An experimental evaluation of toxic gas emissions from vehicle fires

Abstract

Improving fire modelling is a key issue to design efficient safety measures for a safe people evacuation in case of fire. Such an analysis should consider the different impacts of fire on people as temperature, visibility but also toxicity. Most of the standard curves used in tunnel fire studies are based on quite old fire tests without any detailed toxic gas qualification. Very few fire tests were published in that way. Based on those few tests, some standard fire emission factors are available in the literature. The objective of this paper is to review those emission factors considering the different toxic species and dealing with using recent cars. A method is then proposed to define a carbon monoxide equivalent emission factor to consider the different species through their specific threshold. Such an approach can be easily introduced into fire codes. To meet this objective, two series of tests were performed. The first concerns individual combustible materials of cars as plastics and tyres. The second focusses on full car burning tests including a detailed smoke analysis. Those two series of tests lead to an analysis of the smoke toxicity and a comparison of emission factors with standard ones.

Analysis of Li-Ion Battery Gases Vented in an Inert Atmosphere Thermal Test Chamber

“…In closed spaces, slow gas emission rates may be easier to manage with existing gas evacuation capability of the surrounding space, and a prolonged emission period may be desirable. However, it is important to remember that studies of vehicle fires show little difference in the amount of toxic gas release from an EV compared to an ICE, and recent data from Truchot et al [22] shows that an ICE will release a total of 0.4 kg HF compared to 0.7 kg for the EV. Furthermore, their data shows that the initial HF gas release, with the highest concentration, is identical to and independent of the energy carrier and is released from sources that are common to both ICE and EV, e.g., fluorinated plastics and air conditioning refrigerant.…”

“…The Li-ion battery contribution to HF did not appear until 30 min into the fire. The conclusion was that it would not affect the toxicity level at the time of evacuation of occupants from the vehicle, at least when the fire incident is initiated outside of the battery itself, e.g., an external heat source, such as a fire starting in another part of the vehicle or somewhere in the proximity of the vehicle [22].…”

“…Fire studies show that several toxic gases form during combustion of both ICE vehicles and EVs [22]. The acid gases, i.e., HF, hydrogen chloride (HCl), and hydrogen cyanide (HCN), make up a very low volume in terms of total amounts, but deserve consideration for the toxic impact due to their low toxicity thresholds [22].…”

“…Fire studies show that several toxic gases form during combustion of both ICE vehicles and EVs [22]. The acid gases, i.e., HF, hydrogen chloride (HCl), and hydrogen cyanide (HCN), make up a very low volume in terms of total amounts, but deserve consideration for the toxic impact due to their low toxicity thresholds [22]. However, the strong polar nature of these acid gases, as well other halogenated compounds, can be used as an advantage, since it is possible to reduce the concentration of such gases significantly by spraying water and "washing out" the acid and halogenated gaseous species from the emissions [23].…”

Study of fire and explosion hazards of alternative fuel vehicles in tunnels

“…Fires in battery electric vehicles may not be significantly severer than traditional vehicles in terms of fire size [26][27][28]. The major hazard for these vehicles is the thermal runaway of the batteries due to overcharging, short circuits or external heating.…”