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Method for leak detection of HEPA filter in clean room - DOP method
Method for leak detection of HEPA filter in clean room - DOP methodClean room high-efficiency filters are usually used in terminal filtration in clean workshops, clean rooms, and dust-free workshops. They are mainly used to filter dust particles ≥0.3 μm and play a vital role. It is related to ensuring that the clean room can achieve and maintain the designed cleanliness level. Therefore, conducting leak detection tests on the high-efficiency filters in the clean workshop to ensure that they meet the requirements is one of the important means to ensure a clean environment in the workshop. Today, what I will explain to Changrui Air Filter Manufacturer is a method for detecting leaks in high-efficiency filters - the DOP method.1. Testing method: To determine whether there is obvious leakage in the clean room high-efficiency filter itself and its installation, the following points must be tested on site: the filter material of the filter; the connection between the filter material and the inside of the frame; Between the gasket of the filter frame and the filter pack support frame; between the support frame and the wall or ceiling. 2. The materials and instruments used for DOP leak detection include dust source (PAO solvent), aerosol generator, and aerosol photometer. 3. The commonly used aerosol generator is ATI TDA-6C. Handheld Laskin nozzle aerosol generator, which directly uses air without compressed gas as power. Under a working pressure of 20Pa and an airflow rate of 50~2025f3/min, polydisperse sub-micron oil dust aerosol with a concentration of 10~100ug/mL can be generated. The aerosol photometer used is an ATI 2H photometer, with a dynamic measurement range of 0.00005~120ug/L, and a sampling flow of 1F3/min (28.3L/min). 4. Introduce PAO aerosol on the upstream side of the HEPA to be measured. For HEPA in the HVAC system, to make the aerosol concentration uniform when it reaches the HEPA, the aerosol can be introduced directly from the negative pressure side of the system fan. If it is introduced into the duct, it should be introduced at least 10 times the duct diameter away from the HEPA, and corners should be minimized (American Society for Environmental Science and Technology). Under normal circumstances, it is enough to keep the upstream aerosol to the required concentration and the concentration to fluctuate within a certain range. For HEPA in laminar flow hoods and ultra-clean benches, aerosols are introduced directly from the negative pressure side of the system fan. Initialize the aerosol photometer and set the 100% and 0% reference standard values. Initialize and set the alarm value according to the operating requirements of the aerosol photometer. Connect the UPSTREAM sampling tube to the upstream sampling port and measure the concentration of the upstream aerosol. Adjust the generated aerosol concentration according to the operating requirements of the aerosol generator so that the upstream aerosol concentration reaches 10~20ug/mL. |
