At what vapor concentration in air can Gas ignite?

The ignition of gas in the air is influenced significantly by the concentration of the gas, which must fall within a range known as the flammable or explosive limit. For many common gases, the lower flammability limit (LFL) is typically around 10% by volume in air, while the upper flammability limit (UFL) can be significantly higher, often ranging between 16% and 25% for various gases.

Choosing the range of 16% to 25% indicates that it captures the typical conditions under which gas mixtures can ignite. Within this concentration, there is a sufficient amount of fuel (gas) present in the air to allow for combustion to occur, assuming the conditions such as temperature and presence of an ignition source, like a spark or flame, are appropriate.

In contrast, levels below 10% typically lack enough fuel to sustain a flame, while concentrations above 25% might not have sufficient oxygen for combustion. Therefore, the specific range between 16% and 25% is crucial for understanding the conditions necessary for gas ignition.