This Recommended Practice (RP), IEST-RP-CC021.4, 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.

First printing, December 2009 (Supersedes previous versions, including 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).