The industry's most authoritative handbook on flow measurement provides a road map to the field of flow measurement. This best-seller discusses strategies for problem solving and puts the whole array of types of flowmeters at the reader's disposal. The text includes laminar flow elements, critical flowmeters, statistics for measurement, laboratory primary standards, and uncertainty in flow measurement. Emphasis is placed on the importance of accuracy in measurements and ways of ensuring accuracy and avoiding equipment damage through correct forecast of operating conditions, flowmeter selection, installation, calibration, and maintenance. Fundamental considerations such as mixed-phase flow, piping effects, and flow conditioning are examined at length. The problem of attaining a meaningful flow signal through linearization, compensation, and totalization is discussed. Join the thousands of engineers, technicians, managers, and salespeople that have found this reference text an invaluable resource.
TABLE OF CONTENTS Chapter 28 - Flow Measurement Proficiency Testing
To eliminate measurement-based trade barriers to international commerce, Key
Comparisons (KCs) are now being planned in the newly formed Working Group
for Fluid Flow (WGFF) in the CIPM to quantify the equivalency of the flow standards
maintained in the world's National Measurement Institutes (NMIs). This
equivalency will establish the "horizontal comparability" of flow standards across
NMIs.
To validate the accuracies of flow calibration laboratories, flow traceability can
and should be established and maintained to the flow standards maintained in the
country's NMI. This "vertical traceability" quantifies the validity of flow measurement
capabilities within the country's metrological pyramid with the NMI at
the peak of the pyramid.
The purpose of this paper is to describe flow measurement proficiency testing
techniques and their potential for comprising the highly precise KCs needed to
quantify the equivalency of flow standards among NMIs as well as for disseminating
flow measurement traceability from the country's NMI. Examples are given of
recent proficiency testing programs that involved NIST for specific fluids and
flow conditions. These demonstrate the unique levels of precision that can be
attained with appropriate choices of test conditions, transfer standards, test protocols,
and data analyses.
Conclusions are drawn that when proficiency tests have been used both to
quantify the "horizontal comparability," i.e., the equivalency of flow standards
among the world's NMIs and the "vertical traceability" to establish traceability to
the country's NMI, a comprehensive hierarchy in flow measurement will be established.
In it, the uncertainties quoted for flow measurements will be quantified,
verified, understood, and therefore assured for all involved.
Accurate flow measurements are needed for many reasons and for wide varieties
of fluid and flow conditions, for example:
- the custody transfer of scarce material resources and valuable fluid
products, - the measurement, control, and optimization of the productivity of
continuous industrial processes to produce valuable products, and - the monitoring of the environment for public health and safety.
Additionally, accurate results in these areas are needed not only within national
boundaries but also across national borders. To assure the accuracy of flowmeters,
flow standards are established and maintained in National Measurement or
Metrology Institutes (NMIs). Traceability to these standards validates flow measurements
within the nation's borders. To assure flow accuracies internationally,
the equivalent of the flow standards among the world's NMIs needs to be established
and maintained.
