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GB/T 30832-2014 English PDF (GBT30832-2014)

GB/T 30832-2014 English PDF (GBT30832-2014)

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GB/T 30832-2014: Valves -- Test method of flow coefficient and flow resistance coefficient

This Standard specifies the terms and definitions, test equipment and measuring instruments, test requirements, test procedures, calculation and test report for the test of flow coefficient and flow resistance coefficient. The test of flow-pressure loss, flow coefficient and flow resistance coefficient of other similar valves and pipeline shall refer to the methods in this Standard.
GB/T 30832-2014
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 23.060.01
J 16
Valves - Test method of flow coefficient
and flow resistance coefficient
ISSUED ON. JUNE 24, 2014
IMPLEMENTED ON. MARCH 01, 2015
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Test equipment and measuring instruments ... 5
5 Test requirements ... 9
6 Test procedures ... 10
7 Calculation ... 11
8 Test report ... 13
Annex A (informative) Flow characteristics of fluid in valve ... 14
Annex B (informative) Error analysis of test results ... 18
Valves - Test method of flow coefficient
and flow resistance coefficient
1 Scope
This Standard specifies the terms and definitions, test equipment and
measuring instruments, test requirements, test procedures, calculation and test report for the test of flow coefficient and flow resistance coefficient. This Standard applies to.
a) the test of flow-pressure loss, flow coefficient and flow resistance coefficient of valves, pipeline filters, etc. with water as medium;
b) the flow resistance coefficient value of the tested product is greater than 0.1.
The test of flow-pressure loss, flow coefficient and flow resistance coefficient of other similar valves and pipeline shall refer to the methods in this Standard. 2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3101, Quantities and units - General principles
GB/T 17395, Dimensions, shapes, masses and tolerances of seamless steel pipes
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. 3.1 flow; Q
the volume of water flowing through the valve per unit time, in m3/h
3.2 pressure drop; ??p
the circulation of the pipeline.
4.2 Connection pipeline
4.2.1 All the pipeline s before and after the flow meter connection pipeline and test valve shall be round straight pipe. There must be no protrusions, pits, etc. The dimension and deviation of the pipeline shall comply with the provisions of GB/T 17395. The inner surface of the pipeline shall be clean, free from oxide scales and other obstacles that may cause fluid disturbances. The connection end of the pipeline on which the flow measuring instrument and the test valve are to be installed shall be straight.
4.2.2 As shown in Figure 1 or Figure 2, L1 ~ L5 refer to the length of the straight pipe section of the same nominal size as the test valve. L1 is the measuring pipe section used to measure the flow-pressure drop of the test valve
connection pipeline itself. L2 and L3 are the pressure tapping point pipe sections of upstream and downstream connection pipelines of the test valve. L4 is the straight pipe section after the downstream pressure tapping point of the test valve. L5 is the length of the straight pipe before the pipeline pressure tapping point.
4.2.3 The lengths of the connection pipeline of the test value and the pressure tapping point are required as. L2 shall be greater than or equal to 5 times the nominal size of the pipeline; L3 shall be greater than or equal to 10 times the nominal size of the pipeline; L4 shall be greater than 5 times the nominal size of the connection pipeline. Where the L1 straight pipe section is set in the test system, L1 shall be the sum of the lengths of L2 and L3, the length of L5 shall be 15 times larger than the nominal size of the pipeline. If the test system does not set the L1 straight pipe section, the length of L5 shall be 18 times larger than the nominal size of the pipeline. If the rectifying vane is used in the L5 pipe section, the length can be shortened to 8 times the nominal pipeline size.
4.2.4 The length of the connection pipeline of the flow measuring instrument shall meet the requirements of the flow measuring instrument for the length of the connection pipeline. The inner diameters of the connection pipeline and the flange shall not be less than the inner diameter of the flowmeter. It is better to approach the inner diameter of the flowmeter.
4.2.5 Except for the valve connected to the threaded end, the inner diameter of the pipeline connected to the test valve shall not be less than the inner diameter of the connection end of the test valve.
4.2.6 The end face of the connection pipe of the threaded end valve shall try to reach the step at the bottom of the valve thread.
4.3 Pressure tap and connection pipe
Standard, the error of the test result can be analyzed according to Annex B. 5.3 Flow and pressure drop of measuring pipeline
When testing, it shall test the flows and pressure drops of pressure tap pipelines before and after the test value. The conditions and test procedures are same with those for testing the tested valve. Especially for the lower value of the flow resistance coefficient of the tested valve , the flow and pressure drop of the pipeline itself cannot be ignored.
6 Test procedures
6.1 Install the tested valve in the test device shown in Figure 1 or Figure 2. Test valve is at ON state. Start the water pump of the test system to exhaust the air in the pipeline and make it filled with water.
6.2 The test valve is at a certain opening position. When the flow state meets the requirements of 5.2, the test recording shall be performed.
6.3 When there is the pressure drop of the test pipe with same length and specifications with the test pipeline before and after the test valve that can be tested, it shall simultaneously test and record the pressure drop of this section. When there is no the pressure drop of the test pipe with same length and specifications with the test pipeline before and after the test valve that can be tested, after the test for the test valve is completed, remove the test valve, connect the test pipelines. Perform the pressure drop measurement of the test pipeline according to the test procedures and flow point for the tested valve. 6.4 For products without special instructions, the flow resistance coefficient and flow coefficient shall be tested when the product is in the full-on position. It shall perform the maximum flow capacity test of the test device. Test records shall be no less than 5 types of flows (unless there are special requirements). The amount of change in each flow value shall be no less than 10%. The maximum flow rate shall be the upper limit of the operating range specified by the test valve manufacturer. This flow cannot be vaporized.
6.5 Except the valves whose spool position shall change with the flow rate, for the other valves at any opening position, given with the minimum flow,
maximum flow, and average flow between minimum and maximum flows, the
deviation between the maximum and minimum values of the flow coefficient shall not exceed 2%.
6.6 Depending on the type of the valve, different methods can be selected for testing. For products without special instructions, the test data can be. set the flow rate in the pipeline to read the pressure drop of the measuring point, or set ?? - water density, in kilograms per cubic meter (kg/m3).
8 Test report
8.1 Information of tested valve
The test report shall contain the following information.
- name of the valve manufacturer;
- valve structure type (e.g.. globe valve)
- valve nominal size (DN);
- valve model;
- valve number.
8.2 Test data
The unit of measurement in the test report shall be in accordance with the provisions of GB 3101, including the following test data.
- position of the closing piece during the test;
- flow at test time and pressure drop at each measurement point;
- inner diameter of test pipeline;
- temperature of medium in the pipeline;
- thread engagement length (valve with threaded end);
- test date.
8.3 Test results
Report the test results of flow coefficient, flow resistance coefficient, flow coefficient - opening degree chart or flow rate - pressure drop, according to customer's requirements.
Annex B
(informative)
Error analysis of test results
B.1 Error
B.1.1 The measurement error depends in part on the residual error of the instrument or measurement method. After eliminating all known errors by calibration, careful measurement and proper installation, use the same
instrument and the same measurement method. There are still errors that shall never disappear and not be reduced by repeated measurements. This error, based on knowledge of the use of instruments and measurement methods, is called systematic error.
B.1.2 Another source of error is directly reflected by the dispersion of the measurements. The cause may be the characteristics of the measurement
system or the change of the measured variable, or both. The assessment of such measurement error is called as random error. This error requires
measurement and analysis. Finally, the statistical analysis of the fluctuations and stability of the measured variables shall be performed.
B.1.3 When determining the systematic error and the random error, the total measurement error can be calculated by the square root of the sum of the squares of the systematic error and the random error.
B.2 Measures to reduce errors
B.2.1 Improve system stability or steady-state conditions. The deviation or change between one reading of the same variable and the next set of readings is very small, i.e. stability or steady-state conditions.
B.2.2 Reduce the systematic error by using more accurate instruments or standardized test methods.
B.2.3 When testing with the same measuring instrument and the same test method, the number of measurements of the same variable under the same
conditions can be increased to reduce the measurement uncertainty caused by random errors.
B.3 Allowable measurement fluctuations
B.3.1 Direct visual observation of output signal of measurement system
The test condition is that the measurement system is not damped before

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