Gordon M. Ely, IEST Techincal Vice President (CC), WuXi AppTec
FINALLY!!! ISO/TC 209 has published the long-awaited revisions to the cleanroom cornerstone standards 14644-1 and 14644-2. The FDIS ballots for these passed early Fall 2015, but were not without controversy, including requests for the documents to be revised immediately. However, the FDIS voting process (the last stage before publication of an ISO international standard) does not allow for technical revisions, and the technical requests will need to be addressed by the working group in the next revision process. Several countries voted “no” during the FDIS voting process, but the votes were not sufficient to keep the documents from being published.
The publishing of these standards is great news because these have been around since 1999 and really needed to be updated. In the United States, they have both been accepted as national standards by ANSI. The FDA still needs to decide if the standards will be included in their list of Consensus Documents.
A brief description of each follows:
ISO 14644-1:2015 Cleanrooms and associated controlled environments – Part 1: Classification of air cleanliness by particle concentration
This standard covers the classification of air cleanliness in cleanrooms, clean zones, and separative devices exclusively in terms of concentration of airborne particles. Only particle populations having cumulative distributions based on threshold (lower limit) particle sizes ranging from 0.1 µm to 5 µm are considered for classification purposes. The use of light scattering (discrete) airborne particle counters (LSAPC) is the basis for determination of the concentration of airborne particles, equal to and greater than the specified sizes, at designated sampling locations. This document does not provide for classification of particle populations that are outside the specified lower threshold particle-size range, 0.1 µm to 5 µm, and cannot be used to characterize the physical, chemical, radiological or viable nature of airborne particles.
Resolved issue with particle counter calibration requirement of complying with ISO 21501-4. There was significant controversy about the economic requirement involved in mandatory compliance. However, the text was changed from “shall” to “should” to remove the mandatory principle. The standard does say that the instruments are to be calibrated to the standard as much as possible. In the next revision of ISO 14644-1, the working group may make it a requirement.
The classification table has changed slightly with the inclusion of limits where there were none. There is no limit for 5 µm particles for ISO Class 5. EMA does not comply with the ISO standard and has written its own. To set the limit, there is a formula, based on the descriptor.
Sampling locations has had several changes.
The sampling table has been changed to 1) extend room size from 500 m2 to 1000 m2; 2) provide a 95% confidence that 90% of any location chosen will be within compliance; and 3) provide a new method to address room sizes of >1000 m2 by use of a formula (Number of locations = 27 / (room area / 1000 m2))
Since the sample locations are related to the cleanroom area, the number of locations specified in the table is a minimum (additional locations can be done, but not less). The term ‘random’ has been removed and replaced with ‘representative’.
The most important change: the 95% UCL (upper confidence limit) does not need to be calculated for sampling areas with 2 to 9 locations.
‘Ultrafine particles’ has been changed to ‘nanoparticles’ and removed from the standard. These will be addressed in ISO 14644-12.
The sequential sampling plan has been revised, but the method remains the same.
ISO 14644-2:2015 Cleanrooms and associated controlled environments – Part 2: Monitoring to provide evidence of cleanroom performance related to air cleanliness by particle concentration
This standard specifies minimum requirements for a monitoring plan for cleanroom or clean zone performance related to air cleanliness by particle concentration, based upon parameters that measure or affect airborne particle concentration. These requirements invoke the test described in ISO 14644-1:2015 for classification of a cleanroom or clean zone.
It was completely revised into a standard addressing cleanroom particle monitoring only.
Cleanroom validation/requalification is suggested every 12 months unless doing continuous monitoring.
DISCLAIMER: The views expressed in this article do not necessarily reflect the views of the IEST.