What is repeatability? What is indication error? If you understand these two problems, you can understand why so many detectors are inaccurate.
Repeatability is easy to understand, that is, the same area is tested for formaldehyde 2 or several times. The results are different each time, and the gap is very large, indicating that the reliability of the instrument is poor.
Indication error refers to the difference between the data or concentration value displayed by the instrument and the actual formaldehyde concentration value at the detection location. In fact, the measurement is inaccurate and unreliable. The current method of detecting formaldehyde in indoor air quality is mainly based on the national industry standard GB/T18204.22014 "Public Place Hygiene Inspection Methods Part 2: Chemical Pollutants". There are two methods that people are more exposed to.
phenol reagent photometric method
Suitable for environments with low formaldehyde concentration. The basic concept of detection is to pump air into a special absorption liquid through an air pump, and measure the concentration of formaldehyde in the air through changes in color intensity. The measurement results of this method are accurate, but the whole process is very complicated. Samples must be taken on the spot and then returned to the laboratory for analysis. Therefore, the test results are slow to come out and the results cannot be obtained on the spot.
| | electrochemical sensor method
| Suitable for environments with high formaldehyde concentration. The basic concept of detection is to pass the gas containing formaldehyde through the electrochemical sensor at a certain rate. The controller will generate different currents according to the concentration value, and judge the formaldehyde concentration value based on the current intensity. This method has a faster detection speed and can see the results on the spot. Most of the Internet celebrities formaldehyde detector used for sampling inspection are of this type. However, when you disassemble the online shopping detector, you will find that its internal structure is simply spliced together by poor sensing components, which cannot achieve the detection effect of the electrochemical sensor at all. Real electrochemical sensors are both expensive and fragile. Not only are they expensive, their "little hearts" are also very sensitive, and they must be carefully cared for before they can work. Even so, the service life of the equipment is not long and needs to be replaced regularly. If it is not well maintained, it will "parade" immediately.
Therefore, the formaldehyde meter purchased online is so cost-effective. If you buy it for convenience, how can you maintain it carefully? It is too normal to be inaccurate.
For formaldehyde testing, you must find a professional organization:
. Online shopping formaldehyde detectors are inaccurate, which sounds scary. If the measured value is higher than the actual value, it will cause human anxiety; if the measured value is lower, it will directly cause you to have insufficient understanding of the harm of formaldehyde in the room and think it meets the safety limit. In fact, the pollution still exists, and even in the wrong place. The environment that is considered safe is subject to long-term damage.
So, how should we detect formaldehyde in indoor air quality? With a reliable instrument, can we tell whether the environment is safe? No! Measuring the formaldehyde concentration in the air, especially in the room environment, the country There are relative standards, and different sites follow different standards. The measurement methods and the control of environmental conditions during measurement are also different. It is not as simple as just taking an instrument and measuring it at will.
For formaldehyde detection, the room must first be sealed for a required period of time, and then effectively set points according to the local measurement environment, choose a suitable measurement height, avoid vents, ventilation channels , and also consider the environment Microclimate and environmental factors such as temperature and humidity will affect the test results. Therefore, if you want to judge the safety of ambient air index, it is recommended to find a professional organization.
Nowadays, there are many organizations that conduct indoor air quality testing, such as occupational disease prevention and control institutes, various disease control organizations, third-party testing organizations, etc., which can provide testing services.
Pay attention to the following aspects when decorating your home:
1. Use environmentally friendly decorative materials that comply with national industry standards, use as little artificial boards as possible, and use less or no buildings containing preservatives or fluorescent whitening agents coating.
2. The incisions of artificial boards should be coated with coating to allow them to fully dry and solidify, forming a stable protective layer thickness and preventing formaldehyde from evaporating in the boards.
3. It is not suitable to move in immediately after interior decoration. More indoor ventilation is required, and the house can be moved in after there is no odor and the inspection meets the standards.
