M. Butler, P.B. Sunderland, R.L. Axelbaum
Washington University in St. Louis
Advisor: Richard Axelbaum

Abstract
This study examines the types of hydrogen leaks that can support combustion. Hydrogen, methane, and propane diffusion flames on round burners and leaky compression fittings were observed. Measurements included limits of quenching and blowoff for round burners with diameters of 0.006 - 3.18 mm. The measured mass flow rates at the quenching limits were found to be generally independent of burner diameter at relatively large burner diameters. In terms of mass flow rate, hydrogen had a lower quenching limit and a higher blowoff limit than either methane or propane. Hydrogen flames were the weakest flames ever recorded with mass flow rates as low as 0.0039 mg/s, which translates to a thermal power output of 0.55 W. The quenching limits for diffusion flames on round burners with thick walls were found to be higher than for thin walls. The limits were also found to be independent of burner orientation. In other words leaks with low flow rates are able to support flames independent of their orientation. The implications for fire safety are discussed.