Ventilation effects on combustion products

The effects of fire ventilation on combustion products are expressed in terms of relationship between concentration of products and equivalence ratio, phi. For well-ventilated fires, phi < 1.0, where mostly heat and products of complete combustion (such as CO2 and water) are generated. For ventilation-controlled fires, phi > 1.0, where mostly products of incomplete combustion are generated with very high concentrations in a transition region for phi between 1.0 and 3.5. The high concentrations of the products of incomplete combustion are dangerous to life and property. For halogenated materials, this condition occurs for phi < 1.0. The non-flaming region for fires is found to exist for phi > 3.5. Correlations have been developed for the prediction of concentrations of products at various phi values for the assessment of combustion toxicity and smoke damage hazards by zone fire models, such as Hazard 1. The correlations show good agreement with the measured concentrations. The concentrations of the products of incomplete combustion depend on the chemical structures of the materials. For the same phi values, the carbon monoxide concentrations are higher for materials with oxygen atoms in the structure, whereas smoke concentrations are higher for materials with carbon and hydrogen atoms in the structure. The results of the study suggest that it is necessary to examine the combustion behaviour of advanced materials for use in aircraft and other critical applications at various phi values, along with the toxicity experiments.