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What are the methods for leak testing of high-efficiency filters?
What are the methods for leak testing of high-efficiency filters?In many places with extremely high requirements for air quality, such as pharmaceutical factories, electronics factories, operating rooms, etc., the performance of high-efficiency filters is crucial to their environmental impact. To ensure that high-efficiency filters can effectively filter tiny particles in the air, leak testing needs to be performed regularly. Next, I will introduce several commonly used testing methods.The first is the PAO test method, also known as the photometer scanning method. This is a widely used leak detection method. PAO aerosol is emitted upstream of the filter as a dust source, and then the aerosol concentration upstream and downstream is detected by a photometer. By comparing the concentration difference between upstream and downstream, it can be determined whether the filter leaks. This method is relatively simple to operate and the results are relatively accurate. The sodium flame method is also a common one. It sprays and dries a sodium chloride aqueous solution to form a sodium chloride aerosol of a specific particle size as a test dust. Dust-containing air samples are taken before and after the high-efficiency filter, and the filter efficiency is determined based on the turbidity difference of the gas sample. Although this method can effectively detect, the operation process is relatively complicated. The oil mist method is also used for leak detection of high-efficiency filters. It uses oil mist as the dust source and measures the turbidity of the air containing oil mist to compare the changes before and after the filter, to judge the filtering effect. However, the preparation and treatment of oil mist requires certain professional equipment and technical support. The fluorescence method is a relatively new and sensitive leak detection method. Apply a fluorescent agent on the surface of the filter, and then use ultraviolet light of a specific wavelength to irradiate. If there is fluorescence, it means that there is a leak point. This method can quickly and intuitively find the leak location. The particle counting method is based on measuring the number of particles upstream and downstream of the filter for judgment. By comparing the changes in the number of particles, it is determined whether the filter is working properly. However, the accuracy and calibration of the particle counter have a greater impact on the test results. The DOP particle scanning positive pressure leak detection method generates DOP particles upstream of the filter and scans at a specific distance downstream. The number of particles detected is used to determine whether the filter is leaking. In short, the above high-efficiency filter leak detection test methods have their own characteristics and applicable scenarios. In practical applications, it is necessary to select a suitable leak detection method based on specific environmental requirements, filter type, and detection purpose. |
