GB/T 7825-2017 English PDF (GBT7825-2017)

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GB/T 7825-2017: Road vehicles -- Spark-plugs -- Test methods and requirements
GB/T 7825-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 43.060.50
T 37
Replacing GB/T 7825-1987
Road Vehicles - Spark-Plugs -
Test Methods and Requirements
(ISO 11565. 2006, MOD)
ISSUED ON. OCTOBER 14, 2017
IMPLEMENTED ON. MAY 1, 2018
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 6 
2 Normative References ... 6 
3 Test Methods and Requirements ... 6 
Appendix A (Normative) Inspection Rules ... 19 
Foreword
This Standard was drafted in accordance with the rules in GB/T 1.1-2009.
This Standard serves as a replacement of GB/T 7825-1987 Spark Plugs. In
comparison with GB/T 7825-1987, there are several main changes as follows.
---The title of the Standard is modified;
---Terms are deleted (please refer to Chapter 1 in Version 1987);
---Models and Dimensions are deleted (please refer to Chapter 2 in Version 1987);
---Normative References are added (please refer to Chapter 2);
---Certain test items are added. bending strength, thermal-shock resistance,
voltage-withstanding test, room-temperature insulation resistance (please refer
to 3.4.3, 3.6, 3.7.2 and 3.7.3);
---Test method for the durability of resistive spark plug is added (please refer to
3.8);
---Flashover performance test is deleted (please refer to 3.5 in Version 1987);
---Test method and requirement of vibration are modified (please refer to 3.4.4; 3.6
in Version 1987);
---Over-torque test is deleted (please refer to 3.8 in Version 1987);
---Side-electrode bending strength test is deleted (please refer to 3.9 in Version
1987);
---Appendix A “Calibration Method of Calorific Value of Spark Plugs” is deleted
(please refer to Appendix A in Version 1987);
---Inspection rules are modified (please refer to Appendix A; Chapter 5 in Version
1987);
---“Marking and Packaging” is deleted (please refer to Chapter 6 in Version 1987).
This Standard was modified through the Law of Redrafting in accordance with ISO
11565. 2006 Road Vehicles - Spark-plugs - Test Methods and Requirements.
In comparison with ISO 11565. 2006, there are several main technical changes as
follows.
---“This Standard is applicable to spark plugs for spark-ignition engine” is added
to the Scope;
Road Vehicles - Spark-plugs -
Test Methods and Requirements
1 Scope
This Standard specifies the test methods and requirements of the mechanical property
and electrical performance of spark plugs for spark-ignition engine.
This Standard is applicable to spark plugs of spark-ignition engine.
2 Normative References
The following documents are indispensable to the application of this Standard. In terms
of references with a specified date, only versions with a specified date are applicable
to this Standard. The latest version (including all the modifications) of references
without a specified date is applicable to this Standard.
GB/T 6791 Road Vehicles - Spark-plugs and Their Cylinder Head Housing - Basic
Characteristics and Dimensions (GB/T 6791-2012, ISO 28741. 2009, MOD)
3 Test Methods and Requirements
3.1 General Principles
The test of spark plugs shall comply with the following stipulations.
---If there are no specific stipulations, all tests of spark plugs shall be conducted
under normal temperature (23 ± 5) °C and normal humidity (65 ± 20) %.
---Type inspection items and samples of spark plugs shall comply with the test
sequence and requirements stipulated in Table 1.
---Exit-factory inspection items and samples of spark plugs shall comply with the
test sequence and requirements stipulated in Table 2; or the customers’
requirements.
---Each test in Table 1 and Table 2 shall start from new products that have not
been used; tests shall be conducted from the top to the bottom in accordance
with the mark “”.
---Please refer to Appendix A for the inspection rules.
Table 2 -- Spark Plug Exit-factory Inspection Sequence Table
3.2 General Characteristics
3.2.1 Test method
Conduct the method of visual inspection to inspect the characteristics indicated in 3.2.2.
The method of visual inspection refers to the inspection with naked eyes (normal vision
and color discrimination ability) at the most comfortable visual inspection distance
under suitable lighting conditions.
3.2.2 Requirements
3.2.2.1 External sealing washer shall manifest no notches or obvious damages;
corresponding dimensions shall comply with the requirements stipulated by the
manufacturers or the customers.
3.2.2.2 Heat chamber shall be clean; there shall be no foreign substances.
3.2.2.3 Central electrode and side electrode shall be in the right position.
3.2.2.4 No visible corrosion is allowed on the shell. Thread shall manifest no burrs or
damages (which can be determined by whether threaded ring can freely pass through).
The fixation with insulator shall be reliable and manifest no abnormalities.
3.2.2.5 Insulator shall be smooth and consistent; there shall be no abnormalities like
fracture, crack or impact scar.
3.2.2.6 The marking shall be distinct and consistent; it shall also comply with the
requirements stipulated by the manufacturers or the customers.
Test Items Clause Test Quantity (PCS)
Sample No.
General
Characteristics
Dimension
Resistance Value
Thermal Sealing
Performance
Bending Strength
Wiring Screw Tensile
Load
Adopt an exclusive tensile test device; along the axial direction, gradually increase
tensile force at the rate of less than 500 N/s to pull the wiring screw of the spark plug.
3.4.2.2 Requirements
After bearing 980 N of tensile load (low-seat spark plug bears 400 N of tensile load),
the wiring screw shall manifest no abnormalities in all parts.
3.4.3 Bending strength
3.4.3.1 Test method
Adopt the maximum installation torque stipulated in GB/T 6791 to install the spark plug
on a suitable test bench. Within the range of 5 mm from the ends of the insulator,
impose vertical force, which acts on the axial direction of the insulator; the speed of
the force shall be less than 10 mm/min.
3.4.3.2 Requirements
Spark plug shall be able to bear 15 Nm of bending moment at the minimum and shall
not be damaged.
3.4.4 Vibration test
3.4.4.1 Test method
In accordance with the torque stipulated in relevant national standards, install spark
plug on a standard vibration test bench. Parameters of the vibration test shall satisfy.
---Frequency range. 50 Hz ~ 500 Hz, sinusoidal signal;
---Sweep rate. 1 frequency multiplication/min;
---Vibration acceleration. 30 g (294 m/s2);
---Vibration direction. axial direction and radial direction of spark plug;
---Duration. 8 h in each direction.
3.4.4.2 Requirements
After the test, the spark plug shall manifest no abnormalities; it shall pass the
subsequent tests stipulated in Table 1.
3.5 Thermal Sealing Performance
3.5.1 Test method
In accordance with the installation torque stipulated in Table 4, install spark plug on a
Appendix A
(Normative)
Inspection Rules
A.1 Spark plugs shall pass the inspection conducted by the manufacturer’s inspection
department before exiting factory; they shall also be attached with a product quality
certificate.
A.2 Spark plugs shall be inspected by batch. It shall be guaranteed that each batch of
spark plugs are the same model of pro...