The relationship between ISO 17025 vs. ANSI Z540-1

         ISO 17025 is the replacement for ISO Guide 25. It is less lax and adds several new requirements. ANSI/NCSL Z540-1 is ISO Guide 25 (with very few mild changes, otherwise it is word for word) with two sections added to the end to address requirements of MIL-STD-45662A, which is obsolete.

          The Z540-1 is still a very active document, however. Government Agencies and their contractors still require compliance to Z540-1, because ISO 17025 does not address some of the issues in MIL-STD-45662A. Z540-1 is now very close to being reaffirmed (the vote has been taken) and will be a viable document until 2007, even though no realignment to ISO 17025 was made.

         ISO 17025 is much more rigorous document, and those that are accredited by a competent accreditation body to ISO 17025 are nearly always in compliance with Z540-1 (it only takes a few minor additions to the 17025 quality system to comply with Z540-1). On the other hand, those that state compliance with Z540-1 rarely will be in compliance with ISO 17025, because the additional requirements are major, such as uncertainty calculation, method verification, software verification, etc.