What do the units on the gas detector mean to me?
Gas detector is one of the detection instruments commonly used in industrial production. It can detect the concentration of toxic and harmful substances at work, detect the types of gases in the environment, and use corresponding safety protection equipment based on the detection results. But when using a gas detector, many people don't know what the units on the gas detector mean.
What do the units on the gas detector mean?
(1)%VOL (gas concentration volume ratio): detect oxygen and carbon dioxide. Using this unit, the value can be read directly.
(2) %LEL (lower explosion limit): refers to the lowest concentration at which an explosion occurs when flammable gas is mixed with air and encounters minimum ignition energy.
Portable gas detectors usually set an alarm point: below 25% LEL of the lower explosion limit.
For example, the lower explosion limit of methane is 5% VOL, that is, if 5% VOL is divided into one hundred equal parts, it corresponds to 100% LEL. When the detector value reaches the 25% LEL alarm point, it is equivalent to the concentration of methane at this time being 5%VOL*25%=1.25%VOL.
It is still far away from the lower limit of methane explosion of 5% VOL, so there is no need to worry about the danger after calling the alarm. This just reminds you to take corresponding measures immediately.
Such as closing valves, dispersing gas, etc., which serve as alarm prompts. If the value reaches 100% LEL, you should pay attention at this time, indicating that the lower limit of methane explosion concentration of 5% has been reached, which is very dangerous.
(3)PPM: PPM is the abbreviation of part per million in English, which means parts per million. Volume concentration (ppm) means the volume of pollutants contained in one million volumes of air.
Our country's standards and specifications are also expressed in mass concentration units (such as mg/m3).
