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Lower explosion limits (LEL) and the chemical compositions of JP-8, Jet A and JP-5 fuel vapors were determined in a sealed combustion vessel equipped with a spark igniter, a gas-sampling probe, and sensors to measure pressure rise and fuel temperature. Ignition was detected by pressure rise in the vessel. Pressure rises up to 60 psig were observed near the flash points of the test fuels. The fuel vapors in the vessel ignited from as much as 11°F below flash-point measurements. Detailed hydrocarbon speciation of the fuel vapors was performed using high-resolution gas chromatography. Over 300 hydrocarbons were detected in the vapors phase. The average molecular weight, hydrogen to carbon ratio, and LEL of the fuel vapors were determined from the concentration measurements. The jet fuel vapors had molecular weights ranging from 114 to 132, hydrogen to carbon ratios of approximately 1.93, and LELs comparable to pure hydrocarbons of similar molecular weight.

Several test programs have shown that the combustion of methanol in spark ignition engines can cause unusually high corrosive wear of the upper cylinder bore and ring areas. In this study, a 2.3-liter engine fueled with methanol was operated in a nitrogen-free atmosphere to determine the importance of nitric acid in the corrosion mechanism. A 20-hour steady-state test was carried out using neat methanol as the fuel and a mixture of oxygen, argon, and carbon dioxide in place of air. Only trace amounts of NOx and nitric acid were found in the exhaust products during this test. The wear, indicated by iron buildup in the lubricant, was found to be essentially the same in the nitrogen-free test as that detected in baseline engine tests combusting methanol-air mixtures. It was concluded that nitric acid does not play a role in the corrosion mechanism.