Remove the HEPA diffuser and scan the entire filter face, between the filter and the frame, between the frame and the frame, and between the frame and the static pressure box. The scanning head is about 1 inch (about 2.54 cm) from the filter face during scanning, and the scanning speed is no more than 5 cm/s. The scanning is performed back and forth in a straight line, and the lines should be overlapped. During the test, if there is an alarm sound (ie, %LEAKAGE (leakage rate) exceeds 0.01%), it indicates a leak. Scanning inspection is carried out after the leak is blocked or fastened with silica gel. Check a filter for about 5 minutes. During the test, the concentration of the upstream aerosol should be confirmed frequently. Note that a protective mask and a protective eye mask should be worn during the test.