In May, 2007, the International Standards Organisation (ISO) introduced a new standard for the calibration of air and liquid particle counters. This new standard, ISO 21501, incorporates a number of new tests that are designed to reduce count variability between different instruments. Specifically, the standard specifies new counting resolution and counting efficiency tests be performed at routine calibration cycles, typically every six or twelve months.

Do you require your particle counter calibrated to ISO 21501?


Manufacturers of products requiring processing or assembly all goods and materials within a cleanroom environment classified under ISO 14644 should require that Particle Counters be calibrated to the ISO 21501 standard. This is particularly applicable to the pharmaceutical manufacturing facilities employing sterile processing or filling line


This new standard is a much welcome addition to the particle counting industry that will help insure that you obtain repeatable results between all your counters.




Microtechnica offers calibrations to the new ISO 21501:2018 standard.




Older Particle Counters as well as the new can be calibrated to the new standard.




Contact for further details.