What do the units PPM,VOL and LEL in common gas detectors mean respectively?
In the gas detector, the common units are VOL,PPM and LEL, so today we will learn the definitions and relationships of these three units.
First of all, let's talk about VOL, which refers to the volume percentage concentration of a certain gas in the air, usually expressed in%, such as laser methane detector and oxygen detector; For example, the measuring range of the oxygen detector is 1 ~ 25% vol, which means that this oxygen detector can be used to detect places where the oxygen content in the air is between 0~25%.
What is ppm? Ppm refers to the concentration limit of gas in the air, referred to as allowable concentration. As mentioned above, the measurement ranges of hydrogen sulfide and sulfur hexafluoride are usually expressed in ppm. Because the gas leakage concentrations of these two gases may be different in different environments, the sulfur hexafluoride detector supports multiple range selection of 0 ~ 100, 500, 1000, 2000 and 5000ppm.
LEL refers to the concentration value of gas alarm, with percentage as the calculation unit. Its full name is Lower Disclosure Limited, which is abbreviated as LEL. The measurement range of methane detector is 0 ~ 100% LEL. The lower limit of methane explosion is 5% and the upper limit is 15%, so when the concentration of methane in the air is between 5% and 15%, it will explode when it meets an open flame, and when the concentration of methane in the air is below 5% or above 15%, it will not explode when it meets an open flame.
Simply put, VOL stands for volume percentage concentration, PPM stands for concentration, and LEL stands for lower explosion limit. Will this be clear? We have been studying, just to better serve our customers.
Ppm, VOL and LEL are all units of gas concentration. Is there any connection between them?
Before answering this question, let's look at the conversion relationship between ppm, VOL and LEL:
Because the meaning of VOL% is in percentage, and the meaning of PPM is in parts per million, so 10000 PPM = 1 VOL. Therefore, the conversion relationship between VOL and ppm is: 1ppm=0.00001x100VOL, and 1VOL=10000ppm. However, there is no direct conversion between ppm and LEL, so LEL should be converted into VOL first, and then converted from vol and ppm.
