Question 725 Deck Safety

The correct answer is A) the lower explosive limit concentration. Combustible gas indicator meters are calibrated to read the percentage of the lower explosive limit (LEL) concentration of a specific gas or vapor. The LEL is the minimum concentration of a gas or vapor in air below which the mixture is too "lean" to burn or explode. By measuring the percentage of the LEL, the meter can indicate how close the atmosphere is to reaching the explosive range. This is a critical safety feature for detecting potentially hazardous conditions. The other answer choices are incorrect because they do not represent the specific measurement made by a combustible gas indicator meter. Option B refers to the autoignition concentration, option C refers to the flammable limit concentration, and option D refers to the vapor to oxygen ratio, which is not the direct measurement made by this type of meter.