Combustible Gas Detectors

Mixtures of gases and air can be burnt at a wide range of concentrations. In each case, there is a specified minimum concentration above which an ignition source will cause an explosion or flame front propagation. In this case, the Lower Explosive Limit (LEL) of that gas or vapor applies. It is sometimes referred to as the Lower Flammable Limit (LFL). The LEL varies from gas to gas. The minimum concentration of CHC in the air by volume typically ranges from 0.5% to 15%. Based on the system, this concentration is equal to 100%. Combustible gases can be lighter or heavier than air. Prior to monitoring the gas or entering an area containing it, determine the characteristics of the gas. A typical low alarm setting is 20% LEL, a high alarm is 40% LEL, and a high-high alarm is 60% LEL. It is up to the user to decide what setting is appropriate.

Catalytic gas detectors are more reliable in dusty and dirty environments since they are less sensitive to the presence of industrial contaminants. They also perform more reliably under high temperatures, are not affected by pressure changes or humidity changes. All catalytic sensors can detect most combustible hydrocarbons, including hydrogen, which is invisible to infrared. Hydrogen has a smaller footprint than infrared.

 

Calibration does not always need to be done with the gas that most likely to be present. For most applications, the standard calibration gases give excellent results. A calibration kit can be used for any combustible gas. We can recommend the gas to be used and provide instructions for calibration.