Water Flowmeters Water Flow Calibration Facility

1 Page 1 NIST Measurement Services: NIST Calibration Services for Water Flowmeters Water Flow Calibration Facility NIST Special Publication 250 Iosif I. Shinder, Iryna V. Marfenko Open at page → 2 Page 2 NIST Special Publication 250 NIST Measurement Services: Iosif I. Shinder, Iryna V. Marfenko Fluid Metrology Group Process Measurements Division Chemical Science and Technology Laboratory National Institute of Standards a... Open at page → 3 Page 3 Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or... Open at page → 4 Page 4 NIST Measurement Services: NIST Calibration Services for Water Flowmeters Water Flow Calibration Facility NIST Special Publication 250 Iosif I. Shinder, Iryna V. Marfenko Fluid Metrology Group Process Measurements Divisi... Open at page → 5 Page 5 TABLE OF CONTENTS NIST Special Publication 250...........................................................................................4 Abstract............................................................................ Open at page → 6 Page 6 Abstract This document describes the Water Flow Measurement Standards at the National Institute of Standards and Technology (NIST). These primary standards are disseminated using calibration services offered by NIST’s Fl... Open at page → 7 Page 7 NIST’s Water Flow Calibration Facility consists of the 3 fundamental component parts: • flow generation system: comprised of storage tank, pumping system, and a flow control system which actuates the control valves. The... Open at page → 8 Page 8 Table 1. Primary water flow calibration capabilities within the NIST Fluid Metrology Group. Green regions represent operational systems, white regions represent those under construction. Feature Tank 1 Tank 2 Tank 3 Tank... Open at page → 9 Page 9 The WFCF does not have a temperature control system and, therefore, only room temperature calibrations are available. Since pump heating occurs, the temperature increases during the test procedure at a rate of about 0.2... Open at page → 10 Page 10 measurement performance when the conditions of use (temperature, viscosity, and dimensional changes) differ from the conditions used for the calibration. Hence, for a turbine flowmeter calibration, the calibration report... Open at page → 11 Page 11 computed flow result from the standard to the averaged meter indication, or the reciprocal of this ratio. An additional flowmeter is normally used in the test pipe to set flow, to check the flow stability, and possibly t... Open at page → 12 Page 12 Figure 1. A Perspective Drawing of NIST’s Water Flow Calibration Facility. The NIST WFCF is a closed loop flow system that consists of a flow source (centrifugal pumps), flow conditioners, pipe lines, test section for th... Open at page → 13 Page 13 the fine and coarse controls for setting the water flow rate and the pressure in the test section of the WFCF. Once the flow passes through the meter under test and the control valves, it goes through two valves in serie... Open at page → 14 Page 14 Figure 3. Sketch of the Arrangement of Equipment in the WFCF 3700/100 System. 4.3 Error-Free Uni-directional Diverter: Theory and Design The nozzle and diverter are designed to 1) rapidly switch the flow from the collect... Open at page → 15 Page 15 exiting the fishtail. The procedure for conventional diverter correction, which is usually a function of liquid flow rate, is given in many flow measurement standards, see Refs. [2, 5, 6]. The basic concept of the new di... Open at page → 16 Page 16 motion, 2) the liquid jet velocity profile, and 3) the position of the diverter trigger [6]. The full operation sequence of the uni-diverter system is shown in Figure 6. Diverter Nozzle CB unit Proxy sensors Figure 5. Ph... Open at page → 17 Page 17 Figure 6. Collection-bypass Cycle. 5 Uncertainty Analysis for NIST’s Water Flow Calibration Facility In this section, we will analyze summarized in the Table 2 the uncertainties of the WFCF 3700/100. Firstly, we will bri... Open at page → 18 Page 18 Figure 7. Uncertainty Diagram (Ref.1). Table 2. Uncertainty Budget of the WFCF 3700/100 for Mass Collections of 3000 kg and 600 kg. Reference Value Uncertainty, % Uncertainty, % Collected Mass 3000 kg 600 kg 1. Mass unce... Open at page → 19 Page 19 5.1 Techniques for Uncertainty Analysis The uncertainty of a mass flow measurement with the WFCF 3700/100 is based on the techniques described in Refs.[8, 9] The process identifies the equations involved in the flow meas... Open at page → 20 Page 20 5.2.1 Collected Mass Uncertainty 5.2.1.1 Scale Calibration, Mass Standards Calibration, Long-term Stability, and Sensitivity The first component of mass uncertainty we will consider is the weigh scale resolution. For a c... Open at page → 21 Page 21 Pneumatic system Mass standards Stand Figure 8. Weighing System for WFCF 3700/100 and Mass Standards The maximum tank load is about 3700 kg, the reference mass is approximately 540 kg so the number of mass increments nec... Open at page → 22 Page 22 Figure 9. The Scale Calibration Sequence The following system of equations is used to describe the data reduction procedure. () on off ii mMm M=+ ref , (6) where , i m ( ) i Mm are scale indications and corrected masses... Open at page → 23 Page 23 The value of the scale coefficient averaged over the two year period (2004-2005, see Fig.10) is 0.998810.00007. In 2006 the scale coefficient was found to be 0.99884±0.00010 (or ± 0.01%) and this value is included in the... Open at page → 24 Page 24 million and are negligible in comparison with the other types of scale uncertainties mentioned here. 5.2.1.2 Buoyancy Correction The mass values observed by the weigh scales in the static weighing system are subject to b... Open at page → 25 Page 25 1. It changes the direction of the flow stream without splashing or leaking, 2. It channels the desired flow direction to the collection tank, 3. It starts the timer, and 4. It stops the timer. Diverting the flow and sta... Open at page → 26 Page 26 -0.50 -0.40 -0.30 -0.20 -0.10 0.00 600 700 800 900 1000 1100 1200 Q (L/min) 100 (Q t / Q -1) 30s 50s Figure 11. Differences between Traditional and Uni-directional Diverters, where No Correction is Made Figure 12 shows a... Open at page → 27 Page 27 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 600 700 800 900 1000 1100 1200 Q (L/min) 100 (Q tc / Q -1) 30 s 50 s Figure12. Difference between Traditional and Uni-directional Diverter, where Time Correction is Included 2. The u... Open at page → 28 Page 28 28.2 28.4 28.6 28.8 29 29.2 29.4 24400 34400 44400 54400 64400 Time (s) Q (L/s) 20 s run 100 s run Figure 13. Ten Hour Run with 20 and 100 s Collection Times 3. Performance of the uni-directional diverter was assessed by... Open at page → 29 Page 29 9.174 9.176 9.178 9.18 9.182 0 40 80 120 160 200 240 Collection time (s) St Figure 14. Measured Strouhal Number for Different Collection Times Each point represents 7 measurements. Maximum difference between points is ab... Open at page → 30 Page 30 density determination is based on measuring the period of oscillation of a vibrating U- shaped sample tube, which is filled with liquid. This system is equivalent to a spring- mass system, where the mass contains the sam... Open at page → 31 Page 31 Figure 15 shows that experimental data can be fitted with a linear dependence between square of the period of vibrating tube versus the density. Fitted values for A and B are 0.024029(4) 0.000002 m± 3 s 2 /kg and 25.994(... Open at page → 32 Page 32 -0.100 -0.050 0.000 0.050 0.100 0 200 400 600 800 1000 1200 ρ (kg/m 3 ) Residuals (kg/m 3 ) Figure 16. Residuals from the Densimeter Tests. As mentioned before, the coefficients A and B are temperature dependent. In orde... Open at page → 33 Page 33 0.02398 0.024 0.02402 0.02404 18 23 28 33T ( o C) A (m 3 s 2 /kg) Figure 17. Temperature Dependence of the Coefficient, A 25.9 25.95 26 26.05 18 23 28 33T ( o C) B (s 2 ) Figure 18. Temperature Dependence of the Densitom... Open at page → 34 Page 34 The density of the flume water was measured in the same temperature range. It was found that the difference between distilled water and flume water density has weak temperature dependence (Figure 19). 0.315 0.32 0.325 0.... Open at page → 35 Page 35 3 fD St Qπ =  where Ro is the Roshko number, and St is the Strouhal number, where f is the meter frequency, D is the flowmeter diameter, ν is the kinematic viscosity and is the volumetric flow rate. The kinematic visco... Open at page → 36 Page 36 These results show that the flume water kinematic viscosity is very close to the viscosity of distilled water. The difference between viscosities of the flume water and distilled water is shown below (Fig. 21). -0.002 0... Open at page → 37 Page 37 Temperature measurements are made of the flowing liquid and of the atmospheric conditions surrounding the weighing system. These measurements are made using calibrated thermistors placed at various locations along the wa... Open at page → 38 Page 38 PC 1. PCI-MIO-16XE-10 2. PCI-GPIB 3. Serial port interface GPIB RS232NI terminal Block Scale ( Mettler Toledo ) Flow Check Standard ( Controlotron ) ( Vaisala PTU 200 ) Counter ( A g ilent Counter ( A g ilent Counter ( A... Open at page → 39 Page 39 the functions of its various components, and provides details necessary for customers wanting to submit meters for calibration (i.e., pipeline sizes, costs, turnaround time, etc.), and gives a detailed analysis of the un... Open at page → 40 Page 40 Acknowledgment Authors wish to acknowledge and sincerely thank Dr. John D. Wright, Dr. George E. Mattingly, and Dr. Michael R. Moldover for their interest to this paper, fruitful discussions during this Special Publicati... Open at page → 41 Page 41 Appendix: Sample Calibration Report REPORT OF CALIBRATION FOR A TURBINE WATER FLOWMETER May 01, 2006 Mfg.: ABCD Corporation ABCD Serial No: 1234 Pipe Diameter: 100 mm (4 inch) submitted by Waterflow , Inc. Metertown, MD... Open at page → 42 Page 42 NIST Test Number: 836-123456-03-01 Page 42 Calibration Date: July 2, 2003 Figure 1. A photograph of the flow meter installation. The Reynolds number is included in the tabulated data and it was calculated using the follo... Open at page → 43 Page 43 NIST Test Number: 836-123456-03-01 Page 43 Calibration Date: July 2, 2003 K-factor Calibration Curve 0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 0.34 0.345 0 500 1000 1500 2000 Volumetric flow rate, L/min K-factor, Pulse/... Open at page → 44 Page 44 NIST Test Number: 836-123456-03-01 Page 44 Calibration Date: July 2, 2003 calibration result (measurand) so that the sensitivity of the result to uncertainties in the input quantities can be evaluated. The confidence lev... Open at page → 45 Page 45 NIST Test Number: 836-123456-03-01 Page 45 Calibration Date: July 2, 2003 uncertainty. Using the values given above results for the expanded uncertainties are listed in the data table and shown as error bars in the figur... Open at page →