If the propane/air mixture contains more than 9.6% gas, what is the condition?

When a propane/air mixture contains more than 9.6% gas, it is considered "too rich to burn." This means that there is an excess of fuel (propane) in relation to the amount of air (oxygen) available for combustion. A rich mixture has more fuel than can effectively react with oxygen, preventing complete combustion from occurring.

In a combustion process, the ideal scenario is to achieve a balanced fuel-to-air ratio that allows for complete burning of the fuel. When the concentration of gas increases past a certain level, it leads to a diminished presence of oxygen proportionately, which limits the reaction required for combustion. Consequently, this results in conditions where ignition is not possible, and the mixture cannot sustain a flame.

Understanding this concept is vital for managing safety and efficiency in handling and using propane in various applications, as knowing the limits of combustion can help prevent dangerous situations such as incomplete combustion which may produce carbon monoxide.