Measurement Library

FLOMEKO (An IMEKO Conference) Publications (2005)

A Novel Ultrasonic Flowmeter For Low Flowrates In Small Tubes
Author(s): m. Sanderson, R. Al-Rabeh
Abstract/Introduction:
The measurement of the low flowrates of liquids in small tubes is difficult using conventional transit time ultrasonic techniques for two reasons. Firstly, if a diametrical beam is employed then the defining equation for the transit time difference between the upstream and downstream directions has a constant of proportionality which includes the diameter of the tube. Thus as the tube diameter becomes smaller the transit time difference for a given velocity becomes proportionally smaller. This is usually overcome by employing multiple reflections or more commonly an axial flowmeter in which the length over which the transit time difference is measured is an axial length which is de-coupled from the dimension of the diameter. These axial flowmeters can be configured as a U tube. However it has been shown that the effective length of the flowmeter changes with flow velocity and this has to be compensated for in the output of the flowmeter. The second reason for the difficulty in the measurement is that as the flowrate reduces the transit time differences also become more difficult to measure. Time differences of the order of 10ns are usually measured using a digital measurement technique. This often requires multiple measurements of the time difference with a consequent reduction in the response time of the flowmeter.
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Document ID: 03AB5830

Capacitive Ultrasonic Transducers For Gas Flow Metering Applications
Author(s): William Wright, Salem Brini
Abstract/Introduction:
There are various types of flowmeter used in gas flow measurements, including differential pressure meters 1, turbine meters 2-3, and positive displacement meters 4. These common flowmeters are all well characterized and readily available. However, they may cause an unsatisfactory obstruction to the gas flow and an associated pressure drop in the system. Ultrasonic flowmeters 5 are another type of flowmeter that use the interaction of acoustic waves with the moving fluid to measure the fluid flowrate. Ultrasonic flowmeters have many advantages over traditional techniques: they offer little or no obstruction to fluid flow, have a fast response, and may produce a negligible pressure drop in the system. There are three basic ultrasonic techniques. The first operates using Doppler shift 5 and hence relies on the frequency variations between the transmitted and received signals. The second uses crosscorrelation to provide an estimate of the time for a particular disturbance in the flow to travel between two ultrasonic beams a known distance apart 6-7. The third technique makes use of the ultrasonic time-of-flight between transducers using paths upstream and downstream in the fluid flow and such devices are known as transit time ultrasonic flowmeters.
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Document ID: 81EA372B

Flow Measurement Errors Due To Stratified Flow Conditions
Author(s): H. Farid Kemmoun
Abstract/Introduction:
Temperature measurement in height pressure natural gas pipelines for custody transfer as well as for calibration requires one crutial concern to be fulfilled.
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Document ID: 21C2B539

The Performance Of A Multipath, 8-inch Ultrasonic Meter In Pulsating Flow
Author(s): Rob Mcbrien, John Geerlings
Abstract/Introduction:
The performance of a 200 mm (8-inch) FMC EnergySystems (also referred to as Kongsberg) multipath ultrasonic flow meter in high pressure pulsating natural gas flows was evaluated and is discussed in this paper. The tested meter performed within 0.5% of reference flow so long as the root-mean-square (RMS) value of the pulsating velocity component (VRMS) at the meter location did not exceed 0.7 m/sec. This statement also appears to be true for VRMS values that are less than 10% of the mean flow velocity at the meter location. The flow rate measurement errors exceeded 1% at VRMS 1 m/sec. Performance of the meter depends on the level of VRMS at the meter location and not the RMS of the pulsating pressure component (PRMS). Unexpectedly, disabling four out of six operating paths generally improved flow meter performance under pulsating flow conditions. Additional information to definitively explain this result is needed although speculative comment is provided about the possible cause. The evaluated multi-path ultrasonic flow meter performed well under pulsating flow conditions up to a certain pulsation threshold. Meter error as a function of pulsation frequency and pressure/velocity amplitude is presented and discussed.
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Document ID: 8BF96E1A

Report Of CCM/WGFF Meeting
Author(s): Masaki Takamoto
Abstract/Introduction:
[Abstract Not Available]
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Document ID: 21237247

Uncertainties For An Inter-Comparison Of Water Flow Calibration Facilities
Author(s): Jong Paik, Kwang Bock Lee, George Mattingly
Abstract/Introduction:
Inter-comparisons of water flow calibration facilities have been frequently performed to assess the performances of flow measurement laboratories. As required for Key Comparisons (KCs), quantification of flow measurement uncertainties of flow calibration facilities at the level of 0.1 % or better, however, will undoubtedly require test procedures capable of generating measurement data having higher levels of metrological quality than achieved earlier. As well, these procedures will need to generate data sets that are statistically sufficient so that high confidence can be placed in the results from the data analyses. The aim of the KC is to determine the degree of equivalence of water flow standards by comparing them not only as realized, but also through the normal, routine calibration procedures used in the labs. To do this, a high precision transfer standard, a thorough test procedure for the selected test conditions, and a statistical data analysis method appropriate for the data sets are necessary. This paper presents a part of the initial efforts KRISS, as the Initiating Lab, has made to implement the KC for water flow, CCM.FF-K1, see: www.bipm.org .This KC is currently in progress. The test plan which generates statistically sufficient numbers of data points will be presented with pilot comparison results produced by the Initiating Lab and the two Assisting Laboratories.
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Document ID: 497C7B4E

Results Of The North American Natural Gas Flow Calibration Laboratory Comparison: CEESI - Swri - Tcc
Author(s): Pedro Espina
Abstract/Introduction:
A tandem flow meter transfer standard package was used and it consisted of commercial flow meters (a turbine and a multi-path ultrasonic) separated by a commercial flow conditioner. Results indicate that the transfer standard package has day-to-day reproducibilities in the 0.37 % level, at a 95 % confidence interval. This level of performance was less than desired given that the calibration laboratories claim uncertainties better than 0.3 %. The results show a consistency in performance among laboratories at the 0.3% to 0.4% level, which indicates that the three calibration laboratories have equivalent performances within the scope of their claimed uncertainties. In addition, the results did not pointed out any significant installation effect at any of the laboratories. The results from one of the laboratory capable of variable pipeline pressure were inconclusive in regards to this parameter influence on flow meter performance.
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Document ID: 73BF16BF

Multiphase Measurement Using Ultrasonic Technology - Testing A Conceptual Design
Author(s): Craig Coull, Gary Miller
Abstract/Introduction:
The measurement of multiphase flow has become a vital component in the economic viability of many marginal oil and gas fields, particularly on the UK continental shelf. To reduce capital expenditure, most new fields are now being commingled and tied back to existing platform infrastructures for processing, and established facilities are being de-manned and automated. This has raised a requirement for reliable and low-cost measurement systems to facilitate well testing, production optimisation and commercial allocation of the produced fluids. Multiphase meters are invariably used for this purpose but remain too expensive for the ideal deployment of one unit per well-head, they also frequently use radioactive sources. Ultrasonic flowmeters, on the other hand, offer the possibility of a cheaper, more environmentally acceptable solution, with the added potential to operate at high gas volume fractions (90% +), where the accuracy of multiphase meters deteriorates rapidly. Previous research 1 2 3 has shown the potential benefits of ultrasonic technology in the measurement of multiphase and wet gas flows.
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Document ID: 0E12C880

An Update On V-Cone Meter Wet Gas Flow Metering Research
Author(s): Richard Steven, Tom Kegel, Charles Britton
Abstract/Introduction:
With the increasing importance of wet gas flow metering to industry, the Differential Pressure (DP) meter wet gas flow correlations are being increasingly utilised. Currently little information exists regarding the applicability of such correlations beyond the limits of the data sets used to create them. In particular little is known about the repeatability of a DP meter with wet gas flows, meter size and liquid property effects on the validity of the DP wet gas correction factors. In 2001 NEL tested a 6 schedule 80, 0.75 Beta Ratio V-Cone meter with a N2 / kerosene wet gas flow as part of the UK governments Department of Trade and Industry (DTI) funded Flow Programme. In 2002 McCrometer and NEL jointly presented analysis of this data at the North Sea Flow Measurement Workshop (NSFMW) 1. The parameters that affected the over-reading (i.e. the positive error induced by the presence of liquid with the gas flow) were shown and a wet gas flow correlation was offered. For a known liquid mass flow rate or liquid to gas flow rate ratio the meters gas prediction was to 2% with a few outliers. In 2003 McCrometer presented results of repeat tests at NEL and a single wet gas data set from a 4 schedule 80, 0.75 Beta Ratio V-Cone meter tested with natural gas (NG)/ decane at CEESI 2. The V-Cone meter was shown to be repeatable and the results from CEESI were similar to those of NEL. However, in general, the question of what effect meter size and liquid phase properties have on DP meter wet gas overreadings is largely unanswered, even though the applicability of published correlations in different applications is a very relevant industrial issue.
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Document ID: BEC0B007

Turbine Flowmeter Models For Measuring Oil- Gas-Water Three Phase Flow In Vertical Upward Pipes
Author(s): Jin Ningde, Zheng Hua, Zhang Shuying, Liu Xingbin
Abstract/Introduction:
Based on the experimental data obtained by the Annulus Three Phase Flow Tool worked in vertical oil-gas-water three phase flow, we investigated the applicability of existing turbine meter models. In model evaluations, we consider the effects of three phase flow characteristics, such as slip ratio, the gas phase distribution, the gas drift flux velocity. The results show that the momentum model of turbine meter has a good prediction accuracy of total flow rate, and gives a more reasonable physical interpretation. The corrected volumetric model of turbine meter gives a high prediction accuracy of total flow rate, but the applicability beyond the current experimental data is still unclear, and we need to perform the more model test in future within wide range flow conditions.
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Document ID: 7FD129F1

Coriolis Mass Flowmeters: On Measurement Errors In Two-Phase Conditions
Author(s): Alfred Rieder, Wolfgang Drahmhao Zhu
Abstract/Introduction:
Due to their high accuracy, Coriolis flowmeters are widely used in industry for mass flow and density measurement of single-phase liquids or gases. However, the accuracy decreases if a second phase is mixed with the processed liquid. Especially gas bubbles can cause errors. To explain this phenomenon, the bubble theory was proposed by Grumski et al. 1 and Hemp et al. 2. However, this theory only explains negative density and mass flow errors and can not explain positive errors observed in experiments. Furthermore, according to this theory, density and mass flow errors are directly coupled, which is not the case in practice. Fig. 1 shows the typical behaviour of a Coriolis flowmeter. Besides the bubble theory there must be other significant effects that influence the measurement accuracy. The moving resonator model introduced in this paper can explain these effects.
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Document ID: E8A16941

Development Of The Critical Nozzle Flow Meter For High Pressure Hydrogen Gas Dispenser At A Hydrogen Gas Station
Author(s): Shin-Ichi Nakao
Abstract/Introduction:
Several new technologies must be developed to complete the infrastructure for the utilization of hydrogen gas in a hydrogen society of the near future. One of them is the flow meter to measure the flow rate of hydrogen gas when filling it in the storage tank of a fuel cell vehicle at a gas station. The important point is that the flow meter used at a gas station is a transaction meter, which is required to have a superior reproducibility. For example, no adjustment of the flow meter is allowed during the period provided by the metrology law. Furthermore, the maximum pressure of hydrogen gas in the storage tank is going to be raised from 35 MPa to 70 MPa to extend the range of the vehicle, because its range is only about half that of gasoline vehicles when the maximum pressure of hydrogen gas in the storage tank is 35 MPa. At the present time, a coriolis type flow meter is used for a flow measurement of a hydrogen gas at gas stations. However, a coriolis type flow meter with oscillating mechanical parts will have to be evaluated its reliability at such a high pressure for long term use.
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Document ID: 5AB5682E

The Implementation Of Torodial Throat Venturi Nozzles To Maximize Precision In Gas Flow Transfer Standards
Author(s): Pierre Delajoud, Martin Girard, Michael Blair
Abstract/Introduction:
The measurement of the mass flow of gasses in the range up to 50 g s-1 (2500 Nl min-1) is important in a variety of industrial processes and research fields. Precise and stable transfer standards are an indispensable part of the system to support these measurements. Filling the transfer standard role effectively requires instruments that are transportable and easy to use with minimal sensitivity to external influences such as ambient pressure, ambient temperature, upstream geometry and upstream or downstream pressure. In the lower part of this flow range, the transfer standard role has been filled effectively by instruments based on laminar flow elements 1, 2. However, as flow increases, the differential pressure differential pressure across the laminar element increases aggravating temperature influences and eventually the flow regime transitions to turbulent. A well known alternative, particularly for higher flows, is the toroidal throat, critical flow Venturi nozzle. A new flow element based on critical flow nozzles (CFN) has been developed to complement existing laminar flow modules using a common mass flow terminal. The new elements cover the range of flow from 0.02 to 50 gs-1 (1 to 2500 Nl min-1) and beyond. The laminar flow elements are known under the trade name molbloc-L and the CFN based elements are designated molbloc-S.
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Document ID: 8CA15785

Unsteady Transition In Critical Venturi Nozzles
Author(s): E. Von Lavante, B. Mickan
Abstract/Introduction:
The flow field in a typical toroidal Venturi nozzle, operating at critical conditions and shaped according to the recommendations of the ISO Standard 9300, has been investigated using numerical flow simulation. The present study focused on the transitional effects in the boundary layer, occuring at a Reynolds number of approximately one million when it changes its character between laminar and turbulent. Therefore, the computations were carried out for a range of Reynolds numbers between 8 105 and 4 106. The present results were compared with experimental data where available. The unsteady compressible viscous flow in the nozzles was simulated using the Navier-Stokes solver ACHIEVE, developed by the first author. Several models for predicting the laminar-turbulent transition were tested. Significant phenomena associated with the transition were observed, having an influence on the discharge coefficient.
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Document ID: 981C178C

Venturi Tubes With A 10.5 Converget Angle: Development Of A Discharge Coefficient Equation
Author(s): Michael Reader-Harris, Jeff Gibson, David Hodges, Ian Nicholson, Ronnie Rushworth
Abstract/Introduction:
With gas production scenarios now frequently involving multiple gas fields, it is important that confidence in the measurements made by wet-gas meters is increased as this will ultimately help to increase the viability of marginal gas fields. There is an increasing desire to use Venturi tubes for wet-gas measurement, but to ensure accuracy in wet gas it is necessary to understand their behaviour in dry gas first. It was generally assumed until about eight years ago that the discharge coefficient at high Reynolds number in high-pressure gas would be constant and approximately equal to that obtained in water at Reynolds numbers greater than 2 105. However, work carried out at NEL reported by Jamieson et al 1, data reported by van Weers et al 2, and subsequent work at NEL 3-7 showed that the performance of Venturi tubes in gas is very different from that in water. Some discharge coefficients in gas are greater than would have been expected by 3 per cent or even more.
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Document ID: A228647B

Computation Simulation Of Rectangular Long Throated Flumes
Author(s): Hoi Yeung, Julian Turnbull
Abstract/Introduction:
The Environmental Agency requires discharges that exceed 50m3/day be measured to +/-8%. In the UK, open channel structures are extensively used to measure discharge, the performance of which are covered by various hydrometry standards. In reviewing the standard for long throated flumes, it was found that there was very little experimental verification. The behaviour of rectangular long throated flumes was studied both experimentally in the laboratory and computationally. A commercial CFD (computational fluid dynamics) package was used to simulate the flumes. It was found that the results were good in comparison with experimental and prediction by the standard.
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Document ID: 44CABD43

Metrological Control Of Gas Flow Measurement And Conservation Of Mass Analysis In The Bolivia-Brazil Gas Pipeline
Author(s): Julio Palhares, Alcir Orlando, Mauricio Frota
Abstract/Introduction:
Natural resources -natural gas is no exception- generally represents emotional assets of a nation. Not surprisingly too much political debate, governmental whims and economic disarray in both producing and consuming countries have so far prevented a global market to emerge. But there are some financial hurdles too. Shipping gas remains more expensive than shipping oil. Elaborate infrastructure of gas processing (liquefaction plants, storage tanks, re-gasification) is more costly than its oil counterpart. And the transport of gas from wellhead to market requires technologically sophisticated pipelines. Yet its relatively low environmental impact, especially for electric power generation, has attracted consumers wishful to live in a gas-fed world. This, of course, would imply a greater need for cooperation between exporting and importing countries and a constructive dialog between contractual parties to promote the gas industry. After a number of years negotiating mutually agreeable terms and overcoming regional political differences, Brazil and Bolivia finally signed in the mid-1990s a trade agreement to supply Brazil with Bolivian gas for forty years. The consequences were two-fold: Bolivias gas met Brazils growing need to diversify its energy matrix - essentially of hydroelectric origin- and prompted large sums of capital to build up a large-scale gas infrastructure to boost a promising domestic market limited until 1998 to refineries and the oil offshore exploration. As a result, a surge in consumption by industrial consumers- which were responsible for approximately 75 % of the 15 million cubic meters of gas already being transported by Brazilian pipelines in 2000 - brought about the need for improved gas measurement, safety and control. Today, around 45 out of 70 million cubic meters of the total systems capacity are being transported to reach, after a substantial increase in production, an astonishing 90 million cubic meters by the end of this year 1.
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Document ID: 6B4F87B0

Redesign Of The Etap Gas Export System
Author(s): Bob Peebles, Neil Barton
Abstract/Introduction:
This paper describes the reconfiguration of the header and replacement of the control valves of the ETAP gas export system. Early in the design process it was recognised that the revised header configuration would not comply with the requirements of ISO 5167:2003 1 without additional modifications. Consequently, three basic options were considered to remedy this situation.
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Document ID: EF1E3C34

Modelling And Evaluation Of Velocity Profile Effects On Coriolis Flowmeters
Author(s): Joe Kutin, Gregor Bobovnik, Ivan Bajsic
Abstract/Introduction:
The aim of this paper is to discuss velocity profile effects in Coriolis flowmeters. The newgeneration devices try to achieve accuracies better then 0.1 %, and this has to be considered when evaluating the significance of particular influences on their characteristics. Although the velocity profile effect is generally not considered as problematic as, for instance, some dynamic effects (flow pulsations, mechanical vibrations, two-phase flows, etc.), some accessible experimental studies give an indication of its magnitude. For example, three commercial Coriolis flowmeters showed no or in one case just detectable measurement errors under disturbed flow conditions in 1 (a relatively high threshold of 0.25 % was used for reporting a significant effect), but the output of a commercial shell-type Coriolis flowmeter was affected by up to a few percent in 2 (testing with pressurized gas).
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Document ID: F476B5C4

Development Of An Ultrasonic Flowmeter For Hydrogen Gas
Author(s): Satoshi Hoshikawa, Hiroaki Ishikawa, Shin-Ichi Nakao, Masaki Takamoto
Abstract/Introduction:
Flow rate measurement for hydrogen gas is very difficult because the density of this gas is very low and the sound velocity is very high. This difficulty was overcome by improving the structure of the conventional ultrasonic flowmeter, and the ultrasonic flowmeter for hydrogen gas developed herein was evaluated for both steady and unsteady flows. Although the error for the flow rate measurement was slightly negative, the scatter was within 1% for the range from 30 to 240 L/min at a pressure of 100 kPa. It is thought that the flow rate can be measured to within 1% by calibration.
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Document ID: 81D3ACAF

The Effect Of Flow Conditioners On The Performance Of Multi-Path Ultrasonic Flowmeters
Author(s): Bobbie Griffith, Terry Cousins, Don Augenstein
Abstract/Introduction:
The paper describes the performance of Caldon Ultrasonic flowmeters in the presence of different design flow conditioners and straighteners. Tests were conducted with the conditioners at different positions upstream of the meter. The results are compared to the calibration of the meter with a fully developed flow profile one expects in straight pipe. The data collected for the comparison included the repeatability, linearity and shift in the meter factor from that with straight pipe. There has been anecdotal evidence that the presence of conditioners and straighteners impairs the repeatability of ultrasonic flowmeters (UFMs), and hence provability. This paper presents experimental data demonstrating the effect in practice. The paper includes discussion and recommendations with regard to the merits and de-merits of using flow conditioners with multi-path UFMs.
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Document ID: F1289816

Different Meter Tube Requirements For Orifice Plates And Ultrasonic Meters
Author(s): Klaus Zanker
Abstract/Introduction:
Orifice meters are built to rigorous standards that can achieve 0.5% uncertainty of the discharge coefficient (Cd) without the need for any flow calibration. This is achieved by relying on a vast array of empirical data collected in several test facilities over many years. The standards specify the orifice plate, the fitting, the pressure taps and the meter tube, to ensure that geometric and dynamic similarity is maintained with the empirical database.
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Document ID: CC92CAD5

Evaluation Of The Flowmeters Using The Primary Standard For Hydrocarbon Flow In Japan
Author(s): Takashi Shimada, Ryouji Doihara, Yoshiya Terao, Masaki Takamoto
Abstract/Introduction:
The large hydrocarbon flow calibration facility at National Metrology Institute of Japan (NMIJ) 1 was constructed as the primary standard in Japan. It consists of two separate test rigs with kerosene and light oil as working liquids. The normal calibration flow rate range is from 15 to 300 m3/h. This primary standard is based on static and gravimetric methods with a flying start and finish. The expanded uncertainty had been evaluated experimentally and analytically to be 0.03 % for volumetric flow rate and 0.02 % for mass flow rate (coverage factor k 2) 2.
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Document ID: A50498D0

New On-Site Calibration Technique For Large Flow Meters Using Laser Doppler Velocimetry
Author(s): Andy Drysdale, John Frederiksen, Matthew Rasmussen
Abstract/Introduction:
This paper presents a new method of calibrating flow meters of 100 to 1000 mm diameter whilst on-site and in operation using Laser Doppler Velocimetry (LDV). The technique has been tested and demonstrated in the laboratory and in the field. Primarily developed for calibrating district heating meters, the technique is also suitable for measuring flow in other clear fluids. Calibration of installed large district heating meters using traditional methods is difficult, if not impossible. It is often a labour demanding, time consuming and costly task to remove and send a meter for off-site calibration. Using LDV for on-site calibration is an attractive alternative. LDV is an established optical technique for measuring point velocity in clear gasses and fluids and is used in a wide range of R&D applications. Using LDV it is now possible to carry out accredited on-site calibration of large flow meters up to 1000 mm in diameter with water flow velocities from 0.01 to 6.0 m/s.
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Document ID: 22CF4BF6

Basic Design Of Very Large Water Flow Calibration Facility For Nuclear Power Application
Author(s): Hiroshi Sato, Noriyuki Furuichi, Yoshiya Terao, Masaki Takamoto
Abstract/Introduction:
A new test facility has been planned for construction at National Metrology Institute of Japan (referred to as NMIJ) for the calibration of feed water flowmeters for nuclear power plants up to a Reynolds number of 16 million. This very large Reynolds number will be achieved at a flow rate of 3.33 m3/s (12,000 m3/h) and water temperature of 70C in a 600 mm pipe. This new facility has four sets of pumps and reference flowmeters installed upstream of the test section in parallel. These flowmeters will be calibrated at 0.83 m3/s (3,000 m3/h) individually without dismounting from the loop by using a 50t weighing tank, which has been used as the primary standard for the existing flow facility. The flow range can be expanded up to 3.33 m3/s (12,000 m3/h) with all the pumps and flowmeters operating simultaneously. This paper describes the basic design and concept of the new facility, and expectations of the best measurement capabilities. In addition, an experimental plan, which will be essential for applications in nuclear power plants, is suggested.
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Document ID: C3908824

Comparison Of Low Pressure Gas Flow Standards
Author(s): Khaled Chahine
Abstract/Introduction:
A Bell prover with 300 L capacity and a 5-tube mercury sealed piston prover are used as gas flow standards at the National Measurement Institute Australia, NMIA. Together they cover a flow range of 0 to 30 m/hr. Modifications were carried out on these two standards to better determine their delivered volumes. Descriptions of these modifications are presented in this paper. Uncertainty analysis of each standard delivered volume is also presented in this paper. Sonic nozzles were used as flow transfer standards to compare the above standards. An uncertainty analysis of the sonic nozzle coefficients and the results of the comparisons are presented.
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Document ID: C1ED3C71


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