The paper describes a water flow calibration facility combined weighing method and master meter method. The flowmeter calibration system aims at obtaining a very high level of accuracy and assurance of product reliability. Moreover, a new method, synchronous pulse counting method, to improve the calibration accuracy and efficiency of master meter method is proposed. Experimental results show that the computer control system is reliable and the accuracy using weight method and master meter method is up to 0.066% and 0.076%, respectively.
The present comparative performance evaluation has been conducted for the following reasons: - Two-wire vs. four-wire systems - Cost - Accuracy categories of industrial applications - Aim of project - Participating manufacturers
A new primary standard for hydrocarbon flow measurements has been constructed at NMIJ, National Metrology Institute of Japan. The facility is designed for the calibration of hydrocarbon flowmeters in the flow rate range between 3 to 300 m³ / h with an expanded uncertainty better than 0.04 % for volumetric flow rates and 0.03 % for mass flow rates (coverage factor: k = 2). The primary standard applies a static and gravimetric method with flying start and finish. The facility consists of two test rigs with kerosene and light oil as working fluid. The test lines for flowmeters are 50, 100 and...
Coriolis mass flowmeters are widely used in industrial flow measurement. Mass flow is measured directly with very high accuracy (± 0.1% for liquids). These instruments are real multivariable meters, because all meters include direct temperature and density measurements as well. From theses primary measured parameters, , even further variables can be derived; e.g. concentration measurement based on density. The trend in industry shows an increased need for such multivariable instruments, which is due to increased global competition and, thus, requires better process efficiency and stricter...
Commercially available Coriolis mass flowmeters (CMF) show a broad variety of designs, which range from single to dual straight or bent tubes. The new single tube mass flowmeter presented in this paper is slightly bent. The advantage of bent tubes is that thermal stresses are reduced and that the instrument is capable to measure fluids up to 200°C. Furthermore, the slightly bent tube can easily be drained completely. Since the fluid is in contact only with zirconium R60702, mass flow can be determined for a wide variety of corrosive mediums. In particular, zirconium is used for...
PTB’s Thermal Energy Measurement Section built up a new gravimetric test facility, serving as the national primary standard for volume flowrates of water from 3 m³ / h to 1000 m³ / h and temperatures between 3 °C and 90 °C. The maximum Reynold’s number achieves a value of 5.5 · 10 6 . The test facility can be operated in four different modes to generate the water flow and comprises two independent weighing procedures, to obtain highly-valuable measurement results with an expanded combined uncertainty of 0.04%. This paper describes the test facility with particular consideration of the...
A novel Coriolis mass flowmeter insertion probe concept is described suitable for the measurement of the mass flow of liquids flowing in pipes. It is generally similar to that of the turbine meter insertion probe for volume flow measurement except that the turbine is replaced by a small vibrating aerofoil of elliptical cross-section. The weight vector theory of Coriolis mass flowmeters is applied to predict the approximate sensitivity of the probe. The sensitivity so predicted can be comparable to that of commercial (vibrating tube) Coriolis mass flowmeters so that the signal processing...
It is known that under certain conditions (in certain Reynolds number region) we get double row of staggered vortices in fluid flow behind the bluff body. Frequency of generated vortices is directly proportional to the average velocity of fluid and that dependence is linear. Flowmeters based on this phenomenon are known as vortex flowmeters. Origination of vortices causes changes some other parameters such as: pressure, perpendicular forces on fluid flow, etc. Frequency of vortices can be detected by detecting changes of these parameters. Great majority of the vortex flow meters are...
The aim of this theoretical paper is to discuss and compare the measuring characteristics of the Coriolis meter with a straight and slender measuring tube for the lowest three lateral vibration modes. The work is based on an analysis of the analytical approximations of the meter’s characteristics, which are derived from the solutions of a one-dimensional mathematical model. The paper deals separately with the ideal characteristics, the stability-boundary effect, the axial- force effect and the added-masses effect. The influence of the motion sensors’ position is stressed in the presentation...
The flow of a viscous fluid through a straight measuring tube of a coriolis flowmeter was investigated using numerical simulations. Numerical simulations were performed by the Comet code, which is based on the finite volume method. The simulations were made for various Reynolds numbers at several vibrating frequencies of the measuring tube. The evolution of the axial velocity, a distortion of the axial velocity profiles, a secondary flow in the measuring tube, and a twisting moment acting on the tube’s wall were observed. Values of the twisting moment that acts around the centre of the...