1.3.2.3
HEPA/ULPA Filter PAO Leak Test
1.
The airflow filter was challenged with PAO aerosol of fixed concentration. The aerosol was evenly
distributed throughout the cabinet plenum. An aerosol photometer was used to monitor aerosol
penetration downstream of filter, and to scan for the presence of leaks.
2.
Use calculated method, along with ATI TDA-4Blite aerosol generator, the upstream aerosol concentration
can be calculated using the following equation:
Aerosol concentration =
13,500 N
TotalAirfol wCfm
, where N = Number of Laskin nozzle(s) opened
See Chart for Total Airflow below:
Record the concentration below:
3.
Connect the aerosol generator to compressed air or compressed nitrogen supply. Open the aerosol
generator valve(s). Set the supply pressure valve to 23 psi for PAO or 20 psi for DOP.
4.
Turn on the aerosol photometer.
5.
Check background aerosol concentration in room. Make sure it’s not too high. Also check the upstream
aerosol concentration again after the test is completed to ensure same value.
6.
With traverse speed of 5 cm/s (2 in./s), scan the airflow filter media for leakage and record the results
below:
Acceptance: Maximum particle penetration of 0.01% for both filters; no filters leaks present
Results: Pass / Fail
Calculated PAO concentration: g/Liter
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