Which statement is TRUE regarding combustible gas indicators?

Combustible gas indicators are critical tools used for monitoring the presence of flammable gases in various environments. When it comes to their functionality, it is essential to understand that these indicators rely on specific conditions to operate effectively. The statement that they do not work properly in environments where there is a lack of oxygen is correct because most combustible gas indicators operate based on the principle of combustion; they require a certain concentration of oxygen to ignite the gases being measured. In an oxygen-deficient atmosphere, the combustion reaction necessary for the detector to function will not occur, resulting in inaccurate readings or failure to detect the presence of flammable gases altogether.

This limitation underscores the importance of ensuring that the testing environment has adequate oxygen levels for the accurate operation of combustible gas indicators. Knowing this helps users understand how to appropriately utilize these tools and the conditions required for reliable operation.