Which instrument can help indicate the percentage of lower explosive limit in a gas mixture?

The combustible gas indicator is specifically designed to detect the presence of flammable gases and vapors in the air. This instrument provides measurements that indicate the concentration of these gases relative to their lower explosive limit (LEL). By giving a direct reading of the percentage of LEL in a gas mixture, it aids in assessing the potential explosion hazard of the environment being surveyed.

In the context of fire investigations and safety, knowing the percentage of LEL is crucial for determining whether an environment poses a risk for combustible gas ignition. This can be essential information when investigating the cause of a fire or ensuring the safety of an area.

In contrast, a thermometer measures temperature, a gas chromatograph analyzes the composition of gas mixtures but is more complex and not specifically designed for LEL indication, and a pyrometer is used to measure high temperatures, often of surfaces. None of these options serve the specific function of measuring LEL percentages, making the combustible gas indicator the appropriate choice for this purpose.