Introduction to Combustible Gases
Combustible gases are gases that will burn when mixed with oxygen and ignited. Typically, most combustion reactions involve the burning of organic materials containing carbon and hydrogen. Combustion reactions are essential to life, and are exploited to generate power, to provide heat, to run motors, and in many other ways.
Combustible gases can be released into a facility naturally as a byproduct or leaked unintentionally. This presents the hazard of combustion within a facility if the concentration reaches a certain level.
Some combustible gases include:
- Methane (CH4)
- Pentane (C5H12)
- Propane (C3H8)
- Butane (C4H10)
- Hydrogen (H2)
Combustible gas detectors are required whenever there is a possibility of a hazard to life or property caused by the accumulation of combustible gases. 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 the Lower Flammability Limit (LFL)), the combustible gas concentration is too lean for combustion. This is the range in which most combustible gas detectors operate.
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. In between the LEL and UEL, the concentration (measured as a percent of volume in air) of combustible gas will support combustion if exposed to a source of ignition. The flammability of many gases lies in a very limited, concentrated range.
When researching combustible gas detection solutions, facility managers should be aware of the following combustible gas concentration limits: