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High-efficiency filter (HEPA) High-efficiency bacterial filter
High-efficiency filter (HEPA) High-efficiency bacterial filterA high-efficiency filter (HEPA) is made of excellent sub-glass fiber paper, which can filter microorganisms with a particle size above 0.3um, and the filtration accuracy can reach 99.99%.HEPA filter comprises a stack of sub-glass fiber membranes folded back and forth continuously, forming a wavy gasket to place and support the filter medium. HEPA is an internationally recognized best high-efficiency filter material. HEPA was originally used for nuclear energy research protection and is now widely used in precision laboratories and precision equipment protection. The test method for high-efficiency filter leakage uses the dust particle counter method: usually a small sampling volume instrument such as 2.83L/min is used, and the limit specified by the dust particle counting method is used as the judgment standard, or a significant change in the number of particles is found. Operation method: The sampling port is 2 to 3cm away from the filter, and the moving speed is 5 to 20mm/s. Instruments used for DOP or PAO method: smoke generator, leak detector. Method: The sampling head of the receiver is about 2cm away from the filter, and the inspection speed is within 2~3cm/s. Standard: The leakage rate should be less than 99.99%. Leak detection instructions for high-efficiency filters 1. Purpose: By detecting the leakage of high-efficiency filters, the defects of high-efficiency filters and their installation can be found, to take timely remedial measures. 2. Scope: Applicable to the leak detection of high-efficiency filters in clean areas. 3. Responsible persons: Quality Department, Production Department. 4. Procedures: (1) Test method: Dust particle counting scanning inspection method. (2) Test scope: filter material of the filter, the seal of the filter frame the connection between the filter group support frame, and the connection between the support frame and the fixed wall. (3) Detection instrument: Dust particle counter. (4) Detection principle: According to the principle that the light flux scattered by floating particles under a certain intensity of light is proportional to its particle size, the particle scattered light is converted into an electrical signal through photoelectric conversion, which is amplified and processed by a computer to display the particle equivalent diameter and the corresponding particle number. (5) Detection procedure: ① Use the dust particle counter sampling head to scan the air outlet side of the filter. The sampling head is about 2 cm away from the filter. The inspection is carried out along the inner frame of the filter. The scanning speed is less than 5 cm/s. ② When the detection cycle is 10 minutes, the number of 0.5 μm particles is >20, indicating that the leakage exceeds the standard. Repair or replacement is required. ③ After plugging the leak with epoxy resin glue or tightening the bolts, perform scanning inspection again. (6) The detection cycle is tested at least once a year during normal use, and newly installed high-efficiency filters should be tested. |
