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Pedro I. Espina, Roberto Arias
THE CIPM MUTUAL RECOGNITION ARRANGEMENT AND ITS IMPLICATIONS FOR FLOW METROLOGY HARMONIZATION IN THE AMERICAS

Recently, the Comité International des Poids et Mesures (CIPM) decided to provide a structure for the harmonization and comparison of measurement standards for fluid flow and related quantities. As with all other measurement quantities considered by the CIPM, this effort should provide the means by which to ascertain the equivalency of flow standards among the various countries of the World as declared in their entries to the Mutual Recognition Arrangement (MRA) of the CIPM. The CIPM flow harmonization effort will be conducted under the umbrella of a newly created Working Group for Flow and Related Quantities (WGF), which is part of the Consultative Committee for Mass and Related Quantities (CCM).
The newly formed CIPM-WGF creates an opportunity for international cooperation which the Inter-American Metrology System (SIM) can take advantage of by having a structure that parallels and supports the WGF effort. In July of 1999 the SIM Technical Committee moved to create a separate SIM Flow Metrology Working Group which will oversee efforts in metrology areas related to gas and liquid flow, liquid volume, liquid density, liquid viscosity, and air speed. These efforts will include the organization of SIM regional Key Comparisons in support of the calibration and measurement capabilities submitted by each member country to the CIPM-MRA and professional development efforts in support of the establishment of national flow metrology capabilities throughout the Americas economic block.
This paper discusses the common structure shared by all SIM Metrology Working Groups and describes the early efforts of the MWG-Flow towards the harmonization of national standards in the Americas. We summarize the current flow metrology capabilities of the various member countries and briefly describe the results of the intercomparisons that have been conducted so far. Finally, suggestions are provided for future MWG-Flow efforts.

T. T. Yeh, G. E. Mattingly
ULTRASONIC TECHNOLOGY: PROSPECTS FOR IMPROVING FLOW MEASUREMENTS AND STANDARDS

Ultrasonic technology is evolving rapidly. It offers prospects for improving flow measurements, for serving as transfer standards, and possibly for serving as a primary flow standard. This paper describes results from several current NIST projects that have the goal of assessing travel-time ultrasonic flow measurement techniques for their potential in improving flow measurements. These projects include a meter testing program and computer simulations of travel-time techniques in ideal conditions and in measured pipe flows for a range of metering configurations.
Meter test results show that the “as-received” performance of several commercially available, clamp-on, travel-time, ultrasonic flow meters have errors that range from 1% to 3% when measuring high Reynolds number water flows in nearly ideal installation conditions. These errors could be reduced if manufacturers better compensated for pipe flow profile effects using improved software or if they improved the measurement traceability of their meter calibration capabilities to NIST’s flow standards. The reproducibilities of most of these units are 1% or better, thus producing conclusions that these meters could attain accuracy levels commensurate with these reproducibilities if these software or calibration improvements are made.
Results also show that these manufacturers have significantly improved: (1) the awkward requirement for a “zero flow” condition to attain satisfactory performance, and (2) the “remove-replace” variations which plagued these types of meters. Additionally, test results for an in-line, 8-path, travel-time, ultrasonic meter that was set up using only length and time standards showed uncertainties of ±0.2%, or better. These results show that this kind of meter might evolve into a primary standard for flow.
The computer simulations of travel-time metering arrangements provide insight into ways that this technology can improve flow measurements. If it becomes feasible to quantitatively model all the component measurement systems that comprise the ultrasonic metering of a pipe flow using only length and time standards, this technique would be a primary standard at some specified uncertainty. This would greatly expand the capability of primary flow standards, and it would make flow measurements traceable to national standards.

Robert DeBoom, Marc Buttler, Andrew Kolbeck, Aart Pruysen
TRACEABILITY AND UNCERTAINTY ANALYSIS FOR A CALIBRATION PROCESS FOR FLOWMETERS, USING CORIOLIS FLOWMETERS AS REFERENCE

A flow meter manufacturer has recently developed a new system for calibrating its flow instruments. This system is based on the use of Coriolis flow meters as intermediate transfer standards. This new system is referred to as the Transfer Standard Method or TSM.
This paper and presentation will review the test data used to establish the validity of the Coriolis-based TSM, and will describe the process layout and design of the new TSM flow calibration stands. The focus of the paper, however, will be on traceability of the calibrations to national standards and on the uncertainty analysis for the TSM flow stands.
The working mass standards in the MMI (Micro Motion, Inc.) Primary Stand laboratory are traceable to Japanese and United States of America national standards. These working mass standards are used to calibrate and verify the scales of the MMI Primary Stand. The MMI Primary Stand is used to calibrate the reference meters. The reference meters are placed into service in TSM stands.
The uncertainty analysis can be split into four main parts:
A. Uncertainty of the scales in the MMI Primary Stand
B. Uncertainty of the MMI Primary Stand (Best Measurement Capability of the
MMI Primary Stand)
C. Uncertainty of the reference meters, calibrated on the primary stand
D. Uncertainty of the TSM stand (Best Measurement Capability of TSM stand).
This paper and presentation explain, step by step, the uncertainty calculations from scale to flowmeter under test. The end result of this analysis, for worst case conditions, is a Best Measurement Capability of the TSM system of 0.013% on mass and 0.020% on volume.

R. Engel, U. Klages
A NOVEL APPROACH TO IMPROVE DIVERTER PERFORMANCE IN LIQUID FLOW CALIBRATION FACILITIES

A diverting device (diverter) is an essential and error determining component part of a liquid flow calibration facility based upon a static gravimetric system with flying start and finish. The diverter timing error can be considerably reduced by the use of an angular encoding transducer in combination with an appropriate electronic and storage device. Further benefits in diverter performance can be obtained by an electric diverter actuator.

N. Bignell
ULTRASONIC DOMESTIC GAS METERS – A REVIEW

There are many designs of ultrasonic domestic gas meters but all the main ones use the measurement of the transit time of an ultrasonic signal through the flowing gas to estimate its velocity. The shape of the duct and devices to control the waveform of the signal passing through it are significant parts of the design. The transducers used to produce the signal, reciprocal operation and the main techniques to time the transit of the signal to several nanoseconds are discussed. The acceptance of these meters has been restricted and their possible future is discussed.

Ernst von Lavante, Burger Nath
INFLUENCE OF SHAPE DEVIATIONS ON THE MEASUREMENT PRECISION OF VORTEX FLOW METERS

In the present investigation, the problem of accurate determination of volumetric flows by means of the so-called vortex-shedding flow meter in the case of shape changes and deviations of the geometry from the original specifications due to manufacturing tolerances and imperfections was studied. To this end, the flow about the bluff body used in the presently studied vortex-shedding flow meter was numerically simulated using a solver of the unsteady, compressible (air) or incompressible (water) Navier-Stokes equations in two and three dimensions. The computations were carried out for several types of modified geometry including a slightly rotated bluff body, rounded edges representing wear and asymmetrically oriented sensor body called here “paddle”. The results were compared, where possible, with experimental data obtained by the manufacturer. The effects of turbulence were modeled by using the realizable k-ε turbulence model. The resulting flow fields were analyzed using various methods, including visualization, evaluation of several of their global features and DFT of properly chosen variables.

A. G. Rossberg, P. Riegler, F. Buhl, J. Herwig, J. Timmer
DETECTION OF IMPROPER MOUNTING FROM THE SENSOR SIGNAL OF VORTEX ?OWMETERS

In vortex flowmeters, the frequency of vortex formation at a bluff body inserted into the flow is used to determine the flow velocity. The frequency is determined using a sensor that measures the time-dependent distortions of the down-stream flow field. But the (univariate) sensor signal contains more information than just the vortex frequency. We use this inherent extra information to verify if the pipe flow has the form expected for the correct mounting of the flowmeter, and thus, if the flow measurement has the expected high accuracy. In designing the method, special care was taken to leave it robust with respect to uncertainties in the material properties of the fluid. In order to achieve this goal, the method makes use of the scaling properties of the Navier-Stokes equation. We present the theoretical background of the proposed diagnostic functionality and verify it on measurement data. In the experiments, irregularities that lead to more than 0.5% error in the output of the flowmeter can clearly be detected.

Ivo Pothof, Christof Lubbers
CALIBRATION OF THE SLUICE GATES IN THE AFSLUITDIJK

The Afsluitdijk (literally Closing Dike) has been constructed in 1932. The objectives of the dike were flood protection, an area increase for agriculture and a fresh water reservoir (IJssel Lake). The Afsluitdijk comprises two sluice gate structures: the Stevin sluice gates (15 gates) at the West end of the dike and the Lorentz sluice gates (10 gates) at the East end of the dike. Every low tide with Wadden Sea levels sufficiently below the IJssel Lake level, the gates open and fresh water flows into the Wadden Sea. Rising sea levels, bottom depletion and climate change result in decreased discharge capacity. Therefore an additional sluice structure is planned. The discharge coefficients of each of the 12 m wide gates are still based on physical models from 1922 (Karlsruhe), 1927 and 1933 (Delft) with an estimated uncertainty of 20%. A more accurate determination of the discharge capacity of the sluice gate structures is required to establish the design capacity and associated cost of the new structure. Therefore the Ministry of Transport, Public Works and Water Management, Water Management Direction (RWS) has decided to calibrate the sluice gate structures in the Afsluitdijk, aiming for an uncertainty of 5%.
The calibration project is carried out by RWS with support from WL | Delft Hydraulics. RWS carries out the water level and velocity measurements and develops software for primary evaluation and time synchronisation of the data. WL | Delft Hydraulics has developed the calibration method and the uncertainty evaluation for this particular construction, in close co-operation with RWS. Furthermore, WL has performed statistical analyses.
First the global geometry, the typical operation and the possible flow regimes are outlined. Then the instrumentation and approach of the calibration are discussed. The approach requires calibration of the layers near the bottom, the walls and, especially, the water surface. These calibrations are discussed in more detail. Finally an estimate of the total uncertainty of the calibrated discharge through a sluice gate in the Afsluitdijk is given.

Jankees Hogendoorn, Herman Hofstede, André Boer, Helen Danen
A NEW GENERATION OF INLINE LIQUID ULTRASONIC FLOW METERS

The ultrasonic flow meter market has developed rapidly and has seen a significant growth. Due to its high performance and unique properties, ultrasonic flow meters have built up a prominent position in the flow meter market and in many industrial processes. Reputed market research companies claim that the ultrasonic flow meter market is the fastest growing market and expect further explosive market growth.
One of the reasons for this success is that new and innovative product developments have broadened the application capabilities. For example intelligent processing of the transmitted signals allows for higher contents of entrained gas and solids in the medium. By increasing the number of measurement beams, an intelligent configuration of the beams, and innovations in transducer design and electronics, major improvements have been made in the accuracy and the stability of the measurements. From the early days ultrasonic flow meters have been used in the upstream and downstream side of the oil industry. In the early nineties, the first multiple beam ultrasonic flow meter for custody transfer of gas was introduced followed in the late nineties by an UFM custody transfer meter for liquid hydrocarbons.
A broader acceptance of the technology and decreasing prices have further spread the use of ultrasonic flow meters in the chemical and in the water and waste -water industry. The success of ultrasonic flow metering can be explained not in the least because of their inherent benefits over conventional measurement techniques in use today as they operate independently of viscosity, have no moving parts, a very low pressure loss, are maintenance -free and do not require regular or product calibrations.
This paper goes into the technological developments implemented in the new generation ultrasonic flow meters with three beams, such as digital signal processing, transducer design, and internal diagnostics.

Marcos Tadeu Pereira, Nilson Massami Taira
FLOW METROLOGY OF A LARGE WATER DISTRIBUTION SYSTEM


Page 413 of 977 Results 4121 - 4130 of 9762