Related topics

Combustible gas detectors are required whenever there is a possibility of a hazard to life or property caused by the accumulation of a combustible gaseous atmosphere. The Combustible gas detector provides the user with a means of detecting the presence of the combustible gas. The combustible gas detector then issues suitable audible or visual warnings and/or take the specific actions necessary such as increased ventilation, plant shutdown, evacuation or other safety procedures as warranted.

Each type of combustible gas has three important ranges to consider and each of these ranges differ for specific gases, but utilize the same definitions. Below the Lower Explosive Limit (LEL), also known as Lower Flammability Limit (LFL), the combustible gas concentration is too lean for combustion. This is the range in which most combustible gas detectors operate.

Above the LEL the concentration (measured as a percent of volume in air) of combustible gas will support combustion if exposed to a source of ignition. The Upper Explosive Limit (UEL) or Upper Flammability Limit (UFL) is the point where the gas concentration is too rich for combustion, or the oxygen level is too low to support combustion.

Note that LEL and UEL differ for different gases. For instance for Methane, the 100% LEL level is equivalent to 5% by volume in air. For Pentane, the 100% LEL level is only 1.5% by volume in air.

Sierra Monitor has several different combustible gas detectors dependent upon the application.

• Model 5100-02-IT utilizes a catalytic bead technology, a proven, trustworthy technology that has been used to monitor for 0-100% LEL levels of combustible gas for decades.
• Model 5100-28-IT utilizes infrared technology in which the gas concentration is determined by the adsorption of the infrared light at a specific wavelength.
• The 201/2001 Series of Gas Monitors utilize Semiconductor sensors to determine a ppm range of combustible gases.