ANSI/NCSL Z540.3 is a U.S. national standard that establishes technical requirements for calibration labs. The Z540.3 standard was issued in 2006, and has since been updated, by the American National Standards Institute (ANSI) and the National Conference of Standards Laboratories (NCSL). A Z540 calibration is performed in a lab that is compliant with the specific equipment and process requirements of the standard.
For accreditation, labs must demonstrate compliance with ANSI/NCSL Z540.3 requirements regarding measurement and test equipment, accuracy, and service performance. Guidelines are also provided for aspects of calibration, such as measurement uncertainty, document control and service intervals. Operating in full compliance with the standard allows labs to better control calibration risks.
The term ANSI Z540 or NCSL Z540 may be used in reference to either ANSI/NCSL Z540-1 or ANSI/NCSL Z540.3. The Z540-1 calibration standard was the original version from 1994. Though withdrawn as an active standard in 2007, Z540-1 calibrations continue to be offered by labs for customers who have this type of servicing need.
ANSI Z540 and the PFA
Requirements of the Z540.3 standard cover the probability of false acceptance (PFA). The PFA is the probability that a lab’s measurement could incorrectly find an instrument in tolerance, when it’s actually out of tolerance. A Z540.3 accredited calibration lab must maintain a PFA of less than 2%.
Z540 requires traceability of instruments used to perform calibrations to national standards, international standards, or intrinsic standards, with traceability stated on calibration certificates. It does not require traceability to SI Standards.
Transcat Calibrations to Z540 Standards
Transcat’s calibration laboratories are accredited to ISO/IEC 17025, ANSI/NCSL Z540-1, and ANSI/NCSL Z540.3. Each of our labs must undergo regular audits to ensure compliance with the associated standards. For more than 50 years, we have dedicated ourselves to the science of accuracy and risk mitigation. We will work to provide the best service options, whether calibration to a national or international standard is required.