Technical requirements (TR) for specific programs are defined by ANAB to further outline additional requirements for the activities performed by laboratories within those programs. Technical requirements define mandatory requirements that organizations must implement to gain or maintain accreditation. ANAB TR 2501 became effective January 1, 2020. It defines mandatory requirements for ISO/IEC 17025 accreditation of scale and balance calibration laboratories. The requirements outlined in TR 2501 apply to all ANAB-accredited laboratories performing scale and balance calibrations, as well as laboratories seeking ANAB accreditation for these activities.
About TR 2501
TR 2501 intends to resolve inconsistencies with the representation of uncertainties on scopes of accreditation, reported on calibration certificates, and in the development of uncertainty budgets. Additionally, many combinations of capacities and resolutions can occur in the field. It is difficult to represent a realistic view of these combinations while properly stating measurement uncertainties. TR 2501 establishes specific requirements for calibration laboratories when calibrating scales and balances. More specifically, it addresses the contributors to be included in an uncertainty budget for the calibration of scales and balances, traceability, assuring quality of calibrations, proficiency testing, and representation of the scope of accreditation.
TR 2501 PT Requirements
While ISO/IEC 17025 requires laboratories to participate in proficiency testing and ensure the validity of results in section 7.7, TR 2501 further requires that laboratories performing calibrations on scales and balances participate in appropriate proficiency testing (PT) at least once per calendar year covering the scope of accreditation in a 4-year period. Participation must represent the parameters, ranges, measurements, methods, and uncertainty of measurement described in the scope of accreditation.
The laboratory is required to maintain a documented plan that ensures participation for the current year and at least the next three years covering a representative sampling of activities within each major field identified in the scope of accreditation. Additionally, the laboratory must evaluate the risk of the calibrations associated with the scope of accreditation and incorporate that risk analysis as part of the PT plan. Any results found outside of predefined performance criteria, such as unsatisfactory results, must be investigated by the laboratory, and ANAB must be notified of unsatisfactory results, as well. As with most requirements, records of participation per the PT plan must be maintained.
TR 2501 Metrology Traceability Requirements
TR 2501 also defines requirements for metrological traceability that supplement the requirements of ISO/IEC 17025. Laboratories performing calibrations on scales and balances must ensure that all calibration results are traceable to the International System of Units (SI Units), wherever possible. This may be accomplished through NIST or another National Metrology Institute (NMI). Applicant and accredited laboratories may use a national, state, or provincial weights and measures laboratories that are recognized and/or traceable to the country NMI. Use of an NMI other than NIST must be documented as the appropriate NMI relevant for the scope of accreditation and stated uncertainties. Applicant and accredited laboratories may use ISO/IEC 17025 accredited calibration laboratory services wherever available, as well.
Requirements for the Scope of Accreditation in TR 2501
TR 2501 provides additional requirements for the scope of accreditation, along with examples of scopes in the Annex. Scopes of accreditation for laboratories performing calibrations of scales and balances contain:
- Parameter or equipment being calibrated
- Range of scales and balances calibrated
- Expanded uncertainty of measurement or calibration and measurement capability (CMC)
- Reference standard, method, and/or equipment
Find more information and additional documents related to ANAB-accredited laboratories here.