VOCs control engineering common gas representation units or abbreviations, such as LEL, PPM, mg/m3, etc. Let’s summarize below:
Top 01 V/V
V/V represents volume ratio, that is, the proportion of a certain gas in the total volume of the mixed gas;
Top 02 vol%
vol% represents the volume percentage, that is, the percentage of a certain gas in the total volume of the mixed gas;
Top 03 LEL%, UEL%
Explosion limit is one of the main indicators that indicate the dangers of combustible gases, vapors and combustible dust. When combustible gas, vapor or combustible dust is evenly mixed with air (or oxygen) within a certain concentration range, the concentration range that explodes when the fire source occurs is called the explosion concentration limit, which is referred to as the explosion limit for short. A mixed gas (or dust) in this concentration range is called an explosive mixed gas (or dust).
Explosion limit of combustible gases and vapors is generally expressed by the volume fraction (%) of combustible gases or vapors in the mixed gases; the explosion limit of combustible dust is expressed by the mass concentration of the mixture (g/m3).
The lowest concentration that can explode is called the lower explosion limit; the highest concentration that can explode is called the upper explosion limit. The ratio of the difference between the upper and lower limits of the explosion limit and the lower limit of the explosion limit is used to represent its danger degree H; "LEL" is the abbreviation of Lower Explosive Limit . Refers to the lower limit of explosion, which is a technical term for combustible gases. The minimum concentration of combustible gases that encounter open flame explosion in the air is called the lower limit of explosion - "LEL".
"UEL" is the abbreviation of Uper Explosive Limit . Refers to the upper limit of explosion, which is a technical term for combustible gases. The minimum concentration of combustible gases that encounter open flame explosion in the air is called the lower limit of explosion - "UEL" for short.
Common combustible gas explosion limit data table (this table is the volume ratio parameters of 100%LE or 100%UEL)
Top 04 PPM, PPb
ppm concentration (parts per million) is the concentration expressed by the mass of the solute to occupy a million percentage of the total solution mass, also known as the partial million percentage concentration. It is often used in situations where the concentration is very small, and similarly ppb (parts per billion). For gas, ppm generally refers to molar fraction or volume fraction. For solution, ppm generally refers to mass concentration;
1ppm=1000ppb;
Top 05 mg/m³
mg/m³. As the name suggests, for gas, it is how many mg of a certain gas contained in a mixture of 1m³;
Top 06 The mutual conversion between units
V/V=vol%;
vol%=10000ppm;
1ppm=1000ppb;
LEL% is a unit for explosive gas, which contains It means the percentage of volume of a certain explosive gas in the entire gas, expressed in vol%;
or above are the unit of volume ratio for organic gas, and the conversion is relatively simple;
mass concentration mg/m3=M gas molecular weight/22.4*ppm value*[273/(273+T gas temperature)]* (Ba pressure/101325).
