What is 10% LEL?

What is 10% LEL?

The lower explosive limit (LEL) of a flammable gas or vapour is the concentration of fuel in air, below which it can explode. This is different for each gas or vapour, but it’s important to know that a high risk of explosion could be present even with a very low gas concentration.

In order for a fire or explosion to occur, three conditions must be met simultaneously. A combustible gas or vapour must be mixed with oxygen in a specific ratio, along with an ignition source, such as a flame or spark. The proportion of fuel to oxygen that is needed varies with each type of gas.

For example, Methane is flammable at concentrations of 5% and 17% but it is not flammable below 5%. That is why a gas monitor displays a percentage, which is called the LEL.

What is the Upper Explosion Limit?

The upper explosive limit (UEL) is the maximum concentration of a combustible gas or vapour in air that can ignite and cause an explosion Gas detection Australia. This is different for each gas or vapour and can be used to prevent or contain an explosion.

The most common way to measure the LEL is with a Wheatstone bridge LEL sensor or a Photo-Ionization detector. The latter type of device is particularly effective in environments where a Wheatstone bridge sensor doesn’t have enough sensitivity or can be rendered inoperable by the chemicals in the environment.