What are the upper and lower concentration limits at a specified temperature and pressure of a flammable gas?

The upper and lower concentration limits of a flammable gas at a specified temperature and pressure refer to the range within which the gas can ignite and support combustion when mixed with air. These limits are critical for understanding the potential hazards associated with flammable substances.

Flammability limits define the minimum and maximum concentrations of a gas in air at which a flame can propagate. If the concentration of the flammable gas is below the lower limit, the mixture is too "lean" to ignite; conversely, if it exceeds the upper limit, the mixture is too "rich" to support combustion. Understanding these limits is essential for ensuring safety in environments where flammable gases are present, such as chemical processing plants, fuel storage facilities, and labs.

The other terms, while related, describe different aspects of fire and explosion hazards. For instance, flashover refers to a specific fire condition where all combustibles in a room ignite almost simultaneously, indicating a transition to full room involvement. Explosion limits can sometimes refer to similar concepts but are often used in the context of deflagration (rapid combustion) or detonation (supersonic combustion wave) scenarios rather than general flammability. Ignition limits may refer to the conditions required to initiate combustion but do not specifically