This Recommended Practice (RP), IEST-RP-CC021.5, discusses test methods for physical and filtration properties of high-efficiency particulate air (HEPA) and ultra low penetration air ULPA) filtration media.

Application of this RP is by mutual agreement be-tween the customer and the supplier. Use of this RP should be applied, but not be limited to:
a) Acceptance criteria for test methods;
b) Test aerosol and particle size;
c) Test face velocity.


New and Improved in this version:

New:
•    Appendix C, HEPA Filter penetration test “cold” photometric method merged into Section 4.2 of the document. Previously “hot” and “cold” DOP methods were described separately although they utilize the same method. This is a more economical way to include both methods in the document.
•    Added section 4.5 “Testing Electrostatically Charged Media” to address the use of this media type in place of traditional mechanical media for high efficiency filters in certain applications.
Improved:
•    Appendix A, Calibration Period Summary, edited for improved clarity.
•    Appendix B, revised calculations in tables B2 and B3.


First printing, March 2024 (Supersedes previous versions, including IEST-RP-CC021.4, IEST-RP-CC021.3, IEST-RP-CC021.2, IEST-RP-CC021.1)

Testing HEPA and ULPA Filter Media was prepared by Working Group 021 of the IEST Contamination Control Division (WG-CC021).

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