A promoted ignition combustion test apparatus for evaluating the flammability of metallic materials

To sustain the ever-increasing demands of material development for various oxygen applications, a promoted combustion test system was established at the BOC Group for evaluating the flammability of metallic materials in oxygen-enriched atmospheres. The system was designed with the following key features: (1) a cylindrical, vertically oriented, high-pressure vessel with two observation ports; (2) a diaphragm-type oxygen compressor; (3) a dynamic flow regulating device for constant flow rate and pressure controls; (4) two water-cooled, tube heat exchangers; (5) a temperature probing device with 3 thermocouples; and (6) a strip-chart data recording system with digital displays of test pressure and temperature. The pressure vessel, with an internal gas volume of about 5.7 liters, was designed to be operated at maximum working pressure 55.17 MPa (8000 psig) and at maximum temperature 650 degreesF. It is capable of performing a promoted combustion experiment under either static or dynamic flow conditions. Details are presented in this paper to describe the system layout, materials of construction, and system operation as well as performance characteristics. Based on a flow simulation study, the distribution of gas velocity in the vicinity of a rod-shaped test specimen was profiled at selected combinations of gas pressure and now rate under dynamic flow conditions. As a baseline calibration study, threshold pressures and self-extinguishing pressures were determined for metallic materials including Al 6061 alloy, 316 SS and 304 SS in pure oxygen (at least 99.6% purity). The test results are compared with those that were generated from NASA White Sands Test Facility and other industrial laboratories.