Lel Gas What Is The Difference Between Parameters For Gas Detection Ppm And Lel ?when To Use Ppm And When To Use Lel?

What is the difference between parameters for gas detection ppm and lel ?when to use ppm and when to use lel? - lel gas

While measuring the concentration of the gas used in all gas detectors. What are the things that are observed? What is the difference between ppm and lel. when measuring ppm LEL and where to use them?