Effect of Ambient Oxygen Concentration on Heating Performance of Chemical Igniter used in NASA-STD-6001B/ISO-TS16697

Abstract

This paper experimentally examines the heating performance brought by the chemical igniter (used in NASA-STD-6001B and ISO-TS16697) exposed in various oxygen concentrations. Final goal of this study is to discuss about the reliability of the chemical igniter for such material screening test ensuring the fire safeness in space. Prescribed mixture of nitrogen and oxygen was flowed into the test chamber and the chemical igniter is burned under the heat flux gauge. Time-sequence of heat flux brought by the chemical igniter was recorded and analyzed. It is understood that time-sequence curve of heat flux is varied under various oxygen concentration, suggesting that the thermal enthalpy accumulated in the test specimen to be burned has clear dependency on the ambient oxygen concentration. Namely, thermal status of entire test specimen is strongly depended on the environmental condition to be tested, when the chemical igniter is used as the heating source due to its inherent heating properties. Importantly, when ambient gas is strongly diluted (i.e., low oxygen concentration), complete burning of the chemical igniter tends to be prohibited, accordingly, reproducibility becomes less. Under such condition, the weak but long heating is experienced. Because such slow rate of heat supply (for ignition) shall be easily dissipated, resulting that no ignition might be induced by the chemical igniter; Hence, the chemical igniter would be insufficient to be a “universal” heating source for any screening purpose. As substitute, the electric heater (wire igniter) could work effectively to cover the disadvantages of the chemical igniter as presented in this study.