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The term is considered by many safety professionals to be the same as the lower explosive level (LEL). At a concentration in air lower than the LFL, gas mixtures are "too lean" to burn. Methane gas has an LFL of 4.4%. [1] If the atmosphere has less than 4.4% methane, an explosion cannot occur even if a source of ignition is present.
Any mixture of methane and air will therefore lie on the straight line between pure methane and pure air – this is shown as the blue air-line. The upper and lower flammability limits of methane in air are located on this line, as shown (labelled UEL and LEL, respectively). The stoichiometric combustion of methane is: CH 4 + 2O 2 → CO 2 + 2H ...
The limiting oxygen concentration is shown in the lower right of the diagram. The limiting oxygen concentration (LOC), [1] also known as the minimum oxygen concentration (MOC), [2] is defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. It is expressed in units of ...
Methane is extremely flammable and may form explosive mixtures with air. Methane gas explosions are responsible for many deadly mining disasters. [84] A methane gas explosion was the cause of the Upper Big Branch coal mine disaster in West Virginia on April 5, 2010, killing 29. [85]
Additionally, oxygen must be present. [7] The flammability limits of gases are expressed in proportions to the other gases present. [citation needed] For example, for methane, research by Akifumi Takahashi et. al. shows limits between 4.4% for the lower explosive limit and the upper explosive limit at 16.3%. [8]
The Bay Area Air Quality Management District has fined Berkeley after finding explosive levels of methane leaking from at least two cracked gas collection wells in the park. Both have since been ...
Landfill gas released in an uncontrolled way can be hazardous since it can become explosive when it escapes from the landfill and mixes with oxygen. The lower explosive limit is 5% methane and the upper is 15% methane. [16] The methane in biogas is 28 [17] times more potent a greenhouse gas than
[6]: 2 Methane is a major source of water vapour in the stratosphere through oxidation; [7] and water vapour adds about 15% to methane's radiative forcing effect. [8] The global warming potential (GWP) for methane is about 84 in terms of its impact over a 20-year timeframe, and 28 in terms of its impact over a 100-year timeframe. [9] [10]