Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG 633—2005
Gas Disptacement Meters
2005-04-28 Issued
Implementation on 2005-10-28
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China JJG 633-2005
Verification Regudation for
Gas Displacement Meters
JJG 633—2005
Replaces JJG 633--1990
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on April 28, 2005, and came into effect on October 28, 2005.
Responsible unit:
Main drafting unit:
Participating drafting unit:
National Technical Committee for Flow and Capacity Metrology
Zhejiang Quality and Technical Supervision Inspection Institute Heilongjiang Metrology Verification and Testing Institute
China National Institute of Metrology
Zhejiang Tianxin Instrument Co., Ltd.
Henan Institute of Metrology
Shanghai Institute of Metrology and Testing Technology
This regulation is entrusted to the National Technical Committee for Flow and Capacity Metrology to interpret this regulation. Main drafter:
Shen Wenxin
Participating drafter:
Fan Shusha
Kong Qingyan
Zhang Jinming
JJG 633—2005
(Zhejiang Quality and Technical Supervision Inspection Institute) (Heilongjiang Metrology Verification and Testing Institute)
(China National Institute of Metrology)
(Zhejiang Tianxin Instrument Co., Ltd.)
(Henan Institute of Metrology)
(Shanghai Institute of Metrology and Testing Technology) Scope·
References
3 Terms and units of measurement
3.1 Terms ·
3.2 Measurement units
4 Overview
5 Measurement performance requirements
5.1 Accuracy level
5.2 Maximum allowable error
5.3 Repeatability
5.4 Sealing
6 Technical requirements
6.1 Appearance·..
7 Control of measuring instruments
7.1 Evaluation or prototype test
JJG 633—2005
7.2 Initial verification, subsequent verification and inspection in use Appendix A Outline of type evaluation (prototype test) Appendix B Range method
Appendix Saturated vapor pressure of water
Appendix D Format of the inner pages of the verification certificate
Appendix E Format of the inner pages of the verification result notification
JJG 633—-2005
Verification procedure for gas volumetric flowmeters
This procedure refers to and adopts OIML R32 Rotary piston gas meterg and turbine gas meters, 1989 edition and OIML R6 General provisions for gas volumemeters, 1989 edition. 1 Scope
This regulation applies to the type evaluation or prototype test, initial verification, subsequent verification and in-use inspection of gas volumetric flowmeters (including gas rotary flowmeters, rotary piston gas flowmeters and turhine gas flowmeters, etc., hereinafter referred to as flowmeters). This regulation does not apply to the verification of diaphragm gas meters. 2 References
JJF1015-2002 General Specification for Type Evaluation and Type Approval of Measuring Instruments JF1016-2002 Guidelines for Compilation of Type Evaluation Outline of Measuring Instruments OEMI.R6 General provisions for gas volumemeters，1989 edition (General provisions for gas volumetric flowmeters)
0IMI. H32 Rotary piston gas meters and turhine gas metersa， 1989 edition (Rotary piston gas flowmeter and turbine gas flowmeter)
JB/T7385—1994 Gas rotary flowmeter JB/T9329-1999 Basic environmental conditions and test methods for transportation and storage of instruments GB/T17626.2-1998 Electromagnetic compatibility test and test technology Electrostatic discharge immunity test GB/T17626.3-1998 Electromagnetic compatibility: test and test technology Radio frequency electromagnetic field radiation immunity test GB/T2423.4-1993 Basic environmental test procedures for electrical and electronic products Test Db: Alternating damp heat test method When using this procedure, attention should be paid to the current valid versions of the above-mentioned references. 3 Terms and units of measurement
3.1 Terms
3.1.1 Cyclic volume of a volume meter The volume of gas discharged when the flow meter completes a working cycle, that is, the volume of gas discharged when all moving parts, except the indicating device and the intermediate transmission mechanism, return to their initial positions for the first time. 3.1.2 Value of agivcn air volume quaritity The amount of measured gas specified to determine the error of the flow meter. 3.1.3 Test element A device that can accurately read the volume of gas. 3.1.4 Reference conditions A set of temperature, humidity, and air pressure values or ranges specified to ensure that the measurement results can be compared with each other. 3.1.5 Non-reference conditions 1
JJG 633200S
In addition to the reference conditions, the flowmeter can maintain a set of temperature, humidity, air pressure values or ranges within the specified maximum allowable error range, which is the normal working condition of the flowmeter. 3.2 Measurement units
3.2.1 Volume unit: cubic meter, symbol m; or liter, symbol 1 (dm2). 3.2.2 Flow unit: cubic meter per hour, symbol m/h; or liter per hour, symbol L/h. 3.2.3 Pressure unit: Pa (scal), kilopascal or megapascal, symbol Pa, kPa or MPa. 3.2.4 Temperature unit: Celsius, symbol ℃. 3.2.5 Time unit: hour, symbol h
4 Overview
Positive displacement flowmeter is a cumulative flowmeter that records the total amount of fluid flowing through a period of time. When the fluid flows through the flowmeter, the internal mechanical moving parts divide the fluid into individual air chambers of known rotational volume under the action of fluid dynamics, and repeatedly fill and empty them. The number of cycles can be recorded through mechanical or electronic measurement technology to obtain the cumulative flow of the fluid.
5 Metering performance requirements
5.1 Accuracy level
The accuracy level of the flowmeter should generally comply with the provisions of Table 1. 5.2 Maximum allowable error
The maximum allowable error of the flowmeter should comply with the provisions of Table 1. Table 1
Accuracy level
Maximum allowable error (%)
Note: If the flow range is divided into high and low areas by the dividing flow rate (Q,), the Q. value should be ≤0.2Qm, and the maximum allowable error of the low area should not exceed 2 times the maximum allowable error of the high area. 5.3 Repeatability
The repeatability of the flowmeter shall not exceed 1/3 of the maximum allowable error.5.4 Sealing
The flowmeter shall not leak at 1.1 times the nominal pressure.6 General Technical Requirements
6.1 Appearance
6.1.1 Verification Mark
The flowmeter shall have a reliable inspection mark or verification seal.6.1.2 Flow Direction Mark
For flowmeters whose indicating device has a definite reading for only one flow direction, an arrow shall be used to indicate this direction. If the direction of gas flow has been determined by the structure of the flow meter, the flow arrow can be omitted: 6.1.3 Dial markings Each flow meter should have the following markings on the panel or in a suitable place: the same machine type approval or measuring instrument manufacturing license number; the manufacturer's name or trademark;
-Serial number and production date:
Model specification;
-Maximum flow rate: Qm.=m/h;
Minimum flow rate: Qm=m/h;
Maximum working pressure: Pmx=·MPa (or kPa); Temperature range: ..℃℃;
- Rotation volume of flowmeter: V=m (or dm)7 Measuring instrument control
Measuring instrument control includes type evaluation or prototype test, initial verification, subsequent verification, and in-use inspection.7.1 Type evaluation or prototype test
Type evaluation or prototype test shall be carried out in accordance with JF1015-2002 "General Specification for Type Evaluation and Type Approval of Measuring Instruments" and JJF1016-2002 "Guidelines for Compilation of Type Evaluation Outline of Measuring Instruments". The outline of type evaluation (prototype test) is shown in Appendix A.
7.2 Initial calibration, subsequent calibration and inspection during use 7.2.1 Calibration conditions
7.2.1.1 Calibration environmental conditions
1 Reference conditions
Ambient temperature: 15℃~25%;
Relative humidity: 40%~70%;
Atmospheric pressure: 86kPa~106kPa.
2) Non-reference conditions
Ambient temperature: -10%~40%;
Relative humidity: ≤93%;
Atmospheric pressure: 86kPa~106kPa.
7.2.1.2 Calibration equipment
1) Calibration instrument
The flow range of the calibration standard should be compatible with the flow range of the flow meter being tested, and its expanded uncertainty (=2) should be less than or equal to half of the absolute value of the maximum allowable error of the flow meter being tested. 2) Auxiliary measuring instruments
Measurement value reference! Measuring instruments for error calculation must hold a valid verification certificate or calibration certificate and must also meet the following requirements:
Thermometer: graduation value is 0.1°C;
JJG 633—2005
Hygrometer: the error limit is ±5% in the relative humidity range of 20%~90%; -Barometer: the relative expanded uncertainty (1=2) of the corrected indication should be better than 2.5%; -Differential pressure gauge: the accuracy level should be better than Level 1; -Manometer: the resolution of the digital pressure gauge is less than 10Pa, and the graduation value of the water-type pressure gauge is within 20Pa. 7.2.2 Verification items
The items for the initial verification, subsequent verification and in-use inspection of the flowmeter are shown in Table 2. 2. List of Verification Items
Verification Items
Sealing
Indication Error
Repeatability
First Verification
1. "+" indicates items to be inspected, "" indicates items not to be inspected; 2. Visual inspection of appearance in accordance with the provisions of the General Technical Requirements of this Regulation. 7.2.3 Verification Method
Subsequent Verification
In-use Inspection
The basic verification method of flowmeter is to connect the flowmeter to be inspected and the standard instrument in series with a pipeline, and compare the indicated quantities of the two when a certain amount of gas flows through to obtain the indication error. The types of calibration methods are classified according to the standard pushers used, as shown in Table 3. Table 3
Transfer method
Comparison method
Volume method
Standard instrument
Standard flow meter
Piston type gas flow marking device
Bell type gas flow marking device
1) Dynamic method calibration principle and typical test device Calibration method
Dynamic or static
Dynamic or static
Gas flows through the flow meter under test at a specified flow rate, and the initial values of gas volume, time, pulse, etc. flowing through the flow meter and the standard instrument are synchronously accumulated; when the gas volume flowing through the flow meter reaches the given gas volume, the accumulation is stopped at the same time; compare the indicated quantities of the two, as well as the temperature, pressure, degree and other parameters recorded during the detection, and calculate the indication error of the flow meter according to the specified calculation formula. Dynamic method is the preferred calibration method for volumetric flowmeters. Typical test device for flowmeter comparison method: Sonic nozzle gas flow standard device structure is shown in Figure 12) Static method calibration principle and typical test device: When the flowmeter under test and the standard are in a static state, record the initial values of both; open the exhaust valve to make the flowmeter run at a predetermined flow rate, close the exhaust valve when the gas volume reaches the given gas volume, and read the final state of the flowmeter under test and the standard. 633—200S
Static pressure for differential pressure
Sonic nozzle
Filter
Pressure gauge
Vacuum pump
Water column pressure gauge
Differential pressure gauge
Tested device
Thermometer
General speed nozzle gas flow standard device diagram Figure 1
Value, compare the indicated quantities of the two, and calculate the indicated error of the flow meter according to the specified calculation formula based on the temperature, pressure, humidity and other parameters recorded during the test. The typical test device of the static method is shown in Figure 2.
Bell-type pusher
Bell-type control
Level gauge in bell
Discharge outlet
Counter
For differential pressure
Tee-type cabinet
Discharge outlet
For static pressure
Pickup meter
Concave column pressure gauge
Structure of bell-type gas flow standard device
For static pressure
Temperature difference correction meter or hygrometer
@Hygrometer
Figure 2 Schematic diagram of bell-type gas flow standard device 5
7.2.4 Verification procedure
7.2.4.1 Installation
JJG6332005
The installation of the flow meter should comply with the requirements of the instruction manual or be installed according to the installation mark on the flow meter. The flow meter for positioning should be installed according to the positioning state. The diameter of the test pipe for installing the flowmeter should be consistent with the flowmeter. After installation, the axis of the flowmeter and the axis of the pipe should be visually coaxial: the seal at the inlet end of the flowmeter should not protrude into the pipe, and the inner wall of the pipe should be clean and free of scale. The difference between the internal liquid temperature of the wet gas flowmeter and the temperature of the calibration medium and the ambient temperature should not exceed 1C. 7.2.4.2 Sealing inspection
The temperature and pressure measuring instruments in the flowmeter and the calibration system, and each connecting pipeline should have good air tightness under the calibration pressure. The sealing inspection should be strictly in accordance with the operating procedures of the calibration device. The calibration can only be carried out after confirming that the system has no leakage. 7.2.4.3 Pre-operation
Before the test begins, the flowmeter to be tested should be ventilated for pre-operation. In principle, it should flow for 5 minutes at the indicated maximum flow rate, or ensure that the gas volume of the pre-operation is not less than 50 times the rotation volume. For wet gas flowmeters, the test element should be re-aligned to zero position after pre-running. When the air inlet and outlet are confirmed to be connected to the atmosphere, the sealing liquid reference water level should be recalibrated before error verification can be carried out.
7.2.4.4 Verification flow
Generally, within the flow range of the flowmeter, the error test is carried out on the three flow points of 0 (maximum flow), 0.2Q and 0 (minimum flow). If the flowmeter divides the flow range by (dividing flow), the verification flow points are Q0. and Q. For flowmeters with accuracy levels of 0.2 and 0.5, two verification flow points of 0.70 and 040 should be added: for wet gas flowmeters, two flow points of Q and 0.20 should be verified. During the test, the actual flow of each flow point should not deviate from the specified verification flow by more than 5%. Each flow point should be tested at least twice. 7.2.4.5 Temperature measurement
The temperature of the gas flowing through the flowmeter to be tested should be measured more than twice during the error measurement process of each test flow, and the average value should be taken. The temperature measurement position is specified to be on the upstream side of the flowmeter. For wet gas flowmeters, the gas temperature at the outlet should be measured.
7.2.4.6 Humidity measurement
For wet gas flowmeters (hereinafter referred to as water-sealed wet flowmeters) and bell-type gas flow standard devices (hereinafter referred to as water-sealed bells) whose sealing liquid medium is clean water, humidity measurement should be carried out. The humidity of the gas flowing through the flowmeter under test is specified to be measured close to its inlet. It is generally believed that the relative humidity value of the gas after flowing through the water-sealed wet flowmeter or the water-sealed bell is 95%RH
7.2.4.7 Pressure measurement
The pressure of the gas flowing through the flowmeter under test is measured once during each calibration flow, and the pressure measurement position is specified to be on the upstream side of the flowmeter.
7.2.4.8 Differential pressure measurement
When necessary, the pressure difference (differential pressure) between the inlet and outlet of the flowmeter under test should be measured at each test flow rate. 7.2.4.9 Indication error measurement
During a test, the test element of the flowmeter should start and stop at the same position, and the given gas volume or the set number of pulses should be equal to an integer multiple of the rotation volume, or the set given gas volume should be large enough to make the influence caused by the change of the rotation volume negligible. The indication error of each flow point is the arithmetic mean of the errors of multiple independent measurements (try not to perform continuous error measurements at the same flow rate). The indication error of a single measurement is calculated as follows: Qm-Q×100%
Where: E-indication error of the flowmeter;
Q.——The cumulative flow value of the flowmeter, m2 or L; Q.——The cumulative flow value of the standard under the same temperature and pressure state as Q, m or L. (1)
When the gas state parameters in the standard device are different from the state parameters entering the flow meter to be tested, the cumulative flow indication of the standard device should be converted into the value under the inlet state of the flow meter to be tested according to formula (2), and then the Q value calculated according to formula (2) is substituted into formula (1) to calculate the indication error of the flow meter: 273.15+t(p.+p.-pma)zm
Q.-273.15+1*(p+pp-Pm)z
Where:
Q-cumulative flow indication of the standard device, m or L; p. atmospheric pressure, Pa
tg, tm
Pa, m
PHa max.PHm max
are the gas temperatures in the standard and at the flowmeter under test, respectively, ℃; max
are the gas gauge pressures in the standard and at the flowmeter under test, respectively, Pa; Z.. Zm
are the gas saturation vapor pressures in the standard and at the flowmeter under test, respectively, Pa; (2)
are the gas compressibility coefficients in the standard and at the flowmeter under test, respectively. When the pressure difference between the standard and the flowmeter under test is less than two atmospheres, Z, Zm
can be considered as Z, Z=5 Note: For wet gas flowmeters, whether used as standard meters or as tested meters during testing, the average value of the sealing liquid temperature and the outlet gas temperature of the flowmeter is taken as the gas temperature flowing through the flowmeter. For the flowmeter with output frequency signal, the calculation formula of the flowmeter coefficient of each flow point single calibration is K=Q.
where: K—the coefficient of the jth calibration at the i-th flow point, 1/m or 1Yl; N,——the number of pulses of the i-th flow point, the th calibration; Q—the Q. value of the i-th flow point, the th calibration. The average coefficient K of the calibration flow point is calculated as follows: -lK
where: K—the average coefficient of the flow point, 1/m or 1/Ln—the number of measurements.
The average coefficient of the flow meter is calculated as follows: (K+K)
Wherein: K—-average flow meter coefficient, 1/m or 1/L; (K)x——-the maximum value of the average coefficient K of each flow point, 1/m2 or 1/L; (3)
JJG 633-2005
(K)-the minimum value of the average coefficient K of each flow point, 1/m or 1/L. The calculation formula of the indication error of the flowmeter is bZxz.net
×100%
(Ki)x -
Et=(K)+ (K)
=×100%
Wherein: E,—Linearity of the flowmeter, its meaning is the same as E; (6)
Note: For flowmeters with flow ranges divided into high zone and low zone, the K value of the (, point is allowed to be used to calculate the E, value of the zone; the indication error shall meet the requirements of Article 5.2 for the maximum allowable error. 7.2.4.10 Repeatability calculation
a. Verify the indication error of the flowmeter according to the cumulative flow. Its repeatability is calculated as follows: E nux -Erin
Where: E, repeatability of flowmeter;
E—-the maximum error in the calibration flow point: E——the minimum error in the calibration flow point; d
-range coefficient.
b. Verify the indication error of the flowmeter according to the coefficient. The repeatability of the calibration point of the flowmeter is calculated as follows: Kinm - Kirl × 100%
(En),=
Where: (E)—repeatability of the ith calibration point; d, K
-the maximum coefficient in the calibration point, 1/m or 1/L; Kima
K..—The smallest coefficient in the calibration point, 1/m2 or 1/L. The repeatability of the flow meter is determined by the following formula:
En=(ER)imax
7.2.5 Processing of calibration results
A calibration certificate shall be issued for flow meters that have passed the calibration in accordance with the provisions and requirements of this regulation, and a new flow meter coefficient shall be set if necessary; a calibration result notice shall be issued for flow meters that have failed the calibration, and the unqualified items shall be pointed out. 7.2.6 Calibration cycle
For flow meters with accuracy levels of 0.2 and 0.5, the calibration cycle is 2 years, and for flow meters of other levels, the calibration cycle is 3 years; for flow meters that are calibrated periodically, if the indication error calculated according to formula (6) (in this case, K takes the flow meter coefficient given in the last calibration certificate) exceeds the maximum allowable error, and the indication error calculated according to formula (7) meets the requirements, then the calibration cycle is 1 year. 8K
-the largest coefficient among the calibration points, 1/m or 1/L; Kima
K..-the smallest coefficient among the calibration points, 1/m2 or 1/L. The repeatability of the flowmeter is determined by the following formula:
En=(ER)imax
7.2.5 Processing of calibration results
A calibration certificate shall be issued for the flowmeter that has passed the calibration according to the provisions and requirements of this regulation, and a new flowmeter coefficient shall be set if necessary; a calibration result notice shall be issued for the flowmeter that has failed the calibration, and the unqualified items shall be pointed out. 7.2.6 Verification cycle
For flow meters with accuracy levels of 0.2 and 0.5, the verification cycle is 2 years, and for flow meters of other levels, the verification cycle is 3 years; for flow meters that are periodically verified, if the indication error calculated according to formula (6) (in this case, K is the flow meter coefficient given in the last verification certificate) exceeds the maximum allowable error, and the indication error calculated according to formula (7) meets the requirements, then the verification cycle is 1 year.K
-the largest coefficient among the calibration points, 1/m or 1/L; Kima
K..-the smallest coefficient among the calibration points, 1/m2 or 1/L. The repeatability of the flowmeter is determined by the following formula:
En=(ER)imax
7.2.5 Processing of calibration results
A calibration certificate shall be issued for the flowmeter that has passed the calibration according to the provisions and requirements of this regulation, and a new flowmeter coefficient shall be set if necessary; a calibration result notice shall be issued for the flowmeter that has failed the calibration, and the unqualified items shall be pointed out. 7.2.6 Verification cycle
For flow meters with accuracy levels of 0.2 and 0.5, the verification cycle is 2 years, and for flow meters of other levels, the verification cycle is 3 years; for flow meters that are periodically verified, if the indication error calculated according to formula (6) (in this case, K is the flow meter coefficient given in the last verification certificate) exceeds the maximum allowable error, and the indication error calculated according to formula (7) meets the requirements, then the verification cycle is 1 year.
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