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Page 14 of 912 Results 131 - 140 of 9113

Liu Wei, Li Li, Chen Wei, Zhan Jiao, Liu Yahui
The flow performance testing device of the ambient air sampler

In this paper, the flow measurement performance of the ambient air sampler is studied, which is widely used in environmental monitoring, health care and mining enterprises. The paper develops the flow rate performance test device of ambient air sampler, which consists of the high-low temperature test device, the load performance test device, the flow standard device and the pressure measurement device. For various types of ambient air samplers and its calibrators, the device can carry out flow performance tests with the flow range of 10 mL/min ~ 265 L/min, with flow indication error no more than ±2%, the high-low temperature tests with the range of (-20 ~ 40)℃, and the load performance tests in the range (-50 ~ 0)kPa. The uneven capability of temperature adaption of different types of samplers or from various manufacture is found through experiments research, but the flow metering performance of samplers is significantly improved compensated by temperature in this paper. In the load test, the sampler load condition of different ranges or manufacturers are different, which meets the requirement of more than 50 % the air extraction capacity.

Mengna Li, Bodo Mickan, Chunhui Li, Jia Ren, Yan Wu, Ming Xu
The comparison of the gas flow secondary standard facilities at high pressure

The first formal comparison was organized in China for the purpose of determination of the degree of equivalence of the gas flow secondary standard facilities during 2016 ~ 2020. There were 4 participants from China, and PTB was invited as the link lab to connect this comparison with the serial key comparisons of CCM.FF.K5. Based on the flow range of the existing secondary standard facilities of participating laboratories, 3 turbine flow meters were used as transfer standards. Totally 298 sets of measured data were obtained with Reynolds number range of (6.3 × 10^4 ~ 1.4 × 10^7). Results of all participants were considered for the determination of the reference value and the uncertainty of the reference value. The operation conditions were represented by the Reynold number, while the measured value was represented by the relative error of the meter e in (%). The fitted curve based on the relationship between e and the Reynolds number for each single meter was obtained. The degree of equivalence of En was finally evaluated. Among all 298 sets of measured results, there were 282 sets of results with En ≤ 1, while there were 9 sets of results with 1 < En ≤ 1.2.

A. W. Boudaoud, J. D. McGraw, T. Lopez-Leon, F. Ogheard
Traceability of the Primary Nano-flow Measurement System: Measuring the Local Inner Diameter of a Glass Capillary

As part of the Metrology for Drug Delivery ("MeDD II") European joint research project, a primary method for the measurement of liquid flow rates at the nanolitre per minute scale has been developed. This primary standard allows the calibration of flow meters and flow generators such as infusion pumps, pressure controllers and syringe pumps, for flow rates ranging from 10 nL/min to 1500 nL/min with relative expanded uncertainties (k = 2 ) of 12 % and 0.15 %, respectively. The system is based on the measurement of the displacements over time of a liquid/air interface moving inside a cylindrical glass capillary tube. The flow rate is obtained by multiplying the resulting flow velocity by the cross-sectional area of the tube which depends on the square of the capillary’s inner radius. In order to ensure the traceability of flow rate measurements to International System of Units, camera and frame rate calibration procedures have been established. However, the measured flow rates depend on the local value of the inner diameter which must also be traceable. In this paper, we present a method to measure the inner diameter of cylindrical thin-walled capillaries by confocal microscopy. The method allows visualizing the inside of a tube by filling it with a fluorescent solution and acquiring -stacked images along its full height. The mean inner diameter is deduced from the widths of the fluorescent signal in the obtained images which are measured by image processing. The method was applied on capillaries with different inner diameters and the results were compared with the values given by manufacturers. The relative expanded uncertainties (k = 2 ) were estimated to a maximum of 4 %, which is two times lower than the one provided by manufacturers.

P. Žibret, G. Bobovnik, J. Kutin
Implementation of the dynamic flying start-stop method in the pVTt gas flow standard

The gas flow standards using the volumetric method with a constant volume (pVTt) determine the flow rate based on the rate of mass change determined by measuring the density of the gas inside a constant volume. These standards normally use the static method of mass determination and rarely the dynamic one, due to dynamic changes of the gas temperature during mass collection. We have developed the analytical model that predicts the change of temperature in the pVTt system for gas flow rates up to 12 mg/min. Both measurement methods, the static and the dynamic, were implemented in the measuring system, with the dynamic method being corrected using the analytical model. The analytical correction model was validated by a comparison between the flow-rate measurements using the static and the dynamic methods. Based on successful validation of the analytical model we believe the corrected dynamic method is a viable alternative to the static one for the considered flow range.

Jun Ma, Yejun Chen
Influence of Verification Volume and Flow rate on Verification Facility for Water Meters of Piston

According to the JJG 1113-2015 “Verification Facility for Water Meters” calibration regulations, when testing the verification facility for water meters of Piston, the indication error and repeatability of the main standard implement are determined by two parameters, namely the verification volume and flow rate. Experiments show that the setting of two parameters affects the verification results, when the flow rate is set to 25 L/h and the verification volume is 2 L, the indication error and repeatability of the main standard implement meet the requirements of the verification regulation; while when the flow rate increases to 50 L/h, or even larger, the test results do not meet the requirements, i.e. the test results produce a misjudgment of the piston cylinder's metering performance. The main purpose of this paper is to verify the influence of the verification volume and flow rate settings on the piston cylinder's indication error and repeatability through testing.

M. A. de Huu, M. Tschannen, Hugo Bissig
Extending the functionality of the METAS primary standard in gas flow

METAS is the Swiss national metrology institute. Its laboratory for flow operates several primary standards for liquid and gas flow, among which two piston provers with BIPM-registered CMC entries in the range (0.1 to 300) L/min. To extend their functionality, additional working modes have been implemented in the data-acquisition software that allow almost endless measurement possibilities over the flow range (0.002 to 300) L/min. With the current extension of functionalities, all types of flow meters, from critical nozzles to laminar flow elements can now be calibrated under various configurations.In this paper, we will present the changes that have been made to the design, as well as commissioning and validation results with various types of flow meters. The increase in flow rate range towards very low values brings pressure and temperature stability consideration into account that are being treated and presented here. Finally, results from a METAS internal bilateral comparison are presented and show an excellent agreement between two primary standards.

Yuan Liu, Heming Hu, XueLing Qiu, Deyue Zou
Evaluation of ADCP Streamflow Measurements in Open Channel

The purpose of this paper is to explore the potential of calibration of ADCP discharge measurement in open channel, which conclusion can improve the traceability of ADCP. In this paper, the current velocity and discharge synthesis and other important issues are taken into consideration, and establishes a set of rectangular open channel standard discharge facility, and conducts experimental research on the flow measurement by using Workhorse. The moving boat ADCP measurement uncertainty source is analyzed, and the error situation introduced by the approximate solution is analyzed. By estimating the back scattering intensity, a new type of acoustic reflector is designed, so that the signal quality of ADCP can be kept in the best state in the process of towing calibration, so as to ensure the reliability of the WT measurement results. An experimental device for WT, BT, depth measurement is established to evaluate the basic performance of the instrument. At last an ultrasonic transit time flow-meter(UFM) is taken as reference in field situation, to calibrate the discharge directly, the results are close to laboratory calibration.

Han Zhang, Liang Wang, Xinli Dong, Donghong Huang,Peijuan Cao, Yong Li, Ronghui Shang, Shihui Zeng, Xuejian Li
The City Gas Flow Standard Facility within (2~4) MPa

In order to meet the traceability requirements of city gas flow meters, the city gas flow standard facility was built based on master meter method. As the non-fixed usage of master meters and the low temperature of natural gas, the uncertainty evaluation and control of the standard facility were investigated. The results showed that the standard facility used four turbine flowmeters as master meters and has mobility, while the achievable flowrate range is within (60 ~ 8600) m³/h and the pressure range of (2 ~ 4) MPa. The uncertainty of the non-point usage of the master meters was controlled based on the curve fitting method, while the uncertainty of the city gas flow standard facility was 0.26 % (k = 2). Compared with NIM-2014, NIM-2015 was more suitable for master meters with scattered error curves. On this basis, the heat transfer model of the cryogenic natural gas flow in pipeline was established. It was found that the dynamic temperature balance of the facility can be achieved through a longer pre-flow time, which can improve the measurement repeatability. The uncertainty of the calibrated flowmeter is 0.32 % (k = 2). In addition, the comparison experiment with NIM verified the above results.

Biyu Zhu, Chao Chen, Li Ma
Study on the Comparison of Three Typical Gas Flow Standards for Calibrating Low Gas Flowmeter

A gas flowmeter for measuring low flow rate has been widely used in the field of medical, health, environmental protection, energy industry, aerospace, etc. To against Covid-2019, the requirement on the low flow rate has been increasing dramatically. At present, the typical standard devices for calibrating low gas flowmeter mainly include standard bell provers of gas flow, standard piston provers of low gas flow and standard laminar of low gas flow. Different measuring principles are adopted among these typical standard devices. To ensure the consistency of these typical standard devices, a comparison test is performed. The standard devices used in the comparison are of the same accuracy grade, with an extended uncertainty of 0.2 %(k = 2). The piston-type gas flow calibrator of grade 1.0 is selected as the transfer standard, and three flow points with high flow rate, medium flow rate and low flow rate are selected for test. The consistency of measurement results is evaluated by normalized deviation En. The comparison results are acceptable which show that three typical standard devices are accurate and reliable.

F. Arpino, L. Canale, M. L. Cassano, G. Cortellessa, M. Dell’Isola, G. Ficco, A. Tagliabue, F. Zuena
Link between unaccounted for gas in transmission networks and flow-meters accuracy

One of the main issues in natural gas transmission networks is represented by the so-called Unaccounted-for-Gas (UAG), that is the amount of gas related to the unavoidable measurement and estimation errors in the balancing equation of the network. In particular, accuracy of flow-rate measurement in transmission network pipelines is a very crucial issue due to the numerous related metrological criticalities. This paper is aimed at evaluating the influence of the flow-meter accuracy on UAG. To this aim, the rangeability limits of the flow-rate measuring device in delivery points characterized by large fluctuation of gas flows have been investigated, together with the effect of the drift of the instrument due to the absence of punctual periodic calibrations. From the analysis carried out, it was found that about 12 % of the average daily flow rates measured at DSO measuring plants is below the minimum flow rate of the meter and that a significant correlation between monthly UAG and registered rangeability faults of flow-meters has been found.

Page 14 of 912 Results 131 - 140 of 9113