Study on pre-fire characteristics of wire insulation by overload in weakly buoyant environment

Experiments were conducted to study the effect of pressure on the pre-fire characteristics of wire insulation in a low pressure setup. Results show that under 2A the temperature change rate and balanced temperature of wire insulation increased with the pressure decreasing, which could predict the pre-ignition temperature variations in microgravity. Under 10 A, there are three kinds of undermining mechanisms of wire insulation in different pressure. And the pressure has varied influences on the ignition delay time in different ranges. Finally, the oxygen concentration is increased to enhance the chemical reaction rate prohibited greatly in the low pressure. Results show that the range of flammable limit is broadened and ignition delay time is shortened with the increasing of oxygen concentration. Thus the method could be applied to predict the pre-fire process of wire insulation in microgravity to some extent.