Conversion between 1, volume ratio (%Vol) and weight ratio (%LEL): There is no direct mathematical relationship between the conversion between volume ratio and weight ratio, and the density and molecular weight of different gases are different. To convert the volume ratio into weight ratio and volume ratio, it is necessary to know the specific gas types and related parameters.

2. Conversion between ppm and mg/m3: ppm and mg/m3 are two commonly used units to express gas concentration. The conversion relationship needs to consider the molecular weight, temperature and pressure of the gas. The specific conversion formula is as follows:1mg/m3 = (m/22.4 )×1ppm× [273/(273+t) ]× [ba/101325], where m is the molecular weight of the gas, t.