Range Introduction and Purchasing Guide for Combustible Gas Detectors
When the hazards and risks posed by gaseous toxic substances inside a confined space are unknown, gas alarms must be deployed. For confined‑space gas testing, sampling shall be completed before personnel entry.
Combustible gas detectors shall remotely analyze gas composition inside the confined space prior to personnel access, so as to effectively
measure the levels of combustible and toxic gases.
If gas concentration exceeds the alarm threshold, the gas alarm will trigger warnings and prompt personnel to evacuate safely.
It is critical to sample and test gas‑vapor concentrations at the top, middle and bottom layers of a confined space. Some gases are lighter than air and accumulate in the upper zone. Some gases are heavier than air and settle at the bottom. Other gases have nearly the same density as air and distribute in the middle section.
Continuous measurements taken at different heights will produce distinct test results.
What are the typical measuring ranges of combustible gas detectors?
① Sensors from different manufacturers have different response factors for various combustible gases. Refer to manufacturer‑supplied technical data.
② The measuring range is an inherent hardware parameter of the detector and cannot be modified. The standard range for most combustible gas detectors is 0‑100 %LEL. Actual specifications shall follow the manufacturer's documentation.
③ Confirm the unit of your methane calibration gas: is it 2.5 %VOL (volume fraction) or 2.5 %LEL (Lower Explosive Limit)? These two values d
if
fer greatly. The Lower Explosive Limit of methane is 5.3 %VOL.
a) If the calibration gas is 2.5 %VOL methane: convert to 47 %LEL. Set the calibration value to 47 during calibration. b) If the calibration gas is 2.5 %LEL methane: set the calibration value directly to 2.5. (Calibration gas at such low LEL concentration is uncommon, so this case is less likely.)
Poor maintenance will impair combustible‑gas‑detector performance and cause measurement deviation or complete detection failure. Therefore, regular cleaning and servicing are essential preventive measures against equipment malfunctions.
