At present, the international standards mainly implement two standards, namely American standards and European standards. China has just issued new standards for protective masks, mainly referring to American standards.
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, P. Respectively represent different protective objects: N is non-oily particles, R and P are oily particles, but the protective oil particles of R grade can not exceed 8 hours, while P grade has no such limitation. These three categories have three kinds of filtration efficiency. Standards: 95 (95%), 99 (99%), 100 (99.97%), so a total of 9 mask standards. Since biological particles are mostly non-oily particles, N95 is the most basic grade, which means that the non-oily particles can be filtered at 85L/min flow rate up to 95%.
European Standard (CEEN149:2001)
The standard for European protective masks is divided into three levels: FFP1, FFP2, and FFP3. Unlike the US standard, its detection flow rate is 95L/min, and it is dusted with DOP oil.
China's standard GB19083-2003
The principle adopts the American standard. Only China's standard uses only one grade, namely N95. The aerosol uses NaCl non-oily particles, the flow rate is 85L/min, the average particle diameter is 0.26μ, the counting particle size is 0.07μ, and when the filtration efficiency is 95%, the airflow resistance is not more than 35mm. Water column.
Bacterial Filtration Efficiency
Some masks are marked with BFE ≥ 95%. It is the test method of Nelson Labs in the United States. The material is tested by taking 3.0 micron particles at 32 LPM flow.
Introduction to inspection instruments
Both European and American standards are designated for testing with the US TSI-8130 Automated Filter Testers. The American standard N uses the NaCl method, the R standard uses the DOP method, and the European standard uses the DOP method.
The NaCl method of TSI-8130 instrument: the instrument can automatically generate salt particles. The average diameter of the particles is 0.2μm (the average diameter of the aggregate is 0.26μm, the arithmetic mean diameter is 0.07μm). The sample is automatically filtered after passing through the sample at a certain flow rate. Flow, resistance, and transmission rate.
The DOP method uses DOP oil to dust, and the DOP oil particle diameter is an aggregate average particle diameter of 0.33 μm, and the count average diameter is 0.20 μm.
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