Some standard content:
Light Industry Standard of the People's Republic of China
Test Methods for Pulp Pumps
1 Subject Content and Scope of Application
QB/T1698-1993
This standard specifies the test methods, measuring devices, instruments and error analysis for the flow, head, shaft power, speed, concentration and cavitation margin of pulp pumps.
This standard applies to the testing of pulp pumps and the processing of measurement data. The measurement accuracy of pulp pumps is divided into Class B and Class C. 2 Reference standards
GB/T755 Basic technical requirements for rotating electrical machines
GB/T1032 Test methods for three-phase asynchronous motors GB/T3214 Methods for measuring water pump flow
GB/T3216 Test methods for centrifugal pumps, mixed flow pumps, axial flow pumps and vortex pumps GB 10890
Methods for measuring and evaluating noise of pumps
3 Terms
The definitions of terms used in this standard shall be in accordance with GB/T755 and GB/T3216. 4 Tests
4.1 Test contents
The tests for pulp pumps are divided into factory tests and type tests, and the test items shall be in accordance with the requirements of relevant product standards. 4.2 Test equipment and instruments
4.2.1 The test equipment shall include a water (slurry) circulation system, an electrical control system and a digital measurement system. 4.2.2 It is recommended to use a semi-open system for slurry testing as shown in Figure 1. It should be ensured that the liquid flow passing through the measurement section has the following characteristics: a. Axisymmetric velocity distribution; b. Isostatic pressure distribution; c. No vortex caused by the device. 4.2.3 The water (slurry) test circulation system should meet the following requirements: a. The straight pipe section connecting the pump outlet is perpendicular to the end face of the pump outlet flange; b. The pipe diameter should be equal to the pump outlet; c. The volume of the water (slurry) pool should be able to meet the test requirements; d. The location, setting form and manufacturing requirements of the pressure tapping hole should comply with the provisions of GB/T3216; e. When setting a flow measurement device in the pipeline, the length of the straight pipe section before and after it should comply with the specific provisions of the corresponding measurement device; f. During on-site testing, the requirements for measuring flow and pressure should comply with the provisions of GB/T3214 and GB/T3216 respectively. However, the measuring hole can be appropriately enlarged in principle without affecting the measurement accuracy. Approved by the Ministry of Light Industry of the People's Republic of China on March 28, 1993 and implemented on October 1, 1993
QB/T1698-1993
QB/T1698-1993
4.2.4 All instruments used for measurement shall have a verification certificate or report and shall be calibrated regularly as required. 4.2.5 The measurement accuracy of various measuring instruments shall meet the requirements that the systematic error of the measured parameters shall not exceed the requirements of Table 1. The accuracy of the instrument shall meet the following requirements:
a. The accuracy of the flow transmitter shall not be lower than Class 1.0, and other flow measuring instruments shall comply with the provisions of GB/T3214: b. The accuracy of the spring pressure gauge shall not be lower than Class 0.4, and pressure sensors or other instruments with equivalent accuracy may be used; c. The accuracy of the digital speed meter (including the decimal frequency meter) and the slip meter shall not be lower than ±0.1% ±1 digit; d. The error of the thermometer shall be within ±1C;
e. For the measurement of shaft power, when the two-wattmeter method is used, the accuracy of the ammeter, voltmeter, single-phase wattmeter (including low-power digital wattmeter), and frequency meter shall not be lower than Class 0.5, and the accuracy of the three-phase wattmeter shall not be lower than Class 1.0; the accuracy of the mutual inductor shall not be lower than Class 0.2, the accuracy of the bridge shall not be lower than Class 0.2, and when a torque meter or dynamometer is used, its accuracy shall not be lower than Class 0.5; f. The accuracy of the specific gravity meter shall not be lower than 0.01%. Any other test equipment and methods that have been calibrated or compared with relevant national standards and have proven that the system error of measuring relevant parameters of the slurry pump does not exceed the range specified in Table 1 can be used. Table 1 Allowable system error of measuring instruments
Specified value
Permitted value%
4.2.6 When selecting a pointer-type electrical measuring instrument to measure shaft power, the measured value should be within (20~95)% of the instrument range. If a spring pressure gauge is used, the appropriate range should be selected according to the specified head of the slurry pump. The indicator value of its pointer should be more than 1/3 of the pressure gauge range, and its reading should be 1/100 of the measured head. The instrument indication value should be read after the connecting pipe between the instrument and the pressure tapping hole is completely filled with water. 4.2.7 When using an automatic test system, the system error of the instrument, data set and data processing device should not exceed the provisions of Table 1. 4.3 Test conditions
4.3.1 The test in clean water shall comply with the provisions of GB/T32164.3.2 The test in slurry shall comply with the provisions of the corresponding product standards or product use requirements. 4.3.3 The power supply for the test shall comply with the provisions of GB/T1032. 4.3.4 Operation stability
When the slurry pump is tested and operated, the maximum fluctuation range of its main parameters shall comply with the provisions of Table 2. If it exceeds the limit, the cause shall be found and the test conditions shall be improved to comply with the provisions of Table 2 before proceeding.
Table 2 Maximum allowable fluctuation range
Measured value
Maximum allowable fluctuation range, %
Note, when using a differential pressure gauge to measure flow crab, the maximum allowable fluctuation range of the observed liquid column difference is ±6% for Class B and ±12% for Class C. 161
4.4 Measurement accuracy
QB/T 1698—1993
According to the relevant conditions of the devices and instruments specified in this standard and using the test methods described in this standard, the test error limits of each measurement accuracy level shall comply with the provisions of Table 3.
Table 3 Maximum total error limit
Measured value
Shaft power
Pump efficiency
5 Measurement of parameters
5.1 During measurement, the readings of each instrument shall be read at the same time. 5.2 Measurement of flow
The maximum total error limit allowed, %
Flow measurement shall adopt the measuring instruments and methods specified in GB/T3214 (when the test medium is slurry, electromagnetic flowmeter shall be used preferentially). 5.3 Measurement of head
During the test, the head of the pump is the algebraic difference between the total head at the pump outlet and the total head at the inlet, calculated according to Article 9.2. The pressure holes should be located on both sides of the pump inlet and outlet, 2D (i.e., 2 times the inlet and outlet diameter) away from the pump inlet and outlet flanges (when the on-site test is limited by conditions, the distance between the pressure hole and the pump flange can be appropriately increased, but in principle, the measurement accuracy should not be affected). The correction of the friction loss in this distance and the determination of the correction value shall be carried out according to the test medium in accordance with the provisions of GB/T3216. 5.4 Measurement of concentration
5.4.1 The measurement of concentration refers to the test medium being slurry. The measurement shall be carried out at the outlet of the pipeline, i.e., under the condition that it does not affect the measured flow, by sampling using a container.
5.4.2 The number of sampling times shall be three times, with an interval of small flow, specified flow, and large flow, and each sampling shall not be less than 1L. 5.4.3 The three samples shall be dried separately, weighed using a balance, and the average value shall be taken. And determined according to formula (10) in 9.4. 5.4.4 Any method that can ensure the measurement accuracy and meet the relevant standards can be adopted. 5.5 Measurement of slurry specific gravity
5.5.1 Take samples three times at the outlet of the pipeline, i.e. without affecting the measured flow rate, using a container. The interval time should be equally divided during the test, and each time should be no less than 0.5L.
5.5.2 Measure the three samples with a specific gravity meter respectively, and take the average value, which is determined according to formula 9.3 (9). 5.5.3 Any other measurement method that meets the relevant standards can be used. 5.6 Measurement of shaft power
The measurement of the shaft power of the slurry pump shall comply with the provisions of GB/T3216 and GB/T.1032. 5.7 Measurement of slip or speed
5.7.1 The measurement of slip or speed shall preferably use a photoelectric speed measuring instrument, and may also be determined by flash frequency measurement method, induction coil and other measurement methods.
5.7.2 The determination of slip or speed shall comply with the provisions of GB/T1032. 6 Preparation before the test
Before the test, the assembly quality, installation, test equipment and facilities of the slurry pump should be checked to ensure that all tests can be carried out smoothly. 162
7 Operation test
QB/T 1698—1993
7.1 The slurry pump should be tested for operation at the specified flow rate, and the duration shall not be less than 0.5h. 7.2 During the operation test, check whether there is obvious mechanism impact and friction sound. The noise measurement method shall be in accordance with GB10890, and its value shall comply with the provisions of the relevant product standards.
7.3 Check whether the seal is reliable and whether there is any leakage. 7.4 The bearing lubrication should be good, and its temperature rise should be measured at the end of the test using a contact thermometer. The reading measured at the end of the test is the actual measurement value, and its value should comply with the provisions of the relevant product standards. 8 Performance test
8.1 The slurry pump should be operated at the specified flow rate for not less than 0.5h, and the measurement should be carried out after it reaches a stable state. 8.2 The test should start from zero flow and gradually increase to more than 115% of the flow at the maximum flow point. During this period, at least 13 different flow points should be taken (no less than 18 points for slurry). The measuring points should be evenly distributed on the entire performance curve. There should be a certain time interval between each point measurement to ensure that the working condition reaches a stable state. The flow, head, speed and shaft power should be measured at the same time. 8.3 For the measurement of shaft power, the indirect method is used on site (the direct method can be used if conditions permit). The laboratory should give priority to the direct method. The test method and equipment used refer to GB/T1032 and GB/T3216. 8.4 The measurement of cavitation margin refers to the determination of the critical cavitation margin of the slurry pump. The method is implemented in accordance with GB/T3216. 8.5 Reliability test
8.5.1 The reliability test should be carried out after the completion of each test. The assessment of the mean trouble-free working time and the durability test time can be combined. At this time, the durability test time includes the mean trouble-free working time. 8.5.2 The test shall be carried out under the specified working conditions, and the cause, number of failures and corresponding actual working time during the operation time shall be recorded. 8.5.3 During the endurance test, except for maintenance and replacement of wearing parts according to the requirements specified by the manufacturer and replacement of wearing parts according to the specified time, other parts shall not be replaced.
8.5.4 The reliability test time shall comply with the relevant product standards, and its value shall be determined in accordance with the provisions of Article 9.13. 9 Calculation of test results
9.1 Flow
When measuring with a turbine or electromagnetic flowmeter, the flow rate is determined according to the following formula, and other measurement methods are calculated according to GB/T3214. Q
Where Q-flow rate, m2/s;
f-turbine flow transmitter signal frequency, times/s,
f-turbine transmitter instrument constant, times/L.
Where: Q-flow rate, m\/h.
-×10-3
Where: Q—flow rate, L/s.
9.2 Calculation of head
9.2.1 When the outlet and inlet pressures are measured by a spring pressure gauge: a: When the inlet pressure is greater than the atmospheric pressure, the head is determined by the following formula: (1)
Where: H=head, m;
QB/T 1698—1993
pe_pi+(z:
p2——outlet gauge pressure, Pa or MPa;
: 0—medium density, kg/m°;
p,—inlet gauge pressure, Pa or MPa;
g-free fall acceleration, g=9.81 m/s2; Z,--the distance from the center of the outlet pressure gauge to the reference plane, m; Z,--the distance from the center of the inlet pressure gauge to the reference plane·m; V2--the average flow velocity in the pipe at the outlet pressure measuring hole, m/s; V,--the average flow velocity in the pipe at the inlet pressure measuring hole, m/s. Calculation of V:
Where: A2~
Calculation of Vi:
Cross-sectional area of the pipe at the outlet pressure measuring hole, m2.
Where: A~--Cross-sectional area of the pipe at the inlet pressure measuring hole, m. b. When the inlet pressure is less than the atmospheric pressure, the head is determined according to formula (7): V?-V?
H= pe=p+z.+
（4）
（5）
（7）
Where: Z2 is the distance from the center of the outlet pressure gauge to the pump reference plane (the center of the pressure gauge is "+" above the reference and "-" below). 9.2.2 When a mercury pressure gauge is used to measure the outlet and inlet pressures: the head is determined according to formula (8):
H= P(ha - h)+(Z - Z)+V_V
Where: PHg-—mercury density, kg/m;
hz~outlet mercury pressure gauge reading, mm;
h—inlet mercury pressure gauge reading, mm;
Z2-—the distance from the lowest point of the outlet mercury pressure gauge to the reference surface, m, Z, the distance from the lowest point of the inlet mercury pressure gauge to the reference surface, m. 9.3 Specific gravity is determined according to formula (9):
9.4 Concentration is determined according to formula (10):
Specific gravity three test measurements
The average value of the weight of the three samples
Concentration-
The average value of the volume of the three samples
X 100%
9.5 The calculation of shaft power shall be determined according to the methods and equipment adopted in accordance with the relevant provisions of GB/T1032 and GB/T3216. 9.6 The calculation of speed shall be determined according to the methods and equipment adopted in accordance with the relevant provisions of GB/T1032 and GB3216. 9.7
Calculation of pump efficiency
Where:
--Pump efficiency,%;
(8)
(10)
Q--Flow rate, m\/s;
Measured shaft power, W.
Where: Q---Flow rate, m*/h.
Where: Q--Flow rate, L/s.
QB/T 1698—1993
×100%
×100%
9.8 Calculation of unit efficiency (limited to units with matching requirements and specified slurry pumps): er =
Where: ngr—
Unit efficiency, %;
Tested unit input power, W.
Where: Q-
Flow rate, m\/h.
Where: Q—Flow rate, I./s.
X 100%
X 100%
1000 P
9.9 The flow rate Q, head H and shaft power Pa when the speed is changed to the specified speed nsp are calculated according to the following formula: Q/nsp
Q. = Q
H. = H
npo == np
Where: n-
actual measured speed, r/min.
9.10 Draw the performance curve of the slurry pump H. =f(Q.), P=f(Q.), npo=f(Q.) as shown in Figure 2. 9.11 The head, efficiency and tolerance shall be obtained in accordance with the relevant product standards. 9.12 The cavitation margin shall be calculated and determined in accordance with the provisions of GB/T3216. 9.13 Reliability
·（12）
（13）
（14）
（15）
（16)
：(17)
........( 18 )
（19)
（20 ）
9.13.1 When the test adopts the time cut-off method, the test (cut-off) time shall comply with the provisions of the corresponding product standards, and the mean time between failures (MTBF) shall be determined according to formula (21):
MTBF =
Where: n—
Number of test samples:
t——Test (cut-off) time, h;
r—Total number of sample failures within the test (cut-off) time. When r=0, calculate according to r1. 9.13.2 When the test adopts the fixed number cut-off method, the test shall be conducted until the number of failed prototypes is equal to or greater than 2/3 of the number of tested prototypes. The mean time between failures (MTBF) is determined according to formula (22): 165
QB/T1698-1993
MTBF t+t++t
Wherein. t..t2..n.
Test time of the first, second…n prototypes, h. Hu
10 Analysis and estimation of test error
npo=f(Qo)
Ho=f(Qo）
af(Qo)）
Figure 2 Performance curve of slurry pump
The analysis and estimation of test error shall be conducted according to the method in Appendix A. 11 Test report
..( 22)
The test results should be carefully checked and collated into a report after verification. The test report should be signed by the test leader and participants. The test report should generally include the following contents: a. Test location, date, personnel, test unit (stamp); b. Test nature;
C. Manufacturer name, slurry pump model, product number; d. Slurry pump specified value, test level (B or C); e. Test operating conditions (environment, medium); f. Description of test methods and measuring instruments used; g. Test measurement values;
h. Test results (including performance curves); i.Conclusion.
A1 General
QB/T1698-1993
Appendix A
Analysis and estimation of test errors
(reference)
Measurement accuracy is an important basis for evaluating the reliability of test data, which is obtained through the analysis and estimation of test errors. At the same time, through the analysis of test errors, the main error items affecting the measurement accuracy can be found. Take effective measures to improve the measurement accuracy. The error analysis and estimation methods are based on the instruments and test equipment recommended by this standard and the test methods specified in this standard.
A2 Sources and properties of slurry pump test errors
A2.1 The sources of test errors include instrument errors, errors caused by changes in test conditions (such as changes in ambient and medium temperature, test power supply frequency, voltage fluctuations, etc.); test personnel reading errors, test data calculation and processing methods, and curve drawing errors. A2.2 Test errors are divided into three categories according to their nature. a. Gross error is caused by test personnel reading errors, instrument failure, calculation errors, etc. during the test. This type of error is easy to distinguish and eliminate.
b. Systematic error obeys a certain law and is not compensatory. It reflects the correctness of the test and is not affected by the number of measurements, that is, the systematic error of multiple measurements of the same quantity under the same conditions cannot be reduced or eliminated. The systematic error in the test is mainly the instrument error. The second is the additional error of the instrument caused by the use conditions exceeding the prescribed range of use.
c. Random error obeys statistical laws and is compensatory. It mainly refers to the test equipment due to the instability of water flow and random changes in test conditions. The instability of the tested slurry pump operation, personnel reading deviation and other factors caused by the error. Due to the existence of random errors, when the same operating point is repeatedly measured under the same test conditions, irregular changes will occur in each measurement. As the number of measurements increases, the error will gradually decrease.
A3 Provisions for the estimation of test errors
a. The confidence probability is taken as 95% when calculating each error; b. The errors of the measured quantities are considered to be irrelevant or weakly correlated; C. The errors of each measured value are based on the specified points of the slurry pump, and the other points are not calculated: d. The slurry pump only analyzes and calculates the errors of the main quantities such as flow, head, shaft power, and pump efficiency. A4 Error estimation and synthesis principles
A4.1 The measurement errors not specified in this standard refer to relative errors. A4.2 The numerical value of the accuracy grade of the pointer instrument indicates the absolute value of the reference error allowed by the instrument when expressed in percentage (such as pointer-type electrical instruments, spring pressure gauges, etc.). When measuring, if the instrument is not at the full scale value, its indication error (f) should be determined by formula (A1): ×α%
f,=±
Where: Am—full scale value of the instrument;
A——the display value of the instrument during measurement;
α-instrument accuracy grade.
...(Al)
A4.3 Principle of synthesis of system error
QB/T 1698-1993
In the test, each parameter of the slurry pump can be measured directly or indirectly (that is, calculated by measuring the values of each quantity that has a functional relationship with it), so the method of synthesizing the system error is also different. a. The direct measurement value is synthesized according to the "square root sum" method based on the single error of each instrument: f
Where: f.--
System error;
The single error of each instrument used when measuring a certain parameter. b. The indirect measurement value is calculated according to the error transmission law: g2m
Where f=f(Xi, X,.X,) A certain measured value of the slurry pump afx
X,, X2,..X,-the value directly measured by the instrument in the test. (A2)
（A3)
In actual use, when the relative errors of each direct measurement value are known, the above basic formula can be evolved into the following formula to calculate the relative error of the indirect measurement value:
Random error is handled by probability statistics.wwW.bzxz.Net
rXnl af
In actual measurement, the probability distribution of error follows the t distribution, and the unbiased estimate of its variance is: n
[(X,-x)\]
Number of measurements, generally n=10;
In the formula: n——
——each measurement value;
The arithmetic mean of the measurement value;
·（A5)
Represents the standard deviation of any single observation value in a series of equal-precision measurements, which reflects the precision of the measurement. The smaller α is, the greater the probability of small errors, and the smaller the probability of large errors, the more precise the measurement, the better the measurement repeatability, and the better the stability of the test system.
Random error is expressed by relative error f, which is related to the confidence probability and ε, and can be calculated according to formula (A6): f, =± a-1.o
Where: tn-1
Confidence coefficient, which can be found in Table A1.
Table A1Confidence coefficient of t distribution ta-
If a measurement value is expressed by the arithmetic mean of its n measurement values, the limit relative error should be expressed as: f, ± t-.a
Where: n—-
Number of measurements.
A4.4 Estimation of total test error
f=(f's+ fr
A5 Estimation of systematic error
A5.1 Systematic error of direct measurement value
(A6)
(95% confidence probability)
·(A7)
*(A8)
A5.1.1 Systematic error of flow
QB/T 1698—1993
When a turbine (or electromagnetic) flow transmitter is used to measure the flow (other methods shall comply with the relevant provisions of GB/T3214), the systematic error of the flow fsQ can be determined by formula (A9):
fso\=(ftw + f)
Where: fLw-—Instrument error of turbine (or electromagnetic) flow transmitter; fx-——Secondary instrument error.
A5.2 Systematic error of indirect measurement value
A5.2.1 Systematic error of head
When spring pressure gauge is used for measurement (other methods shall comply with GB3214 and relevant regulations), the head systematic error fsH can be determined by the following formula: (ph)[(Fe +)+(Foe + f) J
Where: fspet -
—Indication error of inlet spring pressure gauge; fspe2—Indication error of outlet spring pressure gauge; fsr
—Density error of medium.
A5.2.2 Systematic error of rotation speed fsn
When direct measurement is used, the systematic error of rotation speed is determined by formula (A11): f=(H + fan)2
Where: fsHz---—error of industrial frequency frequency meter; f ssn —-
error of measuring instrument.
·（A10)
（A11）
A5.2.3 The systematic error of shaft power shall be determined according to the provisions of GB/T1032 and GB/T3216 based on the use of different measurement methods and instruments.
A5.2.4 The systematic error of flow rate fsQ, head fsH and shaft power f converted to the specified speed shall be determined by the following formula: fo = (fo + f)
fsH = (fH + 4f%)2
fsp = (fpa + 9f)2
Where: fspa The systematic error of shaft power, its value is determined in A5.2.3. A5.2.5 The systematic error of pump efficiency smp shall be determined by the following formula: fsnp =fa + f+ fa +fspaz
A6 Estimation of random error f.
（A12）
（A13）
（A14）
（A15）
The random error can be calculated by formula (A6) or formula (A7), and the unbiased estimate of the standard deviation α in the formula is usually calculated using the Bessel formula:
- X)°/n -1J2
The condition for using this formula is that X represents the same column of independent equal-precision measurement values, that is, it should be ensured that the same quantity is measured n times under basically unchanged test conditions. For this reason, when conducting random error analysis tests, the valve position of the flow control valve should be kept unchanged, the system should operate stably, and each quantity under this working condition should be measured multiple times in the shortest possible time. At this time, various conditions and environmental factors will not change significantly, and it can be approximately considered as a column of equal-precision measurements, and then its standard deviation is calculated using formula (A15). A7 Test error of each parameter
The test error of each parameter can be calculated according to formula (A8) and the value of each parameter and the error range can be expressed in the following form: Flow Q:Q±(Q·fα)
Head H: H±(H·faH)
Shaft power: P,±(P.·fspa)
Speed n: n±(n·fsn)
Pump efficiency p: ±(·fp)
Additional instructions:
This standard is proposed by the Technical Equipment Department of the Ministry of Light Industry. QB/T1698—1993
This standard is under the jurisdiction of the National Light Industry Machinery Standardization Center. This standard was drafted by the Light Industry Special Pump Research Institute of Jiangsu Institute of Technology. The main drafters of this standard are Wang Yang, Li Long, Liu Xiqin, Chen Cichang170
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