What is a accurate capability of combustible gas indicators?

Combustible gas indicators (CGIs) are essential tools used in the maritime industry, particularly on tankers, to detect the presence of flammable gases in enclosed spaces. They function by measuring the concentration of combustible gases in the air.

The statement that CGIs do not work properly where there is a lack of oxygen is accurate because these instruments rely on the presence of oxygen to function effectively. In oxygen-deficient environments, the combustion reaction necessary for the sensor to detect gases cannot occur properly, leading to inaccurate readings. The sensors often require a certain level of oxygen to maintain their calibration and performance, making them unreliable in conditions where oxygen levels are below the acceptable threshold.

The other options reflect capabilities or limitations of CGIs that do not accurately describe their functionality. For instance, CGIs are not designed specifically to measure oxygen levels; rather, they focus on flammable gas detection. Additionally, testing a tank with only one sample of air may not yield reliable results due to variations in gas concentrations within the tank. Finally, while CGIs can provide a relative percentage of the potential explosive atmosphere, they are typically calibrated to indicate the concentration of combustible gases rather than the percentage chance of explosion directly. Hence, the understanding of the operational limits of CGIs,