Requirements for testing the high-efficiency filters on the FFU:
Before installing the high-efficiency filters, each FFUU unit should be left to idle for at least 48 hours. The testing condition is now considered static.
The rooms related to the testing have been cleaned and disinfected.
During the testing process, technicians and construction personnel must be present and be able to adjust and correct the equipment based on the test results.
Prepare the nitrogen cylinders, aerosol (Emery 3004), smoke generator (TDA-5B), and aerosol photometer (2H) required for the test. The measuring instruments must be calibrated and qualified.
Remove the dispersion plates and protective nets outside the high-efficiency filters.
Close the alarm system of the room and the air conditioning system.
Verification method:
Before the test, remove the secondary medium efficiency filters from the air conditioning boxes and place the aerosol generator in the negative pressure section of the fan and heat it to 400°C.
Connect the inlet of the aerosol generator to the nitrogen cylinder and slowly open the pressure reducing valve of the nitrogen cylinder outlet to maintain a nitrogen pressure of 0.2 to 0.5 Mpa. Immediately, aerosol particles will be generated.
After a stable period of time, use the aerosol photometer to measure the aerosol concentration at the wind speed measurement point of the total supply duct, that is, the upstream concentration value. The measured aerosol concentration should be within the range of 10 to 20 ug/L.
Before testing the downstream aerosol particles, set the reference value of aerosol concentration to the upstream measured concentration value. Use the sampling probe of the aerosol photometer to scan for leaks on the high-efficiency filter and its surrounding structure. During the inspection, the photometer probe should be 2 to 4 cm away from the filter surface and scan back and forth along the inner edge of the filter frame. The scanning speed should be 3 to 5 cm/s. The scanning sequence should be all sections of the filter, between the filter paper and the structure, the structure itself, and other installation nodes.
During the leak detection, two people should operate. One person should use the photometer sampling probe to scan the filter back and forth, and the other person should investigate the numerical values displayed by the photometer and make records.
Acceptance criteria:
When the reading (transmission rate) on the photometer exceeds 0.01% (that is, the maximum leakage concentration downstream of the filter exceeds 0.01% of the upstream concentration), it is considered that the filter is non-compliant， and it needs to be repaired or replaced.
The leakage rate at the structural seal of the FFU high-efficiency filter should be 0； otherwise， it should be reinstalled.
Leakage at the filter material of the FFU high-efficiency filter should be repaired with special glue， but the area of each individual leakage point should not exceed 1% of the total area； the total area of all leakage points should not exceed 5% of the total area； the number of leakage points should not exceed 3. Otherwise， it is necessary to replace the filter. The filter must be replaced.
After repair or reinstallation of the high-efficiency filter， a new integrity test must be conducted. Under normal circumstances， the leakage test is conducted once a year， and if it is non-compliant， it should be replaced.
The official website of Yechang Technology：www.aireplus.com.cn
