By R. Vijayakumar, IEST Fellow, Chair IEST WG-CC034

Leak testing high-efficiency particle air (HEPA) and ultralow-penetration air (ULPA) filters is one important part of verifying their performance as manufactured and in use. The choice of which test procedures are required depends on the performance level of the filters, clean-air device or cleanroom and on the intended application.

IEST-RP-CC034.5: HEPA and ULPA Filter Leak Tests, a recommended practice developed and first published in 1999 by IEST, has been the gold standard for filter leak testing, especially for in-situ validation in pharmaceutical installations. This revision released this month is part of our effort to keep the practice current with revisions and additions every five years.

In this revision, the IEST Working Group revised and included these changes to keep it in line with current practices and to improve the clarity of its recommendations.

• New content on best practices for sample tube length
• Expanded content on:
  • Total leakage test
  • Spatial uniformity acceptance
  • Circular vs. rectangular probe heads (circular not allowed)
  • Considerations in sample port location

The updated recommended practice covers definitions, equipment and procedures for leak-testing HEPA and ULPA filters that may be used in the factory as they are produced, at the job site before installation and after installment in cleanrooms and in unidirectional-flow, clean-air devices.

When used in conjunction with other IEST Recommended Practices, including IEST-RP-CC001, IEST-RP-CC002, IEST-RP-CC006, IEST-RP-CC007, IEST-RP-CC012, IEST-RP-CC021, and IEST-RP-CC028, this recommended practice may be used to define an agreement between customer and supplier in the specification and procurement of HEPA and ULPA filters, and in the testing of unidirectional-flow, clean-air devices and cleanrooms.

IEST-RP-CC034.5 is now available for purchase at IEST’s Bookstore. Cleanroom managers and operators working in all types and sizes of cleanrooms across all industries – including aerospace, semiconductor, and pharmaceutical companies – will benefit from the updated guidance.

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R. Vijayakumar, IEST Fellow and ASHRAE Fellow, is a globally recognized expert consultant in contamination control, aerosol and filtration. He is the chair of IEST WG-CC034 and consultant-in-chief at AERFIL, which provides expert consulting in particle measurements for contamination control, and air filters and filtration.