Improving the repeatability and reproducibility of the Helmke Drum test method

摘要

The Helmke Drum test method, as described in the Institute of Environmental Sciences and Technology's recommended practice IEST-RP-CC003.2, is used to measure particle release greater than 0.5 micrometer (μm) from cleanroom garments. During the current effort to revise IEST-RP-CC003.2, it became clear that the method, as currently written, required revision. Under "Description of Test Limitations," the current method mentions a 1991 inter-laboratory comparison (ILC). However, results from that ILC were too variable to allow meaningful interpretation. A cursory look at the results from this 1991 ILC suggested that a re-evaluation of the data using the statistical analysis outlined in ASTM E691 might yield new insights. The subcommittee of IEST Working Group 003 proposed several changes to the method and a second ILC was conducted in 2001, in which six participating laboratories tested garments per the revised method.