A Novel Concept Of An Old Idea: Electronic Twin Turbine Meters For Custody Transfer
Author(s): Harry H. Dijstelbergen
Abstract/Introduction:
The two primary requirements for custody transfer metering are accuracy and reliability. Reliability is important to reduce cost of maintenance and to limit, in the event of a malfunction, the amount of gas that may be disputed.
Go to Download Page
Email Reference
Document ID:
83E00C03
Improvement To Small Hydrocarbon Flow Calibration Facility At Nmij
Author(s): Kar-Hooi Cheong, Ryouji Doihara, Takashi Shimada, Yoshiya Terao
Abstract/Introduction:
Improvement has been made to the primary standard for small flow of liquid hydrocarbon at NMIJ to upgrade the calibration capability to include volumetric flow range of 0.01 m3/h 0.1 m3/h and also to include kerosene as the working liquid. The best calibration and measurement capability (CMC) is estimated to be 0.064 % for volumetric flow rate and 0.020 % for mass flow rate (coverage factor: k2). In-house comparisons between small and medium hydrocarbon flow facilities at NMIJ were carried out, using servo PD flowmeter and Coriolis flowmeter. Calibration results by Coriolis flowmeter showed a good agreement between the two facilities. However a certain discrepancy was found in the calibration results of servo PD flowmeter between the two facilities. Efforts were made to clarify the discrepancy. Keywords: Small hydrocarbon flow calibration facility, volumetric flow rate, kerosene, in-house comparison, servo PD flowmeter
Go to Download Page
Email Reference
Document ID:
41395A5C
Flowrate Measurements Using Pitot Tubes To Measure Emissions In Circular Ducts
Author(s): Dr Michael Reader-Harris
Abstract/Introduction:
Pitot tubes are commonly used to measure gas flows arising from stack emissions. It is clear from data collected in the 1960s and 1970s that under controlled conditions Pitot tubes can give excellent results. However, it is expected that results in stacks will have much less good accuracy. The way to investigate the difference is to examine the uncertainty of the measurements. Section 2 gives the results from the earlier work. In Section 3 and following the requirement is to identify and assess the sources of uncertainty in the application of Pitot tubes to measurement of gas flows in stacks to monitor emissions. This paper gives numerical values to uncertainty that are intended to be typical. They are not necessarily the best values that could be obtained, but will enable it to be easily seen where the main sources of uncertainty are
Go to Download Page
Email Reference
Document ID:
EB016105
Calibration Uncertainty Of Flowmeters For Hydrocarbon Flow By Using Subtraction Method
Author(s): Takashi Shimada, Ryouji Doihara And Yoshiya Terao
Abstract/Introduction:
The calibration uncertainty of flowmeters using the subtraction method for hydrocarbon flow has been experimentally and analytically evaluated in order to calibrate flowmeters at lower flow rates than the flow rate range calibrated using the calibration facility. An expanded uncertainty has been estimated to be less than 0.8 % at the flow rate ratio of 1/100 in the kerosene test rig of the primary standard facility at NMIJ. The main sources of combined uncertainty due to the subtraction method are the reproducibility of the working standard flowmeters and the temperature measurements. Furthermore, a flowmeter has been calibrated using the subtraction method in order to verify uncertainty analysis. The calibration results obtained by the subtraction method agree with those from weighing method within the quoted expanded uncertainty
Go to Download Page
Email Reference
Document ID:
B35A3734
Evaluation Of Water Flow Measurement Performance Of Portable Ultrasonic Flowmeter Technology
Author(s): Dr.Ing. C. David
Abstract/Introduction:
Non invasive ultrasonic flowmeter technology allows realizing on-site measurements and diagnostics without using intrusive parts. The same sensors can be used to measure flows on a wide range of pipes, liquids and flow rates. Although non-invasive flowmeter technology offers a promising tool for measuring flows, it also requires a lot of care to be used correctly. Sufficient upstream and downstream lengths are needed on the pipe to ensure a full development of the flow profile. A precise knowledge of the pipe dimensions (diameter, thickness and roughness), pipe material and the characteristics of the fluid (type, temperature) is mandatory. Finally, care has to be taken during installation to avoid artifacts due to several parameters
Go to Download Page
Email Reference
Document ID:
BA1997E7
Temperature Compensation Of Liquid Fuel Transaction
Author(s): Ki Won Lim, Seok Jang
Abstract/Introduction:
Liquid fuels at gas stations expand and contract their volume due to temperature variations. In South Korea, the ambient temperature varies between -15 ? in winter and 35 ? in summer. Volume expansion coefficients of liquid fuels are about 0.1 %/?. Rising global temperatures only make this a greater controversial point concerning the monetary benefits to stakeholders. To investigate this issue, we measured the daily change of fuel temperature at gas stations. We also scrutinized the daily, monthly, and annual changes of the temperature for the last 50 years in South Korea. The temperature of the fuel in the storage tank and the delivered fuel at the gas station were also measured. The results show that the temperature of the fuel in the storage tank was kept stabilized regardless of summer or winter. Many factors, such as the surrounding conditions, the fuel filling frequency, and the location of the gas station, have exerted an influence on the temperature of the delivered fuel. The results of this study will contribute to fair transactions and can be applied to establish a national regulation
Go to Download Page
Email Reference
Document ID:
3F88DC1A
Effect Of Low Flow And Extreme Ambient Conditions On Thermowell Performance
Author(s): Robert Mcbrien And John Geerligs
Abstract/Introduction:
An investigation was done to determine if external heating of meter run piping, caused by surrounding ambient air temperatures well above pipeline gas temperature, might lead to measureable errors in temperature measurement (needed for mass flow calculations) using the current AGA Report No. 9 recommended thermowell insertion depths of 0.1 to 0.33 of the pipe internal diameter. It was determined that errors can occur, the magnitude of which will depend on the amount of pipe wall heating, gas flow rate and temperature, and the design of the thermocouples. Detailed description and discussion of the tests and results are presented in this paper
Go to Download Page
Email Reference
Document ID:
CF616992
Interaction Of Ultrasonic Meter Electronics In A Dual Meter Package
Author(s): Robert Mcbrien And John Geerligs
Abstract/Introduction:
A flow performance evaluation of two 8-inch (200 mm) ultrasonic meter (USM) dual meter packages has been conducted to determine if acoustic signal interference between meters can occur and cause meter errors. Each meter package was tested, as received (i.e., no calibration) in high-pressure (5600 to 6100 kPa) natural gas flows over flow ranges, in terms of pipe Reynolds number (Re), from 1x106 to 12x106. Detailed description of the test procedures with presentation and discussion of results, including diagnostic outputs from each meter set, will be presented in the paper.
Go to Download Page
Email Reference
Document ID:
5CD271BD
Measurement Of Gas-Phase Flowrate Of Wet Steam With Low Wetness
Author(s): Masahiro Ishibashi, Tatsuya Funaki, Noriyuki Furuichi,Yoshiaki Matsushita, Shuichi Umezawa, Hiroyuki Shimada,Fumio Inada,Ryo Morita, And Yuta Uchiyama
Abstract/Introduction:
The outline of a new facility to measure the flowrate of gas phase in wet steam flow is introduced. It produces wet steam flow of known wetness by cooling down dry steam. The wetness is estimated based on the extracted enthalpy from the dry steam during the cooling down. All the dominant instruments were calibrated to establish the traceabilities to the national standards. The details of the facility and some results from calibration of orifice, vortex and ultrasonic meters in the facility together with an example of uncertainty analysis are described
Go to Download Page
Email Reference
Document ID:
47408032
The Critical Back Pressure Ratio Of Sonic Nozzles - The Correlation With Diffuser Geometry And Gas Composition
Author(s): Bodo Mickan, Rainer Kramer,Chunhui Li
Abstract/Introduction:
The critical backpressure ratio (CBPR) of sonic nozzles is one of the parameters which are important for the correct application. The CBPR indicates the minimum pressure loss achievable during the use of a nozzle in a test configuration. The conventional design of sonic nozzles, especially those of nozzles according to the ISO 9300, with conical divergent sections (diffusers) is specified to optimize this CBPR. It is a well-known fact that the individual CBPR of a nozzle depends on many parameters such as diffuser angle, length of diffusers, size of nozzle, operating pressure and gas composition. Another well-known fact concerning the CBPR of sonic nozzles is the phenomena of the premature unchoking which occurs especially in applications of small sonic nozzles
Go to Download Page
Email Reference
Document ID:
63191824
Volume Correction Of Domestic Gas Metering In Korea
Author(s): Kyung-Am Park
Abstract/Introduction:
The reference conditions of natural gas transaction are 0 ? and 1.01325 bar in Korea. Gas temperature and pressure of actual gas flow are quite different from the reference conditions. In summer time, atmospheric temperature is higher than are 0 ? and atmospheric pressure is lower than1.01325 bar. But the situation is reverse in the winter. Volume correctors are used to calculate gas volume at the reference conditions in the industrial and commercial gas flow meters. Volume corrector is expensive to use in the home. Volume correction effect in the home is usually less than cost of volume corrector even though gas is used for cooking and heating. So it is one of the best methods to use volume correction factor.
Go to Download Page
Email Reference
Document ID:
F73EFE98
The Conception And The Construction Of A New High Pressure Primary Facility For Gas
Author(s): J.P. VALLET,G. MIAULT,C. WINDENBERGER,P. MANROT,P. Kervevan
Abstract/Introduction:
A new primary facility using the volumetric method (PVT,t) is under construction in Poitiers, France and is planned to become the future national standard within the next few months. This facility will calibrate CFVN(1) transfer standards at High Pressure which will be used with different gases (air - natural gas - nitrogen - ) for calibrating any kind of flowmeters and will establish traceability for national gas flow laboratories as well as for accredited and/or manufacturers and users labs, from atmospheric up to significant pressure levels.
Go to Download Page
Email Reference
Document ID:
917DC0DF
How Safe Is Linearisation Of Flow Meters?
Author(s): T. Cousins
Abstract/Introduction:
For measurement instrumentation the golden rule of design is to optimise the basic mechanism, physics or design and then to use computers and signal processing to refine the concept and make it more useable. The essence is that the processing should be minimal to achieve the end performance. Linearisation is a particular area where this should be the major tenant of design. Unfortunately, a combination of the power of computer, digital signal processing etc. and the almost total integration of the basic structure of meters with processing has made the temptation to take a basically non-linear instrument and linearise it, without due recognition of the potential dangers for consistent measurement. It has also hidden from the user the extent to which these corrections are being carried out and masks the potential risks in operation. The requirements of any linearisation of a meter are that it should be minimal, and should have a stable, well defined reference, reducing the uncertainty of linearisation and ensuring stable operation under all possible conditions
Go to Download Page
Email Reference
Document ID:
1A84D67D
Comparison Of Mfcs Between Inrim And Lmps In The Range (10 To 20000) scm3/min
Author(s): P.G. Spazzini, A. Piccato1, J. Kutin, G. Bobovnik, I. Bajsic
Abstract/Introduction:
During last winter, a bilateral comparison of gas flow rate measurements was carried out between two laboratories: INRIM, Italy and LMPS, Slovenia. Two mass flow controllers (MFCs) were chosen to be used as transfer standards. Although thermal mass flow sensors are not foreseen as superior transfer standards for gas flow rate 1, we tried to find if they can assure proper stability and robustness when the measurement conditions (pressure, temperature etc.) are set under relatively tight control. One of the reasons for their choice was also having a large number of such instruments on our disposal, which allowed selecting a couple of instruments that permitted an easy comparison through the requested range of flow rates. The results of the comparison were found to be interesting, as they produced some unexpected outcome, and were therefore deemed worthy of publication. The elaboration technique employed a study of the stability of the instruments in the short and medium term that are crucial for validation of measurement capabilities of participating laboratories. In this paper, we describe the measurement system and procedure in Section 2 and the data elaboration in Section 3. Results are discussed in Section 4, while Section 5 summarizes the outcomes and suggests some possible future developments of the analysis
Go to Download Page
Email Reference
Document ID:
FEBCE42F
Testing Of Differential Pressure Cone Type Flow Meters To Various International Standards
Author(s): Philip A Lawrence
Abstract/Introduction:
Technology is advancing at an ever increasing rate, as a consequence, engineering methodology and applications in flow measurement are forcing a change for the better. These newer technologies can often bring advances to the operational processes within many industries. These advances can also improve the overall production of a facility by a better performance, better reliability, and lower costs. In the past however, the introduction and use of these newer technologies had been an issue due to the standardization process needed for acceptance. Measurement Standards from organizations such as the International Organization for Standardization, the American Petroleum Institute and the American Gas Association have experienced from time to time some examples of delayed publication. Whilst these paper standards serve to protect and guide companies in their use of technology, they have often prevented the introduction of new and often better technology by virtue of the long process time in production, agreement, and administration of the said standard.
Go to Download Page
Email Reference
Document ID:
F7FA3B1F
The Pressure Drop Behavior Of Tube Bundles In High Viscosity Applications
Author(s): Danny Sawchuk
Abstract/Introduction:
Tube bundles are typically used in applications where the fluid has a high density and low viscosity. This was due to the assumption that they were always the lowest pressure drop alternative when it comes to flow conditioning. The basis of this was due to the fact that a tube bundle has a higher open area that most plate based flow conditioners. Recent testing data has proved that this isnt correct. The substantial length of the tube bundle may actually be causing it to have a significantly higher pressure drop under the right conditions.
Go to Download Page
Email Reference
Document ID:
167F1683
The Development Of A Measurement Standard For The Calibration Of LNG Flow Meters
Author(s): O. Oswin() Kerkhof, P. Peter() Lucas, M.P. Mijndert() Van Der Beek, G.J.P. Gertjan() Kok, G.J. Gerard() Blom, A. Andrea() Peruzzi, F.M. Erik() Smits
Abstract/Introduction:
The trade of Liquefied natural gas (LNG) depends on reliable measurement methods. Trading parties are striving for the smallest measurement uncertainties to reduce their financial exposure. While state-of-the-art measurement methods are generally accepted and have been in place for decennia there is room for improvement. Nine metrology institutes from Europe, one university and three industrial stakeholders have taken up this challenge with further support of several collaborating industrial parties. They have joined forces in a 3-year EU R&D project Metrology for LNG that aims to reduce the measurement uncertainty of LNG custody transfer measurements. The objectives are to develop test & calibration standards, to perform uncertainty evaluations and to contribute to written standards and industry guidelines. The project covers all energy measurement aspects including quantity measurements (tanker volume and flow measurements) and quantity measurements (composition and density).
Go to Download Page
Email Reference
Document ID:
4CD833F4
Raskhod-Ru Cad System For Computer Aided Design Of Flowmeters For Fluid Energy Carriers
Author(s): Ye. Pistun, L. Lesovoy, R. Fedoryshyn
Abstract/Introduction:
Raskhod-RU CAD is developed in order to provide computer aided design of pressure differential flowmeters and to simplify implementation of new normative documents (ISO 5167.1,2,3,4-2003 and GOST 8.586.1,2,3,4,5-2005). This program meets the requirements of the new Standards and provides accomplishment of the following tasks: verification of conditions (constraints) for application of the pressure differential method according to the requirements of new Standards calculation of parameters of primary device, pipe straight lengths and flowmeter in general according to the requirements of new Standards calculation of uncertainty of results of fluid flowrate and volume measurement
Go to Download Page
Email Reference
Document ID:
25B2A97A
Uncertainty Budget Of And First Experiences With The New Multiparameter R+D Gas Calibration Rig
Author(s): A. Pfau, A. Gruen, m. Hull, O. Popp
Abstract/Introduction:
Recently Endress+Hauser Flowtec AG at Reinach, Switzerland, inaugurated a new testing facility for experimental gas flow investigations. The newly developed R+D calibration rig covers process operation points ranging from ambient temperature to 100 C (212 F) and pressures from vacuum (0.5 bar a, 7.25 psi a) to 10 bar a (145 psi a). A special feature is the capability to run air, CO2 or other non-explosive, inert gases, e.g. argon. The line sizes offered range from to 6. The reference meters in use are PD-meters and turbines. The rig is driven by a 160 kW radial blower. It is connected to the quality management system according to ISO17025 but not currently accredited. This paper describes the concept of the rig in detail. It presents first experiences gained during the commissioning phase concerning the control system of a closed loop system. It proves the importance of measuring and controlling the flow distribution in the piping (main flow and bypass flow) in order to ensure a safe operation of the radial blower. Finally, the measurement uncertainty budget is presented covering a set of relevant uncertainty contributors, e.g. gas composition, volume flow, density determination, and flow profile
Go to Download Page
Email Reference
Document ID:
F12D3942
Tests Of The Extended Lee Model Using Three Different Turbine Meters
Author(s): Jodie G. Pope, John D. Wright, And Sherry D. Sheckels
Abstract/Introduction:
We report additional tests of our extended Lee model for calibrating turbine meters. The model accounts for 1) Reynolds number (Re) dependent drag and lift, 2) bearing static drag and 3) bearing viscous drag. Initially, we tested this model using a dual-rotor, 2.5-cm-diameter turbine meter and flow measurements spanning a 200:1 range (50 ? Re ? 109,000) with liquid mixtures spanning a 42:1 kinematic viscosity range (1.2 10?6 m2 / s ? ? ? 50 10?6 m2 / s). The model correlated the volumetric flow data within 3.6 % over the entire Re range. The same data had a maximum deviation of 17 % from the commonly used Strouhal versus Roshko (or Re) correlation. In this work, we tested the model using three different single-rotor turbine meters with diameters of 2.5 cm, 1.6 cm, and 1.9 cm and flow measurements spanning a 75:1 range (140 Re 102,000) with liquid mixtures spanning a 12:1 kinematic viscosity range (1.2 10?6 m2 / s ? ? ? 14 10?6 m2 / s). The model correlates the flow data within 2.3 % for all three meters over the entire Re range. The same data had a maximum deviation of 4.8 % from the commonly used Strouhal versus Roshko (or Re) correlation.
Go to Download Page
Email Reference
Document ID:
4F598195
Critical Flow Venturi Manifold Improves Gas Flow Calibrations
Author(s): Aaron N. Johnson, Chunhui Li, John D. Wright, Gina m. Kline, And Chris J. Crowley
Abstract/Introduction:
We developed a critical flow venturi (CFV) manifold that reduced the uncertainty of flow calibrations from 0.09 % to as low as 0.074 % (at a 95 % confidence level) for flows of air up to 0.84 kg/s (43 000 L/min at reference conditions of 101.325 kPa and 293.15 K). The CFV manifold also reduced the time required to complete calibrations by a factor of 10. Each CFV was installed in the manifold after it was calibrated in dry air using NISTs 677 L PVTt standard with an uncertainty in mass flow of 0.025%. The CFV manifold is used to calibrate customer flow meters at flows up to 21 times the flow of a single CFV. We demonstrate that interference effects between the CFVs in the manifold are negligible and we provide an uncertainty analysis of the CFV array working standard. We used the CFV array as a transfer standard to demonstrate the metrological equivalence of NISTs 677 L and 26 m3 PVTt standards, which agreed to better than 0.059 %.
Go to Download Page
Email Reference
Document ID:
2B5E2FB6
Improving Turbine Meter Technology For Dod Fuel Flow Measurements
Author(s): G. E. Mattingly, J. E. Winchester, R. D. Kauffman, m. D. Vickers, J. m. Ball, W. B. England
Abstract/Introduction:
DoD has critical needs for high accuracy liquid fuel measurements that pervade all stages of DoD engine testing and performance monitoring. Operational mission success often depends on accurate monitoring of fuel consumption rates given known supply onboard for a given mobile weapon system. These needs and this operational-mission-success drive DoD programs to: a) establish and maintain high accuracy fuel flow measurement capabilities, b) use flow meter characterization procedures that enable satisfactory fuel measurement accuracies over the extremely wide ranges of fluid viscosities and flow conditions encountered by all of its engines, in all of their operating conditions, c) devise and use efficient and effective flow metering arrangements, d) innovate and conduct joint services R&D testing, where needed, to validate functional improvements, and e) implement and assess flow meter and calibration improvements from other sources, such as surrogate fluid techniques
Go to Download Page
Email Reference
Document ID:
15C1AD40
Approximation Of The Gas Expansion Process Occurring In Orifice Meters
Author(s): Kenneth E. Starling
Abstract/Introduction:
This paper uses descriptive approximations to analyze the gas expansion process in orifice meters and utilizes mathematical approximations to perform quantitative calculations. For flow of the gas upstream of the orifice plate which is longitudinal and without swirl, gas which impacts the face of the orifice plate experiences a pressure increase and flows radially toward the pipe centerline where the pressure is lower. Gas flowing radially toward the pipe centerline mixes with the flow near the centerline and enters the orifice bore. The pressure drop across the orifice plate causes the fluid passing through the orifice to accelerate and the maximum longitudinal centerline velocity occurs downstream of the orifice plate. Recirculation downstream of the orifice plate causes the maximum centerline velocity to be lower than would occur without recirculation.
Go to Download Page
Email Reference
Document ID:
2DEA36DA
Additional Error Of Flow Temperature Measurement And Its Influence On The Accuracy Of Fluid Flowrate And Volume Measurement
Author(s): Ye. Pistun, F. Matiko And R. Fedoryshyn
Abstract/Introduction:
Additional systematic error of flow temperature measurement is defined and analyzed. It consists of the following component errors: the error caused by heat exchange between the thermometer case and the pipe wall, the error caused by heat exchange between the pipe wall and the ambient air and the error caused by temperature decrease as the gas is throttled through the pressure differential device. To define the last error a new method is developed for calculating the Joule-Thomson coefficient for natural gas. Mathematical models are developed and verified in order to calculate the values of these errors. Recommendations are proposed in order to eliminate the specified errors of flow temperature measurement and to provide improvement of accuracy of fluid flowrate and volume measurement
Go to Download Page
Email Reference
Document ID:
7DAD6359
New Primary Standard For Water Flow Calibration
Author(s): C. David, P. Claudel
Abstract/Introduction:
Tendency to miniaturize all objects is spread widely in industrial sectors such as health, chemistry, automotive and electronics. Hydraulic components of the systems are also concerned and traceability to the international system of units in this domain has to be developed. Concerning liquid flow metering, several manufacturers industrialize instruments specific for small flows. On a metrological point of view, few National Metrological Institutes (NMI) are able to calibrate flowmeters with liquid at flow rate smaller than 1 l.h-1 (2,8.10-7 m3.s-1). During the last five years, LNE-CETIAT (French designated institut) has designed and built a new calibration facility to cope with this need. This paper present the concept of the calibration facility and the first results obtained with this new standard.
Go to Download Page
Email Reference
Document ID:
2B1BEDDF
Testing Long-Wavelength Acoustic Flowmeter Concepts For Flue Gas Flows
Author(s): Lee J. Gorny, Keith A. Gillis, And Michael R. Moldover
Abstract/Introduction:
As a part of NISTs program to standardize measurements of greenhouse gas emissions, we are developing a long-wavelength acoustic flowmeter (LWAF) for accurate, economical measurements of exhaust flows from coal-burning power plants. Measurements of the flue gas mass flow combined with the gass composition are used to determine the emitted CO2 and other by-products of combustion. Today, such measurements have uncertainties of 5 % or more due to the large size of the flue-gas stacks and the flows non-uniform, unsteady, and swirling profile. A LWAF averages the spatial non-uniformities of the axial velocity over the entire cross section in a manner insensitive to flow distortions. In contrast, conventional techniques measure gas flow only at isolated points or averaged along chords across the stack. We constructed a 1:100 scale, calibrated flow facility for the initial development of a LWAF.
Go to Download Page
Email Reference
Document ID:
2C49A135
Calibration Facility For Liquefied Natural Gas Flow-Meters - CFD Modeling
Author(s): Jan Gerl,Peter Lucas,Oswin Kerkhof
Abstract/Introduction:
A new calibration facility for liquefied natural gas (LNG) flow-meters is being developed at VSL for flow-rates up to 300 m3/h. The facility is based on comparing a meter under test to a set of Coriolis meters which are calibrated by a bootstrap technique using a meter traceable to an already existing laboratory-scale gravimetric LNG standard. A behavior of the LNG flow in the developed facility is predicted also by a CFD modeling using an OpenFOAM software. The modeling is focused especially to quality of LNG flow in front of the Coriolis standards including a possibility of cavitation and calculation of flow profiles. In the presentation we will show some results of this investigation - flow behavior at pipe to pipe junctions of various shapes and its impact on the flow quality downstream from the junctions. This work is done within a Metrology for LNG project which is a part of European Metrology Research Programme and is based on a cooperation of several European national metrology institutes
Go to Download Page
Email Reference
Document ID:
0A4BA900
Metrology For Improved Power Plant Efficiency: The Power Plant Project
Author(s): T. Lederer, S. Rudtsch, B. Hay, P. Lau, G. Rietveld, P. Klason, K. Anhalt, O. Bker, L. Chapman, J. Frederiksen, J. Hameury, G. Kok, P. Milota, K. Riski, O. Penttinen, S. Sarge1, R. Strnad, K. Tawackolian And B. Wilthan1
Abstract/Introduction:
Large scale power plants based on nuclear or conventional fuel provide about 80 % of generated electricity in the EU and nearly 90 % of hot water used for district heating. Despite the important and necessary increase of renewable energy by approximately 10 % by the year 2020, large scale power plants will form the backbone for the secure supply of energy for the next few decades. It is evident, that improving the energy efficiency of nuclear, coal and gas plants will generate a significant contribution to energy conservation, preservation of natural resources, reduction of emissions and the protection of the environment. The joint research project called Power Plant (http://www.power-plant-efficiency.de) focuses both on the metrological research necessary to reduce the measurement uncertainty of the important control parameters (temperature, flow, thermal energy and electrical output) of power plants and on research on advanced materials to be used in future turbines. The total results of the research work could lead to an overall additional enhancement of energy efficiency of 2 % - 3 % for all types of large power plants, and a commensurate reduction of emissions. The metrological research activities within the project are organized in 4 work packages (WP) covering temperature (WP1), thermophysical properties (WP2), flow (WP3) and on-site electrical power output measurements (WP4). This paper describes the different work packages and presents some of the preliminary results from WP3
Go to Download Page
Email Reference
Document ID:
D05CDBA9
Allow Coriolis Meter Verification To Reduce Your Proving And Proof-Test Costs
Author(s): Timothy J. Cunningham,Tom Obanion
Abstract/Introduction:
Industry and Agencies are dedicated to ensuring fair and safe measurement in numerous applica-tions such as fiscal transfer of gases and liquids, Environmental compliance and Safety systems. Annual or more frequent proving of flow meters and other devices is common. Coriolis meters are widely known for their stability and linearity over time, suggesting that proving intervals might be extended, reducing Proving and Proof-Test costs. Coriolis Meter Verification uses onboard diagnostics to measure the flowtube stiffness, which is directly related to the flow calibration factor. Each verification checks meter stiffness and compares it to a factory baseline. If the stiffness is unchanged, the calibration factor is correct and the meter will meet its mass flow accuracy specification. Meter Verifications confirmation of the accuracy of the measurement and the integrity of the me-ter provides a means to reduce cost by extending proving intervals
Go to Download Page
Email Reference
Document ID:
D4C675B9
Expert Systems In Ultrasonic Flow Meters
Author(s): Marcel J.M. Vermeulen, Jan G. Drenthen, Hilko Den Hollander
Abstract/Introduction:
Custody transfer ultrasonic gas flow meters are the cash registers of the companies. These cash registers should measure accurately. To determine the accuracy two aspects are addressed: - The calibration: The deviation of an ultrasonic flow meter to the national standards under ideal flowing conditions. - The installation effects: The increase of uncertainty due to the non-ideal on-site installation, as described in the international standards like ISO17089 and OIML R137. A third aspect, the change in uncertainty of the ultrasonic flow meter while in operation, is often overlooked. For example already limited fouling on the bottom of the pipe can give an additional uncertainty of 0.2%. Other aspects like sever flow profile changes due to partly blockage of a flow conditioner, damaged transducers or high levels of ultrasonic noise also play an important role during the operational time of an ultrasonic flow meter
Go to Download Page
Email Reference
Document ID:
1ACD4EB1
Horizontally Installed 8, 0.6 Beta Ratio Venturi Meter Wet Natural Gas Flow Response
Author(s): Richard Steven, Charlie Britton & Joshua Kinney
Abstract/Introduction:
The hydrocarbon production industries use of wet gas flow metering techniques continues to increase worldwide. The demand has driven the development of several sophisticated wet natural gas flow meters that predict both the gas and liquid flow rates simultaneously. However, the cost of such sophisticated wet gas flow meters prohibits their use in many wet gas flow production applications. The relatively simple and inexpensive, and therefore the most common wet gas flow metering technique, is to use a stand alone gas Venturi meter with a wet gas correlation. A wet gas correlation is a correction factor for the positive bias (or over-reading) induced on the meters gas flow rate prediction by the liquid. The main limitation of using a stand alone Venturi meter with a wet gas correlation is that such an approach requires the liquid flow rate to be found by some external means and keypad entered into the flow computer. Only then does the system correct for the over-reading and predict the gas flow rate
Go to Download Page
Email Reference
Document ID:
28CD3EC3
Orifice Meter Diagnostics - A Discussion On Theory, Laboratory Tests, System Interface And Field Results
Author(s): Richard Steven,Casey Hodges
Abstract/Introduction:
the generic family of differential pressure (DP) meters. All generic DP meters operate according to the same physical principles. In 2008 a theoretical DP meter diagnostic concept was described by Steven 1. In 2009 this theoretical concept was developed into a proposed practical industrial system. Swinton Technology and DP Diagnostics have now developed the product (called Prognosis). In 2010 Prognosis was successfully field tested on orifice plate meters by BP and ConocoPhillips (see Skelton 3). Over the last two years the technology has been further refined and systems are now operational in various DP meter applications around the world. In this paper the diagnostic theory for orifice meters is discussed in relation to recent improvements to the diagnostic system. CEESI laboratory test results are shown from the recently upgraded diagnostic system monitoring correctly operating and deliberately malfunctioning orifice meters. Finally, as part of a Prognosis field trial CEESI Measurement Solutions Inc. (CMSI) included Prognosis on orifice meter station auditing projects. The subsequent response of Prognosis to correctly operating and malfunctioning live natural gas orifice meters is shown
Go to Download Page
Email Reference
Document ID:
953C84FA
How Todays Gas Ultrasonic Meter Handles Compressor Pulsations
Author(s): John Lansing
Abstract/Introduction:
To date limited testing has been done to determine the effects pulsation in the gas stream may have on the ultrasonic meters accuracy and performance. Some previous testing does show that there may be an impact on accuracy when the frequency of the pulsation is the same as, or a multiple of, the sampling frequency of the ultrasonic meter. AGA 9 Ref 1 discusses pulsation and indicates errors from pulsation can occur depending upon the level of pulsation. However, as little data exists on the potential affects, it is only mentioned in this document. To more clearly understand the pulsation impact, SICK sponsored tests that were conducted at the TransCanada Pipe Line Didsbury Gas Dynamic Test Facility (GDTF). This is also known as the NOVA Chemical Didsbury Test Facility. The results shown in this presentation are for an NPS 8 - FLOWSIC600 4 + 1 meter, also known as the 2plex design. A series of flow rates, frequency of pulsations, and amplitudes were generated upstream of the meter. The accuracy of the ultrasonic meter was determined by comparison to sonic nozzles that are located upstream of the pulsation source in such a manner so as to be unaffected by the pulsations being generated
Go to Download Page
Email Reference
Document ID:
AD9C05F3
Calibration Of Ultrasonic Flow Meter Using Blow-Down Type High Pressure Gas Flow Standard
Author(s): Ching-Yi Kuo, Yi-Lin Ho, Toralf Dietz, Wen-Bin Wang, Fong-Ruey Yang, Chun-Min Su And Jiunn-Haur Shaw
Abstract/Introduction:
This paper investigates the calibration of a 100 mm ultrasonic flow meter (USM) using the blow-down type high pressure gas flow facility at the Center for Measurement Standards (CMS) in Taiwan. This gas flow facility uses a compact sonic nozzle array (CSNA) as the reference standard. The CSNA is calibrated first by a gyroscope weighing system, and then it is used to calibrate meters from customers. In the typical calibration setup, the meter under test (MUT) is installed downstream of the CSNA. During calibration, the temperature of the gas flowing through the MUT decreases continuously due to decreasing pressure of the gas storage tank together with the thermal effects downstream of the CSNA because of the Joule-Thomson effect. The possible effect of the unstable fluid properties due to large temperature changes at the MUT was evaluated
Go to Download Page
Email Reference
Document ID:
1331DD18
Transmitter Operation A Ten Year Perspective
Author(s): Richard Rans , Warren Peterson
Abstract/Introduction:
Analysis of data over a ten year period reveals important transmitter operating and maintenance insights. Verification data has been factored into its uncertainty components of zero, slope (span), linearity, and hysteresis and then analyzed to demonstrate the long term stability capabilities of intelligent transmitters and expose factor that need to be monitored and controlled to minimize measurement uncertainty.
Go to Download Page
Email Reference
Document ID:
9E477D24
Ultrasonic Flowmeters, Latest Developments Now Used In Praxis
Author(s): D. Laan
Abstract/Introduction:
Already in the early 1980s ultrasonic flowmeters were being used in a variety of applications throughout the industry. Of course not only the technology of 3 decades ago does no longer compare to that of today, but also the experience of the usage of this measurement principle in the field has grown considerably. Developments in technology and application knowledge are at the basis of the growth in applications of ultrasonic flow measurement in the field today. Interestingly enough it can be seen that this growth not only took place in common, technically less challenging, applications but also strongly developed in the direction of high end applications like custody transfer of oil and gas, boiler feed water measurement, steam, LNG. The ultrasonic measurement technology has become known for its excellent versatility and measurement performance. Of which the most important is the long term measurement stability
Go to Download Page
Email Reference
Document ID:
8459DD01
Field Experience Of Ultrasonic Flow Meter Use In CO2-Rich Applications
Author(s): Keith Harper, John Lansing, Toralf Dietz
Abstract/Introduction:
Ultrasonic gas flow meters have gained a wide acceptance in the field of natural gas exploration, transport, storage and distribution as well as in the process industry. There is one major segment, which could not be addressed so far with this technology - high attenuating gases like Carbon Dioxide. On the other hand exploration of less conventional natural gas sources will lead to more diverse operating conditions and compositions for natural gas measurement. One significant change compared to traditional sources is the increased level of CO2 in the gas. While standard applications deal with levels well below 5 mole percent, this amount may be as high as 20 mole percent, or even higher at some installations. Re-injection of CO2 into declining oilfields will require accurate and reliable flow measurement. Such applications contain up to 60% CO2 and require an accuracy level comparable to custody transfer for natural gas. While the flow measurement is currently being done primarily using ?p devices, such as orifice meters, it would be a significant improvement to use ultrasonic meters with their increased functionality, larger turn-down ratio reduced maintenance, and diagnostic capabilities. Applications such as CCS (Carbon capture and storage) with CO2 concentrations near 100% are even feasible today. Table 1 gives a short summary of various applications and the typical amount of carbon dioxide in the gas stream
Go to Download Page
Email Reference
Document ID:
F034766E
Calibration Of Large Proving Tank - Method Validation
Author(s): N. Almeida, E. Batista, E. Filipe
Abstract/Introduction:
Large proving tanks with a volume greater than 1000 L, are used in industry for storing and measuring large quantities of liquids, not only water but also fuel, milk, wine, olive oil, among others. In order to obtain accurate and reliable results, it is necessary to determine the volume inside the proving tank, through its calibration, using appropriate methods and standards. In the volumetric method implemented at the Volume Laboratory of the Portuguese Institute for Quality - Central Laboratory of Metrology (IPQ-LCM) volume standards between 1 L and 500 L are used. In order to reduce the working time and improve the precision of the volumetric method applied to large volumes, a volume standard of 1000 L was installed and several tests were preformed and the results validated through statistical analysis
Go to Download Page
Email Reference
Document ID:
FC4D7BAB
The Effects Of Flow Conditioning On The Performance Of Multipath Ultrasonic Meters
Author(s): Gregor J Brown, Bobbie Griffith
Abstract/Introduction:
Multipath ultrasonic meters have been in development since the 1960s. In early publications and patents, it was noted how multipath meters that employ numerical integration methods could significantly reduce the sensitivity to distortions in the axial velocity profile caused by upstream hydraulic disturbances. Studies of the accuracy of the numerical integration methods have shown that chordal meters with four chords spaced according to the rules of Gaussian integration could typically be expected perform with errors of less than one or two tenths of a percent. One of the most frequently cited advantages of ultrasonic meters is that they are non-intrusive and produce no more pressure loss than a straight piece of pipe. Combined with the lack of moving parts, and the possibility of calibrating an ultrasonic meter on the basis of geometric and timing measurements alone, ultrasonic technology has rightly been viewed as having great potential for custody transfer measurement in the oil and gas industry
Go to Download Page
Email Reference
Document ID:
02A7A2F5
Airspeed Calibration Services: Laser Doppler Anemometer Calibration And Its Uncertainty
Author(s): Iosif I. Shinder, Michael R. Moldover, Mike Hall
Abstract/Introduction:
The National Institute of Standards and Technology (NIST) and the Oak Ridge National Laboratory (ORNL) are improving their airspeed calibration services. Both laboratories use spinning disks to generate linear velocities that are traceable to NISTs length and time standards. We compared their spinning disks using NISTs laser Doppler anemometer (LDA) as a transfer standard. At 10 m/s, the disks differed by (0.11 0.26) %, where the uncertainty is one standard deviation. We discuss the techniques used to calibrate LDAs with spinning disks and their uncertainties
Go to Download Page
Email Reference
Document ID:
C88D800B
Ultrasonic Clamp-On Flow Metering - 50 Years And Counting
Author(s): Peter Baldwin, Izzy Rivera
Abstract/Introduction:
Over the last half century, the ultrasonic clamp-on flow meter in all of its forms has become more and more accepted into industry as a reliable and accurate metering device. While some engineers view these instruments as a retrofit device, others see them as a meter of choice. Whatever the view of the individual, the ultrasonic clamp-on flow meter has come to be recognized as having the biggest growth potential in the metering marketplace. This paper will take a look at the history of clamp-on metering and the way it has developed through the years from early Doppler devices to the transit time meters that are seen today. The paper will also look at the types of applications in which ultrasonic clamp-on meters are being used on a daily basis. Finally, the paper will try and look at the future of the clamp-on meter and where technology and the marketplace may drive it.
Go to Download Page
Email Reference
Document ID:
BA9472CD
The Application Of Small Sonic Nozzles In Test Rigs With Natural Gas
Author(s): Rainer Kramer, Bodo Mickan
Abstract/Introduction:
Test rigs with small sonic nozzles are widely in use for the verification of domestic gas meters. The typical flow rates range from 10 l/h to about 40 m3/h. In the past, the test gas was air in nearly all of the commercial applications. This was sufficient as long as the domestic meters could be tested and verified with air. But nowadays the market faces the introduction of new technologies, especially meters using the so-called thermal mass flow elements. Meters based on this technology require the use of calibration gas which has to be as similar as possible with the gas in application. Otherwise a correct adjustment and verification cannot be confirmed. The application of small sonic nozzles down to 10 l/h in test rigs with natural gases asks for the consideration of new things concerning the correct traceability within the required uncertainties:
Go to Download Page
Email Reference
Document ID:
8F74C51A
Impacts Upon The Measurement Uncertainty Of Liquid-Flow Facilities Originating From Random-Like Variations Of The Flow Parameters
Author(s): Rainer Engel, Hans-Joachim Baade
Abstract/Introduction:
Traceability of the measurement units in fluid flow metering, as the state-of-the-art approach, is practiced as a so-called element-by-element method which relies upon the idealistic assumption that the measurement process in a flow calibration facility can be run under exact steady-state conditions, i.e. absolutely no fluctuations of the flow quantities are assumed to occur during the flow measurement process. Based upon this assumption, it seems to be sufficient that, for traceability purposes, solely the those SI units are quantitatively taken into account which are the composing elements of the fluid flow measurands, the unit fluid flow rate or the total volume flow, respectively
Go to Download Page
Email Reference
Document ID:
D9A1D28F
The Beneficial Impact Of Controlled Very Rough Metering Tube
Author(s): Blaine Sawchuk, Danny Sawchuk, Reginald Selirio
Abstract/Introduction:
The impact of very high pipe roughness values on the long term accuracy of an ultrasonic flow meter is investigated. It appears that we are presently running ultrasonic flow meters in the wrong pipe roughness location on the Moody diagram. Instead, the meter tube should be extremely rough, or it should be shortened with the flow conditioner assuming the role of a very rough pipe, which is fluid dynamically equivalent. This paper revisits basics by using the well-established and accepted (but probably incorrect) pipe flow concepts presented by Moody et al circa ASME 1944, and merges them with the latest understandings of ultrasonic flow meter design and operation experts
Go to Download Page
Email Reference
Document ID:
C179E71F
Achieving Better Liquid Measurement Accuracy Using A Slightly Different Perspective
Author(s): Daniel J. Rudroff
Abstract/Introduction:
Custody Transfer Measurement in the Oil and Gas Business has been described many ways. It has been called An accuracy in measurement, that both the buyers and sellers can agree upon, or The best that can be achieved to meet the contract conditions. But I like to call it The Search for the Truth. Ever since petroleum has been bought and sold, people have searched for better ways to measure on the fly with better accuracies. A big advancement was the pipe prover. API requires an accuracy of the prover volume of 0.02% when compared to a standard such as NIST traceable Seraphin Cans. If we want to put 0.02% into perspective that is 6.45 Teaspoons or a little more than 2 Tablespoons of oil in one 42 gallon barrel. That is very good measurement and that is worse case. That is why we all strive to exceed the 0.02% required by API. We know and understand the value increased accuracy has to our companies
Go to Download Page
Email Reference
Document ID:
2022B977
The Impact On Measurement And Supply Of Natural Gas Due To The Formation And Presence Of Particles Within The Gas Stream
Author(s): David J. Pack
Abstract/Introduction:
Solid particles within natural gas transmission and distribution pipeline systems are known to create varying operational constraints for pipeline operators and end users - from nuisance value to complete stoppage of the gas flow. The solid particles can be extremely variable, both in composition and origin. The particles can consist of discrete elements, or be mechanically and/or chemically driven combinations of soils, iron oxides, iron sulphides, sulphur compounds, salts, metal oxides, hydrocarbons and other contaminants. The most commonly reported contamination related problem is that of the so-called black powder. However, more recently, a new form of contamination has been causing concern for both pipeline operators and in particular industrial end users such as gas turbine equipped power generators. This contamination is mostly sulphur related and is termed as the elemental sulphur formation and deposition process
Go to Download Page
Email Reference
Document ID:
BB2AB8D3
The Investigation On The Flow Characteristic Of Small Mems Nozzle
Author(s): Chunhui Li,Bodo Mickan
Abstract/Introduction:
The experiments of CBPR and discharge coefficient for traditional ISO nozzle and MEMS nozzle were conducted and shown in this paper. From the experimental results, it was clearly that the critical flow could be reached for MEMS, but the CBPR was much smaller than that for traditional nozzle. On the other hand, CBPR was almost fixed for the same nozzle with different Reynolds number. The CBPR for the MEMS with the similar geometric shape increased with the throat diameter increased, and changed with different geometric shape. For the Group B and C with the similar geometry, the discharge coefficient for B direction with longer entrance length was always higher than that for F direction with shorter entrance length. On the base of the experimental results
Go to Download Page
Email Reference
Document ID:
0CF045D8
A Technique To Measure Instantaneous Mass Flow Rate For Time-Periodic Laminar Pipe Flows And Its Verification With A Unique Mass Flow Rate Control Device
Author(s): Blent nsala And Subhashis RAY,TUBITAK Ume
Abstract/Introduction:
The present paper reports a mass flow rate measurement technique which, in principle, is applicable to any time-periodic laminar pipe flows. The referred mass flow rate metering technique is based on the exact analytical solution for fully-developed, laminar, pulsating pipe flows. In this paper, the theoretical background of the measuring technique is summarized. For experimental verification, a mass flow rate control unit was employed which permits any predetermined, time-varying, mass flow rates to be produced that is proportional to the voltage of an electronic input signal to the unit. The basic concept of this unit and its performance are also summarized in the paper. The application of this unit for verifying the performance of the developed mass flow rate measuring technique forms the major part of the paper. Performance tests were carried out for various time variations in mass flow rate pulsations. It is shown that the mass flow rate of the mean flow and that of the pulsating flow can be separated and both can be accurately measured with the proposed method. Comparative measurements show that this technique works extremely well and accurately reproduces the mass flow rate variations in time, imposed by the mass flow rate control unit, even in the case of pressure induced mass flow oscillations that results from the sudden changes in flow rate which are also known as water hammer or pressure surge
Go to Download Page
Email Reference
Document ID:
A23529FA
Operation, Traceability And Measurement Uncertainty Of The Largest Water Flow Calibration Facility In Taiwan
Author(s): Chun-Lin Chiang, Yi-Lin Ho And Chun-Min Su
Abstract/Introduction:
The largest water flow calibration facility in Taiwan had re-established and accredited with ISO 17025 compliance by the Taiwan Accreditation Foundation (TAF) in October, 2011. This modified facility employs comparison method and volumetric (to deliver) method, together with flying start and finish mode, to calibrate water flowmeters with nominal sizes (DN) of 25 mm to 1500 mm. The comparison method covers calibrations in the flow rate range from 0.2 m3/h to 4200 m3/h, while the volumetric method enables calibrations from 125 m3/h to 8000 m3/h. A patented flow control technique is used to stabilize the flow during calibration, allowing the variation of flow rate to be within 1 %. The measurement uncertainty for comparison method was evaluated base on flow rate ranges of the standard meters. The maximum relative expanded uncertainty is 0.7 % and the minimum is 0.21 %. On the other hand, the measurement uncertainty for volumetric method depends on the liquid volume delivered, and the resulting expanded uncertainty has a maximum of 0.25 %. The metrological traceability from the primary standard of National Measurement Laboratory, Taiwan, to this facility was scientifically established through unbroken chain of documented calibrations of standard flowmeters. In this paper, we will show the traceability hierarchy of the system and how the flow measurement uncertainty is evaluated accordingly. Some system operation issues will also be addressed.
Go to Download Page
Email Reference
Document ID:
9161C676
Development And Test Of Flow Conditioner
Author(s): Ivan Juarez - Maximo Cargnelutti - Diego N. Moncada
Abstract/Introduction:
Flow conditioning is one of the tools that measurement engineers have to improve its flow measurement data in order to, on one hand, comply regulatory standards and, on the other, guarantee that economical transactions are clear and transparent without doubts for both parties: seller and buyer. Latest developments in numerical simulation (CFD) using commercial and friendly software permits intermediate and end users to determine which would be the most adequate conditioner available to correct unfavorable conditions, for flow measurement purposes. Besides, due simulation is not sufficient to determine the characteristics of flow conditioners, validation in a Secondary Flow Laboratory need to be carried out as well. This verification is made comparing metering responses from a given meter against a master meter, in several scenarios, where different pipe configurations.
Go to Download Page
Email Reference
Document ID:
3BDEBBDC
Adjusting The Flow Diverters Timer Actuation In Liquid Flow Calibration Facilities
Author(s): R. Engel
Abstract/Introduction:
Introduction - Motivation Theoretical background Numerical correction vs. zero adjustment Provision of timer actuation with incremental adjustment capabilities Iterative timing error correction Conclusions
Go to Download Page
Email Reference
Document ID:
0503E80E
Uncertainty Analysis Of The Low Flow Capability Of A Natural Gas Calibration Facility
Author(s): Thomas Kegel
Abstract/Introduction:
The low flowrate capability of the CEESIowa Natural Gas Calibration facility is based on a series of flowmeter standards installed in a custom designed pipe system. The flow standards consist of three ultrasonic and one coriolis meter. The pipe and valve system design includes meter redundancy that facilitates monitoring the long term consistency of calibration services. The traceability of the flow standards is established using a three step process. It begins with the calibration of a set of four critical flow venturies (CFVs) in direct comparison with a primary flow standard. The four CFVs then serve as transfer standards to calibrate a second set of six CFVs. The six CFVs are then used as transfer standards to calibrate the ultrasonic meter flow standards. This paper details the uncertainty analyses of both the initial calibration and ongoing monitoring of the calibration process. Uncertainty components include calibration processes, gas properties, and the measurements of pressure and temperature. The analysis includes a unique application of statistical techniques to localize the sources of observed random effects
Go to Download Page
Email Reference
Document ID:
0B628475
The Humidity Effect On The Calibration Of Discharge Coefficient Of Sonic Nozzle By Means Of Pvtt Facility
Author(s): Chunhui Li,Bodo Mickan
Abstract/Introduction:
When the pVTt facility was used to calibrate the discharge coefficient of sonic nozzle, the initial pressure was usually as low as possible to reduce the uncertainty. The atmospheric air with humidity was working fluid in NIM, which was used to calibrate the discharge coefficient of sonic nozzle. In a series of experiments, it became obviously that the calibration result of sonic nozzles determined by means of pVTt facility was depending on the initial pressure in the collection vessel if humid air was in use. The experimental facts and discusses two possibilities of physical reason for this effect was presented in this paper.
Go to Download Page
Email Reference
Document ID:
EDDBF3D4
Experimental Study On Critical Back Pressure Ratio Of Sonic Nozzle At Low Reynold Number
Author(s): Heming Hu, Chi Wang, Lishui Cui, Chunhui Li, Tao Meng
Abstract/Introduction:
Sonic nozzle is the most common standard flow meter in gas flow calibration facilities, and it is necessary to test the critical back pressure ratio for nozzles whose throat Reynold numbers are smaller than 2105 , because the critical back pressure ratio is directly related to the accuracy of the facilities. A test system based on nozzle in series method has been built, with the pressure measurement instead of the mass flow rate measurement, to determine the critical back pressure ratio accurately and efficiently. Experimental results show that the critical back pressure ratio is smaller than the designed value for nozzles at low throat Reynold number, and that the smaller the throat Reynold number, the lower the critical back pressure ratio. Probable premature unchoking phenomena can cause further decrease of the critical back pressure ratio, and the degree of the ratio decease is related to the manufacturing level of the nozzles, which also explains the necessity of critical back pressure ratio test
Go to Download Page
Email Reference
Document ID:
2020EC2D