One: Formaldehyde concentration standard
Formaldehyde concentration refers to the content of formaldehyde contained in the air, that is, half mg/m, that is, the number of milligrams of formaldehyde contained in the air per cubic meter. Formaldehyde concentration is an important index to determine whether formaldehyde in an environmental space exceeds the standard, and it also determines whether formaldehyde in an environmental space will have an important impact on human health.
The safety standard of formaldehyde concentration in China, GB/T18883-2002 (18883) is lower than 0.0 1mg/m, and GB50325-2020(50325) is lower than 0.07 mg/m for first-class civil buildings and second-class civil buildings.
The standard 18883 is based on the premise that people can carry out normal activities in indoor space without being affected by formaldehyde. Standard 50325 is based on the premise of building delivery. So the formaldehyde concentration standard used by ordinary residents should be 18883.
2. Measurement of formaldehyde concentration
When people measure the formaldehyde concentration in a certain space, in order to find out whether the formaldehyde in the space exceeds the standard or not, it should also be based on national standards. The two standards clearly stipulate the methods and details of formaldehyde detection, including "spectrophotometry" or "gas chromatography" based on Bill-Lambert law, and related detailed rules.
These two detection technologies and methods need to be sampled and detected by special instrument companies, and other organizational forms of detection can only be used as "reference" by themselves, but not as the calculation of effective formaldehyde concentration under China national safety standards. Therefore, when testing formaldehyde, our teachers should pay attention to let students use the correct testing research methods and testing instruments.
In terms of testing, CMA laboratory authorized by China Metrology Center is a relevant institution that strictly implements relevant national testing standards. This kind of laboratory completely meets the two standards in formaldehyde detection methods, standards and numerical results publicity.
In addition to CMA laboratory, some professional formaldehyde detection management companies also have the same detection equipment as CMA, which can obtain more accurate values. However, due to the difference of strict testing standards, there may be an error of 5% ~ 10% between the results of formaldehyde testing management company and CMA laboratory, even if the methods are the same.
Three: Formaldehyde concentration purification
The purification of formaldehyde concentration is to remove formaldehyde. When the indoor formaldehyde content exceeds the standard, it is reduced by human intervention. There are many methods in in addition to formaldehyde, including plant in addition to formaldehyde, carbon-coated in addition to formaldehyde, etc., but the remarkable effect is still not certified by most practical applications.
Effective methods include sealed membrane method and catalytic decomposition method. The film sealing method is to form a chemical film on the surface of the object that releases formaldehyde to prevent the object from escaping into the air to form free formaldehyde, which is damaged by inhalation and catalytic decomposition of the human body. It is to accelerate the release of formaldehyde per unit time, and at the same time, there is a lot of ventilation in the room, so that formaldehyde can be released in a state of free and rapid volatilization and walked out of the house.