1. Electret, What Are The Important Parameters That Need To Be Considered
Presented at
2005 NAFA Annual Convention
September 23, 2005 by
Ker-Ching (K.C.) Hsieh, Ph,D.
Particle Tech, Inc.
St Paul. MN

2. Filtration Mechanisms For Electret
Mechanical Filtration Mechanisms
Diffusion
Interception
Inertial Impaction
Electrostatic Filtration Mechanisms
Dielectricphoretic Effect/Force
Columbic Force
Image Force

4. Performance Of A Chargeable Media If It Is Not Charged

5. Performance Of A Chargeable Media After It Is Charged

6. Net Effect—Higher Average Life Time Efficiency

7. Examples

8. Particle Deposition On A Single Fiber

9. Possible Gradient Structure

10. Important Parameters Need To Be Considered For Electret
Initial efficiency
Initial efficiency without charge
Shelf life performance
Environmental conditions
Special parameters
aerosol contains alcohol, alcohol vapor and other chemicals, oily aerosol, combustion generated aerosol…..

11. Electrostatic Index

12. Examples
EI1

13. Initial Efficiency With And Without Charges

14. Shelf Life Tests

15. Temperature Effect

16. Humidity Effect

17. Effect of High Temperature and High Humidity

20. Real Life Performance of Electret : 1

21. Real Life Performance of Electret: 1

22. Real Life Performance of Electret: 1

23. Real Life Performance of Electret: 2

24. Real Life Performance of Electret: 2

30. Cigarette Smoke Test

31. Cigarette Smoke Test

32. Summary Charged media are “quite different” from non-charged media.
Charged media have a completely different set of parameters that need to be considered when they are used.
Is it premature for ASHRAE 52.2 to try to use a simplified method to try to compare charged filters and non-charged filters?

33. Summary
Is the “conditioning” step going to solve the disputes between the charged media manufacturers and non-charged media manufacturers? Answer: “No”, on the other hand, it will bring in a whole new set of problems.
“MERV” is strange enough, please don’t make things more confusing by adding this conditioning step.