For combustion to occur after the fuel is in a gaseous state, it must be mixed with air in the proper ratio. If the concentration is too low to burn, it is below the:

When considering the concept of combustion, it is essential to understand the importance of the Lower Explosive Limit (LEL). The LEL refers to the minimum concentration of a combustible gas or vapor in air that is capable of forming a flammable mixture. If the concentration of the fuel is below this threshold, it is not sufficient to support combustion, which means that combustion will not be able to occur.

In practical terms, for combustion to take place, a mixture of fuel and air must be present in a specific ratio. If the fuel concentration is below the LEL, there are not enough fuel molecules in the air to sustain a fire. This concept is critical for safety in environments where flammable gases could be present, as it helps to identify the limits at which ignition can happen.

Other terms like the flash point, Upper Explosive Limit (UEL), and flammable range are related to combustion but serve different purposes. The flash point is the lowest temperature at which a liquid will produce sufficient vapor to ignite, while the UEL indicates the maximum concentration of fuel in the air for combustion. The flammable range encompasses both the LEL and UEL, indicating the entire range of concentrations where combustion can occur. However, specifically regarding the question of a