Što are "PPM" i "LEL" in gas detektori
We often see "PPM" and "LEL" marked on gas detektori. So what are "PPM" and "LEL"? Maybe many people are not very clear. Below, the four in one gas detector will introduce the specific meanings of these two words in detail.
PPM "is the volume specific concentration. PPM "is a representation of solution concentration, where PPM represents parts per million. For a solution: if there is 1/1000 milliliter of solute in 1 liter of aqueous solution, the concentration is 1 PPM. For gases: One of the methods for expressing the concentration of pollutants in the ambient atmosphere. Volume concentration representation method: The volume of pollutants contained in one million volumes of air, known as PPM. Most gas detection instruments measure gas concentration as volume concentration (PPM), but according to Chinese regulations, especially environmental protection departments, gas concentration is required to be expressed in units of mass concentration. Our national standards and regulations also use mass concentration units to represent gas concentration. It is manufactured using the principle that the conductivity of some metal oxide semiconductor materials changes with the composition of the environmental gas at a certain temperature.
LEL "refers to the lower explosive limit. The minimum concentration of combustible gases that can explode when exposed to an open flame in the air is called the lower explosive limit - referred to as percent LEL.
Fixed HOC plin detektor
The maximum concentration of combustible gases that can explode when exposed to an open flame in the air is called the upper explosion limit - referred to as percent UEL. So what is the lower explosive limit? The concentration of combustible gases is too low or too high, and it is not dangerous. It only burns or explodes when it mixes with air to form a mixture or, more precisely, when it encounters oxygen to form a certain proportion of the mixture. Relevant authoritative departments and experts have conducted combustion and explosion analysis on the currently discovered combustible gas, and established an explosion limit for combustible gas below the lower explosion limit. The content of combustible gas in the mixture is insufficient to cause combustion or explosion, and the oxygen content in the mixture above the upper limit is insufficient to cause combustion or explosion.
In addition, the combustion and explosion of combustible gas are also related to factors such as gas pressure, temperature, and paljenje energija. The explosion limit is general expressed as a volume percentage concentration. The explosion limit is a a term for the lower and upper explosion limits. The koncentra of comburnible gases in the air will only explode between the lower and upper explosion limits. Explosion Explosion not dogoditi ispod ili iznad the lower explosive limit.
Stoga, when provođenje eksplozija mjerenja, the alarm koncentracija je općenito set below 25 percent LEL of the lower explosion limit. The measurement range of various combustible gas detectors is 0-100 percent LEL. Fixed combustible gas detektori obično have two alarm points: 10 percent LEL is the first level alarm, and 25 percent LEL is the the second level alarm. Portable comiv gas detectors obično have an alarm točka: 25 percent LEL is the alarm točka.
