How does an increase in ambient temperature affect a flammable gas/air mixture?

An increase in ambient temperature has a significant impact on the behavior of flammable gas/air mixtures, specifically concerning the Upper Explosive Limit (UEL) and the Lower Explosive Limit (LEL).

As temperature rises, the kinetic energy of the gas molecules also increases, resulting in a more vigorous reaction with oxygen in the air. This means that the concentration of the flammable gas needed to reach its UEL increases, since a higher temperature allows the mixture to combust more effectively at higher concentrations of fuel. Thus, the UEL will increase, which means the maximum concentration of gas in the mixture that can still ignite is elevated at higher temperatures.

Conversely, the LEL, which denotes the minimum concentration of gas necessary to sustain combustion, decreases with increased temperatures. As temperature rises, the gas can ignite and sustain combustion at lower concentrations, leading to a lower LEL.

Understanding these changes is critical for safety and risk management in environments where flammable gases are present. It emphasizes the importance of monitoring temperatures in areas where such mixtures exist to prevent accidental ignition.