Some standard content:
Verification Regulations for Velocity Flow Meters
JJG198—1994
Verification Regulations for Velocity Flow Meters
Werinealiun Regulation nr
Veke'ity Fhnw Meter
3.IG 198 - 1994
F19—1901
F20—1989
JG262-
This verification regulation has been approved by the National Institute of Technology in 194509H and will be implemented from December 1, 1094. Responsible unit: China Institute of Metrology Drafting unit: China Institute of Metrology Meter Factory
The technical provisions of this regulation are drafted by the responsible unit. The main drafter of this regulation is:
Sanchi (China Institute of Metrology)
Wang Yuehe (fake watch")
Su Modi (China Academy of Scientific Research)
Additional beneficiaries:
Diamond (Qing Industrial Automation Watch Research Institute) Zhang Haoshi (Gradually Consulting and Certification Testing Technology Research Institute) Zhang Bao (National Science and Technology Commission First Planning and Testing Center) T" (Changsha Electronic Instrument Second")
Yong'an (Bosheng Provincial Planning and Testing Technology Research Institute))1212
Technical Appraisal Requirements
Verification Conditions
Verifier [! and inspection method
-) Attached machine documents and inspection notice
(II) Sealing test...
(I) Metrological performance verification
Verification results and inspection cycle
Appendix [Flowmeter's requirements
Appendix 2 Training format
Appendix 3 Commonly used standard instrument volume calculation formula
Velocity flowmeter verification procedure
This procedure is applicable to the verification of newly manufactured, used and new gas-filled gas flowmeters (hereinafter referred to as flowmeters).
1 Principle
Velocity flowmeter is a flowmeter based on the principle of point-to-point flow measurement. The types of flowmeters are described as follows.
2 Turbine flow meter: Use the impeller of the flow meter to sense the average velocity of the fluid to measure the basic flow rate. Flow meter: The flow meter is proportional to the flow rate. The flow meter is installed outside the pipeline and consists of a flow sensor, a flow meter and a display instrument.
b. Spiral flow meter: In the flow body, a non-streamlined vortex is generated. The fluid rises on both sides of the body and separates the material. The separation frequency of the vortex is proportional to the flow rate. The detection element is a grid. Vortex flow meter consists of three sensors and a display. Vortex flow meter: The flow of the instrument passes through a spiral blade and is rotated around the center line by a strong gas. The flow is condensed in the center of the pipe. The rate at which the vortex center passes through a certain inspection point is proportional to the flow rate. The vortex meter can measure the vortex flow, and the vortex disk sensor and display are corrected. d. Magnetic flowmeter: The induced electromotive force generated by the flow of fluid in the magnetic field is used to calculate and display the flow rate. Flowmeter: Usually consists of an electromagnetic flow sensor, a converter, and a display. Drag wave flowmeter: Uses the propagation characteristics of ultrasonic waves in the fluid to measure the change in base flow. There are two main types:
1) Velocity difference method: Detects and calculates the acoustic pulses in the forward and reverse directions of the fluid flow. 2) The consideration of velocity measurement is to use the principle of acoustic multi-evaluation to determine the flow path of particles in the body to obtain the fluid flow path.
t split vane flowmeter: a orifice plate is installed on the measuring main pipeline, and a jet and a central impeller are installed on the flow path pipeline. The steam is split through the jet to the blades to make the blades rotate. The rotation speed and the number of revolutions indicate the time flow and the accumulated flow of the fluid passing through the meter. The split plate can be more beautiful, and the splitter with different diameters can be used to rectify the flow range.
H, laser Doppler flowmeter 1: According to the multi-frequency shift of the light, the velocity of the particles in the body is obtained. Then the flow velocity is obtained. The point velocity measured by the flow system is calculated according to the known flow section rules or connected: the surface method is required! The net flow velocity is calculated automatically,
. Inlet flow mass meter: The flow meter measures the flow at the specific position inside the flowmeter to determine the flow rate of the pipeline. It includes the measuring head, insert support, flow meter, rotary plate, flow meter, etc. The applicable working fluid is the pressure gauge. The flowmeter is classified as A and requires verification method. Class A: Flowmeter with input flow rate multiple and test coefficient required: vortex flow meter, vortex flow meter with non-rapid condensation, electric dial flow meter with frequency output, inserted turbine flow meter, inlet flow meter, push-type electromagnetic concentration meter with domain input: flow meter that outputs analog signal or can display time flow, micro flow meter, whole wave flow meter, general flow meter, diversion type flow meter and inserted electric density flow meter. Note: If the test data is sufficient, the sieve flow meter can also be calibrated with a screen meter. 2 Technical requirements
4 The flow meter manufacturer shall have an instruction manual. The manual shall state the technical specifications and material of the flow meter. The flow meter calibrated weekly shall also have the previous calibration certificate. bZxz.net
5 Marking
5.1 The flow meter with a one-way measuring plate shall be marked with a flow meter mark in an obvious position of the filling part. S, 2 The flow meter shall be equipped with a nameplate, which shall include: manufacturer's name, product name and model, export number, metering equipment manufacturing license and certification mark, nominal pressure, nominal flow rate or its suitable range, product or flow rate range, accuracy level, and other relevant technical indicators.
6 The flow meter shall be correctly marked. The surface of the newly manufactured flow meter shall be uniform in color, and the coating shall not peel or fall off; the protective glass on the reading bag shall have good transparency and no defects such as reading interruption. 7 The flow meter with a dial shall meet the following requirements 7.1 The unit of the scale value shall be marked on the dial. 7, 2 The handwriting on the dial shall be clear and beautiful, and there shall be no scratches, cracks or other defects that affect the reading and appearance. 8. The flow meter with pointer shall meet the following requirements 8.1 The pointer shall rotate clockwise, evenly and smoothly, without obvious vibration. B.2 The small part of the pointer indicating the unit shall cover 1/4-3/4 of the length of the scale line. 9. The flow meter with digital display shall meet the following requirements 9.1 The displayed numbers shall be clear and neat, and the text symbols and signs indicating the functions shall be clear and correct. 9.2 The welding of the parts shall be flat and smooth, and there shall be no welding or desoldering. 9. The connectors must be firm and reliable, and shall not fall off due to vibration. The flow meter shall be subjected to the point strength test as required, and there shall be no leakage and damage. 0
Push sulfur installation
In the specified flow range, the accuracy level and basic error of the flow meter shall meet the requirements of Table 1. For Class A flow meters (specified in Article 3), the absolute error shall not exceed 1/3 of the absolute error limit specified for the accuracy grade; for Class I flow meters: the repeatability error shall not exceed 1/3 of the absolute error limit specified for the accuracy grade.
12 Flowmeter with standard installation station
3 Verification conditions
12.1 The standard flowmeter (hereinafter referred to as the installation station) and its instruments shall have valid certification certificates. 12.2 The required condensation of the installation shall not exceed 1.2.1217 of the general flowmeter basic error limit.
12.3 Each time the device is put into operation, the maximum allowable time shall be not less than 10 times the flowmeter specified in Article 3. The flowmeter shall ensure that the absolute value of the relative error within the number of pulses in the flow meter during one verification is not greater than ten times the flowmeter's accuracy. 1.12.4 When it is necessary to measure the fluid group flowing through the flowmeter, the temperature shall be reduced according to the flowmeter's own requirements and relevant regulations. The test position should be 5 times the nominal flowmeter length downstream of the flowmeter if there is no adjustment to be made. The influence of the thermometer used on the calibration result should be less than 1/5 of the basic error of the flowmeter.12.5 When measuring the flow pressure of the fluid flowing through the flowmeter, the test position of the flow pressure should be determined according to the flowmeter itself. If there is no special requirement, the device should be installed on the side of the flowmeter to avoid the nominal flow length. The axis of the connecting hole should be vertical to the measuring pipe, and its diameter should be 42. The projection of the pressure hole at the outlet of the measuring pipe should be 11 points on the inner wall of the measuring pipe. Its edge should be flush with the inner surface of the measuring pipe and as sharp as possible without burrs. The error of the dynamometer in the measurement of the model is 1/5 of the error of the model result. When the test liquid is at atmospheric pressure, the nozzle is a flash type. 12.7 The seven test devices are connected to the same average line. 13 Timing Fluid
13.1 Timing System
13.1.1. The calibration fluid should be filled with single-phase fluid, and the flow should be single-phase and lubricated. 13.1.2 The calibration fluid should be non-toxic, free of visible matter, corrosion, etc. 13.2 Setting liquid
[3.2 When calibrating Doppler flowmeters, the bubble content in the setting fluid should be less than that of the overall fluid. 1. When calibrating other flowmeters, the calibration fluid should not be accompanied by slurry. 13.2.2 For flowmeters with reduced flow rate, the viscosity of the calibration liquid should be consistent with the viscosity of the test liquid, otherwise the calibration results should be corrected. 3.2.3 The pressure of the calibration liquid at any point in the pipeline system should be less than 10% of its bubble and vapor pressure. For volatile volatiles, there should be a back pressure downstream of the flowmeter. The recommended back pressure is 2 times the maximum flow rate and 1.25 times the pressure of the saturated vapor of the calibration liquid at low temperature: 13.3 Calibration gas
13.3. For flow rates with an accuracy of not less than 11.5, the temperature of the calibration gas should not change by more than 10% during the annual calibration of each flow point. 5T: For flowmeters with an accuracy lower than level 1.5, during the annual calibration process at each flow point, the measured gas flow rate should not exceed 2 times the actual flow rate. 13.3.2 When the calibrated fluid is earth and steam, a tachometer shall be installed for verification and monitoring, and the tachometer shall be not less than 0.95. In the case where a tachometer is not available, slightly superheated steam with a superheat of not more than 5% shall be used. 14 Environment
14.1 The atmospheric temperature is generally 535°C; the atmospheric relative humidity is generally 4 (45-85%): %.10GlPa
14.2 The power supply should be 1-240V, and the power supply frequency should be (5±2.5)Hz. 14.3 Avoid external micro fields The influence of the flowmeter on the flow rate can be ignored: [4.4 The impact of the dynamic impact on the flowmeter can be ignored: Four verification items and verification methods
(I) Random document and appearance inspection
15 Check the random document and the result will meet the requirements of Article 4, 1218
16 Check the appearance of the flowmeter by the currency daily method, and the result will meet the requirements of Articles 5-9, (III) Sealing test
17 Newly manufactured flowmeters must be tested for sealing performance. The test method is: the flowmeter is subjected to a pressure that is nearly 1.5 times the normal pressure, and the dynamic breaking force source is active for a period of time. The bed force indication does not decrease. After a period of time, the appearance is uniform and the light is clean and full. If there are phenomena such as cracking, etc., then the production style,||tt| |() Metering cavity calibration
18 Before calibration, the calibration method of the meter performance shall be determined according to the standard conditions, 18,1 For all Class A flowmeters that meet the requirements of Articles 19-2.5 and 29-30, calibration shall be carried out: 18.2 For the Class A flowmeters (specified in Article 3), the flowmeter shall be installed on the wing according to the requirements of Appendix 1 of Articles 27 and 31: 20 years of standard flow rate: [00% of the range within 1 week, after full operation for at least 5 minutes), the formal calibration shall be carried out
21 Sparse points
21.1 For the calibration point, at least 3 control points including the small flow rate and the metering pad shall be used for calibration. 21.2 For flow meters with an accuracy level lower than 2.0, the selection of calibration points is as follows: 21.2.1 For class (class) flow meters specified in Article 3, the calibration points should include 4=m, 0.074mx, 0.1500.252, 0.44mx, non-.70%x and mux. When the flow rate of half of the 6 calibration points is less than 0.05%, this calibration point can be ignored. 21.2.2 For Class A flowmeters (specified in Article 3), the calibration points shall be at least 5 calibration points including 4mm and 10mm, and they shall be evenly distributed:
22.1 At least 3 calibration points shall be calibrated:
22.2 For flow ratios of 0.1 and 0.2, each calibration point shall be calibrated at least 6 times. 22.3 For Class A flowmeters (specified in Article 3), if the absolute value of the relative error of the flowmeter counting in one calibration is greater than 1/2 of the flowmeter's value, this calibration point shall be calibrated at least 6 times. During each calibration process, the flow rate, temperature, and base flow rate shall be adjusted according to the following conditions: 24 During the calibration process of each calibration point, the deviation of the calibration flow rate from the calibration point specified in Article 21 shall not exceed -5%:
25 During each calibration, in addition to taking and recording the flow meter display, the instrument display and the calibration time, the fluid density, pressure, and pressure shall be measured and recorded according to the needs. 2 In the case where the fluid density and state have a significant impact on the flow meter indication, the type and state of the calibration fluid shall be consistent with the conditions specified for the flow meter indication. When the flow rate is effective, the minimum value shall be corrected. 27 Instrument coefficient of standard flowmeter
37.1 When the working fluid is liquid, the coefficient of each calibration point and each calibration shall be calculated by formula (1): N 1ip:(s-,li - (l-
武: K,—width of the calibration point observation coefficient, (nr) or [-\;N
例: The number of pulses measured by the flow display instrument at the calibration point: V
The actual volume of the standard flow recorded at the calibration point, 1.: S—The expansion coefficient of the calibration liquid under the calibration conditions; ()
(t), 5-respectively: the calibration point: the fluid temperature at the standard flow recorder during calibration t:-The shrinkage coefficient of the calibration liquid in the calibration condition, respectively: the calibration point, the first calibration The three forces outside the standard instrument and the overflow surface of the flow meter are 1F. (px)r.
and the standard pool is placed together, = D:
=1,2,, for example, for the verification point effect, 3:
-1,2.,, for the verification secondary effect, n3
Note: The same as the flow chamber with the grid flow meter, the change in the volume of the single body caused by the force calculation is small. The energy meter is selected for competition. The temperature can be used without the temperature plate. Under the pressure of cancer, at this time, the effect of the fluid is 27.21. When the acting fluid is gas, the coefficient of each verification point is calculated according to formula (2): Ay P+ pe. (273.13+ 1ta 123,
Da Yi of the inspection leaf, Pa:
7, (2,), two: distinguish as single, calibration point, gas flow meter and standard gas error coefficient at the second calibration: other weeks,
17.3 according to formula (3) to calculate the half-average coefficient of each calibration point. K.-12k
Formula: E-
The average instrument coefficient of each trend point, (n) or [1:27.4 according to formula [ 4) Calculate the meter coefficient K, KK.at (K.) n
The meter coefficient of the flow meter, ()--,
Km-the coefficient of each calibration point, the maximum value, ()-or L\K
The coefficient of each calibration point, the minimum value, (m) or 28 The relative indication of the flow meter is the difference
281 For Class 1 flow meters, when the flow meter is used, the reference difference is used as specified in the specification 4 of your book, and the flow is calculated according to formula (3) The error of the meter's indication.
Er-12(g2×100%
Where:
.--Flowmeter section maximum flow, m or!:
, - etc.: the flowmeter indication at the calibration point, then (6) calculation; - the actual gain of the full flow meter measured at the calibration point, calculated according to formula (7! Fresh: the subscript x represents the initial maximum value of the calculation formula in the brackets at the calibration point, the same below , 14th
test: 7, the first! The flow meter indication at the first calibration point, the indication value under the conditions described in Article 2 until the value after repair 1, the
formula: (· the first; the actual flow rate measured at the first calibration point, a or /28.2 for B final flow, when the flow meter is used in the card plus the provisions, the relative indication error of the flow meter in the formula (8) formula (9)
, - 1 (22+× %)
in:
in the formula,
in the formula:, -
the relative indication error of the flow meter.
The average cumulative flow rate measured by the drip meter at the designated point within the specified time, or 1, calculated according to the formula (calculated by the formula.
The actual average cumulative flow rate flowing through the flowmeter measured by the device at the designated point within a specified time, m or [, calculated according to the formula (i)
English: Calibration point English; When the calibration point is reached, the average cumulative flow rate measured by the device within the calibration time shall be the value of the film under the conditions described in Article 20, or L. Q||t t||Formula: (number, -—first: calibration point the first time the device measured the actual standard agent flowing through the flowmeter during the calibration time! Flow, 1 or 1.
28.3 For a class A flowmeter, calculate the relative error of the flowmeter according to formula (9). This additional formula (9) becomes 1-Kl
where: the previous one is called the linearity of the flowmeter, and its meaning is the same as the opposite (12)
28.3.1 For newly manufactured and repaired flow meters, K is the meter coefficient K of the meter used in the first calibration according to formula (4). Under this condition, formula (12) becomes formula (13): K2x-
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