguishing systems in which water mist is driven by inert gas combine the advantages of typical fog systems and fixed gas extinguishing devices. They have been developed in the last years but are now being used more and more often and the preparation of standards for them is planned for 2020. For this purpose, many fire tests with this system should be conducted. Some of them are discussed in this paper. Two different flow rates of water mist (1.5 or 3 dm3/min) and inert gas (nitrogen or air) were used during hybrid system testing. Some parameters of the fire environment in the compartment such as temperature measured by thermocouples as well as carbon monoxide and oxygen concentrations measured by electrochemical gas sensors are presented here. The characteristic values of the extinguishing process are also included. The assumed times of ensuring safe conditions in the room have been confirmed.

Highlights

Hybrid fire-extinguishing systems combine inert gas and water mist
According to the concept adopted by the members of the NFPA Technical Committee, hybrid fog differs from a twin fluid water mist system in that both gas and water are extinguished in the hybrid system, and in the second case, water is the only extinguishing agent
Considering quantities such as extinguishing time and temperature drop rate when assessing the extinguishing efficiency of the analyzed hybrid system, it can be concluded that the best configuration in this respect was the extinguishing system in which nitrogen-driven water fog was fed with a flow rate of 3 dm3/min

Summary

Introduction

Hybrid fire-extinguishing systems combine inert gas and water mist. This innovative technology is currently being implemented and used in fixed fire-extinguishing devices. According to the provisions of the draft standard being developed [1], a hybrid fire-extinguishing system is a fire-extinguishing system capable of supplying water and inert gases with a given expense and proportion. This mixture is assumed to be the most effective combination of both components, where both extinguishing agents take part in the extinguishing process. The gas serves only as a medium for spraying water [2]

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