21-Nov-2011

Applying ISO methods to counter calibration

Abstract

International standards for the monitoring of airborne particles apply to all cleanrooms or clean zones. The international committee, TC209 Working Group 1, has been examining potential revisions to the first two sections of the ISO 14644 document. One key change in the proposed revision is the normative reference to a calibration standard for the instrument to be used for cleanroom classification. Although calibration will probably create some additional cost, there will be noteworthy benefits in both the repeatability and the reproducibility of the measurements obtained

Dependable results in monitoring airborne particles require well-calibrated particle counters. Joe Gecsey, Met One (Hach), explains how implementing the recent ISO 21501-4 calibration standard can minimise calibration variability.

International standards for the monitoring of airborne particles are used by all industries that employ cleanrooms or clean zones. Some form of airborne sampling for particles is needed for these controlled environments to ensure the quality of the product being manufactured or the success of the process that is being conducted in this controlled or critical environment. Many variables will affect the success of the operations in these areas; the particulate levels in the air are often a significant element in the control of the risk of failure (or, inversely, the likelihood of success) for the controlled operation.

The initial standard for classification of cleanrooms and clean zones from the US, known as “Federal Standard 209E”, had a global impact for many years but was officially replaced in 1999 by a new global standard, ISO 14644-1.

For the past few years, the international committee, TC209 Working Group 1, has been examining potential revisions to the first two sections of the ISO 14644 document. The initial general vote on the proposed revisions by the larger body of nations closed on 2 May 2011; the effective date of the revisions is thought to be imminent.

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