Recently, the Comité International des Poids et Mesures (CIPM) decided to provide a structure for the harmonization and comparison of measurement standards for fluid flow and related quantities. As with all other measurement quantities considered by the CIPM, this effort should provide the means by which to ascertain the equivalency of flow standards among the various countries of the World as declared in their entries to the Mutual Recognition Arrangement (MRA) of the CIPM. The CIPM flow harmonization effort will be conducted under the umbrella of a newly created Working Group for Flow and...
Ultrasonic technology is evolving rapidly. It offers prospects for improving flow measurements, for serving as transfer standards, and possibly for serving as a primary flow standard. This paper describes results from several current NIST projects that have the goal of assessing travel-time ultrasonic flow measurement techniques for their potential in improving flow measurements. These projects include a meter testing program and computer simulations of travel-time techniques in ideal conditions and in measured pipe flows for a range of metering configurations. Meter test results show that...
A flow meter manufacturer has recently developed a new system for calibrating its flow instruments. This system is based on the use of Coriolis flow meters as intermediate transfer standards. This new system is referred to as the Transfer Standard Method or TSM. This paper and presentation will review the test data used to establish the validity of the Coriolis-based TSM, and will describe the process layout and design of the new TSM flow calibration stands. The focus of the paper, however, will be on traceability of the calibrations to national standards and on the uncertainty analysis for...
A diverting device (diverter) is an essential and error determining component part of a liquid flow calibration facility based upon a static gravimetric system with flying start and finish. The diverter timing error can be considerably reduced by the use of an angular encoding transducer in combination with an appropriate electronic and storage device. Further benefits in diverter performance can be obtained by an electric diverter actuator.
There are many designs of ultrasonic domestic gas meters but all the main ones use the measurement of the transit time of an ultrasonic signal through the flowing gas to estimate its velocity. The shape of the duct and devices to control the waveform of the signal passing through it are significant parts of the design. The transducers used to produce the signal, reciprocal operation and the main techniques to time the transit of the signal to several nanoseconds are discussed. The acceptance of these meters has been restricted and their possible future is discussed.
In the present investigation, the problem of accurate determination of volumetric flows by means of the so-called vortex-shedding flow meter in the case of shape changes and deviations of the geometry from the original specifications due to manufacturing tolerances and imperfections was studied. To this end, the flow about the bluff body used in the presently studied vortex-shedding flow meter was numerically simulated using a solver of the unsteady, compressible (air) or incompressible (water) Navier-Stokes equations in two and three dimensions. The computations were carried out for several...
In vortex flowmeters, the frequency of vortex formation at a bluff body inserted into the flow is used to determine the flow velocity. The frequency is determined using a sensor that measures the time-dependent distortions of the down-stream flow field. But the (univariate) sensor signal contains more information than just the vortex frequency. We use this inherent extra information to verify if the pipe flow has the form expected for the correct mounting of the flowmeter, and thus, if the flow measurement has the expected high accuracy. In designing the method, special care was taken to...
The Afsluitdijk (literally Closing Dike) has been constructed in 1932. The objectives of the dike were flood protection, an area increase for agriculture and a fresh water reservoir (IJssel Lake). The Afsluitdijk comprises two sluice gate structures: the Stevin sluice gates (15 gates) at the West end of the dike and the Lorentz sluice gates (10 gates) at the East end of the dike. Every low tide with Wadden Sea levels sufficiently below the IJssel Lake level, the gates open and fresh water flows into the Wadden Sea. Rising sea levels, bottom depletion and climate change result in decreased...
The ultrasonic flow meter market has developed rapidly and has seen a significant growth. Due to its high performance and unique properties, ultrasonic flow meters have built up a prominent position in the flow meter market and in many industrial processes. Reputed market research companies claim that the ultrasonic flow meter market is the fastest growing market and expect further explosive market growth. One of the reasons for this success is that new and innovative product developments have broadened the application capabilities. For example intelligent processing of the transmitted...