This Recommended Practice (RP), IEST-RP-CC001.6, covers basic provisions for HEPA (high efficiency particulate air) and ULPA (ultra-low penetration air) filter units as a basis for agreement between customers and suppliers.

HEPA filters and ULPA filters that meet the requirements of this RP are suitable for use in clean air devices and cleanrooms that fall within the scope of ISO 14644 and for use in supply air and contaminated exhaust systems that require extremely high filter efficiency (99.97% or higher) for submicrometer (μm) particles.

This RP describes 11 levels of filter performance and six grades of filter construction. The customer’s purchase order should specify the level of performance and grade of construction required. The customer should also specify the filter efficiency required if it is not covered by the performance levels specified in this RP.

Supersedes previous versions

HEPA and ULPA Filters was prepared by Working Group 001 of the IEST Contamination Control Division (WG-CC001).