Why is the LEL important in combustible gas detection?
In environments with combustible gas hazards, it is important to know long before the gas concentration reaches the LEL. Typical safety standards require that a gas detection unit give warnings at 10 – 20% of the LEL. Do not confuse the alarm level with the volume of gas required to reach the LEL. For example: Methane has an LEL of 5% by volume in air. For a gas detector to give an alarm at 10% of the LEL, it must trigger when it detects 0.5% by volume. The detector for this application would most likely be calibrated for the range from 0% to 5% gas by volume, but display the reading as 0 – 100% LEL.
