Leak detection in fire extinguishers by the pressure variation method according to time: theoretical bases, proposal of experimental arrangement and first results


A fire is one of the most damaging events to life and nature, which can lead to loss of lives and the destruction of property as well as environmental sites. Fire extinguishers are among the means available to fight low-proportion and intensity fires in a fast, immediate and safe way for the users. Although its firefighting capability is restricted to the outbreak, a fire extinguisher can be very effective, due to its immediacy and readiness. In order to be effective and efficient against fire outbreaks, considering a correct handling by a properly trained user, fire extinguishers must contain aspects that address its reliability. One of the aspects that often compromise the proper performance of a fire extinguisher and affect its reliability and warranty is the leakage rate of propellant gas. This leakage rate, consequently, accounts for a loss of internal pressure before the end of the warranty, and could jeopardize its operation when needed. This paper discusses the leakage rate of propellant gas over time and its measuring. The leak detection method used in this research was the increasing of pressure according to time inside a vacuum chamber, by applying vacuum technology,
considering the fire extinguisher inside the chamber. This method requires an experimental arrangement that evaluates only one fire extinguisher at a time. To take reliable measurements during the experiment, the chamber and all its instrumentation are monitored during three days. Concerning its application in a fire extinguisher production line, the employed method does not appear as the most proper way to evaluate leakage. However, this paper is justified by the fact that said method can verify the occurrence of leakage during a period of time, and can be used as an alternative in a third party laboratory for sample evaluating the production line. One of the goals of this research is demonstrate the physical difference between gas and liquid, when leaking from a pressurized container. In general, gas leakage rates depend on the pressure and temperature of the gas. Endorsing this goal, this paper intends also to present a simple approach on the mathematical modeling of gas leakage rate, and includes a proposal of experimental setup to evaluate this theoretical approach.

DEGASPERI, Francisco Tadeu; PAULA, Deives Junior de; SILVA, Luiz Fernando Batista da; MATTOS, Mauricio; GETSCH, Guilherme. Determinação de vazamento em extintores de incêndio pelo método da variação da pressão em função do tempo: bases teóricas, proposta de arranjo experimental e primeiros resultados. Revista Brasileira de Aplicações de Vácuo; Brazilian Journal of Vacuum Applications, v.38, n.2, p.51-50, 2019.

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