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Key points in selecting a high efficiency air filter
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(1) The longitudinal tensile strength of the filter paper should be not less than 0.7 kN/m, and the transverse tensile strength should be not less than 0.5 kN/m. (2) The thickness of the filter media should not exceed 0.40 mm under the pressure of (3.5±0.2) kPa, and should be uniform without hard lumps, and the surface of the filter media should not have cracks, abrasions, pinholes and colour spots. (3) Regarding the width of the frame, it should be 15mm~20mm, and for filters with a side length of not less than 600mm, the width of the frame should be 20mm. (4) Material and thickness requirements of the frame: cold-rolled steel plate thickness should be 1.0 mm~2.0 mm, after forming and welding, it should be galvanized, plastic spraying or other (5) rust prevention measures; aluminum alloy plate thickness should be 1.5 mm~2.0 mm; stainless steel plate thickness should be 1.0 mm~2.0 mm. (6) Requirements for high-efficiency sealing parts. Regarding the requirements of the production environment of high-efficiency filters, the air cleanliness level in the assembly workshop of high-efficiency air filters should reach level 8, and the air cleanliness level in the assembly workshop of ultra-high-efficiency air filters should reach level 7. (7) Regarding the requirements of sealant, it should be neat and without cracks, and the infiltration height along the filter material and divider should be no more than 5mm. High efficiency filter scanning leak detection test method, including particle counting scanning method and photometric scanning method (8) Particle counting scanning method requirements. ① The test aerosol stability should be required to meet the requirements of the total particle concentration fluctuations of not more than 10% of the test particle size block within 30 min. ② During the test, the concentration of the test aerosol count should not be greater than 1X107 particles per cubic centimetre. ③ Leakage detection tests can be carried out with either a condensation nucleus counter or an optical particle counter depending on the monodisperse characteristics of the test aerosol. When using an optical particle counter for the leak test, the smallest particle size block of the counter should not be selected for the test. ④ The opening area of the sampling probe should be 8 cm2~10 cm2 , and the shape should be square. When using a rectangular probe, the ratio of the side lengths should not exceed 15:1. When selecting the sampling flow rate of the probe, it should be ensured that the difference between the flow rate at the probe opening and the wind speed at the filter surface is not greater than 25%. ⑤ The direction of the probe opening should be parallel to the direction of the airflow, and the distance between the probe and the air outlet surface of the filter should be 1 cm~5 cm. ⑥The scanning probe should move at a constant speed in the direction perpendicular to the airflow, and the moving speed of the probe should not exceed 8cm/s. ⑦ The actual travel speed of the probe of the automatic scanning mechanism should not deviate from the set value by more than 10%. The automatic scanning mechanism should be able to locate and mark the coordinates and detected leakage points during the movement of the probe, and the return of the probe mechanism at any point in the downstream section of the filter. The accuracy should be no more than 1 mm. (9) The requirements of the photometric scanning method. ① test aerosol should be one or more Laskin (Laskin) nozzle occurrence of oily aerosol substances (such as PAO, DEHS, etc.). laskin nozzle working pressure should be 133 kPa, the median diameter of the mass of aerosol occurring should be 0.7 μm, the geometric standard deviation should not be greater than 1.80. (ii) Upstream aerosol concentrations of 10 mg/m3 to 20 mg/m3 are required. ③The scanning probe should be scanned at a distance of 1 cm~5 cm from the surface of the air outlet side of the filter under test for leak detection. ④The scanning speed of the square scanning probe should be no greater than 5 cm/s and the area scanning speed of the rectangular scanning probe should be no greater than 15.5 cm2/s during the scanning process. ⑤ Areas with a local transmission rate of more than 0.01% are judged as leakage defects. |
