Carbon monoxide poisoning: a critical comparison between numerical simulations and a real case study

Carbon monoxide poisoning still represents one of the most frequent causes of death, especially in residential applications with outdate, indoor heating systems without gas detection. Gas leaks are odourless and therefore difficult to identify, especially for sleeping occupants. Moreover, the carbon monoxide intoxication can be caused by either high flow rates with small exposure time or small flow rates associated to longer exposure. These aspects can only be pointed out by transient regime models, and few studies are currently available, especially regarding small scale applications. The present work is based on real, empirical measurement of carbon monoxide saturation due to a gas burner in a residential application. The forecast numerical results, obtained by a numerical model developed in FDS (Fire Dynamics Simulator) – SMV (SMokeView) environment are in good agreement with the measured values. The validated results provide an interesting insight on gas propagation within a typical two‑storey house. Furthermore, the validated model is used to estimate the contribution of small or unwanted air leakages. The results show that only dramatic large openings can avoid hazardous situations, therefore highlighting the importance of proper automatic revelation systems eventually coupled to forced extraction. The modelling clearly shows a high level of sensitivity on the gas flow rate: since carbon monoxide is generated by an incomplete combustion, its mass flow rate depends on the burner maintenance conditions and on the fresh air supply.