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The Metrology Tablet 1

Wilmington Instrument inaugurates a new web posting.  Our intention is to bring important local, national, and international metrology news, memorable dates, and unusual metrology facts from the past, present, and future, in a brief format.

This time we will spotlight one of the fundamental metrology concepts: 


As the backbone of metrology, traceability substantiates and provides a clear understanding of the rank of the measurement result in the measurement hierarchy. 

It also provides the evidence of the embodiment of the unit of measure in relation with the measured quantity, measuring standard, measuring instrument or system, environment, method, operator and all other components and sub-components present in a measurement operation. 

Traceability also provides the overall characterization of the measurement activity in a testing and/or calibration laboratory. Together with the measurement uncertainty, traceability indicates the laboratory level in terms of equipment, personnel training and measurement capabilities.

Definition (as provided in International Vocabulary of Metrology – Basic and General Concepts and Associated Terms (VIM 3rd edition), JCGM 200:2012, BIPM, without Notes:

“Metrological traceability 2.41 (6.10):

property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty”

Example of simplified temperature traceability chart, no data

Example of simplified temperature traceability chart, no data

Traceability diagram example

Traceability diagram example

A traceability diagram or chart may also be called traceability block diagram of a measurement process. Such chart would show the hierarchy of measuring instruments used to measure a given quantity, tracing the order of succession, and the accuracy, of the operations of disseminating the unit of measurement of that quantity. A block diagram of a hierarchy of a measurement process would show the inter-relationship between reference and working standards of various orders of accuracy.

Mr. Metrology

05 January 2021

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