Comparative analysis and classification of measurement procedures and procedures for transferring of unit of quantity as elements of metrological traceability chain of measurement results

The article analyzes types of measurement procedures and procedures for transferring a unit of quantity, such as: primary reference measurement procedures, reference measurement procedures, calibration procedures, validation procedures, end-user measurement procedures and measurement procedures. The article discusses requirements for developing the presented procedures, their research and approval. The article presents a classification of procedures depending on their place in metrological traceability chain, type of determined metrological characteristics and their application in the field of regulation. Based on the results of the analysis of regulatory documents, a table that describes basic requirements for development and approval of measurement procedures and procedures for transferring a unit of quantity is presented. The article also discusses requirements established for conformity assessment procedures for measurement procedures and procedures for transferring а unit of quantity, such as certification, validation and verification of procedures. The article presents definitions and scope of application for conformity assessment of measurement procedures and procedures for transferring a unit of quantity. Based on the analysis of requirements for conformity assessment of procedures, a flowchart for selecting appropriate conformity assessment procedure is presented. Due to this scheme, laboratories will be able to unambiguously choose one or another conformity assessment procedure to approve the required measurement method or method of transferring a unit of value. In particular, in preparation for accreditation for compliance with the requirements of ISO/IEC 17025-2017 “General requirements for the competence of testing and calibration laboratories.” The proposed scheme of choosing a procedure for conformity assessment of a specific measurement procedure eliminates ambiguity of the requirements of regulatory documents.