Fusing ignition of various metal wires for explosion limits measurement of methane/air mixture

In order to find the optimum condition for measuring the explosion limits of flammable gases by using metal wire fusing as the ignition source, the explosion limits of the methane/air system have been measured under various conditions in a bell jar type vessel of volume 3dm3. Metal wires used were of copper, Nichrome, platinum, molybdenum and tungsten, with diameters ranging from 0.3 to 1.0mm. Fusing was made by 12, 24, 36 and 48V of direct current (DC), and also by 100V of alternating current (AC). With these experiments, the effect of ignition abilities on explosion limits measurement has been made clear. As a result, it has been found that the fusing of metals of relatively high melting point, such as molybdenum, with a relatively high electric voltage, e.g., DC 36–48V, is suitable for the explosion limit measurement. The explosion limits of methane in air have been determined to be 4.7–16.3%.