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Search Publications by: Charles D. Ehrlich (Fed)

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Displaying 1 - 24 of 24

Measurement units as quantities of objects or values of quantities: a discussion

August 24, 2018
Charles D. Ehrlich, Leslie R. Pendrill, Luca Mari
Measurement units have historically been defined as quantities (specific properties) of objects, such as the mass of a particular piece of metal or the length of a particular rod. While the current SI Brochure endorses this position, the draft 9th SI

Uncertainty of Error: The Error Dilemma

May 11, 2016
Charles D. Ehrlich
Measurement error has historically been defined in the metrology community as a difference of 'values,' usually as a difference between a 'measured value' and a 'reference value.' The reference value is sometimes considered to be a 'true value,' which is

Fastener Quality Act of 1990; Public Law 101-592

October 16, 2008
Charles D. Ehrlich
The OSS' Technical Standards Activities Program (TSAP) manages responsibilities assigned to NIST under the Fastener Quality Act (FQA) of 1990. Fasteners are a $6 billion U.S. industry critical to the automobile, aerospace, construction, chemical and

Issues and Trends in Legal Metrology (from a U.S. Perspective)

October 16, 2008
Charles D. Ehrlich, H V. Oppermann
Several current aspects of legal metrology are likely to change significantly over the next 10 years to 20 years. Exponential increase in the use of technology in the marketplace requires legal metrology officials to become increasingly knowledgeable in a

Summary Proceedings: Legal Metrology Seminar for the Americas

January 1, 2001
S E. Chappell, Charles D. Ehrlich, Kenneth S. Butcher
This paper provides a report on the Legal Metrology Seminar for the Americas that was held in conjunction with the 85th annual meeting of the National Conference on Weights and Measures (NCWM) in Richmond, VA, from July 16 through July 20, 2000. The

Issues in Purchasing and Maintaining Intrinsic Standards

December 1, 2000
R B. Pettit, K Jaeger, Charles D. Ehrlich
Intrinsic standards offer many advantages over conventional artifact standards, including, in many cases, a very low uncertainty of measurement and no need for periodic re-calibration. Because of the recent increased interest in intrinsic standards, NCSL

A primary pressure standard at 100 kPa

June 1, 1999
James W. Schmidt, Y Q. Cen, Robert G. Driver, Walter J. Bowers Jr., J C. Houck, S A. Tison, Charles D. Ehrlich
Primary pressure standards in the atmospheric pressure range are often established using mercury manometers. To a lesser extent controlled-clearance dead-weight testers in which one component (normally the piston) has been dimensionally measured have also

Metrological Timelines in Traceability

January 1, 1998
S D. Rasberry, Charles D. Ehrlich
Current developments and applications in the field of metrology have increased the need for correct and appropriate usage of the terms and concepts related to measurement traceability. Besides traceability itself, some of the interrelated terms include

Recommended practices for the calibration and use of leaks

January 1, 1992
Charles D. Ehrlich
This document is the consensus view of the Calibrated Leak Subcommittee of the Recommended Practices Committee of the American Vacuum Society. It is divided into four main sections: Description, Calibration, Proper Usage, and Recommended Documentation of

A note on flow rate and leak rate units

April 28, 1986
Charles D. Ehrlich
The confusion in the literature and in the laboratory surrounding the terminology and units of gas flow rates, particularly as applied to calibrated leak artifacts, has prompted this discussion of leak rate units. Special attention is paid to conflicting