Aim: The developed simulation model enables to analyse the changes in air composition in residential rooms with gas appliances. On this basis, one can identify potential threats to the safety of the users of such kind of rooms.

Methodology: The simulation model based on mass balance was used to calculate the composition of the gas atmosphere in a residential room equipped with a gas appliance. The authors presented the methodology of the calculations. For the assessment of the residents safety the authors analysed the concentrations of carbon monoxide and oxygen in the room. The model enabled the authours to carry out simulations for the cases of the most common abnormalities in rooms with gas appliances. The analysis was performed for a bathroom equipped with a gas-fired instantaneous water heater with the power of 20 kW. Each calculation of CO and O2 concentrations in the room took 15 minutes. Calculations were made for various: gas volumes of the room, flow rates of ventilation, carbon monoxide concentrations in combustion gases and inflow times of combustion gases into the room.

Results: The role of ventilation in ensuring safety increases with a decrease in the gas volume of the room. The carbon monoxide and oxygen concentrations reach life-threatening values after a few minutes in a small room and with the lack of or insufficient ventilation. For rooms with a larger volume, and properly ventilated, the concentrations of CO and O2 also reach dangerous levels which may cause at least a serious poisoning. The higher the concentration of CO in combustion gases is, the greater the risk becomes. The permissible concentration of CO in the room (0.008%) is exceeded regardless of the inflow time of the combustion gases into the room and despite proper ventilation, so bathroom users with malfunctioning gas appliances could be constantly poisoned. A key element for ensuring the safety of the users of gas appliances is a combustion gases evacuation system because the ventilation, even when working properly, is not able to ensure safe concentrations of CO and O2 in the room.

Conclusions: The results show that a failure of the combustion gas evacuation system leads to the gas appliance having a negative impact on the health of the residents. The greatest impact on the concentration of CO and O2 in the residential room equipped with a gas appliance is demonstrated by the air flow rate of ventilation and the room volume. The decrease in the concentration of oxygen in the room will take place regardless of whether carbon monoxide is, or is not present in the combustion gases. The best way to completely eliminate the risk of carbon monoxide poisoning is the exchange of gas appliances with an open combustion chamber for appliances with a closed combustion chamber.

Keywords: carbon monoxide poisoning, safety of gas appliances users, simulation model

Type of article: original scientific article