Air filter refers to equipment that uses methods such as filtration, adhesion, or charged capture to remove particulate matter from the air, in order to reduce the concentration of particulate matter in the air and achieve the goal of purifying the air.
Filter testing method
01 Weighting method
The filter is installed in a standard test wind tunnel, with continuous dust generation (usually loess dust) at the upwind end. The mass of dust passing through the filter is measured at regular intervals to obtain the filtration efficiency of the filter during this stage of dust mass calculation. The tested dust particle size range is ≥ 5 μ M.
02 Colorimetric method
Sampling before and after the filter, the dusty air passes through the filter paper, and the contaminated filter paper is irradiated under a light source. Then, a photoelectric tube colorimeter (photoelectric density meter) is used to measure the transmittance of the filter paper before and after the filter; Under the same conditions of dust composition, size, and distribution, the filter efficiency can be calculated using the proportional relationship between optical density and dust accumulation. This method is mainly aimed at particle size ≥ 1 μ Dust particles of m.
03 Counting method
The full name particle counter method uses an aerosol generator to emit a gas flow containing aerosols, collect aerosols upstream and downstream of the filter material on the experimental device, measure their counting concentration values using a condensation nuclear particle counter (CNC) or optical particle counter (OPC), and then calculate the counting filtration efficiency of the filter material. Can measure aerosol concentrations in different particle size ranges.
04 Oil mist method
Generally, DOP (2-ethylhexyl phthalate) oil is used to emit polydisperse liquid aerosols through equipment, with an average particle mass diameter of (0.28~0.34) μ m) Use an oil mist meter to detect the mass optical concentration upstream and downstream of the filter, and then calculate the mass efficiency of the filter element. This method is mainly aimed at particle size ≥ 0.3 μ The particulate matter of m.
05 Sodium flame method
Send out NaCl aerosol through a generator, detect the mass concentration upstream and downstream of the filter element using a nanoflame photometer, and then calculate the mass efficiency of the filter element. For the filter material test, the median mass diameter of the tested aerosol particles is approximately 0.4 μ m. The median diameter of the count is (0.09 ± 0.02) μ m. The geometric standard deviation of quantity is less than or equal to 1.86; For filter tests, the median mass diameter of aerosol particles in the test is 0.5 μ M.