What is the unit of ppm (what does PPB mean)

In gas sensors, the frequency of PPM units is very high, and many gases are detected by PPM units, and these gases are generally toxic gases, such as ammonia, ozone, carbon monoxide, chlorine, hydrogen sulfide, sulfur dioxide, VOC and so on.

So what does PPM mean in gas detection?

PPM is the abbreviation of part per million, which means one in a million when translated into Chinese, which is somewhat similar to our percentage, but more accurate than the percentage.

PPM: 1/10000 1 100000 of gas concentration. ※ 1%= 10000ppm

Description of ppm unit meaning of gas sensor:

Toxic gas refers to toxic gas or toxic vapor that can cause death or permanent health damage through skin contact or breathing during occupational activities, so gas sensors are usually expressed in ppm.

VOL refers to the volume concentration ratio of a certain gas in the mixed gas (air), that is, the volume concentration content of a certain gas in the air. And ppm refers to the concentration ratio of a few parts per million. For example, the concentration of ammonia is 100 ppm, which means that there is 100 volume of this gas in 100 volume of air. The corresponding relationship between ppm and VOL is 1 vol = 1 million ppm, 1%VOL= 10000ppm.

Ppm detection range and alarm value setting of common toxic and harmful gases

As we all know, toxic gases are very harmful to human body. Many times, a little bit in the air may kill people, so it is not accurate to express the content of toxic gases in the air by percentage, which may lead to more casualties because of the error. And PPM is accurate to one millionth, which is much more reliable than percentage.

What is the concept of one millionth accuracy? We can roughly understand that if the molecular size of toxic gas is similar to that of air, then if there is one toxic gas molecule in 654.38+100,000 air molecules, the gas sensor can detect it. At present, the detection accuracy of excellent gas sensors has reached 0. 1PPM, which is equivalent to100000 air molecules. If there is a toxic gas molecule, the gas sensor can detect it.

The unit of PPM can be directly converted into percentage, 1%= 10000PPM, or 1PPM=0.000 1%.

In addition to PPM, there is a more accurate gas unit called PPB, which is one billionth in English. Translated into Chinese is one billion, 1PPM= 1000PPB.

The gas concentration of ppb:11100 million. ※ 1ppm= 1000ppb