The %LEL indication is widely used in portable and fixed combustible gas detectors. It indicates how close the gas concentration is to the lower explosive limit.
What is LEL
LEL stands for Lower Explosive Limit. Below this limit, the mixture of gas and air is too lean to ignite.
What does 10% LEL mean
It does not mean that the area contains 10% natural gas. It means that the concentration has reached 10% of the lower explosive limit value for that specific gas.
Why it is important
Safety systems are activated well before the concentration reaches 100% LEL, in order to provide a significant safety margin.
Alarm levels
Alarm values are determined by the design study, the manufacturer, and the facility's safety procedure. They should not be changed arbitrarily to avoid frequent alarms.
Important note
The %LEL indication is only valid when the sensor is suitable for the specific gas and has been properly checked or calibrated.