JJG 1030-2007 (JJG1030-2007)
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JJG 1030-2007: PDF in English
JJG 1030-2007
NATIONAL METROLOGY TECHINICAL SPECIFICATION
OF THE PEOPLE’S REPUBLIC OF CHINA
Ultrasonic Flowmeters
ISSUED ON: AUGUST 21, 2007
IMPLEMENTED ON: NOVEMBER 21, 2007
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine
_______________________________________________________________________
This Regulation was approved by General Administration of Quality Supervision,
Inspection and Quarantine on August 21, 2007, and shall be implemented since
November 21, 2007.
Jurisdiction organization:
National Flow and Capacity Measurement Technical Committee
Main drafting organizations:
National Institute of Metrology, China
Natural Gas Chengdu Branch, National Crude Oil Large Flowrate Measurement
Station
Participating drafting organizations:
National Water Large Flowrate Measurement Station
Tianjin Institute of Metrological Supervision and Testing
Daniel Measurement and Control Department of Emerson Process Management
Co., Ltd.
Beijing CHANGMIN Tech Co., Ltd.
Beijing WEIYEYUANGUAN Science & Trade Co., Ltd.
Shenzhen JIANHENG Industrial Automation System Co., Ltd.
Tangshan HUIZHONG Instrument Co., Ltd.
National Flow and Capacity Measurement Technical Committee is entrusted for
interpretation of this Regulation.
Replacing “Ultrasonic Flow”
part in JJG 198-1994
Verification Regulation of Ultrasonic
Flowmeters
Main drafters of this Regulation:
Wang, Chi (National Institute of Metrology, China)
Qiu, Fengchun (Natural Gas Chengdu Branch, National Crude Oil Large Flowrate
Measurement Station)
Participating drafters:
Miao, Yusheng (National Water Large Flowrate Measurement Station)
Chen, Xing (Tianjin Institute of Metrological Supervision and Testing)
Wang, Shuishan (Daniel Measurement and Control Department of Emerson
Process Management Co., Ltd.)
Pu, Qihuan (Beijing CHANGMIN Tech Co., Ltd.)
Shi, Lei (Beijing WEIYEYUANGUAN Science & Trade Co., Ltd.)
Xiao, Cong (Shenzhen JIANHENG Industrial Automation System Co., Ltd.)
Zhang, Lixin (Tangshan HUIZHONG Instrument Co., Ltd.)
Table of Contents
1 Scope ... 5
2 References ... 5
3 Terms and Definitions ... 6
4 Overview ... 8
5 Requirements of Metrological Performance ... 10
6 General Technical Requirements ... 11
7 Control of Measuring Instrument ... 12
Appendix A Type Evaluation of Ultrasonic Flowmeter ... 22
Appendix B Special Requirements of On-site Verification ... 33
Appendix C In-use Inspection ... 35
Appendix D Installation Requirements of Ultrasonic Flowmeter ... 42
Appendix E Format of Verification Certificate (inner page) ... 45
Verification Regulation of Ultrasonic Flowmeters
1 Scope
This Regulation is applicable to the type evaluation, initial verification, subsequent
verification and in-use inspection of ultrasonic flowmeters for closed pipes (hereinafter
referred to as flowmeters), which takes time difference method as the principle.
This Regulation is not applicable to the verification of ultrasonic flow measuring
instrument in open channels and closed conduits.
2 References
Through reference, the clauses included in the following standards and regulations
become the clauses of this Regulation.
JJF 1001-1998 General Terms in Metrology and Their Definitions
JJF 1004-2004 Metrological Terms and Their Definitions for Flow Rate
GB 3836 Electrical Apparatus for Explosive Gas Atmospheres
GB/T 18604-2001 Measurement of Natural Gas Flow by Ultrasonic Flow Meter
GB 17820-1999 Natural Gas
GB 50251-2003 Code for Design of Gas Transmission Pipeline Engineering
GB/T 13609-1999 Natural Gas - Sampling Guidelines
GB/T 13610-2003 Analysis of Natural Gas by Gas Chromatography
GB/T 17747.2-1999 Natural Gas - Calculation of Compression Factor - Part 2:
Calculation Using Molar - Composition Analysis
ISO 17089: 2004 (CD) Measurement of Fluid Flow in Closed Conduits - Ultrasonic
Meters for Gas; Meters for Fiscal and Allocation Measurement
ISO/TR 12765: 1997 Measurement of Fluid Flow in Closed Conduits - Methods Using
Transit Time Ultrasonic Flowmeters
AGA Report-1992 No.8 Compressibility Factors of Natural Gas and Other Related
Hydrocarbon Gases
AGA Report No.9-1998 Measurement of Gas by Multipath Ultrasonic Meters
AGA Report No.10-2003 Speed of Sound in Natural Gas and Other Related
Hydrocarbon Gases
ANSI/API MPMS 5.8-2004 Measurement of Liquid Hydrocarbons by Ultrasonic Flow
Meters Using Transit Time Technology
Please make sure to adopt the currently valid version of the above-mentioned
references.
3 Terms and Definitions
3.1 Ultrasonic Flowmeter
Ultrasonic flowmeter refers to a flowmeter which utilizes the transmission characteristic
of ultrasonic wave in fluid to measure flow.
3.2 Ultrasonic Transducer
Ultrasonic transducer refers to a device which can generate acoustic output under the
effect of electric signal and transduce acoustic signal to electric signal.
3.3 Wetted Ultrasonic Meters
Wetted ultrasonic meters refers to flowmeters which embed transducer into fluid
pipelines; allow the transducer to directly contact the fluid.
3.4 Clamp-on Ultrasonic Meters
Clamp-on ultrasonic meters refers to flowmeters which fixate transducer outside fluid
pipelines; whose acoustic wave transmission path penetrates through the wall of fluid
pipelines.
3.5 Transit Time
Transit time refers to the time of ultrasonic signal’s transmission in the fluid medium
part.
3.6 Acoustic Path
Acoustic path refers to the actual path of ultrasonic signal’s transmission among paired
ultrasonic transducers.
3.7 Transmission Angle
Transmission angle refers to the included angle between acoustic path and pipeline’s
axes.
3.8 Single-path Meter
Single-path meter refers to a flowmeter that merely has one pair of transducers.
3.9 Dual-paths Meter
Dual-paths meter refers to a flowmeter that has two pairs of transducers.
3.10 Multiple-paths Meter
Multiple-paths meter refers to a flowmeter that has above two pairs of transducers.
3.11 Meter Body
Meter body refers to a pipe section which is adopted for the installation of components
like ultrasonic transducer; can comply with the stipulations of relevant standards in all
the aspects after going through special manufacture.
3.12 Zero-flow Reading
Zero-flow reading refers to flowmeter’s maximum flowrate reading when the medium
is under a stationary state.
3.13 Pulse Factor
Pulse factor refers to pulse count sent out by a flowmeter when a unit volume of fluid
flows through the flowmeter. Generally speaking, it is also known as K factor, which
shall be expressed in symbol K.
3.14 Flow Conditioner
Flow conditioner refers to a component that can reduce vortex and improve the
distribution of speed.
3.15 Signal Processing Unit
Signal processing unit is constituted of electronic components and microprocessor
system. It is a part of flowmeter.
3.16 Transition Flowrate (qt)
Transition flowrate refers to a flow value between the maximum flow and the minimum
flow. It segments the range of flow into two zones with different allowable errors,
namely, “high zone” and “low zone”.
3.17 Meter Factor
Meter factor refers to a factor that is used to correct the value indicated by flowmeter
in accordance with the result of actual flow verification of the flowmeter. The value is
the ratio of the value indicated by the standard to the value indicated by flowmeter.
Generally speaking, it is expressed in symbol F.
4 Overview
4.1 Operating Principle
Flowmeter takes the measurement of the relations between the time and the flow of
acoustic wave’s transmission in flowing medium as the principle. Generally speaking,
it is believed that acoustic wave’s actual transmission speed in fluid is constituted of
acoustic wave’s transmission speed (cf) under the stationary state of the medium, and
the component of fluid’s axial average flow rate (vm) in the direction of acoustic
transmission. As it is shown in Figure 1, the relations between the downstream and
upstream transmission time, and the various components are as follows:
Where,
tup---time of ultrasonic wave’s upstream transmission in fluid;
tdown---time of ultrasonic wave’s downstream transmission in fluid;
L---length of acoustic path;
cf---ultrasonic wave’s transmission speed in fluid;
vm---fluid’s axial average flow rate;
ϕ---transmission angle.
Figure 1 -- Universal Sketch Map
The two formulas in Formula (1) may be utilized to obtain the formula of fluid flow rate.
Or, similar methods may also be adopted to obtain the transmission speed of acoustic
wave.
Use mathematical functional relationship to unite the obtained fluid flow rates
( ) of multiple acoustic paths. Thus, an estimated value ( ) of
pipeline’s average flow rate may be obtained. Multiply it by flow area (A), then, volume
flow rate (qv) may be obtained, as it is shown in Formula (4):
Where,
Where,
k---number of acoustic paths.
NOTE: even if the number of acoustic paths is provided, the precise form of
will be vary with the arrangement of acoustic paths and the
different calculation methods of numerical value.
4.2 Structural Form
4.2.1 Composition
Flowmeter is mainly constituted of meter body, ultrasonic transducer and its installation
parts, signal processing unit, and (or) flow computer. In terms of on-site wetted
ultrasonic meters and clamp-on ultrasonic meters, pipelines where transducer is
installed may be used as meter body. The transducer of wetted ultrasonic meters
directly contacts the fluid being measured, while the transducer of clamp-on ultrasonic
meters is tightly installed on the external wall of pipelines.
4.2.2 Form
4.2.2.1 In accordance with the installation mode of transducer, flowmeter may be
divided into two forms, namely, wetted and clamp-on.
4.2.2.2 In accordance with the different numbers of transducers, wetted ultrasonic
meters may be divided into single-path meter, dual-paths meter and multiple-paths
meter.
4.2.2.3 The output mode of flowmeter includes: pulse output, analog output and digital
communication output, etc.
5 Requirements of Metrological Performance
5.1 Grade of Accuracy
Table 1 provides recommended accuracy grade series. If a grade of accuracy that is
not listed in this table is adopted, the maximum allowable error needs to comply with
corresponding principles in Table 1 and needs to be clearly indicated in flowmeter
product instruction and flowmeter nameplate. Within the flow range of qt ≤ q ≤ qmax, the
maximum allowable error of flowmeter shall comply with the stipulations in Table 1.
Within the flow range of qmin ≤ q ≤ qt, the maximum allowable error shall not exceed
twice of the maximum allowable error stipulated in Table 1. Furthermore, in terms of
gas flowmeter, the corresponding flow rate of qt shall be not more than 3 m/s; in terms
of liquid flowmeter, the corresponding flow rate of qt shall be not more than 0.3 m/s.
Table 1
5.2 Repeatability
Repeatability of flowmeter shall not exceed 1/5 of the absolute value of the maximum
allowable error stipulated by the corresponding grade of accuracy.
5.3 Flowmeter Factor Adjustment
If meter factor is changed during verification, then, the verification certificate shall
clearly indicate the previous meter factor, the meter factor after the current adjustment
and the amount of meter factor adjustment.
5.4 Requirements of Two-way Measurement Flowmeter
Flowmeter that allows two-way measurement shall be respectively verified in two
measurement directions.
5.5 Requirements of Clamp-on Flowmeter
In terms of clamp-on flowmeter, all the transducers shall be verified; verification shall
be conducted under pipe diameter that is as identical to the adopted pipe diameter as
possible. If the ratio of the used pipe diameter to the verification pipe diameter is larger
than 2, or, less than 1/2, then, the flowmeter in use shall add an additional error of
0.5%.
Grade of Accuracy
Maximum Allowable
Error E
6 General Technical Requirements
6.1 Product Documents
6.1.1 Flowmeter shall be accompanied by an instruction for use.
6.1.2 In terms of clamp-on ultrasonic meters, the instruction for use shall describes
flowmeter’s installation methods and operating requirements in details.
6.1.3 The instruction for use of flowmeter shall provide the operating pressure range
and operating temperature range of transducers; provide the geometric dimensions of
the installation of transducers. In the product documents, wetted ultrasonic meters
shall include an inspection report of geometric dimensions of the flowmeters in exit-
factory inspection.
6.1.4 Flowmeters, which are under periodic verification, shall also have the previous
verification certificate and the inspection report of various in-use inspections after the
previous verification.
6.2 Nameplate and Marking
6.2.1 Flowmeter shall have marking of flow direction.
6.2.2 Flowmeter shall have a nameplate. Generally speaking, meter body or
nameplate shall indicate:
a. Name of manufacturer;
b. Product name and model;
c. Exit-factory serial number;
d. Marking and serial number of permit of manufacturing metrological instruments;
e. Pressure rating (merely restricted to wetted flowmeter);
f. Nominal diameter or applicable pipe diameter range;
g. Applicable operating pressure range and operating temperature range;
h. The maximum, minimum flow or flow rate under operating conditions;
i. Transitional flowrate (when flowmeter has this index);
j. Grade of accuracy;
k. Explosion-proof grade and explosion-proof certificate number (merely restricted
to explosion-proof flowmeter);
l. Year and month of manufacture;
And other relevant technical indexes.
6.2.3 Each pair of ultrasonic transducers shall have permanent uniqueness marking
and installation marking in obvious positions.
6.2.4 When transducer’s signal cable needs to make one-to-one correspondence with
ultrasonic transducer, there shall be permanent uniqueness marking and installation
marking in obvious positions.
6.3 Appearance
6.3.1 Newly manufactured flowmeter shall have satisfying surface treatment; there
shall be no phenomena like burrs, scratches, cracks, corrosion, mildew stains or
stripping of coating. The sealed surface shall be flat; there shall be no damages.
6.3.2 The welding of the connected part of flowmeter body shall be flat and smooth;
there shall be no phenomena like insufficient soldering or de-soldering.
6.3.3 Connectors must be firm and reliable. Connectors shall not become loosened or
fall off due to vibration.
6.3.4 The displayed figures shall be striking and orderly. Character symbols and
markings that express functions shall be complete, distinct and neat.
6.3.5 Keys shall have moderate hand feeling; there shall be no adhesion phenomenon.
6.3.6 The various markings of flowmeter shall be correct. The protective glass on the
reading device shall have satisfying transparency; there shall be no defects that would
interfere with the reading, for example, distorted reading.
6.4 Protective Function
Flowmeter shall have the function of protecting flowmeter factor and recording the
historic modification process, so as to avoid any accidental modification. The value of
flowmeter factor shall be identical to the factor that is input in the previous verification
and shall not be amended.
6.5 Air-tightness
Verify the medium under the maximum experimental pressure, maintain for 5 min,
there shall be no leakage in the various ports of the flowmeter body.
7 Control of Measuring Instrument
The control of measuring instrument includes type evaluation, initial verification,
subsequent verification and in-use inspection. Appendix A stipulates the test conditions,
items and methods of type evaluation. Appendix B stipulates the special requirements
of on-site verification. Appendix C stipulates the test conditions, items and methods of
in-use inspection.
7.1 Verification Conditions
7.1.1 Requirements of flow calibration device
7.1.1.1 Flow calibration device (hereinafter referred to as device) and its matching
instrument shall have valid verification certificate.
7.1.1.2 Uncertainty of the measurement result of the device shall be not larger than
1/3 of the absolute value of the maximum allowable error of the flowmeter being
verified.
7.1.1.3 When the vapor pressure of liquid used for verification is higher than the
ambient atmospheric pressure, the device shall be sealed.
7.1.1.4 When the temperature of fluid that flows through the flowmeter needs to be
measured, temperature measurement may be conducted directly through the
temperature-measuring holes on the meter body. If there is no temperature-measuring
hole on the meter body, it shall, according to the requirements of the flowmeter and
relevant stipulations, determine the measurement location of temperature. If there is
no special requirement, in terms of one-way measurement flowmeter, the location for
temperature measurement shall be set up at the downstream (3 ~ 5)D area (D signifies
internal diameter of pipeline) of the flowmeter; in terms of two-way measurement
flowmeter, the location for temperature measurement shall be set up at least 5D away
from the flowmeter. The influence of measurement error of the used thermometer on
the verification result shall be within 1/5 of the maximum allowable error of the
flowmeter.
7.1.1.5 When the pressure of fluid that flows through the flowmeter needs to be
measured, directly take pressure from pressure ports on the flowmeter body. If there
are no pressure ports on the flowmeter body, it shall, according to the requirements of
the flowmeter, determine the measurement location of pressure. If there are no special
requirements, the device shall install pressure meter at 10D area on the upstream side
of the flowmeter. The axes of the pressure ports shall be vertical to the axes of the
measuring pipe; the diameter shall be (4 ~ 12) mm. The influence of measurement
error of the used pressure meter on the verification result shall be within 1/5 of the
maximum allowable error of the flowmeter.
7.1.2 Fluid for verification
7.1.2.1 Universal conditions
(1) Fluid used for verification shall be single-phase gas or liquid. Use it to fill test
pipeline; its flow shall manifest no vortex.
(2) Fluid used for verification shall be clean; there shall be no visible particles or
fibers.
(3) Liquid flowmeter shall use liquid as the verification medium. Gas flowmeter
shall use gas as the verification medium. In addition, the physical parameters
(density and viscosity, etc.) of the verification medium and the actually used
medium shall be approximate.
7.1.2.2 Liquid used for verification
(1) The pressure of liquid used for verification on any point in the pipeline system
and the flowmeter shall be higher than the saturated vapor pressure. In terms
of easily vaporized liquid that is used for verification, there shall be certain
backpressure at the downstream of the flowmeter. The recommended
backpressure is 1.25 times of saturated vapor pressure of verification liquid
under the highest verification temperature.
(2) During each verification process of each flow point, the variation of liquid
temperature shall not exceed ± 0.5 °C.
(3) The liquid shall not be mingled with gas.
7.1.2.3 Gas used for verification
(1) In terms of flowmeter whose operating pressure is 0.4 MPa and above, the
pressure of gas in the pipeline shall be not lower than 0.1 MPa; try to maintain
the consistency with the actual operating conditions. In terms of flowmeter
whose operating pressure is below 0.4 MPa, pressure of gas in the pipeline
shall not be higher than 0.4 MPa; verification may be conducted under
atmospheric pressure.
(2) Impurities like free water or oil shall not exist; the grain size of solids like dust
shall be less than 5 μm.
(3) In terms of flowmeter whose accuracy grade is not lower than Grade 1.0, in
each verification process of each flow point, temperature variation of gas used
for verification shall not exceed ± 0.5 °C. In terms of flowmeter whose
accuracy grade is lower than Grade 1.0, in each verification process of each
flow point, temperature variation of gas used for verification shall not exceed
± 1 °C.
(4) When gas used for verification is natural gas, the quality of natural gas shall
comply with the requirements of Type-2 gas in GB 17820; the relative density
of natural gas shall be 0.55 ~ 0.80.
(5) When gas used for verification is natural gas, during the verification process,
gas component shall be relatively stable. The sampling of natural gas shall
comply with GB/T 13609; the composition analysis of natural gas shall comply
with GB/T 13610.
(6) During the verification process of each flow point, pressure fluctuation shall not
exceed ± 0.5%.
7.1.3 Verification environment conditions
7.1.3.1 Generally speaking, ambient temperature is (5 ~ 45) °C; humidity is (35 ~ 95) %
RH; atmospheric pressure is (86 ~ 106) kPa.
7.1.3.2 AC power supply voltage shall be (220 ± 20) V; power frequency shall be (50
± 2.5) Hz. Or, in accordance with the requirements of flowmeter, suitable AC power or
DC power may be used (for example, 24 V DC).
7.1.3.3 The external magnetic field shall be so small that its influence on flowmeter can
be neglected.
7.1.3.4 Mechanical vibration and noise shall be so small that its influence on flowmeter
can be neglected.
7.1.3.5 When flammable or explosive fluid, for example, natural gas, is used as the
medium for verification, all the verification devices and their auxiliary equipment, and
verification site shall comply with the requirements in GB 50251. All the equipment and
environment conditions must comply with relevant safety explosion-proof requirements
in GB 3836.
7.1.4 Installation conditions
7.1.4.1 The installation of flowmeter shall comply with the requirements in Appendix D.
7.1.4.2 During verification, in principle, all the components that constitute flowmeter
shall be submitted for verification.
7.1.5 Each measurement time shall be not less than the allowed shortest measurement
time of the device and the flowmeter being verified.
7.1.6 When the pulse output of the flowmeter being verified is adopted for verification,
the pulse count recorded in one verification shall not be less than 10 times of the
reciprocal of the absolute value of the maximum allowed error.
7.1.7 All the electrical apparatus used for verification shall be grounded in the same
point.
7.2 Verification Items and Verification Methods
7.2.1 Verification items
Verification items of the initial verification, subsequent verification and in-use
inspection are listed in Table 2.
Table 2 -- Table of Verification Items
Verification Items Initial Verification Subsequent Verification In-use Inspection
Product documents and
Appearance + + +
Air-tightness + + +
Flowmeter Parameters - - +
Reading Error + + -
Repeatability + + -
Flowmeter Factor Correction + + -
NOTE: “+” signifies items that need to be verified; “-” signifies items that do not need to be verified.
7.2.2 Product documents and appearance inspection
7.2.2.1 Inspect the product documents, which shall comply with the requirements in
Clause 6.1.
7.2.2.2 Use the method of visual inspection to inspect the appearance of flowmeter,
which shall comply with the requirements in Clause 6.2 and Clause 6.3.
7.2.3 Verification of reading error
7.2.3.1 Pre-operation inspection
Connect, initiate, pre-heat; in accordance with the method appointed in the instruction
of flowmeter, inspect the parameter setting of the flowmeter.
7.2.3.2 Air-tightness inspection
Conduct visual inspection to inspect the air-tightness of flowmeter, which shall comply
with the requirements in Clause 6.5.
7.2.3.3 Flowmeter shall operate within the range of 70% ~ 100% of the maximum
verification flow that can be reached; maintain for at least 5 min. Wait till the fluid
temperature, pressure and flow rate become stable, then, proceed to the official
verification.
7.2.3.4 Flow point control and verification factors
(1) Generally speaking, verification shall include the following flow points: qmin, qt,
0.40 qmax and qmax. In terms of flowmeter whose accuracy grade is not lower
than 0.5% and measuring range ratio is not larger than 20:1, add two flow
points: 0.25 qmax and 0.70 qmax. In terms of flowmeter whose accuracy grade
is superior to 0.5% and measuring range ratio is larger than 20:1, add one
verification point, whose flow is 0.1 qmax.
(2) When the device’s maximum verification flow cannot reach qmax, qmax may take
the maximum flow of the device. However, in terms of the maximum flow of
verification, fluid shall be not less than 10 qt; gas shall be not less than 4 qt.
(3) During the verification process, the deviation between each actual verification
flow rate of each flow point and the set flowrate shall not exceed ± 5% of the
set flow rate, or, shall not exceed ± 1% qmax; the corresponding fluid flow rate
of the minimum flow point shall not be less than the minimum flow rate
indicated on flowmeter’s nameplate.
(4) The times of verification of each flow point shall not be less than 3 times. In
terms of flowmeter whose type evaluation and accuracy grade are not lower
than Grade 0.5, the times of verification of each flow point shall be not less
than 6 times.
7.2.3.5 Verification procedure
(1) Regulate flow to the stipulated flow value. After it becomes stable, record the
initially indicated value of the standard and the flowmeter being verified.
Meanwhile, initiate the standard (or standard’s recording function) and the
flowmeter being verified (or the flowmeter’s output function).
(2) In accordance with the operating requirements of the device, operate for a
certain period of time. Meanwhile, stop the standard (or standard’s recording
function) and the flowmeter being verified (or the flowmeter’s output function).
(3) Record the final value indicated by the standard and the flowmeter being
verified.
(4) Respectively calculate the accumulative flow value or instantaneous flow rate
recorded by the flowmeter and the standard.
7.2.3.6 Calculation of reading error
(1) The relative reading error of single verification of flowmeter is:
Where,
Eij---relative reading error of flowmeter being verified in the jth verification in
the ith verification flow point, expressed in (%);
Qij---accumulative flow value displayed by flowmeter in the jth verification in
or
the ith verification flow point, expressed in (m3);
(Qs)ij---accumulative flow value when standard is converted into flowmeter
status in the jth verification in the ith verification flow point, expressed in
(m3);
qij---instantaneous flow rate value displayed by flowmeter in the jth verification
in the ith verification flow point; it may be an average value of
instantaneous flow rate values read in multiple times during a verification
process; expressed in (m3/h);
(qs)ij---instantaneous flow rate value when standard is converted into
flowmeter status in the jth verification in the ith verification flow point,
expressed in (m3/h).
When the standard displays accumulative flow:
Where,
t---time of the jth verification in the ith verification flow point, expressed in (s).
① In terms of liquid flowmeter, calculate (Qs)ij in accordance with the formula
below:
Where,
(Vs)ij---actual volume of liquid measured by standard in the jth verification in
the ith verification flow point, expressed in (m3);
β---volume expansion factor of verification liquid under the verification status,
expressed in (°C)-1;
θs, θm---liquid temperature at the standard and the flowmeter in the jth
verification in the ith verification flow point, expressed in (°C);
κ---compression factor of verification liquid under the verification status,
expressed in Pa-1;
ps, pm---fluid pressure respectively at the standard and the flowmeter in the
jth verification in the ith verification flow point, expressed in (Pa);
When the difference between θs and θm is less than 5 °C, and the difference
between ps and pm is less than 0.1 MPa, the formula above may be simplified
into:
When Gravimetric device is adopted for verification, the density (ρ1) of the
liquid needs to be measured. Meanwhile, in consideration of the influence of
air buoyancy with the density of (ρa), in accordance with the following
formula, convert the mass (Mij) displayed by electronic scale into the actual
volume (Vs)ij:
② In terms of gas flowmeter, calculate (Qs)ij in accordance with the formula
below:
Where,
Ts, Tm---gas thermodynamic temperature respectively at the standard and
the flowmeter in the jth verification in the ith verification flow point, expressed
in (K);
zs, zm---gas compression factor respectively at the standard and the
flowmeter in the jth verification in the ith verification flow point.
(2) The relative reading error of various verification flow points of flowmeter shall
be calculated in accordance with the formula below:
Where,
Ei---relative reading error of the ith verification flow point of flowmeter, expressed
in (%);
n---times of verification of the ith verification flow point;
Eij---relative reading error of the jth verification in the ith verification flow point of
flowmeter.
(3) The relative reading error of flowmeter is:
Where,
ǀEiǀmax---the maximum value of relative reading error of various verification
points in the high zone and the low zone of flowmeter.
The result shall comply with the requirements in 5.1.
7.2.4 Repeatability of flowmeter
When each flow point is repeatedly verified for n times, the repeatability of this flow
point shall be assessed in accordance with the following formula:
Where,
(Er)i---repeatability of the ith verification flow point.
The repeatability of the high zone and the low zone of flowmeter...
......
(Above excerpt was released on 2019-11-30, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/JJG1030-2007
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