Detection Range: The Core for Verifying Combustible Gas Detector Performance
When the hazards and risks of harmful substances in gas within a confined space are undetermined, gas alarms must be deployed. For confined space gas monitoring, pre-entry detection is required. Before personnel access the confined space, a combustible gas detector shall remotely analyze the composition of hazardous gases inside. It can effectively measure the concentration of combustible and toxic gases. If the concentration exceeds the safe threshold, the gas alarm will trigger an alert to warn personnel to evacuate promptly.
It is critical to sample and test the concentration of various gases or vapors at the top, middle and bottom of a confined space. Some gases are lighter than air and accumulate in the upper area; some are heavier than air and settle at the bottom; others have roughly the same density as air and distribute in the middle section. Continuous sampling and detection at different heights will yield different measurement results according to actual conditions.
What is the specific detection range of a combustible gas detector?
① Sensors manufactured by different instrument suppliers feature different response factors for various combustible gases during range calibration. Relevant parameters shall refer to the data provided by the manufacturer.
② The detection range is an inherent property of the gas detector and cannot be modified. Commonly, the measuring range of a combustible gas detector is 0～100%LEL, while exceptions exist. Please consult the manufacturer's documentation for actual specifications.
③ Confirm the unit of your methane calibration gas: 2.5%VOL (volume ratio) or 2.5%LEL (Lower Explosive Limit). There is a substantial difference between the two values. The Lower Explosive Limit of methane is 5.3%VOL. a. If the methane calibration gas is 2.5%VOL, the converted value equals 47%LEL, and the calibration value shall be set to 47. b. If the methane calibration gas is 2.5%LEL, the calibration value can be directly set to 2.5. (Calibration gas at such a low concentration is uncommon, so this case is less likely.)
Insufficient maintenance may cause malfunctions of combustible gas detectors, resulting in measurement deviation or detection failure. Therefore, regular cleaning and maintenance of combustible gas detectors are essential preventive measures against faults.
