How much do you know about the professional terminology of combustible gas alarms?

A combustible gas alarm is an early warning device that mainly detects the gas content in the air or working environment. It plays a vital role in ensuring the safe use of gas in all areas of society.

  

CMC produces fixed commercial and industrial combustible gas detectors, which are often used in large-scale industrial and commercial fields such as petroleum, chemical, metallurgy, scientific research, large supermarkets, etc. They are mainly used to detect natural gas (methane CH₄), liquefied gas (propane C₃H₈, butane C₄H₁₀), hydrogen H₂, hydrocarbon gases (ethylene C₂H₄, propylene C₃H₆) and alcohol vapor (ethanol, methanol), etc., to ensure the safety of factories, warehouses, and laboratories.

To properly use a combustible gas concentration monitor, it’s important to understand its related terminology. Terms like LEL/%LEL, %VOL, alarm point, Ex d explosion-proof rating, IP66 protection, 4–20mA/RS485, and calibration/zero drift can help you select the right model, understand the values, and ensure proper installation and stable operation.

  

The following is a glossary of common terms used in CMC combustible gas alarm hosts:

No. Term Description
1 LEL (Lower Explosive Limit) The lowest concentration of combustible gas in air that can cause an explosion.
2 UEL (Upper Explosive Limit) The highest concentration at which an explosion can occur.
3 ppm (parts per million) Unit of concentration, commonly used for toxic gases.
4 %VOL Volume fraction concentration, used for oxygen and combustible gases.
5 %LEL Percentage of the lower explosive limit, a common measurement unit for gas detectors.
6 Sensor Type Catalytic Bead, NDIR (Non-Dispersive Infrared), Semiconductor, Electrochemical.
7 Response Time (T90) Time required for the detector to reach 90% of the final reading.
8 Recovery Time Time required for the detector to return to baseline after exposure.
9 Zero Drift Change in output when no target gas is present.
10 Span Drift Change in reading over time at a fixed calibration concentration.
11 Explosion-proof Rating Safety rating for use in explosive hazardous areas.
12 Protection Rating (IP) Degree of dustproof and waterproof protection.
13 Alarm Mode Sound & Light Alarm, Relay Output, 4-20mA / RS485 signal output.
14 MTBF (Mean Time Between Failures) Average operating time without failure.
15 Calibration Adjusting detector accuracy using standard calibration gas.
16 Cross Sensitivity Detector response to non-target gases.
17 Detection Principle Catalytic Combustion, Infrared Absorption.
18 Operating Environment Temperature, humidity, explosion-proof zones (Zone 1 / Zone 2).
19 Alarm Set Point Gas concentration threshold at which the alarm is triggered.
20 Sensor Life Typically 2–5 years, depending on sensor type.

If you want to know more about toxic and combustible gas concentration alarms, please contact us:

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