CMS/User Guide - Filterteknik

Appendix GISO therefore defined the requirements for the replacement for ACFTD andasked the National Institute of Standards and Technology (NIST) in the USAto produce a standard, traceable reference material. The new dust’s particlesize distribution has been accurately determined with the aid of modernscanning electron microscope and image analysis techniques.New Test Dust BenefitsThe new ISO Medium Test Dust (ISO MTD) consists of similar materials tothe old ACFTD, but to minimize particle counting errors, it is of a slightlycoarser grade because ACFTD included too many particles smaller than 5µmwhich gave problems during testing.ISO MTD is produced to a standard distribution and stringent quality controlprocedures, thereby ensuring excellent batch-to-batch repeatability. Theseprocedures, combined with a revised ISO APC calibration method give:• A traceable and controlled reference test dust with greatly reduced variationin particle size distribution. This gives the trace-ability required byISO 9000, QS9000 and similar quality management systems.• A procedure for determining the performance of APCs so that minimumacceptable levels can be set by the user.• Improved calibration techniques and procedures.• More accurate calibration.• Improved levels of particle count reproducibility with different equipment.• More accurate and consistent filter test results.Effect on IndustryThe introduction of ISO MTD has necessitated changes to certain ISO standards.74 New ISO Medium Test Dust and its effect on ISO . . .