Question 225Safety & Environmental - Assistant Engineer

The correct answer is D) All of the above. For a substance to burn, the following three conditions must be met: 1) The mixture of vapors from the substance with air must be between the Lower Explosive Limit (LEL) and the Upper Explosive Limit (UEL). This ensures the right fuel-to-air ratio for combustion to occur. 2) The air must contain sufficient oxygen to support the combustion reaction. 3) The temperature of the substance must be equal to or above its fire point, the minimum temperature required to initiate and sustain combustion. The other answer choices are incorrect because they only address one or two of these necessary conditions, rather than all three required for a substance to burn.