The next topic in our "back to the basics" series is flammable hazards. Its important to understand what causes a fire or explosion to occur in a process before you can even think about preventing one.
For each flammable substance there is a level of concentration in air, usually expressed as a percent by volume, that is known as its Lower Flammable Limit, LFL, or Lower Explosive Limit, LEL. Below the LFL, the mixture of fuel and air is too lean to support combustion.
There are 3 important factors to consider when measuring flammability:
Now that we understand what the Lower Flammable Limit is, let's look at how these values are determined and what that means for your application.
LFL is determined empirically. This means that there are variations in the values published by different authorities at different times.