Your company provides comprehensive PAO testing services for the biotechnology and medical industry. Can you please explain the process of PAO testing and how the reports are provided?
PAO testing is suitable for integrity testing (leak testing) of high-efficiency filters. By injecting aerosolized oil mist into the upstream side of the air filter using PAO, and sampling with a photometer probe at the downstream side, the relative concentration of aerosolized particles can be measured due to the difference in light intensity caused by particle diffusion.
Testing Procedure:
1. Ensure the air conditioning system is operating normally and ready for testing. Adjust the airflow velocity and quantity to achieve a balanced state. Use an aerosol generator to release particles upstream, introducing aerosolized oil mist into the upstream side of the air filter.
2. Use an aerosol photometer to detect the concentration of particles upstream. Approximately 10 - 20 micrograms of PAO per liter of air.
3. Once the upstream particle concentration is confirmed, scan the surface of the air filter to identify any leaks.
(If necessary, plastic covers can be used around the air filter to ensure accurate testing.)
4. Scan the surface of the filter. The scanning path can be from the outside to the inside or in a zigzag pattern along the long / short edges, as follows:
a. Test each filter and its frame.
b. When scanning the surface of the filter, position the leak detector as shown in diagram (b), moving in the direction of the short edge to cover the entire filter.
c. When scanning the filter frame, especially the area between the filter and the ceiling grid, the leak detector can be positioned as shown in diagram (a) or (b) to cover all joints.
d. Place the sampling probe of the particle counter, shaped like a cone (10mm x 60mm), about 25mm below the filter and move it at a speed of 50mm/sec.
e. The reading on the aerosol photometer is a percentage value between upstream and downstream. If the value is greater than 0.01, a leak is suspected. Repeat the measurement at approximately 100mm backward. If there is no sustained high reading, continue the testing. If a leak persists, record it for future repair or replacement.
Note: Air filter efficiency = (1 - penetration rate) x 100%
Reporting:
The PAO report will provide values for the concentration upstream and the leakage rate downstream of the filter. The data will be provided approximately 5 - 10 working days after the completion of the test (excluding any additional airflow testing).