This Recommended Practice (RP), IEST-RP-CC007.4, describes the equipment, aerosol properties, processes, and calculations for determining the efficiency of HEPA, ULPA, and super ULPA filters in the factory, using particle counters. The procedure may be applied to production applications. This RP provides guidelines for constructing a suitable test duct and sampling system. Also provided are test criteria for quantifying penetration in the range of 0.030% to 0.00010%, between particles in the size range of 0.1 to 0.3 µm.


The text on discharge methods for charged media has been revised. The discussions on charged media and aerosol for discharge have been split for clarity.

The section on efficiency from scan measurements has added clarification on the size range data required. The governing equations have been corrected and/or clarified.

The section on testing filters with media having MPPS <100nm (usually ePTFE) is revised to note that it is valid only for overall efficiency and not scanned efficiency. Explanation on the recommendation to use the alternate size to 0.1-0.2µm has been added since the efficiency in this size range is expected to be lower than the that between 0.2-0.3 µm since it is closer the MPPS of these filters.

First printing, June 2023 (Supersedes previous versions, including IEST-RP-CC007.3, IEST-RP-CC007.2 and IEST-RP-CC007.1)

Testing HEPA and ULPA Filters was prepared by Working Group 007 of the IEST Contamination Control Division (WG-CC007).