Some standard content:
GB16897—1997
This standard is formulated with reference to FMVSS106 "Brake Hose". This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Automobile Standardization. This standard is drafted by Changchun Automobile Research Institute and the First Automobile Group Company First Car Factory. The main drafter of this standard: Chen Guangzhao.
1 Scope
National Standard of the People's Republic of China
Brake hose
Brake hose
GB16897-1997
This standard specifies the performance requirements, test methods and markings of brake hoses, brake hose connectors and brake hose assemblies for automobiles (including motorcycles) and trailers.
This standard applies to hydraulic, pneumatic and vacuum brake hoses, brake hose connectors and brake hose assemblies used in automobiles and trailers. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB1690-92 Test method for liquid resistance of vulcanized rubber GB6458-86 Neutral salt spray test for metal covering GB10830-89 Technical conditions for the use of automobile brake fluid GB484-93 Gasoline for vehicles
GB485-88
QB gasoline engine lubricating oil
3 Definitions
This standard adopts the following definitions.
3.1 Sheath
A protective device installed on the outside of the hose to improve the hose's ability to resist scratches or impacts. 3.2 Brake hose
A flexible conveying conduit used to transmit or store hydraulic pressure, air pressure or vacuum for automobile brake boosting in addition to the pipe joint in the brake system.
3.3 Brake hose assembly
A brake hose equipped with a pipe joint. Brake hoses may be jacketed or unjacketed. 3.4 Free length
The length of the exposed portion of the hose between the two fittings on the hose assembly in a straight line. 3.5 Brake hose joint
A connector attached to the end of the brake hose, except for the clamp. 3.6 Permanently connected pipe joint
A pipe joint connected by crimping or cold extrusion, or a pipe joint that requires replacement of damaged bushings and ferrules every time the hose assembly is reassembled.
3.7 Burst
A fault that causes the brake hose to separate from the pipe joint or leak. Approved by the State Administration of Technical Supervision on June 30, 1997 350
Implemented on February 1, 1998
3.8 Vacuum pipe system connector
Refers to a flexible vacuum transmission conduit:
GB 16897-1997
a) It is a connector between metal pipes in the brake system; b) No pipe joint is required during installation;
c) When assembled, its non-supported length is less than the total length of the part that contains the metal pipe. 4 Test conditions
4.1 The hose assembly used for the test should be new and should be aged for at least 24 hours. Before the test, the hose assembly should be kept at a temperature of 15 to 32°C for at least 4 hours.
4.2 For the hose assembly for flex fatigue test and low temperature resistance test, all accessories, such as steel wire sheath, rubber sheath, etc., must be removed before being installed on the test equipment.
4.3 Except for the high temperature resistance test, low temperature resistance test, ozone test, and hose joint corrosion resistance test, other tests must be carried out at room temperature within the range of 15 to 32°C.
5 Hydraulic brake hose, hose joint and hose assembly 5.1 Structure
The hydraulic brake hose assembly consists of a brake hose and a brake hose joint. The brake hose and the brake hose joint are permanently connected, and the connection is achieved by the compression or cold extrusion deformation of the joint part relative to the hose. 5.2 Performance requirements
The hydraulic brake hose assembly or corresponding parts shall meet the various performance requirements specified in this article when tested in accordance with the method of Article 5.3 under the test conditions of Chapter 4.
5.2.1 Inner hole through-put after necking
Use the insertion gauge shown in Figure 1 and Table 1. This gauge is inserted into the full length of 76mm under the action of its own weight. Spherical radius (optional)
76 (minimum)
Figure 1 Insertion gauge for hose assembly diameter structure test Table 1 Standard dimensions of insertion gauges
Nominal inner diameter, mm
5.2.2 Maximum expansion
D, mm (minimum)
Mass, g
120±6
Under the pressure of 6.9MPa and 10.3MPa, the maximum expansion of the hydraulic brake hose assembly shall not exceed the value specified in Table 2.
Nominal inner diameterbzxz.net
GB16897-1997
Table 2 Maximum expansion of the free length of the hose
Normal expansion hose
Low expansion hose
Low expansion hose
Normal expansion hose
5.2.3 Burst strength
During the hydraulic test, each sample of the hose assembly must be kept under the pressure of 27.6MPa for 2min, and the hose assembly must not be damaged. The minimum burst pressure of the hose assembly is 34.5MPa. 5.2.4 Compatibility of brake fluid
Except for hydraulic brake hose assemblies using mineral oil or petroleum-based brake fluid, hydraulic brake hose assemblies filled with JG3 grade brake fluid specified in GB10830 should meet the requirements of 5.2.1 and 5.2.3 when tested in accordance with 5.3.3. 5.2.5 Flexural fatigue
After continuous testing for 35 hours according to 5.3.4, the hose assembly shall not be damaged. 5.2.6 Tensile strength
After the hose assembly is stretched at a rate of 25±3mm/min according to 5.3.5, under a tensile force of 1500N, the pipe joint shall not be pulled off or the hose shall not be broken.
5.2.7 Water absorption
After the water absorption test in 5.3.6, the hose assembly shall meet the requirements of 5.2.3, 5.2.5 and 5.2.6. 5.2.8 Low temperature resistance
After the test in 5.3.7, there shall be no cracks visible to the naked eye on the hose surface. 5.2.9 Ozone resistance
After the test in 5.3.8, there shall be no visible cracks on the hydraulic brake hose assembly under a seven-fold magnifying glass. 5.2.10 Corrosion resistance of joints
After the hydraulic brake hose joint is tested in 5.3.9, the base metal of the pipe joint should not be corroded, except for the wrinkles on the joint surface or the change of the protective layer caused by the use of marks.
5.3 Test method
5.3.1 Maximum expansion test
5.3.1.1 Test equipment
The test equipment shown in Figure 2 is used, which includes: 352
a) Hydraulic source;
Adjustment of hose length
GB 16897-1997
Burette with scale
Hose assembly
Pressure supply port
Figure 2 Expansion test apparatus
b) Test water without any additives and free gas; c) Solution tank and pressure gauge;
d) Connector, hose assembly installed vertically on the connector so that pressure can be applied under controlled conditions; e) Measuring tube with 0.05mL scale
5.3.1.2 Test procedure
a) Calibration of the instrument
Before using the test instrument, a simulated hose assembly must be used to determine the calibration correction amount determined when 6.9MPa and 10.3MPa pressure are applied. The simulated hose assembly consists of a seamless steel tube with a minimum wall thickness of 1.52 mm, a free length of 305 mm ± 6 mm, and an outer diameter of 6.3 mm. All joints and accessories used in the hose assembly test should be installed in the system. The expansion reading obtained from the test sample should be subtracted from the calibrated correction. The maximum allowable calibration correction should be 0.08 mL at a pressure of 10.3 MPa. b) Measure the free length of the hose assembly;
c) Install the hose vertically to ensure that the hose is not stretched when pressure is applied to it; d) Fill the hose with the test fluid and exhaust all the gas in the system: e) Close the valve to the graduated measuring tube and apply a pressure of 10.3 MPa for 10 seconds, then release the pressure. 5.3.1.3 Calculate the expansion of the hose at 10.3 MPa and 6.9 MPa pressure. a) Adjust the liquid level in the graduated measuring tube to zero; b) Close the valve leading to the graduated measuring tube, apply a pressure of 6.9 MPa to the hose assembly at a rate of 103 MPa/min, and make the hose pipeline seal under this pressure (when calculating the expansion under 10.3 MPa pressure, the sealing pressure is below 10.3 MPa pressure). c) After 3 seconds, open the valve leading to the graduated measuring tube for 10 seconds,Allow the liquid in the expansion hose to rise into the graduated measuring tube; d) Repeat steps b) and c) above twice, and measure the total amount of test liquid accumulated in the graduated measuring tube after three pressure applications; e) Divide the total amount of liquid in the graduated measuring tube by 3, subtract the calibration correction amount, and the volume expansion can be calculated. This value is then divided by the free length (m) to obtain the volume expansion per meter of the hose. 5.3.2 Burst strength test
a) Connect the brake hose to the pressure system, fill it with water and expel all the air; b) Apply a pressure of 27.6MPa at a rate of 103MPa/min and maintain it for 2min; c) Continue to increase the pressure at a rate of 103MPa/min until the pressure exceeds 34.5MPa; cap,
After the brake hose is deflated
Close the opening with a cap
a reservoir
(brazed to the reservoir)
pipe nut or other
suitable joint
Test hose
Cap or plug
Figure 3 Brake fluid compatibility test
d) Check and record whether the hose is damaged.
5.3.3 Compatibility test of brake fluid
5.3.3.1 Test procedure
a) Connect a hose assembly or a manifold connecting multiple hose assemblies from below to a tank with a capacity of 0.5L and 100mL of compatible brake fluid, as shown in Figure 3;
b) After the hose assembly with the lower end closed is filled with brake fluid, place the hose assembly in a vertical position in the thermostat. 5.3.3.2 Constant temperature treatment
a) Place the hose assembly at 93℃ for 70h;b) Remove the hose assembly and cool it at room temperature for 30min;c) Drain the brake fluid from the brake hose and check the inner hole flow after necking according to the requirements of Section 5.2.1;d) Perform the burst test of the brake hose assembly according to Section 5.3.2 within 3h. 5.3.4 Flexural fatigue test
5.3.4.1 Test equipment
The test equipment is shown in Figure 4. The equipment is dynamically balanced and comprises: a) a movable end, the connector of the hose at this end is closed by a horizontal rod. The horizontal rod is supported on two vertically mounted turntables, the mounting end of the horizontal rod is 100 mm away from the center of the turntable, and the edges of the turntable are in the same vertical plane; b) an adjustable fixed end, on which the opening of the hose connector is mounted, parallel to the movable end and in the same horizontal plane as the center of the turntable;
c) a time display;
d) a water pressure source connected to the open pipe connector. 5.3.4.2 Test preparation
GB16897-1997
a) Remove the external accessories, namely the sheath, anti-mechanical damage ring, mounting bracket, date ring band and spring sheath; b) Measure the free length of the hose assembly;
c) Install the hose assembly on the flexure fatigue machine. The slack should conform to the value specified in Table 3 for the test hose of this specification, and measure the projected length parallel to the axis of the rotating disk. Table 3 Relaxation of free length and flexural fatigue test Nominal inside diameter
4.8 and 6.3
5.3.4.3 Test procedure
Free length
200～~400
>400～480
>480~～600
250~400
a) Supply 1620kPa water pressure and exhaust all gas from the system; b) Drive the moving end to rotate at a rate of 800r/min; c) Check and record whether the hose is damaged.
4200±0.25
Adjustable fixed end
-manifold
Horizontal rod
Moving end
a Flexural fatigue testing machine
Figure 4 Standard flexural test slack adjuster dial
Slack of hose
5.3.5 Tensile strength test
5.3.5.1 Test equipment
GB16897-1997
Flexural fatigue test length
Figure 4 (end)
4.9kN tensile machine, the testing machine should have a recording device for the total tensile force. 5.3.5.2 Test preparation
Plumb the hose assembly so that the hose and the connector are in the same straight line and consistent with the direction of the pulling force. 5.3.5.3 Test procedure
Relaxed length see Table 5
Gradually increase the tensile load, and the movable joint of the testing machine moves at a speed of 25±3mm/min until the hose fails. Record the total load and the type of failure at failure.
5.3.6 Water absorption test
5.3.6.1 Test preparation
Prepare 3 hose assemblies, peel off the outer rubber layer at the center of 28.6mm±2mm in length, and expose the fiber line. When peeling the outer rubber layer, be careful not to damage the fiber line and do not stretch the hose. Measure the free length of the hose assembly. 5.3.6.2 Test procedure
a) Immerse the hose assembly with the outer rubber layer peeled off in distilled water at room temperature and keep it for 70 hours; b) After taking the hose assembly out of the water, within 30 minutes, carry out the burst strength test in 5.3.2, the tensile strength test in 5.3.5 and the flexural fatigue test in 5.3.4 respectively, using different hose assemblies for each test. 5.3.7 Low temperature resistance test
5.3.7.1 Test fixture
The schematic diagram of the fixture structure for the low temperature resistance test is shown in Figure 5.356
Brake hose specimen
5.3.7.2 Test procedure
Driving gear
GB16897-1997
Transition gear
Passive gear
Figure 5 Cold bending test fixture structure diagram
a) If there is a sheath, the sheath should be removed. Straighten the hose assembly and place it in a 40℃ low temperature box for 70h. The mandrel used to bend the hose is also treated in the same way. The 76.2mm diameter mandrel is suitable for hoses with a nominal inner diameter of 3.2mm, and the 88.9mm diameter mandrel is suitable for hoses with nominal inner diameters of 4.8mm and 6.3mm. b) Then, still at 40℃, bend the hose around the mandrel at least 180° at a steady speed within 3 to 5 seconds. c) Visually inspect the hose surface for cracks and record them. 5.3.8 Ozone resistance test
Use a mandrel with a diameter of 8 times the nominal outer diameter of the brake hose. 5.3.8.1 Test preparation
Remove the sheath and tie the brake hose 360° around the mandrel. 5.3.8.2 Expose the hose to ozone
a) Place the mandrel with the hose wound around it at room temperature for 24 hours, and then place it in an exposure chamber filled with a mixed gas concentration of 50 parts per billion ± 5 of air volume, and keep it for 70 hours. During the test, the temperature in the exposure chamber should be 40℃; b) Check whether the hose has cracks under a 7x magnifying glass. Ignore the area where the wrapping is and the area close to it. 5.3.9 Corrosion resistance test of joints
5.3.9.1 Test equipment
The salt spray test chamber should comply with the provisions of GB6458, and both ends of the hose assembly should be blocked. 5.3.9.2 Test the hose assembly for 24 hours in accordance with the provisions of GB6458. Use clean running water not higher than 40℃ to gently clean and remove salt deposits, and then blow dry with air within 2 minutes. 5.3.9.3 Check the joints of the hose assembly and record the results. 6 Air brake hose, hose connector and hose assembly 6.1 Structure
The air brake hose assembly consists of metal pipe connectors (or clamps) at both ends and a hose in the middle. 6.2 Performance requirements
Under the test conditions specified in Chapter 4, each air brake hose assembly or corresponding parts shall meet the requirements specified in this article when tested in accordance with the method specified in 6.3.
6.2.1 Throughput of the inner hole after necking
Use the insertion gauge shown in Figure 6, and require the gauge to be inserted into the full length B under the action of its own weight (see Figure 6). 357
A: 66% of the nominal size of the hose inner diameter.
B: The full length of the connector plus 30mm or more.
The mass of the gauge: 60~100g.
6.2.2 Air tightness
GB 16897—1997
Figure 6 Gauge for measuring the amount of inner hole passing
Ball RA
Test according to 6.3.1, visually check the hose body in the water tank and the part where the joint is installed. There should be no bubbles and local expansion. 6.2.3 Length change rate (except for hose assemblies wrapped with nylon) Test according to 6.3.2, the length change rate of the hose should be within 7%~+5%. 6.2.4 Burst strength
Test according to 6.3.3, the burst pressure of the hose assembly should not be less than 5.52MPa. 6.2.5 Tensile strength
Tested in accordance with 6.3.4, for hose assemblies with a nominal inner diameter less than or equal to 6mm, the hose shall not break and the hose and the connector shall not be separated under a tensile force of 1100N. For hose assemblies with a nominal inner diameter greater than 6mm, the hose shall not break and the hose and the connector shall not be separated under a tensile force of 1500N.
6.2.6 Adhesion strength
Tested in accordance with 6.3.5, the adhesion strength between the rubber layer and the reinforcement layer of the hose shall not be less than 15N/cm. 6.2.7' High temperature resistance
After testing in accordance with 6.3.6, there shall be no visible cracks, carbon deposits or erosion on the inner and outer surfaces of the hose. 6.2.8 Low temperature resistance
After testing in accordance with 6.3.7, the outer surface of the brake hose shall be free of cracks or damage and shall meet the airtightness requirements of 6.2.2. 6.2.9 Oil resistance
After testing in accordance with 6.3.8, the increase in the volume of the hose inner diameter sample shall not exceed 100%. 6.2.10 Tensile strength after immersion in water
After testing in accordance with 6.3.9, the hose assembly shall meet the requirements specified in 6.2.5. 6.2.11 Ozone resistance
After testing in accordance with 6.3.10, the hose assembly shall not have visible cracks on the outer surface of the hose assembly when observed with a 7x magnifying glass. 6.2.12 Zinc chloride resistance of nylon hose
After testing in accordance with 6.3.11, the hose shall not have visible cracks on the outer surface when observed with a 7x magnifying glass. 6.2.13 Corrosion resistance of connectors
After testing in accordance with 6.3.12, the hose connector or clamp base metal shall not be corroded, except for the curled edge at the hose connector and the connector area used as a label.
6.3 Test method
6.3.1 Air tightness test
Close one end of the hose assembly, fill it with air or gas to 1.4MPa from the other end, immerse it in a water tank and maintain the pressure for 3 minutes, observe whether there are bubbles and local expansion, and record them. 6.3.2 Length change rate test
GB16897-1997
Fill the hose assembly with water and exhaust the air inside. Under the condition of 0.1MPa pressure, mark lines at intervals of 300mm in the center of the hose assembly, then increase the pressure to 1.4MPa, maintain the pressure for 5min, measure the distance between the mark lines again, and calculate the length change rate according to the following formula: AL=
Wherein: AL
Length change rate, %;
L2—Li
L—When the pressure is 0.1MPa, the distance between the mark lines, mm, L When the pressure is 1.4MPa, the distance between the mark lines, mm. 6.3.3 Burst test
Immediately after the length change rate test, keep the sample in a naturally relaxed state, and apply water pressure at a pressure rate of about 6.9MPa/min until the hose breaks or the joint falls off, and record the instantaneous pressure value at the burst. 6.3.4 Tensile test
Install the hose assembly with a free length of 450 mm on a tensile testing machine and stretch it steadily at a rate of 25.4 mm/min until the hose breaks or the connector falls off. Record the load value and failure mode when the hose assembly fails. 6.3.5 Adhesion strength test
6.3.5.1 Test equipment
Electronic or optical non-inertial tensile machine or pendulum inertial tensile machine. 6.3.5.2 Test procedure
a) Cut a section of 25.4 mm from the test hose as a sample, then cut out the test layer along the full length of the sample, the depth of which should be cut to the surface where it meets the adjacent layer, and peel it off along the tangent direction. The peeling length should be such that the clamp of the tensile testing machine is sufficient to clamp the peeled outer rubber layer; b) Measure the width of the peeled layer (accurate to 0.2 mm) and make a record; c) After the sample is put on the mandrel, install the mandrel on the clamp of the tensile testing machine so that the peeled layer is evenly and firmly clamped in the clamp; d) Zero the automatic recorder, start the tensile testing machine, make the lower clamp descend at a speed of 25.4 mm/min, and peel the outer rubber layer off from the reinforcing layer at 90° to the sample surface. The minimum force recorded on the characteristic curve drawn by the recorder with peeling length and peeling force as coordinates is the adhesion force;
e) Calculate the ratio of adhesion force to peeling width, which is the adhesion strength, expressed in N/cm. 6.3.6 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Nominal inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, place it in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone resistance test
Perform the ozone resistance test of the air brake hose in accordance with the provisions of 5.3.8. 6.3.11 Zinc chloride resistance test of nylon hose Soak the nylon air brake hose assembly in a 50% concentration zinc fluoride aqueous solution at room temperature for 200 hours. After taking it out of the solution, observe the cracks on the surface of the hose under a 7x magnifying glass. 6.3.12 Corrosion resistance test of joints
Perform the test in accordance with the provisions of 5.3.9.
7 Vacuum brake hose, hose joints and hose assemblies 7.1 Performance requirements
Each vacuum brake hose assembly or corresponding part shall meet the requirements specified in this article when tested under the test conditions of Chapter 4 and the test method specified in 7.2.
7.1.1 Inner hole throughput after necking
Use an insertion gauge to check each vacuum brake hose assembly. For those used in heavy-load conditions, the outer diameter of the gauge is 75% of the nominal inner diameter of the hose; for those used in light-load conditions, the outer diameter of the gauge is 70% of the nominal inner diameter of the hose. 7.1.2 Vacuum degree requirements
After the test in 7.2.1, the shrinkage of the outer diameter of the vacuum brake hose shall not exceed 1.6mm. 7.1.3 Burst strength
The burst pressure of the hose assembly shall not be lower than 2.41MPa. 7.1.4 Bending test requirements
When the vacuum brake hose is bent until the two ends are in contact, the shrinkage of the outer diameter of the vacuum brake hose at the midpoint of the test length shall not exceed the value of the hose of this size given in Table 5. 3608 Low temperature resistance
After testing according to the method in 6.3.7, the outer surface of the brake hose shall be free of cracks or damage and shall meet the air tightness requirements of 6.2.2. 6.2.9 Oil resistance
After testing according to 6.3.8, the volume increment of the hose inner diameter sample shall not exceed 100%. 6.2.10 Tensile strength after immersion in water
After testing according to 6.3.9, the hose assembly shall meet the requirements specified in 6.2.5. 6.2.11 Ozone resistance
After testing according to 6.3.10, the outer surface of the hose assembly shall not have visible cracks when observed with a 7x magnifying glass. 6.2.12 Zinc chloride resistance of nylon hose
After testing according to 6.3.11, the outer surface of the hose shall not have cracks when observed with a 7x magnifying glass. 6.2.13 Corrosion resistance of joints
After the test in 6.3.12, except for the curling edge at the tightening part of the hose joint and the joint area used as a label, the hose joint or clamp base metal should not be corroded.
6.3 Test method
6.3.1 Air tightness test
Close one end of the hose assembly, fill it with air or gas to 1.4MPa from the other end, immerse it in a water tank and maintain the pressure for 3 minutes, observe whether there are bubbles and local expansion, and record them. 6.3.2 Length change rate test
GB16897-1997
Fill the hose assembly with water and exhaust the air inside. Under the condition of 0.1MPa pressure, mark lines at intervals of 300mm in the center of the hose assembly, then increase the pressure to 1.4MPa, maintain the pressure for 5min, measure the distance between the mark lines again, and calculate the length change rate according to the following formula: AL=
Wherein: AL
Length change rate, %;
L2—Li
L—When the pressure is 0.1MPa, the distance between the mark lines, mm, L When the pressure is 1.4MPa, the distance between the mark lines, mm. 6.3.3 Burst test
Immediately after the length change rate test, keep the sample in a naturally relaxed state, and apply water pressure at a pressure rate of about 6.9MPa/min until the hose breaks or the joint falls off, and record the instantaneous pressure value at the burst. 6.3.4 Tensile test
Install the hose assembly with a free length of 450 mm on a tensile testing machine and stretch it steadily at a rate of 25.4 mm/min until the hose breaks or the connector falls off. Record the load value and failure mode when the hose assembly fails. 6.3.5 Adhesion strength test
6.3.5.1 Test equipment
Electronic or optical non-inertial tensile machine or pendulum inertial tensile machine. 6.3.5.2 Test procedure
a) Cut a section of 25.4 mm from the test hose as a sample, then cut out the test layer along the full length of the sample, the depth of which should be cut to the surface where it meets the adjacent layer, and peel it off along the tangent direction. The peeling length should be such that the clamp of the tensile testing machine is sufficient to clamp the peeled outer rubber layer; b) Measure the width of the peeled layer (accurate to 0.2 mm) and make a record; c) After the sample is put on the mandrel, install the mandrel on the clamp of the tensile testing machine so that the peeled layer is evenly and firmly clamped in the clamp; d) Zero the automatic recorder, start the tensile testing machine, make the lower clamp descend at a speed of 25.4 mm/min, and peel the outer rubber layer off from the reinforcing layer at 90° to the sample surface. The minimum force recorded on the characteristic curve drawn by the recorder with peeling length and peeling force as coordinates is the adhesion force;
e) Calculate the ratio of adhesion force to peeling width, which is the adhesion strength, expressed in N/cm. 6.3.6 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Nominal inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, place it in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone resistance test
Perform the ozone resistance test of the air brake hose in accordance with the provisions of 5.3.8. 6.3.11 Zinc chloride resistance test of nylon hose Soak the nylon air brake hose assembly in a 50% concentration zinc fluoride aqueous solution at room temperature for 200 hours. After taking it out of the solution, observe the cracks on the surface of the hose under a 7x magnifying glass. 6.3.12 Corrosion resistance test of joints
Perform the test in accordance with the provisions of 5.3.9.
7 Vacuum brake hose, hose joints and hose assemblies 7.1 Performance requirements
Each vacuum brake hose assembly or corresponding part shall meet the requirements specified in this article when tested under the test conditions of Chapter 4 and the test method specified in 7.2.
7.1.1 Inner hole throughput after necking
Use an insertion gauge to check each vacuum brake hose assembly. For those used in heavy-load conditions, the outer diameter of the gauge is 75% of the nominal inner diameter of the hose; for those used in light-load conditions, the outer diameter of the gauge is 70% of the nominal inner diameter of the hose. 7.1.2 Vacuum degree requirements
After the test in 7.2.1, the shrinkage of the outer diameter of the vacuum brake hose shall not exceed 1.6mm. 7.1.3 Burst strength
The burst pressure of the hose assembly shall not be lower than 2.41MPa. 7.1.4 Bending test requirements
When the vacuum brake hose is bent until the two ends are in contact, the shrinkage of the outer diameter of the vacuum brake hose at the midpoint of the test length shall not exceed the value of the hose of this size given in Table 5. 3608 Low temperature resistance
After testing according to the method in 6.3.7, the outer surface of the brake hose shall be free of cracks or damage and shall meet the air tightness requirements of 6.2.2. 6.2.9 Oil resistance
After testing according to 6.3.8, the volume increment of the hose inner diameter sample shall not exceed 100%. 6.2.10 Tensile strength after immersion in water
After testing according to 6.3.9, the hose assembly shall meet the requirements specified in 6.2.5. 6.2.11 Ozone resistance
After testing according to 6.3.10, the outer surface of the hose assembly shall not have visible cracks when observed with a 7x magnifying glass. 6.2.12 Zinc chloride resistance of nylon hose
After testing according to 6.3.11, the outer surface of the hose shall not have cracks when observed with a 7x magnifying glass. 6.2.13 Corrosion resistance of joints
After the test in 6.3.12, except for the curling edge at the tightening part of the hose joint and the joint area used as a label, the hose joint or clamp base metal should not be corroded.
6.3 Test method
6.3.1 Air tightness test
Close one end of the hose assembly, fill it with air or gas to 1.4MPa from the other end, immerse it in a water tank and maintain the pressure for 3 minutes, observe whether there are bubbles and local expansion, and record them. 6.3.2 Length change rate test
GB16897-1997
Fill the hose assembly with water and exhaust the air inside. Under the condition of 0.1MPa pressure, mark lines at intervals of 300mm in the center of the hose assembly, then increase the pressure to 1.4MPa, maintain the pressure for 5min, measure the distance between the mark lines again, and calculate the length change rate according to the following formula: AL=
Wherein: AL
Length change rate, %;
L2—Li
L—When the pressure is 0.1MPa, the distance between the mark lines, mm, L When the pressure is 1.4MPa, the distance between the mark lines, mm. 6.3.3 Burst test
Immediately after the length change rate test, keep the sample in a naturally relaxed state, and apply water pressure at a pressure rate of about 6.9MPa/min until the hose breaks or the joint falls off, and record the instantaneous pressure value at the burst. 6.3.4 Tensile test
Install the hose assembly with a free length of 450 mm on a tensile testing machine and stretch it steadily at a rate of 25.4 mm/min until the hose breaks or the connector falls off. Record the load value and failure mode when the hose assembly fails. 6.3.5 Adhesion strength test
6.3.5.1 Test equipment
Electronic or optical non-inertial tensile machine or pendulum inertial tensile machine. 6.3.5.2 Test procedure
a) Cut a section of 25.4 mm from the test hose as a sample, then cut out the test layer along the full length of the sample, the depth of which should be cut to the surface where it meets the adjacent layer, and peel it off along the tangent direction. The peeling length should be such that the clamp of the tensile testing machine is sufficient to clamp the peeled outer rubber layer; b) Measure the width of the peeled layer (accurate to 0.2 mm) and make a record; c) After the sample is put on the mandrel, install the mandrel on the clamp of the tensile testing machine so that the peeled layer is evenly and firmly clamped in the clamp; d) Zero the automatic recorder, start the tensile testing machine, make the lower clamp descend at a speed of 25.4 mm/min, and peel the outer rubber layer off from the reinforcing layer at 90° to the sample surface. The minimum force recorded on the characteristic curve drawn by the recorder with peeling length and peeling force as coordinates is the adhesion force;
e) Calculate the ratio of adhesion force to peeling width, which is the adhesion strength, expressed in N/cm. 6.3.6 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Nominal inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, place it in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone resistance test
Perform the ozone resistance test of the air brake hose in accordance with the provisions of 5.3.8. 6.3.11 Zinc chloride resistance test of nylon hose Soak the nylon air brake hose assembly in a 50% concentration zinc fluoride aqueous solution at room temperature for 200 hours. After taking it out of the solution, observe the cracks on the surface of the hose under a 7x magnifying glass. 6.3.12 Corrosion resistance test of joints
Perform the test in accordance with the provisions of 5.3.9.
7 Vacuum brake hose, hose joints and hose assemblies 7.1 Performance requirements
Each vacuum brake hose assembly or corresponding part shall meet the requirements specified in this article when tested under the test conditions of Chapter 4 and the test method specified in 7.2.
7.1.1 Inner hole throughput after necking
Use an insertion gauge to check each vacuum brake hose assembly. For those used in heavy-load conditions, the outer diameter of the gauge is 75% of the nominal inner diameter of the hose; for those used in light-load conditions, the outer diameter of the gauge is 70% of the nominal inner diameter of the hose. 7.1.2 Vacuum degree requirements
After the test in 7.2.1, the shrinkage of the outer diameter of the vacuum brake hose shall not exceed 1.6mm. 7.1.3 Burst strength
The burst pressure of the hose assembly shall not be lower than 2.41MPa. 7.1.4 Bending test requirements
When the vacuum brake hose is bent until the two ends are in contact, the shrinkage of the outer diameter of the vacuum brake hose at the midpoint of the test length shall not exceed the value of the hose of this size given in Table 5. 3602 Length change rate test
GB16897-1997
Fill the hose assembly with water and exhaust the air. Under the condition of 0.1MPa pressure, mark lines with 300mm intervals in the center of the hose assembly, then increase the pressure to 1.4MPa, maintain the pressure for 5min, measure the distance between the marking lines again, and calculate the length change rate according to the following formula: AL=
Where: AL
Length change rate, %;
L2—Li
L—When the pressure is 0.1MPa, the distance between the marking lines, mm, L When the pressure is 1.4MPa, the distance between the marking lines, mm. 6.3.3 Burst test
Immediately after the length change rate test, keep the sample in a naturally relaxed state and apply water pressure at a pressure rate of about 6.9MPa/min until the hose breaks or the joint falls off, and record the instantaneous pressure value when it bursts. 6.3.4 Tensile test
Install the hose assembly with a free length of 450 mm on a tensile testing machine and stretch it steadily at a rate of 25.4 mm/min until the hose breaks or the connector falls off. Record the load value and failure mode when the hose assembly fails. 6.3.5 Adhesion strength test
6.3.5.1 Test equipment
Electronic or optical non-inertial tensile machine or pendulum inertial tensile machine. 6.3.5.2 Test procedure
a) Cut a section of 25.4 mm from the test hose as a sample, then cut out the test layer along the full length of the sample, the depth of which should be cut to the surface where it meets the adjacent layer, and peel it off along the tangent direction. The peeling length should be such that the clamp of the tensile testing machine is sufficient to clamp the peeled outer rubber layer; b) Measure the width of the peeled layer (accurate to 0.2 mm) and make a record; c) After the sample is put on the mandrel, install the mandrel on the clamp of the tensile testing machine so that the peeled layer is evenly and firmly clamped in the clamp; d) Zero the automatic recorder, start the tensile testing machine, make the lower clamp descend at a speed of 25.4 mm/min, and peel the outer rubber layer off from the reinforcing layer at 90° to the sample surface. The minimum force recorded on the characteristic curve drawn by the recorder with peeling length and peeling force as coordinates is the adhesion force;
e) Calculate the ratio of adhesion force to peeling width, which is the adhesion strength, expressed in N/cm. 6.3.6 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Nominal inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, place it in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone resistance test
Perform the ozone resistance test of the air brake hose in accordance with the provisions of 5.3.8. 6.3.11 Zinc chloride resistance test of nylon hose Soak the nylon air brake hose assembly in a 50% concentration zinc fluoride aqueous solution at room temperature for 200 hours. After taking it out of the solution, observe the cracks on the surface of the hose under a 7x magnifying glass. 6.3.12 Corrosion resistance test of joints
Perform the test in accordance with the provisions of 5.3.9.
7 Vacuum brake hose, hose joints and hose assemblies 7.1 Performance requirements
Each vacuum brake hose assembly or corresponding part shall meet the requirements specified in this article when tested under the test conditions of Chapter 4 and the test method specified in 7.2.
7.1.1 Inner hole throughput after necking
Use an insertion gauge to check each vacuum brake hose assembly. For those used in heavy-load conditions, the outer diameter of the gauge is 75% of the nominal inner diameter of the hose; for those used in light-load conditions, the outer diameter of the gauge is 70% of the nominal inner diameter of the hose. 7.1.2 Vacuum degree requirements
After the test in 7.2.1, the shrinkage of the outer diameter of the vacuum brake hose shall not exceed 1.6mm. 7.1.3 Burst strength
The burst pressure of the hose assembly shall not be lower than 2.41MPa. 7.1.4 Bending test requirements
When the vacuum brake hose is bent until the two ends are in contact, the shrinkage of the outer diameter of the vacuum brake hose at the midpoint of the test length shall not exceed the value of the hose of this size given in Table 5. 3602 Length change rate test
GB16897-1997
Fill the hose assembly with water and exhaust the air. Under the condition of 0.1MPa pressure, mark lines with 300mm intervals in the center of the hose assembly, then increase the pressure to 1.4MPa, maintain the pressure for 5min, measure the distance between the marking lines again, and calculate the length change rate according to the following formula: AL=
Where: AL
Length change rate, %;
L2—Li
L—When the pressure is 0.1MPa, the distance between the marking lines, mm, L When the pressure is 1.4MPa, the distance between the marking lines, mm. 6.3.3 Burst test
Immediately after the length change rate test, keep the sample in a naturally relaxed state and apply water pressure at a pressure rate of about 6.9MPa/min until the hose breaks or the joint falls off, and record the instantaneous pressure value when it bursts. 6.3.4 Tensile test
Install the hose assembly with a free length of 450 mm on a tensile testing machine and stretch it steadily at a rate of 25.4 mm/min until the hose breaks or the connector falls off. Record the load value and failure mode when the hose assembly fails. 6.3.5 Adhesion strength test
6.3.5.1 Test equipment
Electronic or optical non-inertial tensile machine or pendulum inertial tensile machine. 6.3.5.2 Test procedure
a) Cut a section of 25.4 mm from the test hose as a sample, then cut out the test layer along the full length of the sample, the depth of which should be cut to the surface where it meets the adjacent layer, and peel it off along the tangent direction. The peeling length should be such that the clamp of the tensile testing machine is sufficient to clamp the peeled outer rubber layer; b) Measure the width of the peeled layer (accurate to 0.2 mm) and make a record; c) After the sample is put on the mandrel, install the mandrel on the clamp of the tensile testing machine so that the peeled layer is evenly and firmly clamped in the clamp; d) Zero the automatic recorder, start the tensile testing machine, make the lower clamp descend at a speed of 25.4 mm/min, and peel the outer rubber layer off from the reinforcing layer at 90° to the sample surface. The minimum force recorded on the characteristic curve drawn by the recorder with peeling length and peeling force as coordinates is the adhesion force;
e) Calculate the ratio of adhesion force to peeling width, which is the adhesion strength, expressed in N/cm. 6.3.6 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Nominal inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, place it in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone resistance test
Perform the ozone resistance test of the air brake hose in accordance with the provisions of 5.3.8. 6.3.11 Zinc chloride resistance test of nylon hose Soak the nylon air brake hose assembly in a 50% concentration zinc fluoride aqueous solution at room temperature for 200 hours. After taking it out of the solution, observe the cracks on the surface of the hose under a 7x magnifying glass. 6.3.12 Corrosion resistance test of joints
Perform the test in accordance with the provisions of 5.3.9.
7 Vacuum brake hose, hose joints and hose assemblies 7.1 Performance requirements
Each vacuum brake hose assembly or corresponding part shall meet the requirements specified in this article when tested under the test conditions of Chapter 4 and the test method specified in 7.2.
7.1.1 Inner hole throughput after necking
Use an insertion gauge to check each vacuum brake hose assembly. For those used in heavy-load conditions, the outer diameter of the gauge is 75% of the nominal inner diameter of the hose; for those used in light-load conditions, the outer diameter of the gauge is 70% of the nominal inner diameter of the hose. 7.1.2 Vacuum degree requirements
After the test in 7.2.1, the shrinkage of the outer diameter of the vacuum brake hose shall not exceed 1.6mm. 7.1.3 Burst strength
The burst pressure of the hose assembly shall not be lower than 2.41MPa. 7.1.4 Bending test requirements
When the vacuum brake hose is bent until the two ends are in contact, the shrinkage of the outer diameter of the vacuum brake hose at the midpoint of the test length shall not exceed the value of the hose of this size given in Table 5. 3606 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, it is placed in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone resistance test
Perform the ozone resistance test of the air brake hose in accordance with the provisions of 5.3.8. 6.3.11 Zinc chloride resistance test of nylon hose Soak the nylon air brake hose assembly in a 50% concentration zinc fluoride aqueous solution at room temperature for 200 hours. After taking it out of the solution, observe the cracks on the surface of the hose under a 7x magnifying glass. 6.3.12 Corrosion resistance test of joints
Perform the test in accordance with the provisions of 5.3.9.
7 Vacuum brake hose, hose joints and hose assemblies 7.1 Performance requirements
Each vacuum brake hose assembly or corresponding part shall meet the requirements specified in this article when tested under the test conditions of Chapter 4 and the test method specified in 7.2.
7.1.1 Inner hole throughput after necking
Use an insertion gauge to check each vacuum brake hose assembly. For those used in heavy-load conditions, the outer diameter of the gauge is 75% of the nominal inner diameter of the hose; for those used in light-load conditions, the outer diameter of the gauge is 70% of the nominal inner diameter of the hose. 7.1.2 Vacuum degree requirements
After the test in 7.2.1, the shrinkage of the outer diameter of the vacuum brake hose shall not exceed 1.6mm. 7.1.3 Burst strength
The burst pressure of the hose assembly shall not be lower than 2.41MPa. 7.1.4 Bending test requirements
When the vacuum brake hose is bent until the two ends are in contact, the shrinkage of the outer diameter of the vacuum brake hose at the midpoint of the test length shall not exceed the value of the hose of this size given in Table 5. 3606 High temperature resistance test
a) Use a core shaft, and the core shaft radius is selected according to the inner diameter of the test hose in Table 4; Table 4
Inner diameter
Bending radius
Bending state
(High temperature aging test)
Bending radius
b) After the hose is wound on the core shaft, it is placed in a constant temperature box at 100℃ for 70h; c) After the hose is cooled to room temperature, remove the hose from the core shaft and straighten it; d) Visually inspect the outer surface of the hose, cut the hose longitudinally, and visually inspect the inner surface. 6.3.7 Low temperature resistance test
a) Use a mandrel, the radius of which is selected from Table 4 according to the inner diameter of the hose to be tested; 359
GB 16897-1997
b) Place the mandrel and the straightened hose together in a 40°C low temperature box for 70 hours; c) Then, in the low temperature box, bend the hose around the mandrel at a constant speed of at least 180° within 3 to 5 seconds, take the hose out of the box and check whether there are cracks on the outer surface. The schematic diagram of the fixture structure for low temperature resistance test is shown in Figure 5; d) If there are no cracks on the outer surface of the hose, perform an airtightness test according to 6.3.1 and record it. 6.3.8 Engine oil resistance test
Use 3 specimens and take the average value of the test results. 6.3.8.1 Test preparation
Cut a rectangular specimen with a length of 51 mm, a width of more than 8.5 mm and a thickness of no more than 1.6 mm from the inner surface of the brake hose or long hose. The specimen is required to be polished on both sides to ensure a smooth surface. 6.3.8.2 Measurement
a) Measure the mass of the specimen in air (W,) and the mass of the specimen in distilled water (W) at room temperature, with the mass unit in mg. If the sample is damp and bubbles need to be removed, measure: a) immerse the sample in acetone solution and then rinse it with distilled water; b) immerse each sample in No. 10 engine oil (in accordance with GB485) at 100℃ for 70 hours, and then cool it in No. 10 engine oil at room temperature for 30 to 60 minutes; c) After quickly immersing the sample in acetone solution, use filter paper to absorb the acetone on the surface of the sample; d) Within 5 minutes after taking the sample out of the coolant, weigh the mass of the sample in the tared weighing bottle and in distilled water: W and W4se) Calculate the percentage of volume increase according to the formula: (W,-W)-(Wl-W.)×100%
Increment two
6.3.9 Water resistance test
Immerse the hose assembly in distilled water at room temperature for 70 hours. After taking it out of the water for 30 minutes, perform a tensile test in accordance with the provisions of 6.3.5. 6.3.10 Ozone r
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