When dangerous levels of combustible gases are not quickly found, the result may be a fire or explosion. Since industrial facilities, medical and research laboratories, manufacturing plants, and other similar settings have the potential for undetected natural gas leaks, reliable and properly designed monitoring systems must be in place as a safeguard against these workplace risks.
Gas detection systems that are designed to alarm when combustible gas is present use LEL Detectors based on catalytic bead or infrared absorption technology. These measure the amount of combustible gas on a scale of zero to one hundred percent (100%) of the Lower Explosive Limit, or “LEL” of the target gas.
Combustible Gas Sensing
Often there is a choice of sensors that can be used to detect combustible gases. The two most common are Catalytic Beads and Infrared. Catalytic bead sensors detect the presence of any combustible gas by safely burning a small amount of the gas on a hot ceramic bead coated with a special catalyst. These sensors will detect any combustible gas, including hydrogen, but are subject to drift and poisoning. Poisoning can occur if certain substances containing silicon or similar compounds come in contact with the bead; if this happens, the compounds can coat the bead with an insulation layer that can keep the Catalytic Bead sensor from responding to a combustible gas. The only sure way to ensure the operation of a catalytic bead sensor is periodic calibration or bump tests where sensor response is measured when actual gas is applied to the sensor.
Infrared sensors use a completely different technique. These sensors measure the absorption of infrared light by hydrocarbon gases. Since they are microprocessor-based, they perform multiple self-checks to ensure correct operation without the need for bump tests. As with all sensors, they should be calibrated periodically to make sure they generate accurate readings.
In sophisticated gas detection systems, the output of LEL detectors is generally combined into a single combustible gas alarm, either a strobe or horn, or both. This is very important in situations where the environment is noisy and where a simple display output is insufficient. In smaller systems, alarm horns and strobes can be directly attached to each gas detector to provide instant local warnings of hazardous conditions.
Expandable Wireless Networks
With most facilities now adopting multiple wireless networks, today’s gas detection systems can be equipped with wireless LEL detection technology using ultra-low-power infrared sensors. Battery-powered wireless LEL detectors can be deployed around hot work sites, temporary buildings, and other areas where the installation of permanent detectors is unwarranted.
As part of normal maintenance, periodic calibration is extremely important in making sure your combustible gas detection system is fully functional and ready to provide that all-important early warning should hazardous conditions exist. Calibration procedures should be easy to follow and as automated as possible to eliminate human error. GDS Corp gas detectors include a user-prompted two-point calibration procedure that reduces errors and ensures that all calibration upper and lower performance limits are met.
If you choose the proper sensor, keep up regular maintenance and perform periodic calibrations, you can be sure that your combustible gas detection system will be ready to protect your equipment and keep your employees safe when hazardous conditions occur.