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Page 9 of 914 Results 81 - 90 of 9134

Jieqiang Ji, Xuemei Geng, Yan Fang, Xiaojie Wu, Guofu Chen, Ningning Zhang, Zhiyu Fang, Leming Cheng
Investigation on the influence of valve opening on measurement accuracy for ultrasonic flowmeters

The applications of portable clamp-on ultrasonic flowmeters in on-line detection have lots of advantages. However, the measurement accuracy of ultrasonic flowmeters is often affected by various factors, such as pipe characteristics, flow fields and fluid medium. In this work, both experiments and CFD simulations are carried out to study the flow field changing caused by valves, and the influences of valve opening on measurement accuracy for ultrasonic flowmeters. The experiment results showed that, with the decrease of valve opening, the value of repeatability of indication error is increasing. At the same valve opening, with the distance closer to the valve, the deviation of the indication error for multiple measurements is increasing. In the simulation section, an error calculation model based on the numerical simulation is proposed, which is in good agreement with the experimental results. Both ball valve and butterfly valve are calculated, and the following conclusions are obtained: (1) for the ball valve, when the distance of measurement point to valve is less than 10D, the indication error is greatly affected by the orientations of linear velocity extracting (UL). When the valve opening is lower than 50 %, the variation tendency of measurement error at different orientations of UL are relatively random. (2) Compared with the ball valve, the variation tendency of measurement error downstream of the butterfly valve are more regular. With the increase of the distance to the butterfly valve, the measurement error is less affected by the orientations of UL. The correction factors of error at different distances downstream of the butterfly valve are given for different valve opening degrees.

Jiguang ZHU, Huizhe CAO
Validity Guarantee of Measurement Data in Application of Big-diameter Heat-meter in China’s Heating System

There are many limitations for the accuracy assurance technology of large-diameter heat meters characterized by laboratory calibration mode, which is hard to adapt to the complicated situation of heating system in China. Aiming to improve the measurement data accuracy of heating system thermal quantity, this paper proposes a new technical method by installing elbow sensor in the natural heating pipe bend to obtain the exact measure reference value. The method is based on the studies of current quality control conditions of big-diameter heat-meters, the flow measuring capability of heat-meters inside the hot water pipeline, the demand of heating operation to flow measurement accuracy, the online-verification technical model of flow measure, and the comparison between external clamp-on ultrasonic heat-meter and elbow heat-meter measurement ability under the situation of heating operation. The measurement data show that the elbow sensor of heat-meter prepared by the industrial ordinary elbow has the accuracy level of 3 % and the long-term stability can reach 0.3 %. Compared with the clamp-on ultrasonic flowmeter, the elbow sensor can better provide a stable measurement reference value at the heating site.

Liang Zhang, Hulin Guo, Guixiang Lu, Yucheng Chen
Performance Improvement of Stack Simulator

In order to improve the performance of the old Stack Simulator, NIM built two new facilities. One is a close loop wind tunnel, which can simulate the real flue gas conditions. The wind tunnel can change the flow rate, temperature, pressure, gas composition and turbulence in the test section. It is used to calibrate the velocity measurement devices such as three-dimensional pitot tubes used in Relative Accuracy Test Audit (RATA). Another facility is a new Stack Simulator, which can simulate the flow field conditions in the real stack. It is used to evaluate the average velocity measurement of RATA devices.

Elsa Batista, Hugo Bissig, John Morgan, Anders Niemann, Annemoon Timmerman, Florestan Ogheard
Metrology for Drug Delivery project – results and impact

This paper presents the major impacts of the work developed in EMPIR Project - MeDD II, Metrology for Drug Delivery in the reference standards used for flow rate determination of drug delivery devices and the results obtained in each work package, with a special focus on the primary standards developed by the partners using different technologies. These new primary standards were validated via an inter-laboratory comparison using two different type of flow meters and a precision syringe pump, in a range from 1500 nL/min down to 5 nL/min. This inter-comparison was performed between nine participating laboratories, each with different methodologies, measurement principles, flow ranges,operating conditions, and measurement uncertainty values.

Jin Song, Chao Chen, Yiping Liu, Haiyang Li
Investigation on Sampling Flow Rate Calibration Method of Air Sampler

In order to obtain the most accurate and effective sampling flow rate calibration method of air sampler, several different equipments were used under two different installation conditions in this paper. According to the experimental results, the calibration results of ultrasonic flowmeter and special orifice flowmeter will be affected by the installation conditions. Consequently, while ultrasonic flowmeter and special orifice flowmeter are used to sampling flow rate calibration, it is necessary to first calibrate the two flowmeters with filter paper, and then use the corrected results to calibrate the sampling flow rate. Based on the results of further experiments, calibration datas of gas roots flowmeter and special orifice flowmeter are consistent with the results obtained from gas flow standard facilities by negative pressure method, at the same time, there is still an error of 3 % ~ 5 % when corrected ultrasonic flowmeter is used. Therefore, gas flow standard facilities by negative pressure method and gas roots flowmeter can be directly used for sampling flow rate calibration of air sampler, if it is not convenient , special orifice flowmeter which calibrated with filter paper is also a good choice, ultrasonic flowmeter is not recommended.

K-H. Cheong, R. Doihara, N. Furuichi, M. Nakagawa, R. Karasawa, Y. Kato, K. Kageyama, T. Akasaka, Y. Onuma, T. Kato
Measurement of the Infusion Flow Rate Produced by a Novel Non-electric-powered Infusion Pump

Intravenous (IV) fluid therapy is a common medical practice that is widespread worldwide, and the method has remained unchanged for more than a century. The IV bag is suspended from an IV stand or pole, and the pressure created by gravity is used to administer the drug. However, this method inevitably reduces the mobility of patients, and may cause accidents such as falls during movement. To solve these problems faced in home care, nursing home, and hospital settings, this study aims to develop a non-hanging, non-electric-powered IV infusion pump with reasonable portability and operability. In this study, instead of gravity, atmospheric pressure is used as the driving force. The infusion device developed is required to achieve a certain level of dosing stability and accuracy, in line with medical guidelines and ideally as comparable to the existing gravity method. We developed a number of prototypes based on different pressurization mechanisms using vacuum piston cylinders as the driving source in order to find an optimum mechanism capable to produce a stable flow rate comparable to the suspended drip system. Tests on performance in terms of discharged flow rate were conducted on three feasible prototypes based on three different pressurization mechanisms, using a gravimetric test bench built for this purpose. The tests show that the pressurization mechanism using an inflating air bag to compress a drip bag has the best performance in terms of flow rate stability.

XING Jing-fang, QU Hong-qiang, HUI Ji, ZHENG Xue-jing, HU Fang-shu, WANG Ying-jie
Simulation and optimization study on the methane combustion chamber

This paper simulated and optimized the combustion chamber of the direct metering of the natural gas calorific value experimental platform. This material conducted a numerical simulation of methane combustion in the combustion chamber using ANSYS Fluent software, and the effects of different mixture inlet pipe length, combustion chamber diameter, and methane nozzle diameter on carbon monoxide emission concentration were studied. Aim to promote the complete combustion of methane, a more appropriate combustion chamber structure, and size were determined through carbon monoxide emission concentration. Through the comparison and analysis of the temperature field, velocity field, and concentration field of each component, it is suggested to set the length of the inlet pipe to 25 mm, and set the diameter of the combustion chamber and methane nozzle as 44 mm and 1.5 mm, respectively. After optimization, carbon monoxide emission concentration decreased from 27.9 PPM to 17.8 PPM, decreasing by 36.2 %.

X. Zheng, X. Zhipeng, J. Qing, Z. Gaoming, T. Jianbing
A Novel Multi-Parameter Calibrator for Ventilator Tester Based on Reciprocating Plunger

Ventilators are widely needed when the COVID-19 is a global outbreak, and they are used to provide mechanical ventilation for patients who are physically unable to breathe, or breathe insufficiently. A ventilator tester is an instrument used to verify and calibrate ventilation parameters of ventilators like gas flow, tidal volume, frequency. As a measuring device, the ventilator tester also needs to be calibrated periodically. And different parameters are usually calibrated with different devices. In order to improve calibration efficiency and accuracy, a novel multi-parameter calibrator for ventilator tester based on reciprocating plunger is proposed in this work. The system composition is introduced and mathematical models are deduced. According to calibrating regulation, different calibrating modes are simulated and realized.

R. Doihara, K.-H. Cheong, N. Furuichi
Evaluation of Microflow Calibration Rig using Static Weighing System with Flying Start-and-Finish Method

A Liquid microflow calibration rig was designed and evaluated. The developed calibration rig has a static weighing system and improved diverter valves for small flow rates. The weighing system succeeded in reducing an uncertainty due to an evaporation effect by using a detachable weighing tank. Experimental results of evaporation effect were introduced. In this study, two types of devices were introduced so that a Flying Start-and-Finish (FSF) method was implemented into the static weighing system. One of these devices is a set of diverting valves, and the other is a syringe pump with a linear encoder. Estimation tests were conducted. Diverter timing errors for the set of diverting valves were estimated to be about 6 ms.

Tao Meng, Chang Zhou, Li Liu, Huichao Shi, Dongjun Li, Bo Wu
Establishment of Micro Liquid Flow facility at NIM

In order to meet the needs of micro-flow measurement in industrial, biological and medical fields, the National Institute of Metrology (NIM) has established a micro liquid flow facility based on dynamic weighing method, with the flow rate range of 100 nL/min ~ 150 mL/min. The facility is composed of two sets of high accuracy electronic balances as the main standard, and three Coriolis mass flowmeters and two sets of independentpipeline systems according to different flow rate ranges. It has been designed a special degassing, a filter and a pipe air exhausting system, as well as a group of weighing containers and syringes of different specifications. An acquisition method of weighing value based on the fluctuation frequency is adopted to effectively reduce the uncertainty introduced by dynamic reading. A ‘dual time’ method is used to realize the synchronization between weighing system and meter under test by the "time stamp" with resolution of 1 ms. The uncertainty sources of balance that came from weighing accuracy of mg magnitude, short-term drift and long-term stability are evaluated by experimental method. In addition, the uncertainty introduced by liquid evaporation and capacity change of middle pipe are also analyzed. The results show that the facility uncertainty is better than 1.5 % (k = 2) at 100 nL/min flow rate, and the uncertainty is better than 0.1 % (k = 2) when the flow rate is above 1 mL/min.

Page 9 of 914 Results 81 - 90 of 9134