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At present, there are mainly two standards in the world: the American standard and the European standard. China has just issued a new standard for protective masks, which mainly refers to the American standard.
American Standard (NIOSH Standard)
Developed by the National Institute for Occupational Safety and Health. It divides the standard of masks into three categories: N, R and P. Respectively represent different protection objects: N is non-oily particles, R and P are oily particles, but the effect of R-level protective oily particles cannot exceed 8 hours, and P-level has no such limitation, these three categories have three kinds of filtration efficiency Standards: 95 (95%), 99 (99%), 100 (99.97%), so there are 9 mask standards. Since biological particles are mostly non-oily particles, N95 is the most basic level, which means that the filtration efficiency of non-oily particles can be up to 95% at a flow rate of 85L / min.
European Standard (CEEN149: 2001)
The standard of European protective masks is divided into three levels: FFP1, FFP2, FFP3. The difference with the American standard is that its detection flow rate is 95L / min, and it is dusted with DOP oil.
China Standard GB19083-2003
The principle adopts American standards. However, China ’s standard adopts only one grade, N95. Aerosols use NaCl non-oily particles with a flow rate of 85L / min, an average particle size of 0.26μ, and a counted particle size of 0.07μ. When the filtration efficiency is 95%, the airflow resistance is not greater than 35mm. Water column.
BFE (Bacterial Filtration Efficiency)
Some masks are marked with BFE ≥ 95%, which is a test method of the Nelson laboratory in the United States. It uses 3.0 micron particles to detect the material at a flow rate of 32LPM.
Introduction to Inspection Instruments
Whether it is a European standard or an American standard, it is specified to use the US TSI-8130 Automated Filter Testers instrument for testing. American standard N type uses NaCl method, R type uses DOP method, European standard uses DOP method.
The TSI-8130 instrument uses the NaCl method: the instrument can automatically generate salt particles. The average diameter of the particles is 0.2 μm (the average diameter of the aggregate is 0.26 μm, the average diameter of the arithmetic is 0.07 μm). The instrument automatically prints out through the sample at a certain flow rate. Flow rate, resistance, transmittance.
The DOP method uses DOP oil to generate dust. The diameter of the DOP oil particles is the aggregated average particle diameter of 0.33 μm, and the counted average diameter is 0.20 μm.
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