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The Need for Leak Detection of High Efficiency Filters
The Need for Leak Detection of High Efficiency FiltersFirst, the current situation of pharmaceutical enterprises on the leakage detection of high-efficiency filtersWith the development of the pharmaceutical industry, some pharmaceutical companies continue to carry out technological transformation of enterprises to improve product quality. Most of the current pharmaceutical companies on the installation of air purification systems to confirm the first 5 items are serious and specific implementation. However, the leakage test of high-efficiency filters is neglected, even though very few pharmaceutical production enterprises do leakage test of high-efficiency filters because they are not equipped with an aerosol generator, but use particle counter to scan the upstream dust source under the condition that the dust source does not reach the requirement of concentration, which is very easy to produce leakage test, and even some enterprises don't perform leakage test of filter at all. The leak detection test is the basis of particle determination, and its importance is no less than particle determination. Such as the U.S. Federal Standards 209A and 209B have been pointed out: Second, the need for leak detection GMP regulations: preparations, APIs, baking, packaging, preparations used in the production of raw materials, and direct contact with the drug packaging materials should be carried out in a clean area. The clean room or clean area of the pharmaceutical production enterprise refers to the dust particles and microbial contamination needed to carry out the prescribed environmental control of the area, its building structure, equipment, and use have the function of reducing the intervention, generation, and retention of the pollutant sources in the area. The PAO test should be carried out after the installation or replacement of high-efficiency filters, and should generally be done at least once a year under normal conditions of use to see if any changes have occurred. This is a detailed and complicated work, but it is an important part of the cleanliness test and should not be ignored. Principle of leakage testing of high-efficiency filters HEPA filter leakage testing is an important part of air purification system verification, the purpose of HEPA filter leakage testing is to measure the permissible amount of leakage and find out where the defects of HEPA filters and installation are so that remedial measures can be taken. The working principle of the PAO method is: that PAO aerosol occurs on the upwind side of the tested HEPA filter as a dust source, and a photometer is used for sampling on the downwind side. The scattered light generated by the dusty gas through the photometer is converted into electricity by photoelectric effect and linear amplification and is quickly displayed by the microampere meter. Collected air samples through the diffusion chamber of the photometer, due to the diffusion of particles caused by the difference in the intensity of the light, by determining the intensity of this light, the photometer can measure the relative concentration of aerosols. That is, the PAO test measures the penetration rate of high-efficiency filters, and high-efficiency filters have the following relationship between their efficiency and penetration rate: K = (1 - α) × 100 per cent K: high-efficiency filter penetration rate α: high-efficiency filter efficiency In air purification engineering, the PAO method is mainly used for leakage tests after installation of high-efficiency filters and sub-high-efficiency filters, especially for laminar flow or turbulent flow requiring class 10000 or higher cleanliness, it is extremely important to carry out the leakage test.PAO leakage test is aimed at the high-efficiency filters on laminar flow benches, laminar flow hoods, self-cleaners as well as aseptic tunnels, and filling line equipment. The PAO leak test for HEPA filters focuses on checking for small pinholes in the filter media and other damage such as frame seals, gasket seals, and leaks in the filter frame. When the reading (penetration rate) on the photometer exceeds the standard it is considered that the filter is not qualified and should be patched or replaced. The leakage rate at the seal of the high-efficiency filter should be 0. The leakage of the high-efficiency filter media is allowed to be repaired, but the area of a single leakage can not be greater than 1% of the total area, and the area of all leakage can not be greater than 5% of the total area, or it must be replaced. |
