ISO 29463-4:2011

Overview

ISO 29463-4:2011 defines the scan method - the reference test procedure for determining leakage of high-efficiency filter elements. Applicable to filters from ISO 35 H to ISO 75 U, this part of the ISO 29463 series specifies how to detect and localize local penetrations (leaks) in filter elements by scanning the downstream face with a sampling probe while challenging the filter with an aerosol at the most penetrating particle size (MPPS). The document also describes alternative normative leak tests (oil thread, photometer) and solid PSL aerosol methods for specific filter classes.

Key technical topics and requirements

• Scope and applicability: Leak testing of filter elements (ISO 35 H–ISO 75 U); intended for use with ISO 29463-1, -2, -3 and -5.
• Principle of the scan method: Introduce a controlled test aerosol into the upstream air, mix it to a homogeneous challenge, operate the filter at nominal airflow, and map downstream particle flow distribution to find local penetrations.
• Aerosol and particle sizing: Tests use MPPS particles; mono-disperse or poly-disperse aerosols are permitted. Particle sizing/selection is referenced to ISO 29463-3 and measured using devices such as condensation particle counters (CPC) or optical particle counters (OPC).
• Test apparatus essentials: aerosol generator and conditioning, mixing duct, upstream/downstream sampling points, traversing/scanning probe assembly, partial flow extractors, particle counters, differential pressure measurement and data acquisition.
• Scanning procedure: Defined probe geometry, speed and track coverage (including frame, corners and gasket areas) to localize leaks; stationary probe measurements follow up on detected anomalies.
• Alternative methods: Annex A - oil thread leak test; Annex B - aerosol photometer scan; Annex E - solid PSL aerosol; additional informative annexes cover parameter determination and example evaluations.

Practical applications

• Quality control and production testing of HEPA/ULPA filter elements to verify integrity before installation.
• Acceptance testing after shipment or installation in critical environments (cleanrooms, pharmaceutical, semiconductor fabs, healthcare isolation rooms, nuclear containment).
• Maintenance and troubleshooting to locate leaks caused by damage, gasket failure or improper mounting.
• Credentialing test labs that perform accredited filter leakage measurements using particle-count-based methods (CPC/OPC).

Who should use this standard

• Filter manufacturers and R&D teams
• Independent aerosol/filter test laboratories
• HVAC and cleanroom engineers, facilities managers in pharma/biotech/semiconductor/healthcare
• Regulatory bodies and specifiers defining filter performance and commissioning tests

Related standards

• ISO 29463-1, -2, -3, -5 (classification, aerosol production, flat media and element testing)
• ISO 29464 (terminology)

Keywords: ISO 29463-4, scan method, leakage test, HEPA filter, MPPS, aerosol generator, particle counter, oil thread test, photometer leak test, PSL aerosol.