11 March 2016

HEPA Filter Integrity Testing for Cleanrooms

Our NATA Technician performs HEPA filter integrity testing on a ceiling suspension type supply air HEPA filter installation within an ISO Class 8 Cleanroom.  He is shown using a photometer to scan the HEPA filter to the cold DOP test method requirements of AS1807.6 standards.

ISO 14644-1:1999 Cleanroom Classifications

As per ISO 14644-1:1999; a cleanroom is “a room in which the concentration of airborne particles is controlled, and which is constructed and used in a manner to minimize the introduction, generation and retention of particles inside the room, and in which other relevant parameters, e.g. temperature, humidity and pressure, are controlled as necessary”. ISO Cleanroom classifications are as follows:

Typically, high-efficiency particulate arrestance (HEPA) filters are used within the incoming supply air system of the cleanroom to remove contaminants and ensure a specified concentration of airborne particles within the cleanroom.   For example; an ISO Class 8 Cleanroom may be used in pharmaceutical applications such as the production of topical creams, non-medical grade food supplement manufacturing such as protein powders or some dairy manufacturing that does not require live cultures.

HEPA Filter Integrity Testing

The HEPA filter integrity test is typically performed on cleanroom supply air HEPA filters using a photometer to scan the filter surface for pinhole leaks that could allow the transmission of contaminant particles that would be unacceptable in a critical application.  The most-common onsite HEPA integrity test method is the Cold DOP test, as described in AS1807.6 and 1807.7.

Some points of interest to clean room operators:

• Access is required to the relevant air handling unit related to the HEPA filter to be tested.
• The air system should be operating as normal for the duration of the HEPA test, so the introduced test aerosol will be pulled through the HEPA filter.
• Access is also required to the air output side of the HEPA filter, so that a NATA technician is able to scan the HEPA filter surface at 25mm from the installation for traces of the test aerosol.
• A HEPA integrity test certificate is provided upon completion of the test.

Airepure are a NATA accredited organisation that complies with the requirements of ISO/IEC 17025:2005 (Airepure Australia Accreditation Number: 19257).  We provide a range of professional on-site testing services as part of your cleanroom certification to the ISO 14644-1 Cleanroom Standards.  These services include:

• HEPA filter integrity testing
• Particle counting
• Room pressure differential testing
• Assessment of room air change rates

See here for details regarding the scope of our NATA accreditation services for cleanrooms.

The HEPA module shown is a ceiling suspension type (CST) room-side replaceable HEPA module, which typically used as a terminal filter hood for pharmaceutical and biotech cleanrooms, or wherever hoods are regularly validated for performance and leak-free operation.

Airepure’s CST HEPA module is available in HEPA (99.99% to 0.3μm) and ULPA (99.9995% to 0.12μm) grade efficiencies.