SIST EN ISO 8031:2020

SLOVENSKI STANDARD
oSIST prEN ISO 8031:2020
01-april-2020
Gumene in polimerne cevi ter cevni priključki - Ugotavljanje električne upornosti in
prevodnosti (ISO/FDIS 8031:2020)
Rubber and plastics hoses and hose assemblies - Determination of electrical resistance
and conductivity (ISO/FDIS 8031:2020)
Tuyaux et flexibles en caoutchouc et en plastique - Détermination de la résistance et de
la conductivité électriques (ISO/FDIS 8031:2020)
Ta slovenski standard je istoveten z: prEN ISO 8031
ICS:
23.040.70 Gumene cevi in armature Hoses and hose assemblies
83.140.40 Gumene cevi Hoses
oSIST prEN ISO 8031:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 8031:2020

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oSIST prEN ISO 8031:2020
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 8031
ISO/TC 45/SC 1
Rubber and plastics hoses and hose
Secretariat: DIN
assemblies — Determination of
Voting begins on:
2020­02­17 electrical resistance and conductivity
Voting terminates on:
Tuyaux et flexibles en caoutchouc et en plastique — Détermination de
2020­05­11
la résistance et de la conductivité électriques
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 8031:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

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oSIST prEN ISO 8031:2020
ISO/FDIS 8031:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
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
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ISO copyright office
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Published in Switzerland
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oSIST prEN ISO 8031:2020
ISO/FDIS 8031:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measurement of resistance of conductive, antistatic and non-conductive hoses .1
4.1 General . 1
4.2 Apparatus . 1
4.2.1 Test instruments . 1
4.2.2 Electrodes and contacts . 2
4.3 Preparation and cleaning for the test . 3
4.4 Conditioning . 4
4.5 Procedure for hoses with conducting lining (on full hose length) . 4
4.6 Procedure for hoses with conducting cover . 4
4.6.1 Method for full hose lengths . 4
4.6.2 Method for test pieces as tested in the laboratory . 5
4.7 Procedure for hoses with conducting compounds throughout . 6
4.7.1 Method for hoses up to 6 m in length . 6
4.7.2 Method for hoses over 6 m in length . 6
4.8 Hose assemblies fitted with metal end fittings . 6
4.9 Test procedure to determine the electrical resistance through the wall of hoses
and hose assemblies . 7
4.9.1 General. 7
4.9.2 Test procedure for hoses (without end fittings). 7
4.9.3 Test procedure for hose assemblies with metallic end fittings but without
an internal wire helix in contact with the end fittings . 8
5 Measurement of electrical continuity between metal end fittings of hose assemblies .10
6 Measurement of electrical discontinuity of hose assemblies .10
7 Measurement of electrical resistance of a hose assembly lining (conductive or static
dissipating) or hose assembly cover (conductive or static dissipating) in contact
with the metal end fitting .11
7.1 General .11
7.2 Apparatus .11
7.3 Preparation and cleaning for the test .11
7.4 Conditioning .11
7.5 Test procedure .11
8 Test report .13
Annex A (informative) Recommended terminology and limits for electrical conductivity
and resistance .15
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oSIST prEN ISO 8031:2020
ISO/FDIS 8031:2020(E)

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 non­governmental, 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 and rubber products,
Subcommittee SC 1, Rubber and plastics hoses and hose assemblies.
This fourth edition cancels and replaces the third edition (ISO 8031:2009), of which it constitutes a
minor revision.
The main change compared to the previous edition is that the 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.
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oSIST prEN ISO 8031:2020
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Introduction
This edition of ISO 8031 addresses the problems encountered in field testing and during product
acceptance tests in a production facility in following the test procedures specified in ISO 8031:1993
and a more practical approach is suggested. Also, a test procedure for determining electrical continuity
between the end fittings of a hose assembly without actually measuring the resistance has been
introduced. This test is frequently carried out in the field and in the factory when the product standard
does not require the exact electrical resistance to be measured, but only requires verification of electric
conductivity between both metal end fittings.
Special test methods to determine the electrical resistance through the hose wall (now required in
some product standards for hoses used in explosive atmospheres) have been added.
Some test methods which have been a standard practice in the hose industry for some time have now
been included, as have several new methods to determine the ability of a hose assembly (with metal end
fittings) to dissipate static electric charges when the metal end fitting is connected to earth. A total of
four new explanatory sketches are included. The hose and hose assembly product standard applicable
will have to specify which method is most suitable for the purpose of verification of the required
property.
Annex A, an amended version of ISO 8330:2007, Annex A, has been included.
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oSIST prEN ISO 8031:2020
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 8031:2020(E)
Rubber and plastics hoses and hose assemblies —
Determination of electrical resistance and conductivity
1 Scope
This document specifies electrical test methods for rubber and plastics hoses, tubing and hose
assemblies to determine the resistance of conductive, antistatic and non­conductive hoses and the
electrical continuity or discontinuity between metal end fittings.
All the test methods described for rubber hoses in this document can also be applied to plastics hoses.
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 2878, Rubber, vulcanized or thermoplastic — Antistatic and conductive products — Determination of
electrical resistance
ISO 8330, Rubber and plastics hoses and hose assemblies — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8330 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/
4 Measurement of resistance of conductive, antistatic and non-conductive hoses
4.1 General
Rubber hoses may have a conducting lining only or a conducting cover only, or may be manufactured
from conducting rubber compounds throughout. A method of test is specified for each of the three
possible types of construction.
4.2 Apparatus
The following apparatus is required and shall be basically as described in ISO 2878.
4.2.1 Test instruments
1)
4.2.1.1 To determine the resistance of conductive, antistatic and non­conductive hose , the test should
preferably be made with an instrument specifically designed for measuring insulation resistance, having
a nominal open-circuit voltage of 500 V d.c., or with any other instrument known to give comparable
results. The instrument shall be sufficiently accurate to determine the resistance to within ±10 % unless
1)  See ISO 8330 and Annex A for details of construction.
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oSIST prEN ISO 8031:2020
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specified otherwise. During the test, not more than 3 W shall be dissipated in the specimen, to prevent
erroneous results due to effects of temperature. The power dissipated shall be determined by the square
of the open-circuit voltage divided by the measured resistance.
The resistance values obtained will vary with the applied voltage, and errors may occur when low test
voltages are involved. In cases of dispute, the voltage applied to the test piece shall be not less than 40 V,
except where this conflicts with the requirement not to dissipate more than 3 W in the test piece.
4.2.1.2 For tests requiring the measurement of the electrical continuity between end fittings or through
continuous internal or external bonded wires, the instrument used shall be an ohmmeter sufficiently
accurate to determine the resistance to within ±10 %.
4.2.1.3 For tests where, according to the product standard, determination of the electrical continuity
between the end fittings of a hose assembly is required, without measurement of the actual electrical
resistance, a 4,5 V battery in combination with a 4 V (0,3 A) test lamp can be used.
4.2.1.4 For determination of the electrical resistance through the hose wall (required by some hose
product standards for hoses used in explosive atmospheres), the instrument used shall be an ohmmeter
12
with a capacity of 10 Ω and the measurement shall be made at 500 V d.c. The instrument shall be
sufficiently accurate to determine the resistance between the lining and the cover as measured through
the hose wall to within ±5 %.
4.2.2 Electrodes and contacts
4.2.2.1 General
For tests conducted in a laboratory, the equipment described below shall be used. For field tests, and
for routine tests and product acceptance tests in a manufacturer's plant, this equipment is not practical,
and alternatives may be used as described in 4.6.1, 4.7.1.2 and 4.7.2.3.
+2
Electrodes shall be formed on the surface as bands 25 mm wide around the circumference by
()
−1
means of a conductive silver lacquer, colloidal graphite or a conductive liquid.
When a conductive liquid is used, the electrode contact area shall be completely wetted and shall
remain so until the end of the test. Unless otherwise specified, the conductive liquid shall consist of
— 800 parts by mass of anhydrous poly(ethylene glycol) of relative molecular mass 600;
— 200 parts by mass of water;
— 1 part by mass of wetting agent;
— 10 parts by mass of potassium chloride.
When a conductive silver lacquer or colloidal graphite is used, the surface resistance between any two
points on a sample of the dried film shall not exceed 100 Ω.
Clean metal contacts shall be applied to the electrodes so that the contact area is approximately the
same size as, but no greater than, the electrodes, except where otherwise stated.
In the case of hoses of less than 50 mm bore, it is difficult to apply the conducting liquid accurately to
the hose bore, and it is preferable to use a brass plug of external diameter equal to or greater than the
hose internal diameter (ID), coated with conducting liquid and then pushed 25 mm into the hose.
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oSIST prEN ISO 8031:2020
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4.2.2.2 Special electrodes and contacts
The following special electrodes and contacts shall be used for the determination of the electrical
resistance through the hose wall, and other test methods:
a) Outer electrode: a copper sheet­metal band, of standard width 25 mm, clamped around the outer
hose wall (see Figure 1).
b) Inner electrode:
1) for hoses of less than 50 mm bore size, it is recommended that a tight-fitting brass plug (solid for
small bore sizes and hollow for larger sizes), of minimum length 2 × the pitch of the helical wire(s)
(for hoses incorporating helical wires) or 0,5 × ID (for hoses without helical wires), be used;
2) for hoses of more than 50 mm bore size, it is recommended that an adjustable copper sheet-
metal band, tightly fitting the bore of the hose (expanded against the lining by spring action), of
minimum width 25 mm, be used;
c) Contacts for connecting the electrodes to the ohmmeter should preferably be soldered or brazed to
the electrodes to minimize resistance between ohmmeter and electrode (see Figure 1).
d) Alternative to b): a 25-mm-wide conducting foam plug completely wetted with a suitable conductive
liquid (see 4.2.2.1) of outside diameter slightly larger than the inside diameter of the hose to ensure
a snug fit with good electric contact with the hose lining and connected to a suitable insulated
conductor (see Figure 3, items 1 and 3). This electrode is recommended for use with hoses with
corrugated linings or linings which are less flexible than rubber (i.e. PTFE).
e) In order to establish good electrical contact with the cover of a corrugated hose, it is recommended
that a conducting foam strip 25 mm wide, completely wetted in suitable conductive liquid (see
4.2.2.1), be placed round the full outside circumference of the hose, underneath the electrode
described in item a) above.
4.3 Preparation and cleaning for the test
The surfaces of the hose or test piece shall be clean. If necessary, they may be cleaned by rubbing with
fuller's earth (magnesium aluminium silicate) and water, washing with distilled water and allowing to
dry. Do not use organic materials which attack the rubber or cause it to swell, and do not buff or abrade
the test surfaces.
The surface of the hose shall not become deformed either during the application of the contacts or
during the test. When using test pieces, the supports shall be outside the test length. When testing a
long length of hose, the hose shall be uncoiled and laid straight on polyethylene or another insulating
material. Care shall be taken to ensure that the hose is insulated from any leakage path along the length
of hose.
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oSIST prEN ISO 8031:2020
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a)  Outer electrode for all sizes b)  Inner electrode for bore sizes >50 mm

a
To ohmmeter.
Figure 1 — Examples of inner and outer electrodes as described in 4.2.2.2
4.4 Conditioning
Normally, the articles shall be conditioned for at least 16 h under one of the following sets of standard
conditions:
— (23 ± 2) °C and (50 ± 5) % relative humidity;
— (27 ± 2) °C and (65 ± 5) % relative humidity.
However, where very long lengths of hose are being tested, it is permissible, by agreement between
supplier and customer, to use the conditions prevailing in the factory, warehouse or laboratory,
provided that the relative humidity is not greater than 70 %. For testing in the field and for routine and
product acceptance tests in a manufacturer's factory of short lengths of hose and hose assemblies, this
applies as well.
4.5 Procedure for hoses with conducting lining (on full hose length)
Apply suitable electrodes as specified in 4.2.2 on the inside surface at each end of the hose. The edge of
the electrode band shall be coincident with the end of the hose. When using a conductive liquid, care shall
be taken to avoid creating a leakage path between the lining and the reinforcement or cover of the hose.
Apply the metal contacts to the electrodes.
Apply the test voltage and measure the resistance (5 ± 1) s after the application of the voltage.
For field tests and routine and product acceptance tests in the factory, the equipment specified in
2
4.2.2.1 is too complicated and impractical. Instead, clean copper or brass contacts at least 100 mm
in area, shaped to fit the inside surface of the hose lining and held in position manually, can be used.
Alternatively, suitable electrodes as described in 4.2.2.2 can be used.
4.6 Procedure for hoses with conducting cover
4.6.1 Method for full hose lengths
Apply electrodes as specified in 4.2.2.1 on the outside surface at each end of the hose.
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oSIST prEN ISO 8031:2020
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Apply the metal contacts.
Apply the test voltage and measure the resistance (5 ± 1) s after the application of the voltage.
For field tests and routine and product acceptance tests in the factory, the equipment specified in
2
4.2.2.1 is too complicated and impractical. Instead, clean copper or brass contacts at least 100 mm
in area, shaped to fit the outside surface of the hose cover and held in position manually, can be used.
Alternatively, suitable electrodes as described in 4.2.2.2 can be used.
4.6.2 Method for test pieces as tested in the laboratory
4.6.2.1 Test pieces
Prepare the test pieces by cutting five lengths of hose approximately 300 mm long from samples taken
at random from a production run. Condition the test pieces in accordance with 4.4.
Position electrodes as specified in 4.2.2.1 symmetrically along the test piece so that the distance
between their nearest edges is (100 ± 1) mm (see Figure 2).
Ensure that contact is maintained with the electrodes around the circumference and that the contact
pieces are sufficiently long for the two free ends to be held securely by a tensioning clip (see Figure 2)
such that the fit of the electrodes is as tight as possible, consistent with the means employed.
Dimensions in millimetres
Key
1 test piece
2 metallic foil contact pieces wrapped around conducting electrodes and held by clips
3 500 V d.c. insulation tester
4 insulated support or clamp
Figure 2 — Electrodes and contacts for testing as described in 4.6.2.1
4.6.2.2 Test procedure
Place the test piece on blocks of polyethylene, or other insulating material, to provide a resistance of
11
greater than 10 Ω between the test piece and the surface on which the blocks are supported. Ensure
that the leads from the instrument do not touch each other, the hose or any part except the terminal to
which each is connected. Connect the leads from the test instrument to the appropriate contact piece.
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oSIST prEN ISO 8031:2020
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Apply the test voltage and measure the resistance (5 ± 1) s after the application of the voltage.
Avoid breathing on the test surfaces and thus creating condensation that may lead to inaccuracies.
4.7 Procedure for hoses with conducting compounds throughout
4.7.1 Method for hoses up to 6 m in length
4.7.1.1 Apply suitable electrodes as specified in 4.2.2.1 on the inside surface at one end of the hose
(end A) and on the outside surface at the other end (end B).
Apply the metal contacts to the electrodes.
Apply the test voltage and measure the resistance (5 ± 1) s after the application of the voltage.
4.7.1.2 Repeat the test, applying the electrodes to the outside surface at end A and to the inside surface
at end B.
For field tests and routine and product acceptance tests in the factory, the equipment specified in
2
4.2.2.1 is too complicated and impractical. Instead, clean copper or brass contacts at least 100 mm
in area, one shaped to fit the inside surface of the lining, the other shaped to fit the outside surface of
the cover, and held in position manually, can be used. Alternatively, suitable electrodes as described in
4.2.2.2 can be used.
4.7.2 Method for hoses over 6 m in length
4.7.2.1 Apply suitable electrodes as specified in 4.2.2.1 on the inside surface at a minimum distance of
50 mm from one end of the hose and on the outside surface at distances of 3 m and 6 m from the same end.
Apply the metal contacts to the inside electrode and to the outside electrode at 3 m from the inside
electrode.
Apply the test voltage and measure the resistance (5 ± 1) s after the application of the voltage.
4.7.2.2 Repeat the test between the inside electrode and the outside electrode at 6 m from the inside
electrode. The difference between these resistance values shall be regarded as the resistance for 3 m of
the hose.
4.7.2.3 Repeat the tests at the other end of the hose length.
For field tests and routine and product acceptance tests in the factory, the equipment specified in
2
4.2.2.1 is too complicated and impractical. Instead, clean copper or brass contacts at least 100 mm
in area, one shaped to fit the inside surface of the lining, the other shaped to fit the outside surface of
the cover, and held in position manually, can be used. Alternatively, suitable electrodes as described in
4.2.2.2 can be used.
NOTE The purpose of this test is not only to measure and compare the resistance of the end 3 m of hose
but to ensure that the homogeneity of the hose construction is maintained throughout manufacture. This test is
normally performed as part of type testing.
4.8 Hose assemblies fitted with metal end fittings
4.8.1 When it is required that the resistance of a hose assembly be measured, the leads of the test
instrument shall be attached directly to the metal end fittings.
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4.8.2 Some hoses, especially thermoplastics hoses, have conductive layers within the hose construction.
These hoses shall be tested as assemblies made with fittings and assembly techniques specified by the
hose and fitting manufacturer.
4.9 Test procedure to determine the electrical resistance through the wall of hoses and
hose assemblies
4.9.1 General
This test is usually carried out as a type test only. It is required by some hose product standards for
hoses used in an explosive atmosphere. The test is carried out only when required by the hose produc
...