GB/T 21296.5-2020 PDF English
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Automatic instruments for weighing road vehicles in motion - Part 5: Crystal quartz type
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GB/T 21296.5-2020: PDF in English (GBT 21296.5-2020) GB/T 21296.5-2020
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 17.100
N 13
Automatic instruments for weighing road vehicles in motion
- Part 5: Crystal quartz type
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: JUNE 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Type and composition ... 8
5 Measurement requirements ... 8
6 Technical requirements ... 13
7 Installation and maintenance requirements ... 16
8 System function and data requirements ... 19
9 Test methods ... 19
10 Inspection rules ... 27
11 Marking, packaging, transportation, and storage ... 29
Appendix A (Normative) Additional accuracy classes ... 30
Appendix B (Normative) Test method of crystal quartz load receptor-signal assemble
module ... 34
Automatic instruments for weighing road vehicles in motion
- Part 5: Crystal quartz type
1 Scope
This Part of GB/T 21296 specifies the terms and definitions, type and composition,
measurement requirements, technical requirements, installation and maintenance
requirements, system function and data requirements, test methods, inspection rules, as
well as marking, packaging, transportation, and storage of crystal quartz automatic
instruments for weighing road vehicles in motion (hereinafter referred to as quartz
dynamic vehicle weighing instruments).
This Part applies to the combination of single or multiple crystal quartz sensors installed
in the controlled weighing area in a way of embedding in the road surface during the
dynamic driving of road vehicles; automatic instruments for weighing vehicles in
motion that measure and obtain the vehicle wheel loads (if applicable), axle loads
(including single-axle loads) and whole loads.
2 Normative references
The following documents are indispensable for the application of this document. For
the dated references, only the editions with the dates indicated are applicable to this
document. For the undated references, the latest edition (including all the amendments)
are applicable to this document.
GB/T 7724 Electronic weighing meter
GB/T 14250 Terminology of weighing instruments
GB/T 15395 General technical specification for cabinet of electronic equipment
GB/T 21296.1-2020 Automatic instruments for weighing road vehicles in motion -
Part 1: General technical specification
GB/T 26389 Method of classified type of weighing instrument products
JJG 338 Verification Regulation of Charge Amplifiers
3 Terms and definitions
The terms and definitions defined in GB/T 14250 and GB/T 21296.1-2020 and the
value is between 0.85 times the lower limit of nominal voltage and 1.1 times the
upper limit;
b) Weighing instruments using direct current (DC) online power supply (including
rechargeable batteries that can be fully charged when the instrument is working):
The voltage value is within the range from the specified minimum voltage to 1.2
times the nominal voltage (or the upper limit of working voltage range);
Note: The lowest voltage refers to the lowest voltage value at which the weighing instrument
can operate normally before automatic shutdown.
c) Weighing instruments powered by batteries (including non-rechargeable batteries
or rechargeable batteries that cannot be charged online): The voltage value is
within the range from the specified minimum voltage to the nominal voltage (or
the upper limit of working voltage range);
d) Weighing instruments powered by 12 V automobile battery: 9 V~16 V;
e) Weighing instruments powered by 24 V automobile battery: 16 V~24 V.
5.8 Unit of measurement
The unit of measurement of mass and load of crystal quartz dynamic vehicle weighing
instruments is kilogram (kg) or ton (t).
5.9 Operating speed
Within the nominal operating speed range, crystal quartz dynamic vehicle weighing
instruments shall maintain the corresponding metering performance requirements and
technical requirements. When it exceeds the operating speed range, no result will be
output. Or according to the requirements of 9.3.8 in GB/T 21296.1-2020, a violation
prompt will be given.
This operating speed range can be adjusted or determined according to the test
situations during the field weighing test.
6 Technical requirements
6.1 Overview
Quartz dynamic vehicle weighing instruments shall meet the requirements of 6.2~6.8
and the provisions of Clause 6 in GB/T 21296.1-2020.
6.2 General technical requirements
Quartz dynamic vehicle weighing instruments shall be designed and manufactured to
6.3.3 Insulation resistance
The impedance of crystal quartz sensor shall not be lower than 100 GΩ.
6.3.4 Anti-corrosion requirements
Crystal quartz sensors shall be effectively protected against corrosion and rust.
If a cladding or coating layer is designed on the surface, the cladding and coating layer
shall be smooth and intact. The coating shall have high adhesion strength; shall be firm,
uniform, and consistent in color. There shall be no defects such as spots and scratches.
6.3.5 Metal frame strength
The strength of metal frame shall meet the stability and reliability requirements of long-
term continuous operation.
6.4 General technical requirements for charge amplifier
The electrical parameters and degree of protection of charge amplifier shall meet the
requirements of the design and application of quartz dynamic vehicle weighing
instruments. If necessary, according to the test method of JJG 338, test and detect its
parameters such as nonlinear error, high-low pass cutoff frequency.
6.5 General technical requirements for weighing meter
The electrical parameters and degree of protection of weighing meter shall meet the
requirements of the design and application of quartz dynamic vehicle weighing
instruments; and comply with the relevant provisions of GB/T 7724.
6.6 Vehicle identification device
Quartz dynamic vehicle weighing instruments shall be equipped with vehicle
identification devices, such as ground-sensing coil vehicle detector, infrared light
curtain (grating), laser vehicle separator, etc. The devices shall be able to detect whether
the vehicle is in the weigh zone.
6.7 Interface
Quartz dynamic vehicle weighing instruments can be equipped with interfaces to
connect external equipment. When using the interface, the weighing instrument shall
keep working normally and without error. And it can be ensured that the metering
performance is not affected. External equipment generally includes: ground-sensing
coil vehicle detector, infrared light curtain (grating), road gate, red-green indicator light,
vehicle separator, camera, voice control equipment, computer, etc.
6.8 Anti-interference performance
It shall comply with the provisions of A.1.2 and A.4.2 in Appendix A of GB/T 21296.1-
2020.
7 Installation and maintenance requirements
7.1 Overview
The realization of the accuracy class of quartz dynamic vehicle weighing instruments
is not only related to the design, production and installation of the weighing instrument
itself; but also related to the levelness, slope, curvature, road strength and other
conditions of the weigh zone; and is related to the daily maintenance of the weighing
instrument. Users shall have a correct understanding of this.
Quartz dynamic vehicle weighing instruments shall meet the requirements of 7.2~7.8
and the requirements of Clauses 7 and 8 in GB/T 21296.1-2020.
7.2 Road survey, site selection and layout
7.2.1 Road survey and site selection
The quartz dynamic vehicle weighing instrument shall be installed on the road section
where the vehicle travels in a straight line. If there is a curve, the length of the straight
section shall not be less than 64 m. The installation position of crystal quartz load
receptor/sensor is selected near the length of 3/4 of the weigh zone of the straight
section. It shall meet the requirements of Table 10, Table 11, Table 12, and Table 13 in
GB/T 21296.1-2020.
7.2.2 Layout
The accuracy of quartz dynamic vehicle weighing instruments is related to the crystal
quartz sensor’s performance, number of rows, layout method, road conditions (such as
road surface smoothness), and quality of buried installation. According to the
application requirements, the manufacturer shall select and decide the combination
method and installation quality requirements.
The layout of some typical applications is shown in Figure 1.
Place the sensor to its installation position. Before the installed potting compound is
completely solidified, the sensor shall not be moved. No vehicles shall pass or roll over
it.
7.6 Grinding
After the potting compound particles are completely cured, the overflowed and cured
compound is removed by grinding, to ensure that the top of the sensor bearing surface
is flush with the road surface.
Flatness requirements: After the crystal quartz sensor is installed, the sensor and the
road surface form an organic whole; that is, the crystal quartz sensor has become an
integral part of the road. The flatness of the road including the sensor shall meet the
requirements of Table 10, Table 11, Table 12, and Table 13 in GB/T 21296.1-2020.
7.7 Control cabinet waterproofing and grounding
The control cabinet is equipped with power supply and electronic weighing meter. The
grounding resistance shall be less than 4 Ω. There shall be measures to prevent rain. It
shall meet the requirements of GB/T 15395. When the basic steel bar is used as the
grounding electrode of the weighing system, the grounding resistance should be less
than 4 Ω.
7.8 Maintenance
During the operation and use of the equipment, the user shall conduct regular and
irregular inspections and necessary maintenance, including:
a) Check and clean, to ensure that there are no falling objects such as stones, bolts
and nuts in the controlled weighing area - hard objects with a size (height)
exceeding 10 mm. It can cause the height difference between the sensor and the
road surface, thereby affecting the weighing accuracy;
b) Check whether there are cracks on the road surface of the controlled weighing
area and the bearing surface of the sensor. It shall repair the cracks with a
length >0.5 m and a depth >5 mm;
c) Check whether there are pits caused by missing materials on the road surface of
the controlled weighing area and the bearing surface of the sensor. It shall repair
the pits on the road surface with a depth >5 mm and a size (diameter) >25 mm;
d) Check whether the pavement slabs in the controlled weighing area have
phenomena such as settlements, displacements, or frost boiling. If so, it shall redo
the hardened pavement in time;
e) Within 25 m before and after the controlled weighing area, no deceleration belts
shall be set up which will cause the vehicle to bump and vibrate up and down;
f) The rest shall meet the requirements of Clause 8 in GB/T 21296.1-2020.
8 System function and data requirements
It shall meet the requirements of Clause 9 in GB/T 21296.1-2020.
9 Test methods
9.1 General
The test shall be carried out at the site where the quartz dynamic vehicle weighing
instrument is used.
9.2 Preparation before testing
9.2.1 Requirements for test environment
The test shall be carried out under stable ambient temperature conditions. The
temperature change during the test is not more than 5 °C. The temperature change rate
is not more than 5 °C/h.
9.2.2 Check of installation condition
Check the installation site conditions of the quartz dynamic vehicle weighing
instrument; the setting of lane separation device; the combination of the crystal quartz
sensor and the road surface; and the flatness and slope of the apron at both ends of
quartz dynamic vehicle weighing instrument. It shall meet the requirements of 7.1.
9.3 Weighing-in-motion tests
9.3.1 Reference vehicle
The reference vehicle used for the dynamic test shall be permitted by the relevant
national technical specifications; and shall be the vehicle expected to be used by the
tested quartz dynamic vehicle weighing instrument. It shall use the quartz dynamic
vehicle weighing instrument system to judge the number of vehicle axles and the
distance between the axles, to classify the vehicles. In addition to two-axle rigid
vehicles, there shall be at least two different types of reference vehicles, to
accommodate different axle structures, tractor/trailer structures, tractor/trailer
connection systems and suspension systems.
At least two models shall be selected from the following three models:
b) It shall be ensured that, the error of the conventional true value of the static
reference axle load of two-axle rigid reference vehicle determined by it DOES
not exceed 1/3 of the dynamic maximum permissible error;
c) The access apron approaching the load receptor shall be in the same plane as the
load receptor. The access apron shall be of sufficient length to fully support the
vehicle being weighed. There shall be no lateral inclination. If it is impossible for
the apron and the load receptor to be in the same plane, measures shall be taken
to ensure that in the process of determining the weight of the reference vehicle,
the levelness of all wheels of the reference vehicle when passing through the load
receptor is kept within ±3 mm.
9.3.3.4 Consider changes in reference conditions and in reference vehicles
If the vehicle shall travel a considerable distance from the control weighing instrument
to the quartz dynamic vehicle weighing instrument under test, the environmental
conditions shall be paid close attention. It is advisable to avoid the situation where the
error that may be caused by the difference in weather cannot be determined. At the same
time, it shall also consider the possible influence of fuel consumption and other factors
on the weight reference value.
9.3.3.5 Determination of the conventional true value of the whole reference vehicle
Place the whole reference vehicle on the control weighing instrument for weighing, to
obtain the conventional true value of the whole load of the reference vehicle.
9.3.3.6 Determination of the conventional true value of single-axle load for two-
axle rigid reference vehicle
For weighing instruments that provide a single-axle load, the following method shall
be used to determine the conventional true value of the single-axle load of two-axle
rigid reference vehicle:
a) According to the regulations, on the control weighing instrument, perform static
weighing on each single axle of the two-axle rigid reference vehicle in turn;
record each single-axle load. After both single-axles are weighed, calculate the
sum of the two single-axle loads - that is, the whole load (VM); record the VM
value. Each single axle shall be weighed 10 times. It shall be weighed 5 times in
the vehicle forward and reverse directions, respectively. Each of the above
weighing shall ensure that the vehicle is stationary and stable. The axle of the
vehicle shall be level. All wheels are fully supported on the load receptor. Turn
off the engine. Release the brakes. The transmission is set to neutral. If necessary,
wooden wedges may be used to prevent the vehicle from slipping.
b) According to formula (1), calculate the average single-axle load of each single-
axle of two-axle rigid vehicle:
EVM - The error of whole load.
b) The maximum error BETWEEN the displayed or printed whole load AND the
conventional true value of the whole load determined by the static weighing
method of the whole vehicle shall not exceed the maximum permissible error of
the first verification.
9.3.4.7 Test of abnormal speeds of passing through weighing instrument
Use a two-axle reference vehicle to carry out performance tests at the following three
different speeds:
a) Greater than 10% of the maximum operating speed (vmax);
b) Less than 10% of the minimum operating speed (vmin);
c) Variable speed running test (When exceeding the maximum speed variation range,
it shall be as specified by the manufacturer).
Quartz dynamic vehicle weighing instrument shall be able to detect the above abnormal
operation states. Unless it can indicate or print alarm information at the same time, it
shall not indicate or print weighing data.
10 Inspection rules
10.1 Type inspection
10.1.1 Type inspection conditions
Quartz dynamic vehicle weighing instruments shall be subject to type inspection under
the following conditions:
a) Before the first batch of new products are put into production;
b) The first batch of products after major changes in design, process, key components
(crystal quartz sensor, charge amplifier, or digital data processing device);
c) When required by the national technical agency.
10.1.2 Type inspection items
During the type inspection, all the metrological requirements and technical
requirements specified in Table 8 shall be inspected and tested. When the inspection
conditions are limited, in accordance with the requirements of Appendix E in GB/T
21296.1-2020, the module test shall be performed using the simulation test method.
10.2.3 Test of crystal quartz sensor
Whether the crystal quartz sensor meets the requirements of Clause 6; see Appendix B
for the test method.
10.2.4 On-site inspection
10.2.4.1 Preparation before on-site installation
Before the product arrives at the installation site, an on-site installation condition
investigation shall be carried out. If the requirements are not met, it shall fully
communicate with the user; make rectification or change the location first. After the
equipment is delivered to the site and ready to be installed, check whether the
installation tools are available and whether the installation materials are sufficient.
Equipment installation shall be carried out when weather conditions permit.
10.2.4.2 Inspection after on-site installation
After the product is installed for the first time, on-site inspection shall be carried out.
Only after passing the inspection, can the product be delivered and attached with the
corresponding product conformity certificate. The on-site inspection shall be carried
out according to the items except the crystal quartz sensor test in the exit-factory
inspection in Table 8. In the case of multi-lane layout, the dynamic test is carried out
respectively according to the expected lanes.
11 Marking, packaging, transportation, and storage
It shall meet the requirements of Clause 12 in GB/T 21296.1-2020.
Appendix A
(Normative)
Additional accuracy classes
A.1 General
A.1.1 Additional accuracy class of whole loads
The additional accuracy class of whole loads of quartz dynamic vehicle weighing
instrument is divided into 2 classes, which are represented by symbols: 7, 15.
A.1.2 Additional accuracy class of vehicle axle loads (including single-axle load)
The additional accuracy class of vehicle axle loads of quartz dynamic vehicle weighing
instrument is divided into 2 classes, which are represented by symbols: G, H.
The axle load of the same quartz dynamic vehicle weighing instrument can have
different accuracy classes.
A.2 Maximum permissible errors of dynamic tests
A.2.1 Maximum permissible error (MPE) for additional accuracy class of whole
loads
The maximum permissible error of the additional accuracy class of whole loads in
weighing-in-motion shall take the larger value of the following a) or b):
a) Use the scale interval as the smallest unit to round the calculation results in Table
A.1 to the nearest values;
b) For the first verification and subsequent verifications, 1 scale interval (1d) is
multiplied by the number of times of axle weighing in whole loads of vehicle. For
in-service inspection, 2 scale intervals (2d) are multiplied by the number of times
of axle weighing in whole loads of vehicle.
The maximum permissible error of the additional accuracy class of whole loads shall
comply with the provisions of Table A.1.
Appendix B
(Normative)
Test method of crystal quartz load receptor-signal assemble module
B.1 General
Before leaving the factory, it shall test the crystal quartz load receptor-signal assemble
module.
The crystal quartz load receptor-signal assemble module is composed of a crystal quartz
sensor and a charge amplifier; bears the load; and outputs a voltage signal.
The crystal quartz load receptor-signal assemble module shall be connected to a meter
that conforms to the manufacturer's design and intended use conditions for testing.
B.2 Test devices
The test devices of crystal quartz load receptor-signal assemble module consist of a
loading device, a crystal quartz sensor support platform, and a high-precision digital
voltmeter (or data collector). The combined system expansion uncertainty shall not
exceed one third of the maximum permissible error of the tested sensor.
The test loading device is a force standard machine or a force testing machine. It shall
be equipped with a support platform with sufficient length; to ensure that the bottom of
crystal quartz sensor is completely supported by the platform, and the sensor is not
suspended. The maximum load value that the loading device can apply shall not be less
than the max rated load on single position.
The schematic diagram of the principle and structure of the loading test is shown in
Figure B.1.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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