GB/T 9248-1988 Performance evaluation method for flowmeters for incompressible fluids
Some standard content:
National Standard of the People's Republic of China
Methods of evaluating the performance offlowmcters for incompressible fluids 1 Subject content and scope of application
1.1 Subject content
UC 681.121.8
GB9248--88
This standard specifies the performance evaluation method of incompressible fluid flowmeter and the method of flow rate performance test results. 1.2 Scope of application
1.2.1 This standard is applicable to the flowmeter for measuring single-phase incompressible fluid in sealed pipelines. For example: electromagnetic flowmeter, turbine flowmeter, float (rotor) flowmeter and volumetric flowmeter. 1.2.? Flowmeters used under special operating conditions shall not only meet the requirements specified in this standard, but also meet the requirements specified in other relevant standards.
1.2.3Some test items or requirements specified in this standard may not be applicable to some types of flow meters, while some types of flow meters may need to add other test items or requirements. Therefore, they can be added or deleted according to the relevant product standards according to the different varieties, types, structural principles, etc. of flow meters.
2 Reference standards
GB4729 Performance evaluation method of electric and pneumatic analog transmitters for measurement and control systems GB 2624 Flow measurement throttling devices Part 1 Throttling devices are angle-connected pressure, flange-connected pressure standard orifice plates and angle-connected pressure standard nozzles
GB 1451 Vibration (sinusoidal) test method for industrial automation instruments ZBY247 Industrial automation instrument terminology
ZBN10002 Flow measurement instrument terminology
3 Terms
In addition to ZBY247 and ZBN10002, this standard also uses the following terms. 3.1 Flowrate
The quotient of the amount of fluid flowing through the cross section of a pipe in a short time interval divided by the time interval. The time interval should be short enough so that the flow can be considered to be steady during this time. 3.2 Total (cumulative flow) quantity
The total amount of fluid flowing through the cross section of a pipe in a period of time. Numerically, it is equal to the integral of the flow over time. 3.3 Flowmeter
An instrument for measuring the flow rate or total amount of fluid in a closed pipe. Usually composed of a primary device and a secondary device, 3.4 Steady flowsteadyfluw
National Municipal Industry and Commerce Commission Product Public Port 042 Industry Device
10000101 Safety
GB924888
The flow rate, pressure, density and temperature of the fluid flowing through the measuring pipe section do not change with time, so as not to affect the required measurement accuracy.
Note: The observed steady flow is actually the flow in which these parameters vary slightly with the time-independent semi-mean value. It is not actually a "(statistical) semi-mean steady flow".
3.5 Starting flow rate starting low
The flow value when the flowmeter starts to indicate continuously. The flowmeter does not indicate the error in this discussion: 4 Basic performance test
4.1 Test equipment requirements
a. The test pipeline should be filled with test fluid: b. The fluid flow state should be a steady flow:
Note: Except for the calibration (standard) device using variable head high-level portable unsteady flow state. c. At the flowmeter inlet, the flow state should have a fully developed distribution: d. The basic error limit of the flow calibration (standard) device should be less than ten or equal to one-half of the basic error limit of the flow meter being calibrated. When it is greater than one-third, its error must be considered;
e: The standard instruments and measuring instruments used in the test, such as standard flow meters, standard containers, thermometers, pressure gauges, differential pressure transmitters, density meters, viscometers, etc., should all be inspected and qualified by the metering department; f. The measuring range and basic error limit of the above-mentioned standard instruments and measuring instruments should be sufficient to ensure that the basic error limit of the entire flow calibration (standard) device meets the specified requirements. 4.2 Flow meter installation requirements
4.2.1 Installation position
The flow meter should generally be installed according to the manufacturer's regulations. If there is no regulation, the flow meter can be installed in any position that coincides with the center line of the pipeline for testing, but the position shall not be changed during the entire test. 4.2.2 Pipeline system
If there is no special regulation, the flow meter should generally be installed on a pipeline with a nominal diameter consistent with its upstream and downstream joints, and its deviation shall be in accordance with the relevant product standards.
The joint seal between the pipeline and the flow meter should not be buried in the fluid. 4.2.3 Configuration of upstream and downstream straight pipe sectionswwW.bzxz.Net
In order to make the flow state reach the fully developed velocity, a straight pipe section that meets the relevant product standard requirements should be installed on the upstream and downstream of the flow meter.
4.2.4 Pressure tapping port and detection hole position:
In order to correctly measure the static pressure, pressure loss and temperature of the fluid, the position of the temperature decay detection port should generally meet the following specifications:
P (fluid static pressure) - 10 times the nominal diameter of the pipeline (10,) from the upstream end of the flow meter. a
P: (upstream pressure measurement) 1 times the nominal diameter of the pipeline (ID) from the upstream end of the flow meter: h.
P: (downstream pressure) - 4 times the nominal diameter of the pipeline (tD,) from the downstream end of the flow meter: c.
d,? (Fluid temperature) - 5 times the nominal diameter of the pipe (5D%) from the downstream end face of the flowmeter. The pressure port and the detection hole should be located in the horizontal direction, perpendicular to the pipe. The hole diameter is about 3-12mm. Generally, it is 8% of the pipe diameter. There are no burrs and wide openings at the opening inlet, and there should be a chamfer with a radius not greater than 0.1 of the hole diameter. 4.2.5 Pipeline roughness
The inner wall of the pipe within the length of the nominal diameter of the flowmeter at least 10 times upstream and downstream should be clean, without dents, burrs, scale and peeling. The specific requirements for pipeline roughness should comply with the relevant standards. 4. The connection configuration of the accessories connected to the flow calibration (standard) device should be described in detail, such as the type of temperature detector joint, the depth and size of the extension into the pipe, etc.
4.3 Test flow rate requirements
4.3.1 The performance of the flowmeter is affected by the physical properties of the fluid. Therefore, the specified liquid should be used as the test fluid: if no specific discussion is made, the shear level water should be used as the test fluid, and the humidity should be controlled at 5~-40℃. If other fluids are used, their viscosity and density must be determined by measuring and checking the table before the test.
4.3.2 Air should not be trapped in the fluid. At any point in the pipeline system and flowmeter, the pressure of the test fluid should exceed its saturated steam pressure.
4.3.3 The fluid should not contain particles larger than 15μm. The particle content should be less than 1mg/1. The fluid sampling of the test particulate matter should be carried out when the flow rate of the calibrated flowmeter reaches 50% of the upper limit of the measurement range (hereinafter referred to as the upper limit value).
4.3.4: When using volatile fluid as the test fluid, its vaporization characteristics at the working temperature should be considered; if there is vapor loss during the test, it should be calculated.
4. 4 Test requirements 4.4.1 Ambient atmospheric conditions are shown in Table 1. Table 1 Ambient atmospheric conditions Relative humidity Atmospheric pressure Reference test conditions 60%~73% 86~-1C6 kPa Note: The maximum allowable change rate of ambient temperature during the test period is 1r:/10min. 4.4.2 Dynamic reference conditions General test conditions 5~-35 C 45% 85°C -106°C 45% 85°C -106°C kPa
The nominal value of the gas source or power supply shall be in accordance with the manufacturer's regulations, or agreed upon by the user and the manufacturer. The deviation of the power source shall comply with the provisions of Table 2.
Harmonic sum
(AC)
Fundamental
(True flow)
Nominal value +
1
Nominal value
Less than 5%
Minimum value 0.3%
(Not applicable: flowmeter with backup power supply) 4.4.3 Other environmental conditions
Dust content
Nominal value=1K
2
of ambient temperature! Only under this condition,The dew point should be at least 10 times higher than the temperature of the flowmeter shell (
not more than: ppm
air particles should not be larger than 3μm
field: except for the ground field, other external magnetic fields should be small enough to have a negligible effect on the flowmeter. Mechanical vibration: The vibration of the flowmeter should be small enough to have a negligible effect on the flowmeter. External pressure should be small enough to have a negligible effect on the flowmeter during the flowmeter test. 4.4.4 Signal
Input signal The potential or electrical fluctuation of the flowmeter should have no significant effect on the test. 4.4.54#
a. Electrical signal output flowmeter
GB 9248—88
The load impedance value specified by the manufacturer should be used. If more than one value is given, it can be selected according to the following principles: if the output is a DC voltage signal, take the minimum value specified; if the output is a DC current signal, take the maximum value of the specified chain. b. Pneumatic signal output flowmeter
Unless otherwise specified by the manufacturer, the load impedance of the pneumatic output should be a rigid pipe with an inner diameter of 4ⅡⅡ and a length of 8m, followed by a 2cm air thief, and each air joint should be sealed. 4.5 Basic error and repeatability test
4. 5. 1 General provisions of the test
4.5.1.1 The calibration (standard push) device used to check the flowmeter should be operated under specified and stable environmental conditions. When changes in environmental conditions affect the test results, records should be kept at all times. 4.5.1-2 The flow test points should be distributed throughout the measurement range. There should be at least five points including the upper and lower limits (or 10% of the range nearby). The number and distribution of the test points should be commensurate with the required test accuracy and the nature of the assessment. 4.5.1.3 The input of each flow test point should be kept stable, and the reading should be recorded after the indication of the calibrated flowmeter stabilizes. 4.5.1.4 Due to flow fluctuations and random instability of the calibration (standard > device, etc.), each test point should be tested multiple times and the indication should be read at least three times.
For pulse output flowmeters, a sufficient number of pulses should be accumulated to minimize measurement errors. 4.5.1.5 During the test, any adjustments to the flowmeter should be included in the report, and the impact of these adjustments on the performance determined under reference conditions should be stated.
4.5.2 Basic error test and result expression method 4.5.2.1 Basic error is tested under reference test conditions. If the influence of the measurement error can be ignored, it is allowed to test under the general test conditions specified in Table 1.
4.5.2.2 Compare the indicated values corresponding to each flow test point with the corresponding actual values, and the deviation is expressed as a percentage of the actual value or E limit value.
According to the average value of each group of deviations obtained at each test point, plot the error curve relative to the flow rate. The average value greater than the actual value is a positive deviation, otherwise it is a negative deviation; the largest positive or negative deviation is the basic error of the calibrated flow meter. 4.5-2.3 For pulse output flow meters, the number of pulses per unit flow can be read several times continuously at a fixed flow value and the average value can be taken as the basic error of the flow meter: then plot the curve of the number of pulses per unit flow relative to the flow rate, and the average pulse value can be used to calculate the deviation of each flow point from the actual flow, and plot the error curve. The value of the flowmeter related to the Reynolds number can be expressed by the relationship between the Reynolds number or the parameters related to the Reynolds number and the error or coefficient of the flowmeter.
4.5.2.4 Basic error limit envelope
The basic error limit envelope of the flowmeter is a curve of the maximum allowable error of the flowmeter, which is expressed by the positive and negative percentage of the relative error on the ordinate and the percentage of the upper limit of the flow rate on the abscissa. The maximum positive and negative deviations of each test point of the flowmeter tested under the reference test conditions should fall within the range of the basic error limit envelope. There are three typical basic error limit envelopes, as shown in Figure 1. a: The envelope with a certain positive and negative percentage of the upper limit as the maximum deviation. Figure 1a is the envelope with 1% of the upper limit as the maximum deviation:
b. The envelope with a certain positive and negative percentage of the indicated flow as the maximum deviation. Figure 1b is the envelope with ±1 Mbps of the indicated flow as the maximum deviation:
c. The envelope curve of the maximum deviation is taken as a positive or negative percentage value of the indicated flow or a positive or negative percentage value of the upper limit. The value in between is taken as the envelope curve of the maximum deviation. Figure 1 is a comparison of the values taken when the upper 1% of the indicated flow or ±0.2% of the upper limit is the maximum deviation.
Relative error %
CB9248-88
al limit 1
h indicated flow rate-1
indicated flow rate 31% or limit ±0.2% of its maximum Figure 1
Typical basic error limit envelope
Package source and grade A juice
GB 9248:-88
Under the same test conditions, for the same flow test point in the same direction in the flow measurement range, connect the values measured multiple times and calculate the standard deviation S of each test point according to formula (1). The maximum value is taken as the instrument repeatability. The single-component property can also be expressed as the percentage of the upper limit value or the average percentage of the values of each test point, as shown in formula (2) or formula (3): S = Vz(Q, -Q)/(n -- 1)
VE(Q. - )/( -1) × 100%
V2(Q. - Q):/(n - 1)
2×100%
Wherein: Q: the value measured at the same test point each time the average value of the above values:
Qnx upper limit value;
n—number of tests,
5 Influence quantity test
5.1 General provisions of the test and expression of the influence of influence quantities (1)
5.1.1 When testing the influence of each influence quantity, other conditions should be kept within the specified range to observe the changes in flowmeter performance caused by changes in the influence quantity or changes in flow characteristics. If necessary, The test is carried out at ten flow test points to determine the serious impact point of the influencing quantity.
5.12 For some influencing quantity tests (for example, ambient temperature, mechanical vibration and turbulence, etc.), due to the size of the flow meter, the weight and the test equipment conditions, it is impossible to test the flow meter under the actual flow of the test fluid. Therefore, in this case, the test is carried out in the flow meter filled with liquid or in a simulated state. a. If it can be proved in theory that the influence of the influencing quantity on the performance of the flow meter is independent of the instrument size, it can be tested by testing the same type of small-sized instrument.
b. The influence of the influencing quantity on the mechanical structure of the flow meter should be tested with an instrument of actual size filled with static liquid. 5.1.3 If the influence of the influencing quantity on the flow meter is a linear parameter, it is usually a list of coefficients of various influencing factors, such as: the influence of power supply resistance is %/V of the range, the influence of power supply frequency is %/Hz of the range, the temperature drop is %/C or the influence is % of the range within the temperature range.
If the influence on the flowmeter is nonlinear, a limit error diagram of the lower limit value with the change of the range should be drawn.
Limit error diagram of the lower limit value with the change of the ambient temperature
5.2 Test items
5.2.1 Fluid viscosity
GB 9248
Environmental sensitivity
Limit error of measuring range with temperature
Continued Figure 2
For flowmeters working in the environment where the fluid viscosity changes, the test should be carried out with fluids of low precision or the same fluid with different temperatures producing viscosity changes. 1. When selecting the test fluid, the viscosity range of the flowmeter to be calibrated should be considered. The ideal fluid viscosity test is to use a method of exchanging fluids of different viscosity at a constant temperature. If it is not possible to perform the test at a constant temperature, the effect of fluid temperature on the flowmeter must be measured first. The change in the flowmeter lower limit value caused by the fluid at three different viscosities (including the upper and lower limit viscosities) can be recorded. Note: For a single test, if the fluid viscosity does not change by more than 10%, the effect of fluid humidity on the flowmeter may not exceed the limit. 5.2.2 Fluid temperature
Place the flowmeter at a constant ambient temperature, measure and record the changes in the flowmeter lower limit value and range caused by the fluid at three different temperatures (including the upper and lower limit temperatures), and the deviation of each temperature is ±2 (. The selected fluid temperature should be different enough from the test environment temperature to show the effect of fluid humidity on the flowmeter. 5.2.3 Fluid density
Place the flowmeter at a constant ambient temperature, measure and record the flowmeter's lower limit value and range change when the fluid is at a different density (including the lower limit density). The range of fluid density should be wide enough to show the influence of fluid density on the flowmeter. 5.2.4 Reynolds number
The results of fluid viscosity change and flow temperature dependence test can be used to show the function of Reynolds number. 5.2.5 Velocity distribution
Determine the deviation of the flowmeter from the reference velocity distribution (usually the greater than 3°C) of the flowmeter. Connect the following pipe fittings to the end of the specified straight pipe section length for testing: a. There are two points on the surface with standard velocity radius: b. On the vertical axis of the sample, three standard velocity diameters are connected; the diameter is gradually increased (length is 3·pipe diameter) 10) Record the lower limit of the flowmeter under test respectively, and compare the lower limit of the flowmeter with the range obtained by the single-stage flowmeter. In order to calculate the influence of deviation from the reference velocity distribution: If the manufacturer does not specify the length of the upstream and downstream straight pipe sections, the test can be carried out at any point within the length of the upstream straight pipe section less than 5.2.6 Static pressure
The purpose of this test is to first measure the change of the lower limit and range of the flowmeter caused by the static pressure change. Secondly, check whether the flowmeter has good sealing performance under the rated working pressure. Change the static pressure from atmospheric pressure to the rated working pressure of the flowmeter at four equal intervals. Record the lower limit and range changes of the flowmeter at these four pressures respectively. For some flowmeters, this test should also be carried out under a static pressure lower than atmospheric pressure. 2.7 Overrange
General provisions for overrange test:
GB9248—88
a. Overrange limit (usually 125% of the upper limit); b. Overrange duration (usually 10 minutes); c. If there is reverse flow. Perform upper and lower limit overrange tests. Then measure the change in the lower limit value and range of the flowmeter. 5.2.8 Change in power supply voltage and rated frequency
When conducting this test, the load impedance shall comply with the provisions of Article 4.4.5. The combined test or DC voltage change test shall be carried out according to the voltage and frequency of the AC power supply listed in Table 3, or the test shall be carried out in accordance with the relevant standards of the manufacturer. Record the change in the lower limit value and base range during each set of tests. Table 3
5.2. 9 Short power interruption
Nominal value
Nominal value
Nominal value
110% of nominal value
110% of nominal value
110% of nominal value
85% of nominal value
85% of nominal value
85% of nominal value
Nominal value
105% of nominal value
95% of nominal value
Nominal value
105% of nominal value
Nominal value 95% of nominal value 105% of nominal value 95% of nominal value 105% of nominal value 95% of nominal value 105% of nominal value 110% of nominal value 110% of nominal value 85% of nominal value 85% of nominal value 85% of nominal value This standard is used to determine the transient process and recovery time of the flowmeter when switching from the normal power supply to the backup power supply. During the test, the input signal should be kept at 50% of the range. For DC-powered flowmeters, the power interruption time is 5, 20, 100, 200, 500ms. For AC-powered flowmeters, the power interruption time is 310, 20, 200ms, 1s. Each interruption time test shall be repeated 10 times, with the time interval between two tests being at least 10 times the interruption time. Record the following values of the flowmeter:
Maximum instantaneous positive and negative changes in the output;
b. The time it takes for the output to reach 99% of its steady-state value after the power is reconnected: any permanent changes in the output.
Changes in gas source pressure
Stabilize the output signal of the flowmeter at the upper limit. Observe and record the changes in the flowmeter output when the gas source pressure is the nominal value and 90% and 110% of the nominal value. 5. 2. 11 DC power supply reverse protection
For the secondary installation of a two-wire flowmeter with power supply reverse protection, the maximum allowable reverse power supply voltage should be applied to check for light loss. The inspection should be carried out at an output value of 90% to 95% by changing the nominal voltage of the flow meter by ±10%. 5.2.12 Common mode interference
This test is only applicable to secondary devices whose terminals are insulated from ground. The test circuit is shown in Figure 3. Input source: Input signal source: GB 9248 --88. Calibrated current: 50Hz AC single core with adjustable phase and amplitude. Calibrated current meter: adjustable current element. b. DC common mode + interference. Figure 3 Common mode interference test circuit. Apply 250V voltage with the same frequency as the main power supply (or as specified by the manufacturer) between each input and output terminal and ground. At the same time, change the phase of the interference voltage (0°~360\). Record the lower limit value of the current meter and the maximum change of the range. Then use DC voltage instead of AC voltage for test. Use 50V (or as specified by the manufacturer) DC voltage or 1000 times the input range, whichever is smaller. Apply positive and negative voltages for testing, and record the lower limit of the current meter and the maximum change of the range. 5.2.13 Cross-mode interference
The purpose of this test is to determine the influence of the main frequency AC signal superimposed on the input signal on the output. The test circuit is shown in Figure 1.
Constant signal source
Test requirements:
The test is carried out on the S0% range;
With the effective current meter
Adjustable phase amplitude
SHz current transformer is a pressure unit
Figure 4 Cross-mode interference influence test circuit
h. One end of the transformer secondary coil which is not directly connected to the flowmeter should be grounded; for the flowmeter with isolated input and output, its output end should be grounded when measuring the input. Test method and steps:
Series:
GB9248—88
The superimposed voltage is generated from the transformer secondary coil, and the transformer secondary is connected in parallel with the 1C2 switch. It is in phase with the input signal. First disconnect the flowmeter from the test circuit. Adjust the transformer primary voltage to set the analog voltage on the parallel circuit to 1V peak value, then connect the circuit, change the transformer voltage phase (0°~360\), and record the maximum change of the flowmeter output signal.
If the cumulative change is greater than 0.5% of the total range, the change can be reduced by 0.5% by reducing the step voltage. Then record the corresponding series voltage value.
5.2.14 Connection
This test is only applicable to flowmeters with electrical input and output terminals insulated from the ground. Ground each input and output terminal in turn, and record the transient and steady-state changes of the lower limit and range. Note: The effect of grounding the signal source is eliminated. 5.2.15 Load impedance of electrical output flowmeter
Record the changes of the lower limit and range of the flowmeter caused by the load impedance changing from the minimum value specified by the manufacturer to the maximum value. 5.2.16 Load of gas output flowmeter
During the test, the gas source quality is kept at the nominal value. Set the input signal to 10%, 50% and 50% of the range L respectively for the test. First, different amounts of air flow into the flowmeter output connector, and measure the output pressure at each gas flow rate. Then, different amounts of air flow into the flowmeter output connector again, and measure the output pressure at each exhaust flow rate. After that, draw a line of functional convection. The line is shown in the figure. Output t
(vehicle area)
Exhaust class
length is determined by the line:
Figure 5 Pneumatic flowmeter pressure flow curve
a. Maximum gas flow (output 2(:kPa) h, manned exhaust flow (output lcokPa); surplus gas volume m3:
c. When the gas flow changes from 0.2m\/h to 0.4m/h (under reference conditions). Changes in box\ pressure: d, when the exhaust volume changes from o.2mh to o.4m (under reference conditions). Changes in output pressure\. 5.2.17 External magnetic field
Place the flowmeter in a main power frequency variable magnetic field with a field strength of 400A/m (effective value) and test it in three mutually perpendicular magnetic field directions, and change the power supply voltage phase (0~363\) that generates the magnetic field to determine the maximum change value of the flowmeter when the output signal point is 10%0.
5.2.18 Installation position
GB9248—88
When performing each compensation ratio test, the flowmeter shall be installed according to the provisions of Article 2.1. If the installation position is not specified, observe the influence of the attenuation caused by the oblique installation. The test results shall be included in the report. 5.2.19 Temperature control: For flowmeters with inseparable primary and secondary devices, the test shall be carried out as a whole piece: b. For flowmeters with separate secondary and secondary devices, the test shall be carried out as a whole piece as much as possible, or the following specified wave is carried out: first, let the secondary device bear the temperature influence test, while the primary device of the flowmeter works under normal test conditions, and then let the flowmeter and secondary device bear the flow tension test while the secondary device works under normal test conditions. The flowmeter shall be tested in the following temperature sequence: 20℃.40℃.55.20℃.CC, -19℃, -25℃.20℃ for two consecutive cycles. No adjustment shall be made during the test. The difference of each mixing degree is 10.2 (the temperature point at each level should be kept for a long enough time to make the flow meter reach thermal stability.
Changes in the output signal value of the flowmeter: The test should be carried out at the above-mentioned high and low humidity points within the maximum and minimum workpiece temperature range specified in the system - record the changes in the lower limit value and process. Note that the flow meter should have the same temperature change as the flow meter when the air flows out of the flowmeter: During the test, the flow rate and temperature of the flow meter should remain unchanged. 5.2.20 Mechanical vibration
The mechanical vibration that the flowmeter may encounter during operation is determined by the test results. The change of lower limit compensation and range caused by vibration is to ensure the good firmness of the flowmeter under vibration. The test procedure is as follows:
Before the test, first perform a performance test on the flowmeter and record the lower limit value and range: a.
During the test, the input signal should be set above 50: The flowmeter should be installed on the vibration table according to the manufacturer's specifications: c. The vibration table, mounting plate and all mounting brackets should have sufficient rigidity to minimize the dynamic transformation ratio of the flowmeter: d.
The flowmeter is subjected to the test on the track perpendicular to the main part. The test is divided into three stages in the following order and carried out in turn. After all the tests in three stages are completed, the final measurement is carried out. Stage 1: Initial perturbation response inspection This stage is to check the flowmeter's response to vibration and test its resonant frequency, and collect data for the final resonance. The frequency range of the flowmeter is used for verification, and the displacement and speed end values are used for verification. The resonance test is carried out according to the working conditions of the flowmeter (the installation site is selected according to Table 1). The frequency range is set to the frequency range and the continuous frequency sweep is performed with a logarithmic sweep rate of about 0.5 minutes. Before scanning, remember the signal value of the flowmeter, then observe and record the frequency, amplitude and rate of resonance when the output value changes significantly during the beat period. [Workshop (field research) On-site (general use) Through-flow (· Temporary use) Current dynamic minimum level) Pipeline (source dynamic level) Pipeline (vibration reduction station) Position reduction rate Suppression record Phase II: Durability test GB 924888
The flowmeter is subjected to the maximum mechanical vibration frequency found in the first stage for half an hour in three mutually perpendicular planes. If the resonance point is not found, it is vibrated at the high frequency specified in the working conditions. The third stage: Final vibration response check
The method and parameters for finding the final resonance are the same as those for finding the initial resonance in the first stage. The final resonance frequency and amplitude found are compared with the initial resonance point. If there is a difference between the two, it may be caused by inelastic deformation that causes the mechanical structure to begin to break. Final measurement:
After the vibration test, the mechanical condition of the flowmeter should be checked for good, and the change of the lower limit value and the maximum range of the flowmeter in the test layer should be measured. 5.2.21 Humidity
a. For flowmeters whose primary and secondary devices cannot be separated, the test should be carried out in an integrated manner; b. For flowmeters whose primary and secondary devices can be installed separately, the test should be carried out in an integrated manner as much as possible, or the primary and secondary devices should be subjected to humidity influence tests separately according to the corresponding methods specified in Article 5.2.19, Item 1. Before the test, the flow meter is placed in the test environment for 24 hours, and then the lower limit and range are tested. Then the flow meter is placed in a closed test box with atmospheric pressure (the temperature in the box is 38~40℃, and the relative humidity is 9L%~95%) for at least 48 hours. The power is turned on in the last 4 hours, and the lower limit and range are tested at the end of this cycle. After the test, the flow meter should still remain in working condition, and the temperature in the box should be reduced to below 25℃ in no less than 1 hour. During this period, the closed test box should reach saturation, and the maximum change of the lower limit and range is recorded. After that, open the box door and visually check whether the flow meter has signs of breakdown, condensate accumulation, and component damage. Finally, after the flow meter is placed in the environment for another 24 hours, the lower limit and range are tested, and compared with the measured data before the test to determine its performance impact.
6 Other tests
6.1 Pressure loss
The pressure loss (△P) before and after the flowmeter shall be tested at all flow test points specified in Section 4.5.1.2. The location of the pressure tapping holes of P1.P2 shall be in accordance with Section 4.2.4 and calculated according to the following formula. Ap = Pt-
6.2 Starting flow
Measure and record the minimum flow value when the flowmeter starts to indicate continuously. The indication error is not counted at this time. 6-3 Output signal ripple content
The peak-to-peak value and fundamental frequency content of the output ripple content shall be tested and recorded at the maximum and minimum loads when the input signal is 10%, 50% and 90% of the range.
6.4 Insulation resistance
This test shall be carried out according to the actual requirements and the relevant standards. 6.5 Insulation strength
This test shall be carried out according to the actual requirements and the relevant standards. 6.6 Energy consumption
6.6.1 Power consumption
Test at the specified nominal voltage and nominal frequency and at the highest voltage and lowest frequency respectively. Adjust the flow through the flowmeter so that the power consumption of the flowmeter reaches the maximum value, and record the wattage and volt-ampere. 6.6.2 Gas consumption
Change the input signal, observe and record the maximum gas consumption of the flowmeter. 6.7 Accelerated life test
Flowmeters with mechanical or electro-mechanical components should be tested. Considering the working principle and mechanical structure of the flowmeter, this testThe purpose of this phase is to check the flowmeter's response to vibration and test its resonant frequencies and to collect data for the final resonance of the load. The frequency range of the flow meter test, the displacement value and the speed end value are selected according to the working conditions of the flow meter (the installation site is selected according to Table 1. The resonance test is carried out according to the specified frequency range and the frequency sweep is determined by logarithm. The sweep speed is about 0.5 times the frequency per minute. Before sweeping, record the signal value of the flow meter. Then observe and record the frequency, amplitude and the rate of resonance when the output value changes significantly during the sweep period. [Workshop test (field research) On-site (general use) Through-through (· Temporary use) Lowest dynamic level) Pipeline (connected source dynamic level) Pipeline (vibration station) Position drop amplitude Suppression record Phase II: Durability test GB 924888
The flowmeter is subjected to the maximum mechanical vibration frequency found in the first stage for half an hour in three mutually perpendicular planes. If the resonance point is not found, it is vibrated at the high frequency specified in the working conditions. The third stage: Final vibration response check
The method and parameters for finding the final resonance are the same as those for finding the initial resonance in the first stage. The final resonance frequency and amplitude found are compared with the initial resonance point. If there is a difference between the two, it may be caused by inelastic deformation that causes the mechanical structure to begin to break. Final measurement:
After the vibration test, the mechanical condition of the flowmeter should be checked for good, and the change of the lower limit value and the maximum range of the flowmeter in the test layer should be measured. 5.2.21 Humidity
a. For flowmeters whose primary and secondary devices cannot be separated, the test should be carried out in an integrated manner; b. For flowmeters whose primary and secondary devices can be installed separately, the test should be carried out in an integrated manner as much as possible, or the primary and secondary devices should be subjected to humidity influence tests separately according to the corresponding methods specified in Article 5.2.19, Item 1. Before the test, the flow meter is placed in the test environment for 24 hours, and then the lower limit and range are tested. Then the flow meter is placed in a closed test box with atmospheric pressure (the temperature in the box is 38~40℃, and the relative humidity is 9L%~95%) for at least 48 hours. The power is turned on in the last 4 hours, and the lower limit and range are tested at the end of this cycle. After the test, the flow meter should still remain in working condition, and the temperature in the box should be reduced to below 25℃ in no less than 1 hour. During this period, the closed test box should reach saturation, and the maximum change of the lower limit and range is recorded. After that, open the box door and visually check whether the flow meter has signs of breakdown, condensate accumulation, and component damage. Finally, after the flow meter is placed in the environment for another 24 hours, the lower limit and range are tested, and compared with the measured data before the test to determine its performance impact.
6 Other tests
6.1 Pressure loss
The pressure loss (△P) before and after the flowmeter shall be tested at all flow test points specified in Section 4.5.1.2. The location of the pressure tapping holes of P1.P2 shall be in accordance with Section 4.2.4 and calculated according to the following formula. Ap = Pt-
6.2 Starting flow
Measure and record the minimum flow value when the flowmeter starts to indicate continuously. The indication error is not counted at this time. 6-3 Output signal ripple content
The peak-to-peak value and fundamental frequency content of the output ripple content shall be tested and recorded at the maximum and minimum loads when the input signal is 10%, 50% and 90% of the range.
6.4 Insulation resistance
This test shall be carried out according to the actual requirements and the relevant standards. 6.5 Insulation strength
This test shall be carried out according to the actual requirements and the relevant standards. 6.6 Energy consumption
6.6.1 Power consumption
Test at the specified nominal voltage and nominal frequency and at the highest voltage and lowest frequency respectively. Adjust the flow through the flowmeter so that the power consumption of the flowmeter reaches the maximum value, and record the wattage and volt-ampere. 6.6.2 Gas consumption
Change the input signal, observe and record the maximum gas consumption of the flowmeter. 6.7 Accelerated life test
Flowmeters with mechanical or electro-mechanical components should be tested. Considering the working principle and mechanical structure of the flowmeter, this testThe purpose of this phase is to check the flowmeter's response to vibration and test its resonant frequencies and to collect data for the final resonance of the load. The frequency range of the flow meter test, the displacement value and the speed end value are selected according to the working conditions of the flow meter (the installation site is selected according to Table 1. The resonance test is carried out according to the specified frequency range and the frequency sweep is determined by logarithm. The sweep speed is about 0.5 times the frequency per minute. Before sweeping, record the signal value of the flow meter. Then observe and record the frequency, amplitude and the rate of resonance when the output value changes significantly during the sweep period. [Workshop test (field research) On-site (general use) Through-through (· Temporary use) Lowest dynamic level) Pipeline (connected source dynamic level) Pipeline (vibration station) Position drop amplitude Suppression record Phase II: Durability test GB 924888
The flowmeter is subjected to the maximum mechanical vibration frequency found in the first stage for half an hour in three mutually perpendicular planes. If the resonance point is not found, it is vibrated at the high frequency specified in the working conditions. The third stage: Final vibration response check
The method and parameters for finding the final resonance are the same as those for finding the initial resonance in the first stage. The final resonance frequency and amplitude found are compared with the initial resonance point. If there is a difference between the two, it may be caused by inelastic deformation that causes the mechanical structure to begin to break. Final measurement:
After the vibration test, the mechanical condition of the flowmeter should be checked for good, and the change of the lower limit value and the maximum range of the flowmeter in the test layer should be measured. 5.2.21 Humidity
a. For flowmeters whose primary and secondary devices cannot be separated, the test should be carried out in an integrated manner; b. For flowmeters whose primary and secondary devices can be installed separately, the test should be carried out in an integrated manner as much as possible, or the primary and secondary devices should be subjected to humidity influence tests separately according to the corresponding methods specified in Article 5.2.19, Item 1. Before the test, the flow meter is placed in the test environment for 24 hours, and then the lower limit and range are tested. Then the flow meter is placed in a closed test box with atmospheric pressure (the temperature in the box is 38~40℃, and the relative humidity is 9L%~95%) for at least 48 hours. The power is turned on in the last 4 hours, and the lower limit and range are tested at the end of this cycle. After the test, the flow meter should still remain in working condition, and the temperature in the box should be reduced to below 25℃ in no less than 1 hour. During this period, the closed test box should reach saturation, and the maximum change of the lower limit and range is recorded. After that, open the box door and visually check whether the flow meter has signs of breakdown, condensate accumulation, and component damage. Finally, after the flow meter is placed in the environment for another 24 hours, the lower limit and range are tested, and compared with the measured data before the test to determine its performance impact.
6 Other tests
6.1 Pressure loss
The pressure loss (△P) before and after the flowmeter shall be tested at all flow test points specified in Section 4.5.1.2. The location of the pressure tapping holes of P1.P2 shall be in accordance with Section 4.2.4 and calculated according to the following formula. Ap = Pt-
6.2 Starting flow
Measure and record the minimum flow value when the flowmeter starts to indicate continuously. The indication error is not counted at this time. 6-3 Output signal ripple content
The peak-to-peak value and fundamental frequency content of the output ripple content shall be tested and recorded at the maximum and minimum loads when the input signal is 10%, 50% and 90% of the range.
6.4 Insulation resistance
This test shall be carried out according to the actual requirements and the relevant standards. 6.5 Insulation strength
This test shall be carried out according to the actual requirements and the relevant standards. 6.6 Energy consumption
6.6.1 Power consumption
Test at the specified nominal voltage and nominal frequency and at the highest voltage and lowest frequency respectively. Adjust the flow through the flowmeter so that the power consumption of the flowmeter reaches the maximum value, and record the wattage and volt-ampere. 6.6.2 Gas consumption
Change the input signal, observe and record the maximum gas consumption of the flowmeter. 6.7 Accelerated life test
Flowmeters with mechanical or electro-mechanical components should be tested. Considering the working principle and mechanical structure of the flowmeter, this test
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