ppm is part-millionthreshold or part-millionthreshold. In pesticide applications, it was often used to represent the concentration of the spray solution, that is, the number of parts containing the active ingredients of the pesticide in one million parts of the spray solution. According to international regulations, the part-millionth ratio is no longer expressed in ppm, but is expressed in mg/L or mg/cubic decimeter, mg/L.
ppm, simply put, is the volume concentration representation, volumes of pollutants contained in the air of one million volumes.
mg/m³mass concentration representation, mass number of pollutants contained in air per cubic meter.
Most gas detection instruments measure the gas concentrations volume concentration (ppm). According to my country's regulations, especially the environmental protection department, the gas concentration is required to be expressed in units of mass concentration (such as: mg/m³), and our country's standards and specifications are also expressed in units of mass concentration (such as: mg/m³). Is there any relationship between
ppm and mg/m³? Is there a conversion formula? Of course, there is one such thing as
. The conversion of concentration unit ppm to mg/m³ is calculated according to the following formula:
mg/m3=M/22.4×ppm×(273/(273 T))×P/101325. Where M is the gas molecular weight, T is the temperature, and P is the pressure.
The above formula is a standard algorithm, but in our actual calculation work, temperature and pressure can be ignored. For the sake of calculation convenience, it can be recorded as: ppm=(mg/m³)/(M/22.4), M is the molecular mass of the substance, and the molecular mass of formaldehyde (HCHO) is 30 (H=1, C=12, O=16).
The editor gives an example to calculate: the formaldehyde concentration is 0.1mg/m³, ppm=0.1/(30/22.4)=0.07 (rounded), is 0.1mg/m³=0.07ppm.
