For high-efficiency filters installed at the end of the clean room to send and exhaust air, apply the scanning method to the filter installation frame and full-section leak detection. The scanning method includes a leak detector method (photometric method) and a particle counter method with a small sampling amount of 1 L/min. For ultra high efficiency filters, there are two kinds of scanning methods: condensation counter method and laser particle counter method.
1. Leak detection method leak detection (1) The leak detection filter has to have measured the amount of wind, and it runs between 80% and 120% of the designed wind speed.
(2) When multiple filters are installed on the same air supply surface, it is advisable to use only one filter at a time when the structure permits.
(3) When several or all filters must be exposed to the aerosol at the same time, in order to cause uniform mixing of all filters, it is advisable to introduce leak detection aerosols at the suction side of the fan or in the branches in front of these filters. The upwind side concentration was measured immediately before the filter to be inspected.
(4) For high-efficiency filters, when the leak detection instrument is a logarithmic scale, the aerosol concentration on the upwind side should exceed 104 times the small scale of the instrument; when the leak detection instrument is a linear scale, the concentration of the aerosol on the upwind side must reach 80~ 100 μg/L. The leak detection instrument should have a measurement range of 0.001 to 100 μg/L.
2. Particle Counter Method Leak Detection (1) The detected filter must have measured the air flow rate and run between 80% and 120% of the design wind speed.
(2) The number of particles of atmospheric dust should be measured on the upwind side of the high-efficiency filter to be tested. The particle size must be greater than or equal to 0.5 μm, and the concentration must be greater than or equal to 3.5×104 particles/L; , The particle size is greater than or equal to 0.1μm, its concentration must be greater than or equal to 3.5 × 106 ~ 3.5 × 107 particles / L.
(3) If the concentration on the windward side does not meet the requirements of the above item, then unfiltered air should be introduced. If the regulations are not reached, the particle counter method and the condensation counter method should not be used for leak detection. During the leak detection, the sampling port is placed 2 to 3 cm away from the surface of the inspected filter, and moved at a speed of 5 to 20 mm/s to scan the entire section of the inspected filter, the sealant, and the mounting frame.
This article comes from Xinsheng air filter manufacturer's official website: