Revisions were made to the ISO 14644-1 and -2 regulations in November 2015, coming into effect in January 2016. Because these standards regulate the classification of airborne cleanliness, the changes impact companies in a wide range of industries – anywhere that a clean-room is utilized. In this document, we provide a comprehensive overview of the new ISO 14644-1 regulations.
The changes were effected in an effort to simplify and streamline the classification process for clean-rooms, and to update the standards in line with contemporary practice and thought.
ISO 14644-1 specifies classes of cleanliness for clean-rooms in terms of concentrations of particles in the air. Specific testing methods are required to determine the class. ISO 14644-1 covers classification procedures where the particles are sized between 0.1-5 microns. Nano-particles are covered by ISO 14644-12.
A significant change from the 1999 version of the standard pertains to maximum concentration limits. As can be seen in the table below, a greater than or equal to 5 microns particle concentration has been removed from ISO Class 5 clean areas. Previously, the limit was 29 particles per cubic meter.
Table showing new maximum concentration limits.
This change was instituted because it had been found that sampling and statistical limitations for particles in low concentrations, as well as sampling limitations for particles over 1 micron in size, made the previous classification inappropriate.
Another key change regards sample locations. The table below determines the number of sample locations.
Table showing number of sample locations required.
The formula provided is: NL = 27 x 3/1000)
For room sizes above 6m2, there has been an increase in the number of sample locations required. Where the previous version of the standard required the Upper Confidence Limit (UCL) 95% calculation for sample locations between 2-9, the revisions render this unnecessary as it is now pre-calculated.
The new standards dictate that the determination of sampling locations will be based on a semi-random sampling technique that is based on a hypergeometric distribution. This marks a major change from current practice, and means that every time a zone is classified, the sample locations may be different. Where a risk assessment indicates that a specific location needs to be examined, this can be done in addition to the random locations.
A further change relates to instrument calibration. There is now a need to use ISO 21501-4 compliant particle counters, where previously this was not specified – any calibrated instrument would have sufficed. Not all instruments will meet the new requirements – if such an instrument is used, an explanation needs to be added to the test report.
To ensure compliance with the new standards, companies need to take necessary action before the end of 2016.
