Question 106Safety & Environmental - Assistant Engineer

The correct answer is A) oxygen. According to Coast Guard regulations, each ship with an inert gas system must have a portable instrument capable of measuring the concentration of hydrocarbon vapor in the inert atmosphere, as well as the concentration of oxygen. This is important to ensure the inert gas system is functioning properly and maintaining the required oxygen levels, which should be below 8% to prevent the risk of explosions. The other options (B, C, and D) are incorrect because the regulations specifically require the measurement of oxygen levels, not water vapor, nitrogen, or carbon dioxide.