GB 7542-1987 Rubber hoses for braking of railway rolling stock GB7542-1987 Standard download and decompression password: www.bzxz.net

National Standard of the People's Republic of China
Rubber brake hoses for rsilway locomotive and carUDC678.4.06:625
.25:621-59||tt ||GB7542-87
This standard applies to rubber hoses for braking of railway rolling stock (hereinafter referred to as hoses). This hose is used to transport compressed air under the conditions of -50 to 10 50C and the working pressure is not greater than 0.9MPa (9kgf/cm*). This standard was formulated with reference to the international standard ISO2398-1978 "Industrial Compressed Air Hose". 1 Structure and size
The hose consists of an inner rubber layer, a tape layer, an outer rubber layer and a head rubber. The size of the hose should comply with the requirements in Table 1. Table 1
Inner
Dimensions
36
Diameter
Tolerance
±1. 0
Outer||tt ||Size
53
Diameter
Tolerance
±1.0
Adhesive layer thickness
Not less than
Inner rubber Layer
2.3
Note: ① Specifications not listed in the table can be resolved through negotiation with the manufacturer. Outer rubber layer
1.2
Number of tape layers
5
mm
Finished product length
Size
565|| tt||②The strength of the cotton canvas used for tape shall not be lower than the provisions of 203A in the GB2909.1-82 "Cotton Canvas for Rubber Industry" standard. 2 Technical Requirements
2.1 Appearance Quality
Tolerance
±5
Except that the cumulative axial length of the wrinkled skirt traces of water-wrapped cloth does not exceed 5% of the total length of the hose, Others comply with the GB1189-81 "Hose Appearance Quality" standard.
2.2 Performance
Performance requirements should comply with the provisions of Table 2.
3 Inspection Methods
3.1 The appearance quality of the hose shall be visually inspected.
3.2 Use special measuring tools to check the hose length, inner diameter, and outer diameter. 3.3 Hose wind pressure test: Block one end of the hose, connect the other end to the air pump or air source, and gradually increase the wind pressure to 0.9MPa at a speed of 0.7MPa within 6 seconds. Maintain this pressure for 5 minutes before putting it into water. At this time, there should be no air leakage in the hose. 3.4 The hydraulic test is carried out according to GB5563-85 "Hose Hydraulic Test Method". 3.5 Adhesion strength, tensile strength, elongation at break and aging tests are carried out in accordance with the provisions of GB5562-85 "Physical Test Methods for Hose Adhesive Layers".
The cold resistance coefficient test is carried out in accordance with the provisions of GB6035-85 "Determination of tensile resistance coefficient of vulcanized rubber". 3.6
The Ministry of Chemical Industry of the People's Republic of China approved the implementation on 1987-12-01 on 1987-03-13
Test project
0.9MPa (9kgf/em) wind pressure test||tt| |1.4MPa(14kgf/cm2)
Hydraulic test
Working pressure
Explosion pressure
Adhesion strength
Tensile strength
Elongation at break
not less than
not less than
not less than
aging performance (70℃×72h)
cold resistance coefficient (-45℃ ) is not less than
Inspection rules
4
GB7.542—87
Table 2
The change in outer diameter is not greater than the change in
length Not greater than
The twist change is not greater than
Not greater than
Not less than
Outer rubber and cloth
Inner rubber and cloth, cloth and cloth||tt ||Inner rubber
Outer rubber
Inner rubber
Outer rubberWww.bzxZ.net
Change rate of tensile strength
Change rate of elongation at break||tt ||Inner rubber
Outer rubber
Unit
mm
MPa
MPa
kN/m
MPa| |tt||%
%
Indicator
No leakage
6
10
20
0.9(9kgf /cm)
5.4(54kgf/cm)
1.5(1.5kgf/cm)
2.0(2.0kgf/cm)
10(100kgf/cm*)
11(110kgf/cm)
300
350
+25～-25
+10～-30
0.35| |tt||0. 4
The manufacturer guarantees that the hose delivered from the factory complies with the provisions of this standard. The quantity of each batch shall not exceed 5,000 pieces and shall be accompanied by a quality certificate. 4.1
4.2 The appearance quality, inner and outer diameters and length dimensions of the hoses should be inspected one by one. 4.3 Two samples of each batch of hoses should be taken for wind pressure and hydraulic tests. 4.4
Two samples should be taken from each batch of rubber hoses for product physical and mechanical performance testing. 4.5 If any item of the performance test shown in Table 2 fails, double the number of samples from the batch of products will be taken for retesting of the unqualified items. If there is still one unqualified sample after the retest, the batch of products will be deemed unqualified. Taste. 5 | ×60mm.
5.2 The hoses are bundled in bundles of 10 and must be bundled securely. 5.3 During transportation and storage, hoses should be kept away from direct sunlight and rain and snow. It should be kept clean, prohibited from contact with acids, alkalis, oils, organic solvents and other substances that affect rubber quality, and should be kept 1m away from heating devices. 5.4 The warehouse temperature should be maintained between -15~+35℃ during storage. 5.5
During storage, the hoses should be laid flat, and the stack height should not exceed 1m. If the storage time is too long, it should be stacked once every six months. Under the condition of complying with Articles 5.3, 5.4, and 5.5 of this standard, the manufacturer should ensure that the hoses are stored for no more than one and a half years from the date of manufacture. 5.6||tt| |During the storage period, its physical and mechanical properties should comply with the provisions of this standard. Add explanation
This standard is under the jurisdiction of the National Technical Committee for Standardization of Rubber and Rubber Products. This standard was jointly drafted by Tianjin Rubber Hose Factory and the Institute of Standards and Metrology of the Ministry of Railways. The main drafters of the standard are Liu Yufang, Cui Junying, and Han Jinyi
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