This standard specifies the test system, test procedures and calculation methods for measuring the flow coefficient and flow resistance coefficient of general valves. This standard is applicable to measuring the flow resistance coefficient of gate valves, globe valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plug valves, check valves, foot valves, pressure reducing valves and gate valves, throttle valves when the water flow through the valve reaches a steady flow. Flow coefficient of flow valve, ball valve and butterfly valve. JB/T 5296-1991 Test method for flow coefficient and flow resistance coefficient of general valves JB/T5296-1991 Standard download and decompression password: www.bzxz.net

Machinery Industry Standard of the People's Republic of China
Test methods for general valve flow coefficient and
flow resistance coefficient
1 Subject content and scope of application
JB/T 5296-91| |tt||This standard specifies the test system, test procedures and calculation methods for measuring the flow coefficient and flow resistance coefficient of general valves. This standard is applicable to measuring the flow resistance coefficient of gate valves, globe valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plug valves, check valves, foot valves, pressure reducing valves and gate valves, throttle valves when the water flow through the valve reaches a steady flow. Flow coefficient of flow valve, ball valve and butterfly valve. 2 Reference Standards
GB3100 International System of Units and their Applications
Gl33101 General Principles of Quantities, Units and Symbols 3 Terminology
3.1 Flow Q
Flow per unit time Volume of water in the valve, m/h. 3.2 Steady flow
As time changes, the flow rate of water flowing through the measurement section does not change significantly. 3.3 Velocity
The average water flow velocity calculated based on the flow rate Q and the inner diameter of the pipe d, m/s. 3.4 Pressure loss Ap
The pressure drop when water flows through the valve, Pa.
3.5 flow coefficient C
When the pressure difference between the two ends of the water flowing through the valve is 100kPa, the flow through a given stroke is measured in m/h, and the medium density is the flow value of kg/m2, m2 .
3.6 Flow resistance coefficient K
The valve pressure loss www.bzxz.net
can be a dimensionless coefficient.
3.7 Pipe length L
The length of the pipe between the front and rear pressure holes of the valve (excluding the length of the valve body), m. 3.8 Resistance coefficient along the way
The friction loss of the water flow passing through the pipe section is a dimensionless coefficient related to Reynolds number. 4 Test coefficients and test procedures
4.1 Test system
The test system is shown in Figure 1.
4.1.1 Test section
The inner diameter of the pipe connecting the front and back of the test valve should be consistent with the nominal diameter of the test valve. The straight length of the pipe is specified in the figure. People's Republic of China Machinery The Ministry of Electronics Industry approved the implementation on 1992-07-07 on 1991-07-22
625
4.1.2 back pressure device
JB/T 5296 --- 91
Ensure that the pipeline behind the valve is filled with water and has sufficient pressure and a post-valve device to prevent cavitation. 4.1.3 Flowmeter
Use a rotary or Venturi flowmeter to measure the flow of the valve or pipeline, or use a calibrated Container measurement and charging
100
lod
1. Controllable water source 2-thermometer 3.-throttle valve; 4 flow meter; 5---pressure hole, 6- Pressure difference measuring device; 7—Test valve; 8—·Regulating valve Figure 1
4.1.4 Pressure difference measuring device
Determine the pressure loss value (including pressure difference instrument, pipe, etc.). 4.1.5 Pressure tapping hole
LOd
atod
The hole on the pipeline for measuring pressure. The center line of the pressure tapping hole should be perpendicular to the axis of the pipeline and located in a horizontal position. The cross-section should be round, and its edges should be clean, sharp or slightly rounded, without burrs, linear edges or other irregular shapes. The hole diameter should be equal to or smaller than 0.1cl. The diameter should not be less than 1mm, and the maximum should not be larger than 12mm. The cross-sectional area of ??the pipe connecting the pressure difference measuring device is not less than the area of ??the pressure hole. 4.1.6 Thermometer
Use a temperature sensor or a mercury thermometer to measure the temperature of the water. 4.2 Measurement error
4.2.1 The flow error is ±2% of the actual flow rate, and the resolution and repeatability of the instrument should be within 0.5%. 4.2.2 The pressure difference error is 10% of the actual pressure difference. 4.2.3 Temperature error: The accuracy of measuring the temperature of the water flow at the entrance is ±1C. For any test of specified flow rate. During the test, the water flow door temperature should be maintained within 3 degrees.
4.3 Test procedures
4.3.1 For products without special instructions, the flow coefficient is measured when the valve is in the fully open position. 4.3.2 Install the test valve in the system shown in the figure, and the test water temperature is 5~40℃. 4.3.3 Record all readings after the water flow has no pulsation and reaches a steady flow state. 4.3.4 Measure and record the pressure loss at no less than 5 flow rates (unless otherwise stated on the product). These flows should include the minimum flow, maximum flow and the average flow rate between them. The measured flow rate should ensure the generation of case flow, but the minimum Reynolds number Re is 4×104.3.5. The pressure loss Δp of the test valve is equal to the total pressure loss A force1 value measured by the pressure difference measuring device minus the pipeline pressure loss at the corresponding flow rate. (i.e.
4.3.5.1 Remove the test valve from the test system and directly connect the pipelines (or directly connect the pipelines with pipes that will not cause significant pressure loss) and measure the pressure loss value of the pipelines individually. 4.3 .5.2 The pressure loss △ of the pipeline can also be calculated by formula (1): Ap2
where; --- the pressure loss of the pipeline. 100kPa: the inner diameter of the pipeline, m.
630
,
d
2
0
JB/T 5296
91
Medium density, k/m, (taken as ==1 )
4.3.6 When the test valve is supplied with the connecting joint, the connecting joint shall be regarded as part of the valve. 5 Test results and calculations
5.1 Test results
Test The results can be expressed in the following two ways: a.
tabulate the pressure loss values ????at the corresponding flow rate; draw a logarithmic coordinate diagram of the pressure loss △ and the flow rate Q b.
5.2. Coefficient calculation
5.2.1 The flow resistance coefficient is calculated according to formula (2):
Where: Ap\---The pressure loss of the test valve, 100kpa. 5.2.2 The flow coefficient is according to formula (3. ) Calculation: K = 2Ap
pua
-Q
N
(
Replace each measured value with A into the formula (3 ), you can calculate a set of flow coefficients, and then obtain the arithmetic mean of (5.2.3 The relationship between valve flow coefficient and flow resistance coefficient is: CAN
2
where : A-——The cross-sectional area of ??the valve flow channel, m2. 5.2.4 Conversion formula between flow resistance coefficient and equivalent length: K
Where:
1
Equivalent length | |tt||5.3 Test report
The test report shall include the following contents:
a.
b.
c
d.||tt ||e,
f.
Production name;
Model and specification of test valve;
Applicable medium;
Factory number or production Catalog;
Source of test valve;
Express the test results as described in 5.1 and (or) 5.2. Note:
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D||tt. ||This standard is proposed and administered by the Hefei General Machinery Research Institute of the Ministry of Mechanical and Electronic Industry. This standard is drafted by Li Deyu, the main drafter of this standard.
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