Some standard content:
This standard is revised to adopt ISO4925:1978 "Non-petroleum-based brake fluids for road vehicles" (English version). GB12981-2003
This standard is redrafted based on ISO4925:1978 "Non-petroleum-based brake fluids for road vehicles" (English version). Appendix A lists the comparison between the chapter and article numbers of this standard and those of ISO4925:1978. In order to better suit my country's national conditions, this standard has been revised when adopting ISO4925:1978 "Non-petroleum-based brake fluids for road vehicles" (English version). Appendix B gives a list of these technical differences and their reasons for reference. For ease of use, this standard has also made the following editorial changes to ISO4925:1978: In accordance with the requirements of GB/T1.1-2000, the standard layout format has been modified according to Chinese habits; - The quality requirements expressed in ISO4925:1978 in chapter and article descriptions are given in table form. This standard replaces GB12981-1991 and GB10830-1998. The main changes of this standard compared with GB12981-1991 are as follows: - HZY2 brake fluid is cancelled and HZY5 brake fluid is added; - In type inspection, metal corrosion and other items use national standard sample rubber cups and metal test pieces that meet the standards; - The compatible liquid used in the compatibility test is a standard sample; The referenced standards in each appendix are cancelled and are all cited in the text; - The original Appendix K is cancelled; the original Appendix L is changed to Appendix M; - The brake fluid humidification method is added to the B method, and the original standard moisture absorption method is listed as the A method; Determination of humidification The method for determining the water content of brake fluid only adopts one method of SH/T0086;
Add Appendix A "List of corresponding clauses between this standard and ISO4925:1978" (informative appendix); - Add Appendix B\List of technical differences between this standard and ISO4925:1978 and their causes" (informative appendix); - Add Appendix M\Standard samples of HZY3 and HZY4 brake fluid compatibility test fluids" (informative appendix); - Add Appendix N "Determination of rust prevention performance of brake fluid" (informative appendix). In this standard, Appendices A, B, M, and N are informative appendices, and Appendices C, D, E, F, G, H, J, K, and L are normative appendices. This standard comprehensively specifies the technical indicators for evaluating the comprehensive performance of brake fluid products from the perspective of brake fluid production and use. It is the quality level that should be achieved when identifying motor vehicle brake fluid products. It is also the technical basis for brake fluid manufacturers to control product quality during the production process and for national quality and technical supervision departments to regulate the product quality of the brake fluid industry. This standard was proposed by China Petrochemical Corporation. This standard is under the jurisdiction of the Technical Unit for Standardization of Synthetic Lubricants of China Petrochemical Corporation. This standard was drafted by Chongqing Yiping Lubricant Branch of China Petrochemical Corporation and the Highway Research Institute of the Ministry of Communications. The main drafters of this standard are Yan Zili, Guo Yiming, Chen Dapeng and Liu Xingsheng. The standard GB12981-1991 replaced by this standard was first issued on June 6, 1991, and GB10830-1998 was first issued on March 31, 1989.
1 Scope
Motor Vehicle Brake Fluid
GB 12981-2003
This standard specifies the requirements and test methods for non-petroleum-based brake fluids used in hydraulic brake systems of motor vehicles. The products specified in this standard are suitable for hydraulic brake systems of motor vehicles with styrene-butadiene rubber or ethylene-propylene rubber as seals, cups or double-lip seals. The products specified in this standard are not recommended for use in polar environmental conditions. This standard applies to the identification and finalization of motor vehicle brake fluid products, factory inspection, user re-inspection, etc. It can also be used as a technical basis for national quality and technical supervision agencies to conduct random inspections of market product quality. 2 Normative references
The clauses in the following documents become clauses of this standard through reference in this standard. For all dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties that reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all undated references, the latest versions apply to this standard. GB/T 265
Method for determination of kinematic viscosity and calculation of dynamic viscosity of petroleum productsGB/T 514
GB/T 710
GB/T 2520
GB/T 3190
GB/T 4756
GB/T 5231
GB/T 7304
Technical conditions for liquid thermometers for testing petroleum productsHot-rolled thick steel plates and wide steel strips of high-quality carbon structural steelCold-rolled electro-tinned thin steel plates
Chemical composition of deformed aluminium and aluminium alloys
Manual sampling method for petroleum liquids
Chemical composition and product shape of processed copper and copper alloysDetermination of acid value of petroleum products and lubricants (potentiometric titration)GB/T 8926
GB/T 9439
Determination of insoluble matter in used lubricating oil
Grey iron castings
GB/T13818
Die-cast zinc alloy
SH/T 0086
SH 0164
Determination of water content in concentrate of engine coolant (Karl Fischer method)Rules for packaging, storage, transportation and delivery acceptance of petroleum productsSH/T 0430
HG 2865
Determination of equilibrium reflux boiling point of brake fluid
Automobile brake rubber cup
Technical conditions for automobile hydraulic brake wheel cylinder
QC/T 77
QC/T311 Technical conditions for automobile hydraulic brake master cylinder 3 Terms and definitions
Brake fluidbrake fluid
The working medium for transmitting pressure adopted by the hydraulic brake system of motor vehicles. 3.2
wet equilibrium reflux boiling point
wet equilibrium reflux boiling point (WERBP) is the equilibrium reflux boiling point of the solution measured after the brake fluid sample is humidified by a certain method. 3.3
standard sample
GB 12981—2003
A standard sample is a batch of samples with chemical, physical, biological, engineering technology or sensory performance characteristics that are sufficiently uniform, have been technically identified, and are accompanied by a certificate stating the relevant performance data. 3.4
blister
The holes and concave spots that appear on the surface of the test cup. 3.5
chipping
The state in which small pieces fall off the outer surface of the test cup. 3.6
scuffing
The state in which the test cup obviously loses its original shape due to erosion after the test. 3.7
Silicone base brake fluid (SBBF) is a type of brake fluid containing not less than 70% by mass of organic siloxane in its components. 3.8
Sloughing
refers to the presence of loosely attached carbon black on the surface of the cup after the test. When the cup is placed on a piece of white paper and 500 weight is pressed on the cup, a circle of visible ink will appear on the white paper. 3.9
Sticky
refers to the drawing state of the cotton wool when a small ball of medical cotton wool touches the surface of the test cup. 4 Requirements
This standard is divided into three products: HZY3, HZY4 and HZY5 according to the safety requirements for motor vehicle use. They correspond to the international general products DOT3, DOT4, DOT5 or DOT5.1 respectively. The technical requirements of this standard are shown in Table 1. Table 1 Technical requirements for motor vehicle brake fluids
Equilibrium reflux boiling point (ERBP)/℃
Wet equilibrium reflux boiling point (WERBP)/℃
Kinematic viscosity/(mm2/s)
-40℃
100℃
Not less than
Not less than
Not greater than
Not less than
Liquid stability (ERBP) change/℃
Not greater than
High temperature stability (185℃±2℃, 120min±5min)Chemical stability "
Quality index
No precipitation and suspended matter, clear and transparent liquid; silicone type HZY5 brake fluid is purple transparent liquid
7. 0~11.5
±[3+0.05×(ERBP-225)]
±[3+0.05×(ERBP-225)]
Test method
SH/T0430
Appendix C
GB/T265
GB/T 7304b.5
Appendix D
Corrosion (100℃±2℃, 120h±2h) State of metal sheet after test
Mass change/(mg/cm2)
Tinplate
Test solution properties after test
Volume fraction of sediment/%
State of rubber cup after test
Hardness reduction/IRHD
Root diameter increase/mm
Low-temperature fluidity and appearance
-40℃±2℃,144h±4h
Time for bubbles to float to the liquid surface/s
-50℃±2℃,6 h±12 min
Time for bubbles to float to the liquid surface/s
Evaporation performance (100℃±2℃, 168h±2h)Evaporation loss mass fraction/%
Residue properties
Residue pour point/℃
Not more than
Not more than
Not more than
Not more than
Not more than
Not more than
Table 1 (continued)
Quality index
No visible pitting and surface roughness, fading or color spots are allowed
No gel at 23℃±5℃, no crystalline substances formed on the glass container wall or metal surface
7.0~11. 5
No deterioration due to bubbling or shedding
When observed through the test solution, the lines on the hiding power diagram are clearly discernible. The test solution has no sludge, precipitation, crystallization, and no stratification10
When observed through the test solution, the lines on the hiding power diagram are clearly discernible. The test solution has no sludge, precipitation, crystallization, and no stratification35
When rubbed with fingertips, the precipitation does not contain granular sand and abrasives-5
GB 12981-2003
Test method
Appendix Ed
Appendix F
Appendix G
GB 12981-2003
Water solubility (22h±2h)
-40℃
Time for bubbles to float to the liquid surface/sNot more than 60℃
Volume fraction of sediment in the test solution/%Not more than Liquid compatibility (22h±2h)
Volume fraction of sediment/%
Oxidation resistance (70℃±2℃, 168h±2h)Appearance of metal sheet
Mass change of metal sheet/(mg/cm2)
Cast iron sheet||t t||not more than
not more than
Rubber compatibility (SBR rubber cup and EPDM rubber specimen)
Hardness reduction value (SBR rubber cup and EPDM rubber cup or specimen)/IRHD
120℃
Cup appearance
Root diameter increase (SBR rubber cup)/mm
not more than
Volume change fraction (EPDM rubber cup or specimen, 70℃ and 120℃)/%
Table 1 (continued)
Quality indicators
The lines on the hiding power diagram are clearly recognizable when observed through the test solution. The test solution has no sludge, precipitation, crystallization, and no stratification10
The test solution has no stratification
0.05 (identification)
0.15 (commodity)
Observing through the test solution, the lines on the cover avoidance diagram are clearly recognizable. The test solution has no sludge, precipitation, crystallization, and no stratification. The test solution has no stratification.
There is no visible pitting and pitting outside the contact surface between the metal sheet and the tin foil. Discoloration or color spots are allowed. Trace colloid deposition is allowed.
No bubbling, shedding
0.15~1.40
Test method
Appendix H
Appendix H
Appendix J
Appendix K
Stroke simulation performance (85,000 strokes, 120℃±5℃, 6.86MPa±0.34MPa)
Metal parts status
Cylinder and piston diameter changes/mm
Leather cup status|| tt||Hardness reduction value/IRHD
Increase in root diameter of leather cup/mm
Interference of lip diameter of leather cup/%
Not more than
Not more than
Not more than
Not more than
Liquid loss during any 24,000 strokes/mL
Working state of cylinder piston
Not more than
Liquid loss during the last 100 strokes/mLNot more than
State of test liquid after test
Liquid state
Precipitation volume fraction/%
Appearance of cylinder
Not more than
The arbitration test shall be based on Method A in Appendix C of this standard. b The pH value should be determined according to the following steps:
Table 1 (continued)
Quality indicators
No visible pitting or pitting on metal parts. Discoloration or color spots are allowed. 0.13
No excessive scratches, deformation, blistering, cracks, molting or appearance changes
No sticking and poor working conditions
No unremovable precipitation and colloidal attachments 1.5
During the test, no more than trace amounts of precipitation are deposited on the cylinder body and other metal parts. No precipitation that cannot be wiped off with a cloth dipped in ethanol is attached to the brake cylinder body
GB12981—2003
Test method
Appendix L
a) Weigh 4g of sodium hydroxide (NaOH) in a beaker, add a small amount of distilled water, pour into a volumetric flask and dilute to 1000mL, so as to prepare a substance concentration of 0.1 mol/L sodium hydroxide aqueous solution b) Prepare ethanol/distilled water mixed solvent according to the volume ratio (80%/20%), and adjust the pH value to 7.0±0.1 with 0.1mol/L sodium hydroxide aqueous solution at 23℃±5℃. If the consumption of 0.1mol/L sodium hydroxide aqueous solution exceeds 4mL, the mixed solvent should be re-prepared.
c) Prepare a sample with equal volumes of brake fluid sample and ethanol/distilled water mixed solvent with pH 7.0, and determine the pH value of the sample according to GB/T7304 method. The determination result is used as the pH value of the brake fluid. C
Silicone type HZY5 brake fluid does not undergo this test. d It is allowed to use a leather cup that meets HG 2865 for this test. The arbitration shall be based on the test conducted using the national standard sample. e
Liquid compatibility test Take 50mL ± 0.5mL of brake fluid and 50mL ± 0.5mL of compatibility test standard sample to make a mixed solution. The remaining test steps shall be carried out according to Appendix H, but the time for the bubbles to float to the liquid surface shall not be measured. 5 Test method
The test method shall be carried out in accordance with the relevant provisions in Table 1 and Appendix C to L. 5
GB 12981-2003
6 Inspection rules
6.1 Inspection classification
The products involved in this standard are divided into type inspection and factory inspection. 6.2 Type inspection
6.2.1 The type inspection items conduct a comprehensive evaluation of product quality, that is, all technical requirements specified in the standard are inspected. 6.2.2 Under normal circumstances, all items except stroke simulation performance should be inspected once a year. 6.2.3 Type inspection should be carried out when any of the following situations occur: - When the product is identified and finalized;
- When the product is transferred to another production plant;
- During formal production, major technical changes are made to raw materials, production processes or operating procedures, which may affect the product structure, product performance or product intrinsic quality;
- Resuming production after a long-term suspension of production;
- When the results of the factory inspection are significantly different from the results of the previous type inspection, and it is impossible to determine the factors causing the difference and the impact on product performance;
- When the national quality and technical supervision, inspection and quarantine agency proposes a requirement for type inspection; - When the user has special requirements.
6.3 Factory inspection
Inspection that must be carried out before the product is delivered to the distributor or user. 6.3.1 Factory inspection items:
-Appearance,
Equilibrium reflux boiling point;
-Wet equilibrium reflux boiling point;
-Kinematic viscosity (100℃ and -40℃); -pH value;
Corrosivity;
Rubber compatibility.
6.4 Batch rules and sampling plan
6.4.1 Products produced by the same production unit for 24 hours continuously, using the same raw materials and following the same operating process, or products produced by multiple production shifts, but using the same raw materials and following the same operating process, and mixed evenly by multiple shifts, are considered a batch. 6.4.2 Sampling shall be carried out in accordance with GB/T4756. Take two samples (2L each) from the average sample, or randomly select 1% of the packaged products for factory inspection and sample retention respectively. 7 Marking, packaging, transportation, storage
In addition to complying with SH0164, the packaging, marking, storage, transportation and delivery acceptance of this product must indicate the number and name of the standard implemented by the product, the equilibrium reflux boiling point and the wet equilibrium reflux boiling point of the product on the outer packaging of the product. 6
Scope of application
Normative references
Terms and definitions
1) Appearance
2) Equilibrium reflux boiling point
Appendix A
(Informative)
List of corresponding chapter and clause numbers of this standard and those of ISO 4925:1978 Table A.1 Correspondence between this standard and ISO4925:1978
3) Wet equilibrium reflux boiling point
4) Kinematic viscosity
-40℃
100℃
5) pH value
Liquid stability
High temperature stability
Chemical stability
7) Corrosion
Low temperature fluidity and appearance Observation
-40℃
9) Evaporation performance
Water tolerance
—40℃
11) Liquid compatibility
-40℃
12) Oxidation resistance
13) Rubber compatibility
14) Stroke simulation performance
5 Test method
6 Inspection rules
Marking, packaging, transportation, storage
8 Articles of this standard Table 9 List of technical differences between this standard and ISO4925:1978 and their causes Table 10 Determination of the boiling point of brake fluid by wet equilibrium reflux Chapter and article number of this standard
Table 1 Column 2
Table 1 Column 3
Table 1 Column 4
Table 1 Column 5
Table 1 Column 5
Table 1 Column 6
Table 1 Column 7
Table 1 Column 7
Table 1 Column 8
Table 1 Column 9
Table 1 Column 9
Table 1 Column 10
Table 1 Column 11
Table 1 Column 11
Table 1 Column 12
Table 1 Column 12
Table 1 Column 13
Table 1 Column 14
Table 1 Column 15
Appendix A
Appendix B
GB 12981—2003
ISO4925:1978Chapter and Article Number
GB 12981--2003
11 Test method for liquid stability of brake fluid
2 Test method for metal lamination corrosion of brake fluid
Test method for low temperature fluidity and appearance of brake fluidTest method for hair loss of brake fluid
Test method for water capacity of brake fluid
Test method for anti-oxidation of brake fluid
Test method for rubber cup adaptability of brake fluid
Stroke simulation test of brake fluid
HZY3, HZY4 brake fluid compatibility test method Standard sample Test method for anti-rust property of brake fluid
Table A.1 (continued)
This standard Chapter and Article Number
Appendix D
Appendix E
Appendix F
Appendix G
Appendix H
Appendix K
Appendix L
Appendix M
Appendix N
ISO4925:1978 Chapter and Article Number
Appendix B
(Informative Appendix)
List of technical differences between this standard and ISO4925:1978 and their causes Table B.1 gives a list of technical differences between this standard and ISO4925:1978 and their causes. Table B.1 Technical differences between this standard and ISO4925:1978 and their causes Chapter and Article Number
Technical differences
Added the requirements for the applicable fields of this standard. ISO4925:1978 has no such additions.
It cites the Chinese standard that adopts international standards or foreign advanced standards, rather than the international standards or foreign advanced standards cited by ISO4925:1978.
It adopts some definitions in the US Federal Highway Transportation Safety Administration standard FMVSSNo116.
It adopts the two definitions of wet equilibrium reflux boiling point and standard sample, and changes the clause-style expression of ISO4925:1978 to a table-style expression.
Reference to the US Federal Highway Transportation Safety Administration standard FMVSSNg original
GB 12981—2003
Added according to the nature and function of this standard. To suit my country's national conditions.
The meaning of this definition will be understood differently in different application occasions.
Adapt to my country's national conditions
Make the standard writing conform to the requirements of my country's standard
GB 1.1--2000.
Adapt to the current status of international brake fluid products and my country's national conditions.
116(1996) "Motor Vehicle Brake Fluid" adds two types of products corresponding to DOT4 and DOT5 (HZY4 and HZY5), and adds corresponding requirements in the technical indicators. ISO4925:1978 does not have these two types of products.
Brake fluid wet equilibrium reflux boiling point determination adopts SAE J1703. Due to ISO 4925:1978 and SAEJ1703 humidification methods, but not ISO4925 humidification methods. At the same time, the humidification method principle is the same, and the humidification results are consistent. A simple and easy humidification method (B method) is added. In the liquid stability test, the chemical stability test and liquid compatibility test use the Chinese standard sample prepared by the preparation method of the American Society of Automotive Engineers standard sample SAERM-66-04, instead of the standard sample specified in ISO4926:1978. In the liquid stability test, the chemical stability index uses the index of SAEJ1703, not the index of ISO4925. The corrosion test uses the Chinese standard sample metal corrosion test piece. The evaporation performance test is carried out according to the steps of SAEJ1703. Therefore, in order to increase the operability of the standard and adapt to my country's national conditions, the SAEJ1703 method was adopted. Method B is also a simple humidification method used in other tests (such as water tolerance test, etc.) in ISO4925 and SAEJ1703.
Adapt to my country's national conditions.
Adapt to international advanced standards and my country's national conditions. The corrosion test metal specimens have been made into Chinese standard samples according to international standards.
Adapt to the testing technology level of my country's laboratories and move closer to the international advanced level. wwW.bzxz.Net
GB12981-2003
Chapter and article number of this standard
Table B.1 (continued)
Technical differences
ISO has been deleted from the rubber compatibility test. The natural rubber material in ISO 4925:1978 uses EPDM rubber, and the volume change fraction also adopts the technical indicator of no more than 10% required by the American Society of Automotive Engineers standard SAEJ1703 "Motor Vehicle Brake Fluid". The rubber cup adopts the Chinese standard sample. The rubber test conditions adopt 70℃, 70h and 120℃, 70h in SAEJ1703 "Motor Vehicle Brake Fluid". In the stroke simulation test, the master cylinder and sub-cylinder that meet the standards of my country's automobile industry are allowed to be used.
The test method is listed in the normative appendix of the standard, and a guide clause is added. This is different from ISO4925:1978, which lists all the test methods in the main article.
Add inspection rules, ISO4925:1978 does not have this clause. According to the corresponding clauses of the Federal Highway Transportation Safety Administration standard FMVSSNo7
116, this clause is added in combination with the requirements for product standard writing, ISO4925:1978 does not have such a requirement.
Deleted Appendix A "ISO styrene-butadiene rubber (SBR) brake cups conforming to ISO4925 standard", Appendix B "ISO corrosion test pieces", Appendix C "Natural rubber brake cups conforming to ISO4925 standard" and Appendix D "Hiding power chart" in ISO4925:1978. Added Appendix A, Appendix B, Appendix M and Appendix N. Original
Adapts to the new requirements of the development of materials in the international automotive industry and adapts to my country's national conditions.
Adapts to my country's national conditions.
Adapts to my country's standard writing requirements GB 1.1
2000 regulations, making the arrangement of standard clauses more reasonable. Adapts to my country's standard writing requirements. Adapts to my country's national conditions.
Adapts to the general requirements of international products such as brake fluids and adapts to my country's national conditions.
The test rubber cup and metal corrosion test piece adopt the standard samples of my country, and the hiding power chart is included in the appendix of the corresponding test method, so that the standard writing is more in line with the requirements of my country's standard writing regulations GB1.1-2000.
It meets the requirements of GB20000.2---2001 and adapts to my country's national conditions.
C.1 Scope
Appendix C
(Normative Appendix)
Determination of wet equilibrium reflux boiling point of brake fluid
GB12981-2003
This method is suitable for determining the wet equilibrium reflux boiling point of brake fluid, so as to evaluate the downward trend of the equilibrium reflux boiling point of brake fluid after moisture absorption, and indirectly judge the high temperature anti-gas blocking performance of brake fluid. C.2 Method Overview
This method is divided into two types: A method and B method. Method A is to place 350mL of brake fluid and 350mL of humidity control fluid in two identical desiccators for humidification. When the water content of the control fluid is increased from 0.50% to 3.70%, the wet equilibrium reflux boiling point of the humidified brake fluid is measured; Method B is to directly add 2.1mL of distilled water to 60mL of the brake fluid sample to be tested, mix well, and then measure its wet equilibrium reflux boiling point.
C.3 Instruments and Reagents
C.3.1 Corrosion Test Cups: 4 corrosion test cups or equivalent threaded top, straight-sided cylindrical glass containers, with a volume of about 475mL, a height of about 100mm, an inner diameter of about 75mm, and a tin-plated steel cover with a clean, water-proof and water vapor-proof lining (see Figure C.1). C.3.2 Dryers and covers: 2 bowl-shaped glass dryers, with an inner diameter of 250mm and a total height of about 295mm. The top opening of the dryer cover is equipped with a No. 8 rubber plug, and the dryer is equipped with a ceramic orifice plate with a diameter of 230mm (see Figure C.2). Aperture: 0.8±0.1
Cooling liquid level
Unit: mm
About 475ml.
1—Tin-plated steel cover,
Corrosion test cup;
A rubber cup;
A test piece assembly.
Figure C.1 Corrosion test apparatus
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