NIST NISTIR 6969
Selected Laboratory and Measurement Practices and Procedures to Support Basic Mass Calibrations
|Publication Date:||1 September 2014|
This NIST IR of Selected Publications was been compiled as an interim update for a number of Good Laboratory Practices, Good Measurement Practices, Standard Operating Procedures, Statistical Techniques and Reference Tables. This interim publication was used as a reference document for the CD-ROM Mass Metrology Course (SP 1001) prepared by the NIST Office of Weights and Measures in 2003 and was updated again in 2012.
Many of these procedures are updates to procedures that were originally published in NBS Handbook 145, Handbook for the Quality Assurance of Metrological Measurements, in 1986, by Henry V. Oppermann and John K. Taylor. The 2003 updates incorporated many of the requirements noted for procedures in ISO Guide 25, ANSI/NCSL Z 540-1-1994, and ISO/IEC 17025 laboratory quality systems. The major changes incorporated 1) uncertainty analyses that comply with current international methods and 2) measurement assurance techniques using check standards. No substantive changes were made to core measurement processes or equations, with the exception of SOP 2, Standard Operating Procedure for Applying Air Buoyancy Corrections. Procedures were updated in 2003 in conjunction with Jose A. Torres-Ferrer.
The CIPM 1981/91 equation for calculating air density was added to SOP 2 in 2003 and updated in 2012 based on the 2007 CIPM equation.
The following Practices and Procedures were new in the 2012 publication: Good Measurement Practices for:
• Assignment and Adjustment of Calibration Intervals for Laboratory Standards (11)
• Standard Operating Procedure Selection (12)
• Ensuring Traceability (13)
• Selection and Use of Sensitivity Weights in Weighing Procedures (14)
Standard Operating Procedures for:
• Assignment of Uncertainty (29)
• Process Measurement Assurance Program (30)
• Standard Operating Procedure for the Calibration of Weight Carts (33)
The essential portions of SOP 29, Standard Operating Procedure for Assignment of Uncertainty were first published in 1994 for the NCSL Conference and Symposium and to assist State weights and measures laboratories comply with the ISO Guide to the Expression of Uncertainty in Measurements (1993).
Key updates in 2012 were made to address updated definitions of metrological traceability. Key updates in 2014 have been to clarify procedures after national review by users as well as to add example uncertainty budget tables in each SOP.