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.
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...
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...
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...
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...
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.
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...
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...
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%.
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.