What is the efficiency of the air filter? The ratio of the amount of dust collected by the filter to the amount of dust in the unfiltered air is " filtration efficiency " .
Different operating environments require different levels of cleanliness, so different efficiency filters and comparable fresh air volumes are required to meet different cleanliness levels.
Among the factors that determine filtration efficiency, the dust " quantity " The meaning of the filter is varied, so the calculated and measured filter efficiency values ​​are different. In practice, there is the total weight of dust, the number of particles of dust; sometimes the amount of dust for a typical particle size, sometimes the amount of all dust; and the amount of light that is indirectly reflected by a specific method (colorimetric method), The amount of fluorescence (fluorescence); the instantaneous amount of a certain state, and the weighted average of the efficiency value of the whole process of the dust. therefore The same filter is tested by different methods, and the measured efficiency value will be different . Without the test method, the filtering efficiency cannot be discussed.
Therefore, different air filters should be tested by different methods . When selecting a filter, you should not only consider the efficiency of the air filter, but also its test method and test dust.
In the world, the efficiency of the filter was tested by the atmospheric dust group counting method in the world. In 1990 , GB12218-1990 "Test Method for Performance of General Ventilation Filters" was issued.
For high-efficiency air filters, test dust and test methods vary widely across countries. For example, GB/T6165-1985 “Test Method for High Performance Air Filter Performance, Transmittance and Resistance†issued by China adopts oil mist method and sodium flame method as statutory performance test methods; UK adopts sodium flame method ( BS3928-1969 ; The DOP (dioctyl phthalate) method proposed by the United States. Countries have proposed air filter standards based on the proposed test method standards, such as BS5295 in the UK with DOP as test dust. Standard, developed by the European Association of Air Handling Equipment Manufacturers EVROVENT4/9 , the comparison of various air filter standards and efficiencies at home and abroad is shown in Table 3-3 .
The test methods for air filters commonly used at home and abroad are :
(1) Weighting method
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