ISO 8789:2020

ISO 8789:2020 pdf free.Rubber hoses and hose assem blies for liquefied petroleum gas in motor
vehicles – Specification.
4 Materials and construction
4.1 Materials
The hose shall consist of:
a) a smooth-bore rubber lining-resistant rubber suitable for liquefied petroleum gas;
b) a reinforcement of natural textile, synthetic textile or corrosion-resistant metal wire (stainless steel) applied by any suitable technique;
c) a cover of oil- and weather-resistant rubber (if, however, the hose is reinforced with corrosion- resistant wire, no cover is required).
4.2 Construction
The lining and cover shall be of uniform thickness, concentric and free from holes, porosity and other defects. The cover finish may be smooth or fabric-marked. To avoid the formation of bubbles due to gas permeation, the cover shall be pin-pricked.
NOTE There is a possibility that national regulations define the type of reinforcement to be used.
5 Dimensions and tolerance
5.1 Inside diameter
When measured in accordance with Iso 4671, the inside diameter shall be between the minimum and maximum values specified in Table 1.
5.2 Minimum bending radii
The hoses shall not be used at bend radi, measured at the inside of the bend, smaller than the minimum bend radii specified in Table 1.
5.3 Concentricity
When determined in accordance with ISO 4671, the concentricity, based on a total indicator reading
between the bore and the outside surface of the cover, shall be no greater than 1,0 mm.
5.4 Length
The length of supplied hoses and hose assemblies shall be the subject of agreement between the manufacturer and the purchaser.
NOTE Recommendations for lengths of supplied hoses and tolerances on lengths of hose assemblies are given in Table C.2.
6 Physical properties of rubber compounds
When determined by the methods listed in Table 2, the physical properties of the compounds used for the lining and cover shall conform to the values specified in Table 2.
Tests shall be carried out on test pieces taken from the hose. No tests shall be carried out within 24 h after manufacture of the hose.
7 Performance requirements
7.1 General
Unless otherwise specified, condition test pieces in accordance with Iso 23529 before testing.
7.2 Visual examination
All hoses and hose assemblies shall be examined for visible defects in the cover and inspected to verify that the hose identification is correct and has been properly applied and marked.
7.3 Finished hose and hose assemblies
When determined by the methods listed in Table 3, the physical properties of the finished hose shall conform to the values specified in Table 3.
8 Requirements for fittings
8.1 Fitting material
The fittings shall be made of stainless steel, brass or plated ferrous material to prevent corrosion.
8.2 Fitting description
Fittings of the crimp-on type or of the reusable screw-together type shall be used. The swivel nut shall be provided with a UNF thread (in accordance with ASME B1.1 for inch threads) or in accordance with ISO 68-1 for metric threads, and sealing is preferably by means of a 450 flare. Other types of sealing surface are acceptable provided the hose assembly meets the test requirements. The fitting design shall be such that the fittings can be applied without removal of any cover material.
NOTE There is a possibility that the material specifications and the type of fitting used are affected by national regulations.
9 Requirements for hose assemblies
9.1 Leakage test
When the hose assembly which has be prepared from a hose (400 ± 10) mm long and filled with a propane gas at a pressure of 3,0 MPa (30 bar) is immersed in water for a period of 5 mm, the assembly shall not show any sign of leakage while underwater.ISO 8789 pdf download.

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