What is the most easily ignited percentage of methane from a heated surface in a mixture of CH4 and air?

In the context of the ignition of methane (CH4) in the presence of air, the most easily ignited concentration typically falls within the flammability range of the gas mixture. Methane is known to have a lower explosive limit (LEL) of approximately 5% by volume in air. This means that when methane concentrations are at or above this level, there exists a risk of ignition when exposed to a heat source, such as a heated surface.

The reason the 5-6% range is particularly notable is that it's at the lower end of the flammability limit where the likelihood of ignition increases significantly. Above this range, the gas mixture becomes more volatile, further facilitating ignition. Thus, a mixture of 5-6% methane in air represents a critical concentration for ignition. As the concentration moves higher, the potential for ignition continues to increase until reaching the upper explosive limit, but the ease of ignition is notably highest around this percentage.

In contrast, concentrations below this range (such as 3-4%) would not provide sufficient methane to support combustion when exposed to heat, and higher concentrations (like 7-8% and above) would also have their own risks, but the earliest and easiest point of