ASHRAE Standard 41.10 2020
$38.46
ASHRAE Standard 41.10-2020 — Standard Methods for Refrigerant Flow Measurement Using Flowmeters (ANSI Approved)
| Published By | Publication Date | Number of Pages |
| ASHRAE | 2020 | 48 |
Standard 41.10 prescribes methods for refrigerant mass flow rate measurement in laboratory and field applications using flowmeters. The 2020 edition of Standard 41.10 includes updated references and new reference to ANSI/ASHRAE Standard 15, “Safety Standards for Refrigerant Systems.” A new appendix for informative references has also been added. Additional changes were made to improve clarity and readability. This standard complies with ASHRAE’s mandatory language requirements.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | ANSI/ASHRAE Standard 41.10-2020 |
| 3 | CONTENTS |
| 4 | FOREWORD 1. PURPOSE 2. SCOPE 2.1 This standard applies to refrigerant mass flow rate measurements in laboratory and field applications where the entire flow stream of the refrigerant enters and exits the flowmeter either as a vapor-only or liquid-only state during data recording. 2.2 This standard does not apply to 3. DEFINITIONS |
| 5 | 4. CLASSIFICATIONS 4.1 Operating State 4.2 Refrigerant Flow Measurement Applications. Refrigerant flow measurement applications that are within the scope of this standard shall be classified as one of the following types. 4.3 Flowmeter Categories 4.4 Refrigerant Flow Measurement Methods. Refrigerant flow measurement methods that are within the scope of this standard include, but are not limited to, the methods listed in Table 4-1. Each of these refrigerant flow measurement methods is describe… 5. REQUIREMENTS 5.1 Test Plan. A test plan shall specify the refrigerant flow rate measurement system accuracy and the test points to be performed. The test plan shall be one of the following documents: |
| 6 | 5.2 Values to Be Determined and Reported. The test values to be determined and reported shall be as shown in Table 5-1 if required by the test plan in Section 5.1. Use the units of measure that are shown in Table 5-1 unless otherwise specified in the… 5.3 Accuracy. A selected refrigerant flowmeter shall meet or exceed the required refrigerant flow measurement system accuracy specified in the test plan in Section 5.1 over the full range of operating conditions. 5.4 Measurement Uncertainty. The uncertainty in each refrigerant flow measurement shall be estimated using the method in Section 8 for each test point. Alternatively, the worst-case uncertainty for all test points shall be estimated and the same valu… 5.5 Lubricant Circulation Rate. The lubricant circulation rate through the flowmeter shall be not more than 2% for a liquid refrigerant flowmeter or not more than 1% for a gaseous refrigerant flowmeter unless otherwise specified in the test plan in S… 5.6 Lubricant Sampling Port. A sampling port in accordance with ASHRAE Standard 41.4 3 shall be provided for extracting samples of liquid refrigerant and circulating lubricant for use in determining lubricant circulation rates if required by Section 5.5 |
| 7 | 5.7 Verify Single-Phase Flow 5.8 Steady-State Test Criteria for Refrigerant Mass Flow Rate Measurements for Compressors That Do Not Incorporate Pulse-Width Modulation. Refrigerant mass flow rate test data shall be recorded at steady-state conditions unless otherwise specified in… |
| 9 | 5.9 Steady-State Criteria for Refrigerant Mass Flow Rate Measurements for Compressors that Incorporate Pulse-Width Modulation. Compressors that operate using pulse-width modulation vary the refrigerant flow rate by alternatively switching the refrige… |
| 10 | 5.10 Unsteady Refrigerant Mass Flow Rate Measurements. If required by the test plan in Section 5.1, refrigerant mass flow rate test data shall be recorded |
| 11 | 5.11 Refrigerant Properties. Refrigerant properties shall be obtained from NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties (REFPROP)4 or from the refrigerant supplier if a constituent of the refrigerant bei… 5.12 Leak Testing. The refrigerant system shall be leak tested. Use a vacuum pump to evacuate the refrigerant system to a pressure less than 26.7 Pa (200 µm). After achieving this vacuum, close valves to isolate the refrigerant system from the vacuu… 5.13 Refrigerant and Lubricant Charging. If the refrigerant system is not precharged with lubricant, install the lubricant charge as prescribed by the UUT manufacturer, and then evacuate the system to less than 26.7 Pa (200 µm) unless otherwise spec… 5.14 Safety Requirements. Test apparatus shall be designed and constructed in accordance with ASHRAE Standard 15 5. Materials of construction shall be selected based on refrigerant flammability, toxicity, structural strength, rigidity, corrosion resi… 5.15 Flowmeter Installation. The selected flowmeter shall be installed in accordance with instructions from the flowmeter manufacturer or the source of the flowmeter. 5.16 Operating Limits. Operating conditions during flow rate data measurements shall not exceed limits for pressure, pressure differential, temperature, fluid velocity, or pressure pulsation specified by the flowmeter manufacturer to achieve the meas… 5.17 Input Power. If required by the test plan in Section 5.1, compressor input power shall be measured in accordance with ASHRAE Standard 41.11 6. 6. INSTRUMENTS 6.1 Instrumentation Requirements for All Measurements 6.2 Temperature Measurements. If temperature measurements are required by the test plan in Section 5.1, the temperature measurement system accuracy shall be within the following limits unless otherwise specified in the test plan: |
| 12 | 6.3 Pressure Measurements 6.4 Time Measurements. Time measurement system accuracy shall be within ±0.5% of the elapsed time measured, including any uncertainty associated with starting and stopping the time measurement unless (a) otherwise specified in the test plan in Secti… 7. REFRIGERANT FLOWMETER TEST METHODS 7.1 Coriolis Flowmeters. Coriolis flowmeters provide direct measurement of gaseous or liquid mass flow rates. In a Coriolis flowmeter, the gaseous or liquid refrigerant flows through a vibrating sensor tube within the meter. An electromagnetic coil l… |
| 13 | 7.2 Thermal Flowmeter. Thermal flowmeters provide direct measurement of gaseous or liquid refrigerant mass flow rates. The basic elements of the thermal mass flowmeters are two temperature sensors on opposite sides of an electric heater that supplies… 7.3 Volume Displacement Flowmeters. Both gas and liquid flow rate can be measured accurately using a volume displacement flowmeter. The quantity of fluid collected during a specified time interval is measured gravimetrically or volumetrically. The fl… 7.4 Orifices, Flow Nozzles, and Venturi Tube Flowmeters. ASME PTC 19.5 9 and ASME MFC-3M 10,11 describe measurement of gaseous or liquid refrigerant flow in pipes using orifices, flow nozzles, and venturi tubes, including construction proportions and… |
| 18 | 7.5 Turbine Flowmeters for Gaseous or Liquid Refrigerant Volumetric Flow Measurements. Turbine flowmeters are volumetric flowmeters that have a turbine rotor suspended on low-friction bearings in the gaseous or liquid refrigerant stream. The rotation… 7.6 Variable-Area Flowmeters for Gaseous or Liquid Refrigerant Volumetric Flow Measurements. Variable-area flowmeters are volumetric flowmeters that consist of a float that is free to move vertically inside a tapered transparent tube that has a gradu… |
| 19 | 7.7 Ultrasonic Flowmeters for Gaseous or Liquid Refrigerant Velocity Measurements. Ultrasonic flowmeters measure gaseous or liquid refrigerant flow velocity by measuring the change in sound frequency of the moving refrigerant. Use of a clamp-on or im… 7.8 Vortex-Shedding Flowmeters for Gaseous or Liquid Refrigerant Velocity Measurements. Vortex-shedding flowmeters are used to determine gaseous or liquid refrigerant velocities. Piezoelectric methods, strain-gage methods, or hot-film methods are use… |
| 20 | 7.9 Drag-Force Flowmeters for Gaseous or Liquid Refrigerant Velocity Measurements. Drag-force flowmeters determine gaseous or liquid refrigerant velocity. Piezoelectric or strain- gage methods are used to sense dynamic drag-force variations. A body i… 8. LUBRICANT CIRCULATION RATE MEASUREMENTS 8.1 Symbols. Table 8-1 defines the symbols used in Section 8. 8.2 Lubricant Circulation Rate Measurement without an Auxiliary Lubricant Separator. Apply the procedures prescribed in ASHRAE Standard 41.4 3 to determine the lubricant circulation rate through the flowmeter Cf. Refer to Section 5.6 for sample port … 8.3 8.3 Lubricant Circulation Rate Measurement with an Auxiliary Lubricant Separator |
| 22 | 9. UNCERTAINTY REQUIREMENTS 9.1 Uncertainty Estimate. An estimate of the measurement system uncertainty performed in accordance with ASME PTC 19.1 12 shall accompany each refrigerant flow measurement. 9.2 Method to Express Uncertainty. Assumptions, parameters, and calculations used in estimating uncertainty shall be clearly documented prior to expressing any uncertainty values. Uncertainty shall be expressed as shown in Equation 9-1. |
| 23 | 10. TEST REPORT 10.1 Test Identification 10.2 Unit Under Test Description 10.3 Instrument Description 10.4 Measurement System Description 10.5 Test Conditions 10.6 Test Results 11. REFERENCES |
| 25 | INFORMATIVE APPENDIX A: INFORMATIVE REFERENCES |
| 26 | INFORMATIVE APPENDIX B: AN UNCERTAINTY ANALYSIS EXAMPLE FOR A CORIOLIS FLOWMETER B1. Estimate Uncertainty in SI Units B1.1 Define the Measurement Process B1.2 List Elemental Error Sources |
| 27 | B1.3 Calculate Systematic and Random Uncertainty of Parameters B1.4 Calibration Error Estimate. The manufacturer stated that the flowmeter test facility calibration error was 0.05%. On further investigation of their calibration uncertainty analysis, the error appears to consist mainly of a bias error that can be… |
| 28 | B1.5 Data Acquisition Error Estimate. The frequency meter that will be used was specified by the manufacturer to be ±0.010% of the reading for readings greater than 40 Hz. Because the inaccuracy in determining frequency was only specified as a perce… B1.6 Data Reduction Error Estimate. The mass flow will be a function related to the measured frequency as shown in the first two columns of Table B-3. Various linear curve fits were reviewed to determine which had the smallest error over the entire o… B1.7 Calculate the Bias and Precision Errors for Each Parameter. The results from the previously defined elements are now summarized at each of the four calibrated flow rates in Table B-4. The summing of the terms is by the root-sum-square method bec… B1.8 Propagate the Bias and Precision Errors |
| 29 | B1.9 Calculate Uncertainty. Select UADD or URSS as models for combining the bias and precision errors of the test result, and obtain the uncertainty. URSS will be used because a 95% confidence level is desired. The value of t for the Student’s t-di… B1.10 Report |
| 30 | B2. Estimate Uncertainty in I-P Units B2.1 Define the Measurement Process |
| 31 | B2.2 List Elemental Error Sources B2.3 Calculate Systematic and Random Uncertainty of Parameters B2.4 Calibration Error Estimate. The manufacturer stated that the flowmeter test facility calibration error was 0.05%. On further investigation of their calibration uncertainty analysis, the error appears to consist mainly of a bias error that can be… B2.5 Data Acquisition Error Estimate. The frequency meter that will be used was specified by the manufacturer to be ±0.010% of the reading for readings greater than 40 Hz. Because the inaccuracy in determining frequency was only specified as a perce… B2.6 Data Reduction Error Estimate. The mass flow will be a function related to the measured frequency as shown in the first two columns of Table B-8. Various linear curve fits were reviewed to determine which had the smallest error over the entire o… |
| 32 | B2.7 Calculate the Bias and Precision Errors for Each Parameter. The results from the previously defined elements are now summarized at each of the four calibrated flow rates in Table B-9. The summing of the terms is by the root-sum-square method bec… B2.8 Propagate the Bias and Precision Errors B2.9 Calculate Uncertainty. Select UADD or URSS as models for combining the bias and precision errors of the test result, and obtain the uncertainty. URSS will be used because a 95% confidence level is desired. The value of t for the Student’s t-di… B2.10 Report |
| 34 | INFORMATIVE APPENDIX C: AN UNCERTAINTY ANALYSIS EXAMPLE FOR A DIFFERENTIAL PRESSURE FLOWMETER C1. Estimate Uncertainty in SI Units C1.1 Define the Measurement Process. The equation used to calculate mass flow rate of a gas through an ASME long-radius nozzle, provided in Section 7.4.2 is as follows (SI): |
| 35 | C1.2 List Elemental Error Sources |
| 36 | C1.3 Estimate Elemental Errors C1.4 Calculate the Bias and Precision Errors for Each Parameter. The estimates from the previously defined elements in Table C-3 are now summarized for each elemental term using the root-sum-square method because 95% confidence is desired. The degree… |
| 37 | C1.5 Propagate the Bias and Precision Errors. The individual parameter errors are propagated into the flow rate according to a Taylor series expansion. The relative bias limit for the mass flow equation is as follows: |
| 38 | C1.6 Calculate Uncertainty. Select UADD or URSS as models for combining the bias and precision errors of the test result, and obtain the uncertainty. URSS will be used because a 95% confidence level is desired. The value of t for the Student’s t-di… C1.7 Report |
| 39 | C2. Estimate Uncertainty in I-P Units C2.1 Define the Measurement Process. The equation used to calculate mass flow rate of a gas through an ASME long-radius nozzle, provided in Section 7.4.2, is as follows (I-P): C2.2 List Elemental Error Sources C2.3 Estimate Elemental Errors |
| 40 | C2.4 Calculate the Bias and Precision Errors for Each Parameter. The estimates from the previously defined elements in Table C-8 are now summarized for each elemental term using the root-sum-square method because 95% confidence is desired. The degree… |
| 42 | C2.5 Propagate the Bias and Precision Errors. The individual parameter errors are propagated into the flow rate according to a Taylor series expansion. The relative bias limit for the mass flow equation is as follows: |
| 43 | C2.6 Calculate Uncertainty. Select UADD or URSS as models for combining the bias and precision errors of the test result, and obtain the uncertainty. URSS will be used because a 95% confidence level is desired. The value of t for the Student’s t-di… C2.7 Report |
| 44 | INFORMATIVE APPENDIX D: PRESSURE COMPENSATION REQUIRED FOR AN ELEVATION DIFFERENCE D1. Pressure Compensation Required for an Elevation Difference D2. Example |
| 45 | INFORMATIVE APPENDIX E: FLOWMETER ACCURACY COMPARISONS |
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