The National Metrology Institute of Japan (NMIJ) maintains high air speed standard and its calibration facility is capable of a relative expanded uncertainty (k = 2) of 0.63 % in the air speed range 40 m/s to 90 m/s. The model equation for measurement uncertainty in the high air speed calibration wind tunnel, which is the working standard, employs a method that cancels out the density term of the fluid. This is due to the fact that the density on the wind tunnel and DUT side is considered to be the same, i.e., the air speed values on the wind tunnel and DUT side are based on the same Bernoulli's principle. Therefore, the calibration environment of this standard is registered in the KCDB (CIPM MRA database) as ambient, which is independent of temperature and pressure changes throughout the year. However, there is a need to develop a calibration method for anemometers which are not based on Bernoulli's principle, as calibration targets. In this presentation, the reproducibility of air speed values in the wind tunnel is experimentally discussed, especially in the calibration environment, as the density of air changes throughout the year. In addition, the relative uncertainty of the density due to the difference of air density derivation formulas will be compared. Finally, the measurement uncertainty with the corrective coefficient of the anemometer under calibration due to the density change of air will be discussed.

Currently many National Metrology Institute (NMIs) as well as advanced calibration laboratories are using piston gas flow standards with mercury sealing method for gas flow calibration in the low pressure range. The flow in the small range is about cc/min. In this work, the low pressure gas flow calibration system at VMI is presented, designed and manufactured by the Taiwan National Metrology Institute, CMS/ITRI. The flow range is within (0.002 - 24) L/min. The uncertainty of the reference system is assessed against the ISO/IEC Guide 98-3:2008 document, Uncertainty is evaluated from individual influence sources such as category A and B assessments. The standard uncertainty/relative standard uncertainty and degrees of freedom of the sources can be evaluated individually and then combined to produce a composite standard uncertainty/combined relative standard uncertainty and an effective degree of freedom. Finally, the relative expanded uncertainty is obtained by multiplying the relative standard uncertainty associated with a coverage factor at the 95 % confidence level of the measurement result.

To solve the hard problem of large diameter Pitot Pipe flow meter source tracing and parameter obtaining, we propose the similarity principle, which means making one (set) model that has same geometric structure but scaling down of the actual applied flow meter (prototype for short). We calibrate the model with gas flow standard facility, determine the mathematical formula and characteristic parameters of flow calculation, then applied on prototype. Base on DN4000 pipe air flow rate measurement project, we design a differential pressure flow meter based on the principle of Pitot static tubes for prototype. Models of DN1200, DN800 and DN400 are made at the same time. In order to verify the correctness and feasibility of the solution, this project is carried on in two steps. In first step, we make the models of DN600, DN300 and DN150, then test them with gas low standard facility, figure out the relationship of parameter of different diameter. In second step, we test the models of the flow meter actually in used. Base on the two groups of test results, we can find out the parameter of the flow meter actually in used. This essay is a phase summary of step one. The result shows that the Pitot tube flow meter with same geometric structure and similarity ratio is 2, their flow coefficient difference would not be larger than 5 %.

A new, miniature design of a clamp-on ultrasonic transit-time difference flow meter for use in liquids is presented, with particular application to small diameter, thin walled metal pipes, opening up new areas of application, including smart water metering. The particular embodiment of the hardware is low cost and can be installed by unskilled users, and uses a type of guided wave mode that is significantly different to previous examples of clamp-on flowmeters that have used a leaky guided wave in the pipe to generate compression waves in the liquid. In the example presented in this paper, the entire liquid-pipe system acts as a wave guide, providing large amplitude ultrasonic signals with outstanding signal to noise, even from a drive voltage of just a few volts. The flowmeter is capable of measuring flow rates down to a few millilitres per second, with an accuracy better than 0.5 millilitres per second. The results presented mainly focus on 15 mm diameter copper pipes of wall thickness 0.7 mm, but the same approach works well on pipes with larger diameters and slightly thicker walls, up to around 30mm diameter in the current embodiment, In many instances, in previous work, the presence of the guided wave modes has prevented clear interpretation of the ultrasonic signals that are detected.

Water cut is one of the key parameters in the process of oil and gas production. In the present study, wepropose a microwave resonant cavity sensor(MRCS) which can work in both TM010 and TM110 modes, andestablished a water cut measurement of vertical upward oil–water two-phase flow in the range of 0-100 %. The response characteristics of the two resonant modes to water cut are analyzed by the coupling simulation offlow field and electromagnetic field using COMSOL finite element simulation software. A flow experimentisconducted with the designed MRCS measurement system. The sensitivity of the two modes resonantfrequency in different water holdup range is compared. The results show that 95 % of the experimental points’ relative errors is less than ± 5 %.It is indicated that the model can predict water hold with high accuracy, which may provide a solution for wellhead water cut measurement of oil field.