BS 3832:1981 download free.Specification for Wire reinforced rubber hoses and hose assemblies for hydraulic installations.
1 SCOPE AND FIELD OF APPLICATION
1.1 BS 3832 specifies requirements for
two types of embedded wire hose of Internal diameter from 5 to 51 mm, for use with common hydraulic fluids, such as mineral oils, soluble oils, oil and water emulsions, aqueous glycol solution, and eater, at temperatures ranging from
—40°Cto+ 100°C.
The hose is not suitable for use with castor oil-based and ester-based fluids.
1.2 An annex is included, giving dimensional details of widely used hoses, but these are for information only and do not form part of the specification.
1.3 BS 3832 does not include requirements for end fittings. It is limited to the performance of the hose and hose assemblies.
2 REFERENCES
ISO 1307, Rubber hose — Bore sizes, tolerances on length, and test pressures.
ISO 1402, Rubber hose — Hydrostatic testing.
ISO 2719, Petroleum products — Determination of flash point — Pensky -Martens closed cup method.
ISO 2977, Petroleum products and hydrocarbon solvents — Determination of aniline point end mixed aniline point.
ISO 3016, Petroleum oils — Determination of pour point.
ISO 3448, Industrial liquid lubricants — ISO viscosity
classification.
3 MATERIALS AND CONSTRUCTION
3.1 The hose shall consist of a seamless oil- and water- resistant synthetic rubber tube, one or more layers of high tensile steel wire, and oil- and weather-resistant synthetic rubber cover. The cover may be fastened to the hose by means of a cotton layer, or other suitable material.
3.2 The hose shall be concentric In accordance with the following specification:
The measurements of the wall thickness at different points shall not differ by more than the following values:
— up to and including 6,3 mm nominal bore : 0,8 mm
— over 6.3 up to and including 22 mm nominal bore:
1,0mm
— over 22mm nominal bore:1,3mm
4 DIMENSIONS
The bore of the hose shall meet the requirements of table 1.
NOTE — ISO 1307 has not been followed for nomin bore or permitted range; the dimensions adopted In table 1 ire In accordance with those specified by the Society of Automotive Enneers (U.S.A.). which are In wide use In numerous countries throughout the wo,ld.
5.2 The hose shall withstand without damage a proof test pressure of twice the design working pressure, maintained by the method described in Iso 1402.
NOTE — The design working pressures in table 2 are based on a bursting safety factor of 4.
6 MINIMUM BEND RADIUS AND CHANGE IN LENGTH AT DESIGN WORKING PRESSURE
6.1 The hose shall be capable of performing at design working pressure when curved to a radius no smaller than that given in table 3.
NOTE — Should any portion of the hose be curved to a radius smaller than the specified bend radius, performance capability of
the hose is reduced.
6.2 The change in length of hose at the design working pressure shall be not greater than specified in table 3.
7 TOLERANCE ON LENGTH
7.1 The hose shall be supplied in lengths as specified by the purchaser, subject to a tolerance on the specified lengths of ± 1 % or ± 3 mm, whichever Is the greater.
7.2 When no specific lengths have been ordered, the percentages of different lengths in any given delivery shall be as follows:
— over 13 mm : not less than 65 %
— 7,5 to 13 m : not more than 35 %
— 1 m to 7,5 m: not more than 10 % No length shall be less than 1 m.
8 IMPULSE TEST REQUIREMENTS
8.1 Four unaged samples of hose with end fittings shall be tested.
8.2 Means shall be provided for applying a pulsating
pressure internally to a hose assembly at a rate of between
0,5 and 125 Hz (30 and 75 cycles per minute). A typical
schematic hydraulic circuit for the hose test rig is given for
guidance in figure 1.
8.3 Each cycle shall comply with the requirements of the pressure impulse cycle (see figure 2) as appropriate.
The rate of pressure rise during the first part of the pressure impulse cycle shall be between 3 500 and 7 000 bar/s (350 and 700 MPa/s) determined as illustrated in figure 3.
8.4 The fluid to be used in the test shall be fully fortif led
mineral oil of viscosity grade ISO VG 46 (46 mm2/s at
40 °C) In accordance with ISO 3448 and with the following
characteristics:
T.st mithod
pour point. max. — 28°C ISO 3016
0
flash point, closed, mm. 190 C ISO 2719
aniline point 100 ± 10°C ISO 2977
Other oils may be used by agreement between the interested parties.
8.5 The free length of hose under test shall be 3,5 times the minimum bend radius, subject to the tolerance given in 7.1, for hose up to and including 22 mm, and shall be not less than 0,4 m for larger sizes (see figure 4).
8.6 The test pieces shall be connected to the apparatus and, in the case of hoses up to and including 22 mm nominal bore, they shall be bent through 1800 so that the fittings are parallel and the distance between the two ends of the hose at the fittings is twice the minimum bend radius, + 5 % —0 as shown in figure 4. Hose over 22 mm nominal bore shall be left in a straight condition, or alternatively bent through 900.
8.7 Type 1 hose, when tested at 125 % of the design working pressure for hoses of nominal bore 25 mm and smaller, and at 100% of the design working pressure for nominal bore 31,5mm and above, at a temperature of 93 ± 5°C shall withstand a minimum of 150 000 impulses cycles.
Type 2 hose, when tested at 133% of the working pressure, subject to a maximum of 350 bar (35 MPa), at a temperature of 93 ± 5°C shall withstand a minimum of 200 000 impulse cycles.
There shall be no leakage or other malfunction after the specified number of impulse cycles.
Any failures adjacent to the end fittings shall be disregarded and repeat tests carried out. Failure due to coupling blow-off or rupture adjacent to the fittings (within 25 mm) shall not be interpreted as a true hose burst but as failure due to the fitting attachment and shall be recorded as such.
9 COLD FLEXIBILITY REQUIREMENTS
Hose and/or hose assemblies shall be subjected to a temperature of —40 °C for 24 h. After this time and wtile still at —40 °C, the specimens shall be flexed in a period of 8 to 12 s over a mandrel having a diameter equal to twice the minimum bend radius specified in table 3. Hose up to and including 22 mm In diameter shall be bent through 180° over the mandrel and hose over 22 mm in diameter shall be bent through 90° over the mandrel.
After flexing, the sample shall be allowed to warm to room temperature and shall be visually examined for cover cracks and subjected to a proof test as described in 5.2. There shall be no cover cracks or Ieaka9e.
10 MARKING
The hoses shall be marked with information as agreed between the purchaser and the manufacturer.