IMEKO Event Proceedings Search

   

Page 239 of 977 Results 2381 - 2390 of 9762

Michael Carter, William Johansen, Charles Britton
Performance of a Gas Flow Meter Calibration System Utilizing Critical Flow Venturi Standards

A set of Critical Flow Venturis (CFVs) were manufactured by Flow Systems and calibrated by NIST in Gaithersburg, MD. Subsequently these flow standards along with pressure and temperature standards have been integrated into a gas flow meter calibration (GFC) system. Performance data and an uncertainty analysis will be discussed. Calibration data on these CFV standards will be used to inter-compare the NIST and CEESI primary facilities.

Michael Bair, Casey Rombouts
Improvements in the Implementation of Laminar and Sonic Based Gas Flow Meters in  the Range of 2 X 10-5 G‧S-1(1 Ncc Min-1)   to 100 G‧S-1  (5000 NL‧Min-1)

During the middle of the last decade, DH Instruments (now Fluke Calibration) developed an improved primary calibration chain based on dynamic gravimetric measurements and a successive addition technique to provide significantly lower uncertainty in gas flow from 2 x 10-5 g•s-1 (1 Ncc min-1) to 100 g•s-1 (5000 Nl•min-1). Recently, in order to disseminate the lower uncertainties achieved to the flow measurement community, significant improvements were made to the laminar and sonic based flow meters supported by the gas flow references. The improvements include the use of NIST (USA) Refprop gas property data, a new Reynolds number and pressure characterization, lower uncertainties in absolute and differential pressure monitoring, and filtration designed directly into the meter. These improvements decreased the uncertainty of the population of these instruments and should also improve their reliability. This paper discusses these advances and the benefits to gas flow metrology.

Thiago Cobu
Modeling Laminar Flow Meters For Process Gases

We calibrated three models of commercially-manufactured, laminar flow meters (LFMs) with nitrogen at four pressures (100 kPa, 200 kPa, 300 kPa, and 400 kPa) over a 10:1 flow range using NIST’s primary flow standards and a physical model. Without additional calibration, each LFM was used to measure the flow of three process gases (Ar, He, and CO 2 ) over the same pressure and flow ranges with a maximum error of only 0.5 %. The calibration and flow measurements used the gas-property data from NIST’s database REFPROP 8.0 and a physical model for each meter that accounts for the viscous pressure drop, compressibility and non-ideal gas behavior, slip flow effects, kinetic energy effects, gas expansion effects, and thermal effects. The three LFMs have design differences that illustrate the dependence of the model corrections on LFM construction and the gas used. The LFM model improves results for the conditions tested by a factor of 4 over the flow coefficient and viscosity coefficient plots commonly used to present LFM calibration data.

Chun-lin Chiang, Yi-lin Ho, Jian-yuan Chen
Novel Modification of Large Water Calibration Facility

Traditionally, the method used to determine measurement errors of water meters is the so-called "collection" method, in which the quantity of water passed through the water meter is collected in a vessel. Then the quantity is determined volumetrically or by weighing. Other methods with permitted accuracy levels are also accepted by international standards. Now some types of flow meters have relatively high accuracy and can be used to substitute volume tanks as flow standards for error tests of water meters. A flow laboratory which has the water meter test facility has the largest flow capacity in Taiwan. It adopts “collection” method and "delivering" method for error tests of water meters with nominal size (DN) equal to or less than 300 mm and DN from 400 mm to 2 000 mm respectively. Nevertheless, test facilities which introduced volume tanks and "delivering" method were normally processed of an unstable flow rate because of the reducing of water level in the volume tank during the measurement and then affected the measurement accuracy of tests. This paper describes the modification of the test facility. The "master meter" method was substituted for "collection" method and will had a maximum test meter size up to 800 mm. The maximum test flow rate could be to 4 200 m³/h and the measurement uncertainty was estimated to be 0.2 %. A novel design of a multi-channel flow adaptive control device was provided for improving the flow stability of "delivering" method. It used a number of drains with control valves to adjust the flow during the measurement. The maximum test flow rate could be up to 10 000 m³/h and the maximum test meter size could reach to 1 500 mm.

Christopher David, Pierre Claudel
Novel Water Flow Facility in France - Range Extension to Low Flow Rates (10000 ml/h down to 1 ml/h)

In order to extend the French water flow calibration range, LNE-CETIAT is on progress to build a new reference for flow rate measurements ranging from 10 l·h-1 down to 1 ml·h-1. This new facility based on a gravimetric principle (ISO 4185) will enable calibration with water temperature between 10 °C and 50 °C. Flow is regulated by the combined use of a tightly regulated “upstream” pressure (0,1 to 10 bar) and the use of capillaries under laminar flow. The expected relative uncertainty for the water flow rate is 0.1 % with a coverage factor k = 2 (95% confidence). The paper described the design and the ongoing implementation of this new calibration facility.

Yu-Ming Shen
Fluid Dynamics Model for Liquid Flow Calibration Facility

Some designs for liquid flow calibration facility are studied by employing liquid dynamics theory. The flow equation in test pipe, the overflow formula in water tower and the module of liquid film attached in the tank are put forward and calculated. This paper provides theoretical references for designing liquid flow calibration facility.

Ying Yan Qu, Terry Lucke, Simon Beecham
Measuring Flowrates in Partially-Filled Pipes in Siphonic Roof Drainage Systems

While a variety of flow measurement devices are available to measure the flowrate of water through closed pipe systems, these devices generally only function correctly when the pipes are completely full of water. Accurate measurement of water flowrates in partially- filled pipes is extremely difficult. In siphonic drainage systems, this problem is further compounded by the unsteady flow conditions that occur in the pipework during the priming process. This has been a major obstacle to understanding the performance of these systems in practice. In order to accurately model the priming process in multi-outlet siphonic roof drainage systems, a method of estimating the instantaneous flowrates through the partially- filled individual pipes needs to be developed.
This paper describes an experimental method of determining flowrates in partially-filled pipes using a propeller-type current meter to measure flow velocity and a pressure transducer to measure water depth and a modified version of the continuity equation. A computational model is presented which estimates the unsteady flowrates passing through partially-filled pipework. Overall, the experimental results are promising and correspond well with the model. The results of this study will ultimately be used to develop an unsteady flow model of the priming process in multi-outlet siphonic roof drainage systems.

Jan Gersl, Libor Lojek
European Comparison of National Water Flow Laboratories

The results of supplementary comparison of European national water flow laboratories - Euramet 1046 - are reviewed. The comparison started in May 2008 and the measurements were finished in June 2009. Eleven laboratories took part in the comparison - namely: Austria (BEV), Bosnia and Herzegovina (IMBH), Czech Republic (CMI - pilot laboratory), France (CETIAT), Greece (EIM), Hungary (MKEH), Lithuania (VMT/LEI), Republic of Macedonia (BoM), Norway (Justervesenet), Slovakia (SMU) and Switzerland (METAS). Two electromagnetic flow-meters were used as transfer standards. Laboratories were compared in a range of flow-rates between 1 m³/h and 10 m³/h with water of temperature near to 20 °C. The data were evaluated by the standard methods.

Cui Lishui, Lixu
A Kind of New Calibration Method for the Volume of Bell Prover

A new 1 m³ bell prover is developed by flow laboratory in China national institute of metrology. Laser tracker and laser interferometer is applied to measure the volume of the bell prover. The result suggests this kind of geometric method is feasible and the uncertainty of result is less than 0.1%.

Miroslava Benkova, Stefan Makovnik, Ivan Mikulecky, Vlastimil Zamecnik
Bell Prover – Calibration and Monitoring of Time Stability

This paper is focused on the calibration and measuring of the geometric parameters of a bell prover, that served as a standard of volume of gas flow. It also includes methods for monitoring of time stability of the bell prover: intra- and inter- laboratory comparison measurements, Shewhart analysis and planned evaluation of recalibration intervals.

Page 239 of 977 Results 2381 - 2390 of 9762