LEL stands for Lower Explosive Limit. It is a term that identifies the lowest concentration levels of a gas or a vapor that is able to burn in the air. Different gasses and vapors will have different LEL’s, so it is important to know what it is for anything that is used in a facility. Many chemicals will give off vapors or gasses when just sitting in an open container, or when being used. As the concentration of the vapor increases, it is important to make sure that they are kept below the LEL or they would represent a serious fire or explosion hazard.

When using potentially flammable things that can create gasses or vapors it is important to take the necessary steps to keep the concentration below the LEL. There are many ways that this can be done. The ideal option is to take steps to ensure that gasses and vapors are not released into the air. This will not only reduce risk, but also help to minimize exposure to the chemicals. Another option is to ensure proper ventilation in the area. By ventilating the area the concentration of the gas or vapor will be kept low since new fresh air is brought through.

It is important to note that just because LEL has been reached does not mean that there will be an immediate fire or explosion. In order for that to take place, there must not only be a sufficient concentration of the gas or vapor in the air, but also a source of ignition. When the LEL has been reached, however, any type of ignition source could cause a serious fire or explosion.

For most chemicals, the LEL is going to be 5% by volume or below. Some chemicals are far below this level. Any time a potentially dangerous chemical is being used or stored in a facility, it should be labeled with its LEL so that the proper safeguards can be put in place.

GHS Guide
OSHA Safety Signs Guide
OSHA Label and Sign Color Chart
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