NIST Handbook 143
State Weights and Measures Laboratories Program Handbook

7. Specific Technical Guidelines

The following information is primarily from the NVLAP Calibration Laboratories Technical Guide, and is used here as the technical guidelines for evaluation of traceability resulting in the issuance of a Certificate of Traceability.

"This section provides examples and guidelines, not requirements, to technical experts and interested calibration laboratories, on good laboratory practices and recommended standards. Therefore, the guide language reflects this philosophy through the use of "shoulds" instead of "shalls" (along with other less prescriptive language) when describing criteria. Absolute requirements are not presented here since they depend on the measurement uncertainty for which an applicant laboratory wishes to be accredited. This is a business decision for each laboratory and beyond the scope of this voluntary program. Simply stated, to be [recognized or] accredited an applicant laboratory must have a quality system and be able to prove (and document) that it does what it says it does (i.e., correctly calibrate to a stated uncertainty).

This guide is dynamic in that new parameters may be added and existing criteria updated and improved."

Recognition Parameter Summary

Each laboratory must specify the range and uncertainty level for each parameter for which it requests recognition. Uncertainties must be defined at each level. For example, a chart must be available that will state each nominal mass, each nominal volume, and so on, with the associated uncertainty.

Table 3. Recognition parameter summary

*General estimates of ranges only. Detailed uncertainties must be provided for each parameter and range.