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Y. Klyuchka, D. Doroshenko, R. Kornіienko. Research on the time to reach fire-hazardous concen-trations in a room during a natural gas leak. Р. 193-205.

Research on the time to reach fire-hazardous concen-trations in a room during a natural gas leak

 

Klyuchka Yurii

National University of Urban Economy named by O.M. Beketov

https://orcid.org/0000-0003-1066-4217

 

Doroshenko Daria

National University of Civil Protection of Ukraine

https://orcid.org/0000-0003-4222-9359

 

Kornienko Ruslan

National University of Civil Protection of Ukraine

https://orcid.org/0000-0003-4854-283X

 

DOI: https://doi.org/10.52363/2524-0226-2025-42-13

 

Keywords: methane, leakage, sampling, lognormal law, mass flow rate

 

Аnnotation

 

The paper investigates the stochastic nature of the time it takes for natural gas (methane) to reach the lower flammability limit when it leaks in a closed room. The relevance of the problem is due to the widespread use of gas and increased risks, in particular, due to damage to infrastructure in the context of military aggression by the Russian. Since the time depends on many random factors, such as the mass flow rate of gas, which is determined by the pressure and the area of the leak, mathematical modeling of the gas accumulation process was performed for three scenarios of the area distribution of the leak. A detailed statistical analysis was performed for the three samples of time values obtained. The basic indicators (mean, median, standard deviation, asymmetry coefficient) were calculated and revealed a high right-sided asymmetry for all samples, indicating their non-compliance with the normal law. Testing the hypotheses of conformity to distributions (normal, gamma) using the Shapiro-Wilk and Kolmogorov-Smirnov criteria gave a negative result. Even the hypothesis of lognormal distribution, which is often used for similar processes, was rejected by formal tests using the same criteria. Visual analysis using a Q-Q plot confirmed the test results: for logarithmic time values, all three samples showed a clear S-shaped curve characteristic of leptokurtic distributions with “heavy tails.” This indicates that standard models, including the lognormal model, systematically underestimate the probability of both abnormally small and abnormally large values of the time to reach the lower concentration limit of flame propagation. The results obtained show the importance of taking into account “heavy tails” when assessing risks and developing preventive safety measures.

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