Past literature has reported on the occurrence of violent energy releases (VER) involving either high surface area aluminum structured packing or brazed aluminum heat exchanger (BAHX) samples subjected to promoted ignition-combustion testing in liquid oxygen (LOX) environments. In each of these situations, both the aluminum packing samples and the BAHX specimens contained relatively thin sections of aluminum. The aluminum thickness ranged from 0.2 to 0.25 mm for the aluminum packing and the fin portion of “thin fin” BAHXs. Other “thick fin” BAHXs tested had nominal fin thicknesses ranging from 0.41 mm to 0.46 mm. Similar flammability data have not been reported for thick wall (4.1 mm), 3003 tubular aluminum heat exchanger material which may be used in LOX applications. The impetus for this program was to study the promoted-ignition combustion behavior of thick wall, tubular aluminum samples in various LOX environments using both a localized hydrocarbon promoter and uniformly dispersed hydrocarbon film. Tests were also conducted in various gaseous oxygen (GOX) environments using uniformly dispersed hydrocarbon films.
Promoted ignition-combustion tests were conducted on 4.1 mm thick aluminum ubes in LOX at pressures ranging from 101 kPa (0 psig) to 3551 kPa (500 psig). Tests in GOX were also conducted at 170 kPa (10 psig) and 274 kPa (25 psig). The resultant flammability characteristics of the aluminum tube specimens are compared to previously studied BAHX samples since both may be used in LOX applications.