Internal combustion engine response to presence of combustion inhibitors in ambient air

Many motor vehicles (fire-fighting cars and trucks, helicopters, airplanes etc.) are used for conflagration extinguishing purposes. It is clear that their engines aspirate air containing combustion inhibitors, which are used for flame suppression, but until now there is no available information about the influence of this fact on engine performance. This paper presents results of an experimental study on the influence of combustion inhibitors, such as Halon 1301 (CF₃Br) and CO₂, contained in the ambient air, on the performance of compression ignition (CI) and spark ignition (SI) engines. Substantial differences in the response of CI and SI engines to the inhibitor presence in the aspirated air are revealed. Starting from relatively small concentrations of CF₃3Br, an increase of the CI engine speed and a simultaneous decrease of the brake specific fuel consumption are observed. The speed rise may attain up to 80% of its initial value. Dramatic deterioration, approximately by a factor of 3, in the efficiency of the SI engine's catalytic converter (CC) is observed after a short-time exposure of the SI engine to the ambient air containing Halon 1301. Chromatographic analysis of exhaust gases during an exposure of the engines to CF₃Br inhibitor shows the presence of harmful substances that are highly corrosive, and dangerous for human health.