# ## Focus on gas and dust detection for 11 years

Gas solution, gas analysis, dust detection overall solution service provider

National free consultation hotline

# Relationship and conversion of gas concentration mg / m3 and ppm

There are two ways to express the concentration of pollutants in the ambient atmosphere (air):

1. Mass concentration method: mass number of pollutants contained in air per cubic meter, ie mg / m 3

2.Volume concentration representation: the volume of pollutants contained in one million volumes of air, that is, ppm

The concentration expressed by the mass of pollutants in the atmosphere per cubic meter is called mass-volume concentration, and the unit is milligram / cubic meter or grams / cubic meter. Most of the gas concentrations measured by the online smoke monitoring system are volume concentration (ppm). According to China's regulations, especially the environmental protection department, the gas concentration is required to be expressed in units of mass concentration (such as: mg / m3). Our country The standard specifications are also expressed in mass concentration units (such as: mg / m3).

What is the relationship between these two gas concentration units, mg / m3 and ppm? How are the two converted?

Using the mass concentration unit (mg / m3) as the expression method of air pollutant concentration, it is convenient to calculate the true amount of pollutants. But the mass concentration is related to the temperature and pressure environmental conditions of the test gas, and its value will vary with the temperature and pressure And other environmental conditions vary; in actual measurement, the temperature and atmospheric pressure of the gas need to be measured at the same time. When using ppm as a description of the concentration of pollutants, this problem does not occur because of the volume ratio.

Conversion of concentration unit ppm to mg / m3: Calculated as follows:

Where: M — molecular weight of the gas,

T — temperature

Ba — pressure

Gas concentration refers to the pollutants in the atmosphere. Common volume concentration and mass-volume concentration are used to indicate its content in the atmosphere.

1.Volume concentration

Volume concentration is expressed as the volume of pollutants in the atmosphere per cubic meter (cubic centimeters) or (ml / m3). The commonly used method is ppm, that is, 1 ppm = 1 cubic centimeter / cubic meter = 10-6. In addition to ppm, there are ppb and ppt. The relationship between them is:

1ppm = 10-6 = one millionth,

1ppb = 10-9 = one billionth,

1ppt = 10-12 = one trillionth,

1ppm = 103ppb = 106ppt

2.mass-volume concentration

The concentration expressed by the mass of pollutants in the atmosphere per cubic meter is called mass-volume concentration.

Its conversion relationship with ppm is:

X = M · C / 22.4

C = 22.4X / M

In the formula: X—the concentration value of pollutants expressed in milligrams per standard cubic meter;

C—concentration value of pollutant expressed in ppm;

M—the fractional amount of the pollutant.

Note: This formula is a commonly used quick calculation formula. For gas detection, the calculation results of the quick calculation formula basically meet the requirements for use. Relationship between mg / m3 and ppm and conversion formula

#### Latest Information Articles 