ISO 11425:2018

INTERNATIONAL ISO
STANDARD 11425
Second edition
2018-11
Rubber hoses and hose assemblies for
automobile power-steering systems —
Specification
Tuyaux et flexibles en caoutchouc pour circuits de direction
assistée — Spécifications
Reference number
©
ISO 2018
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Types of hose . 2
5 Construction and materials . 2
6 Dimensions and tolerances . 2
7 Performance requirement . 3
7.1 Impulse resistance . 3
7.2 Burst pressure requirement . 3
7.3 Change in length . 3
7.4 Low-temperature flexibility . 3
7.5 Adhesion . 4
7.6 Ozone resistance. 4
7.7 Volumetric expansion. 4
7.8 Contamination . 4
7.9 Corrosion of end fittings . 4
7.10 Proof pressure requirement . 4
7.11 Cold-start requirement (type approval test for type 4 hose assemblies only) . 4
7.11.1 Requirement . 4
7.11.2 Test method . 5
7.12 Low-pressure burst pressure requirement (type 4 hose assemblies only) . 5
8 Marking . 5
Annex A (normative) Method of test for volumetric expansion . 6
Annex B (normative) Method of test for contamination . 8
Annex C (informative) Typical outside-diameter ranges .10
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber & Rubber Products,
Subcommittee SC 1, Rubber and plastics hoses and hose assemblies
This second edition cancels and replaces the first edition (ISO 11425:1996), of which it constitutes a
minor revision.
The main changes compared to the previous edition are as follows:
— In Clause 2, normative references have been updated.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 11425:2018(E)
Rubber hoses and hose assemblies for automobile power-
steering systems — Specification
WARNING — Attention is drawn to the need to ensure that appropriate precautions are taken to
ensure the safety of personnel carrying out the methods of test specified in this document.
1 Scope
This document specifies requirements for five types of hose and hose assembly used in automobile
power-steering systems, the five types differing in their pressure ratings and volumetric expansion.
They are for use with fluids in the temperature range −40 °C to +135 °C.
This document is based on performance tests. In order to take account of technological developments,
no requirements are included for specific materials, detailed construction or manufacturing methods.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1402, Rubber and plastics hoses and hose assemblies — Hydrostatic testing
ISO 2719, Determination of flash point — Pensky-Martens closed cup method
ISO 2909, Petroleum products — Calculation of viscosity index from kinematic viscosity
ISO 2977, Petroleum products and hydrocarbon solvents — Determination of aniline point and mixed
aniline point
ISO 3016, Petroleum products — Determination of pour point
ISO 3819, Laboratory glassware — Beakers
ISO 4671, Rubber and plastics hoses and hose assemblies — Methods of measurement of the dimensions of
hoses and the lengths of hose assemblies
ISO 4788, Laboratory glassware — Graduated measuring cylinders
ISO 4793, Laboratory sintered (fritted) filters — Porosity grading, classification and designation
ISO 6803, Rubber or plastics hoses and hose assemblies — Hydraulic-pressure impulse test without flexing
ISO 7326:2016, Rubber and plastics hoses — Assessment of ozone resistance under static conditions
ISO 8033, Rubber and plastics hoses — Determination of adhesion between components
ISO 8330, Rubber and plastics hoses and hose assemblies — Vocabulary
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 10619-2, Rubber and plastics hoses and tubing — Measurement of flexibility and stiffness — Part 2:
Bending tests at sub-ambient temperatures
ISO/TR 11340:1994, Rubber and rubber products — Hydraulic hose assemblies — External leakage
classification for hydraulic systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8330 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
hose assembly
hose with either permanent or re-usable end fittings attached
4 Types of hose
Hoses shall be one of the following five types:
a) Type 1: low-pressure hydraulic fluid return hoses and hose assemblies.
b) Type 2: medium-pressure low volumetric expansion hoses and hose assemblies.
c) Type 3: medium-pressure medium volumetric expansion hoses and hose assemblies.
d) Type 4: medium-pressure high volumetric expansion hoses and hose assemblies.
e) Type 5: high-pressure low volumetric expansion hoses and hose assemblies.
5 Construction and materials
The hose shall consist of:
a) a rubber lining;
b) a reinforcement;
c) a rubber cover or alternatively, for type 5 only, a textile cover.
The hose shall be uniform in quality and free from porosity, air holes and foreign inclusions.
6 Dimensions and tolerances
6.1 The hose shall have a inside diameter in accordance with the requirements of Table 1. When
determined in accordance with ISO 4671, the actual bore shall be within ±0,4 mm of the inside diameter.
Table 1 — Inside diameter
Dimensions in millimetres
Type 1 Type 2 Type 3 Type 4 Type 5
— 6,3 — — —
9,5 9,5 9,5 9,5 9,5
— 12,7 — — 12,7
6.2 The concentricity based on a total indicator reading between the bore and the outside surface of
the cover, determined in accordance with ISO 4671 shall be not more than 0,75 mm.
NOTE Typical ranges of outside diameters available are given in Annex C.
2 © ISO 2018 – All rights reserved

7 Performance requirement
7.1 Impulse resistance
When subjected to a pulse test carried out in accordance with ISO 6803, using the following conditions,
each of at least four test pieces shall withstand a minimum of 225 000 cycles with no more than ISO/
TR 11340:1994 class 3 leakage at fittings, and no rupture or ballooning of the hose.
Test fluid temperature: 135 °C ± 2 °C
Ambient temperature during test: 100 °C ± 5 °C cycle rate: 30 to 40 per min
Cycle data:
Pressure rise time: 0,20 s ± 0,10 s
Pressure dwell time: 0,65 s ± 0,20 s
Pressure drop time: 0,20 s ± 0,10 s
Test pressure: Design working pressure as given in Table 2.
7.2 Burst pressure requirement
When tested in accordance with ISO 1402 the hose or hose assembly shall withstand the minimum
burst pressure given in Table 2.
Table 2 — Hydrostatic-pressure requirements
Inside diameter Design working pressure Proof pressure Minimum burst
pressure
Type
mm MPa MPa MPa
1 9,5 1,75 3,5 7,0
2 6,3 9,0 18,0 36,0
9,5 8,0 16,0 32,0
12,7 7,0 14,0 28,0
3 9,5 10,0 20,0 40,0
4 9,5 9,0 18,0 36,0
5 9,5 15,5 31,0 62,0
12,7 14,0 28,0 56,0
NOTE  All pressure values specified are gauge pressures.
7.3 Change in length
Hoses of types 1, 3 and 4 shall not change in length by more than +0 % and –8 % and hoses of types 2
and 5 shall not change in length by more than +2 % and 4 % at the appropriate design working pressure
given in Table 2.
7.4 Low-temperature flexibility
After conditioning at a temperature of –40 °C ± 2 °C for a period of 72 h, bend a test piece around a
mandr
...