Rubber and plastics hoses and hose assemblies - Determination of electrical resistance and conductivity (ISO 8031:2020)

This document specifies electrical test methods for rubber and plastics hoses, tubing and hose
assemblies to determine the resistance of conductive, antistatic and non-conductive 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.

Gummi- und Kunststoffschläuche und Schlauchleitungen - Bestimmung des elektrischen Widerstands und der elektrischen Leitfähigkeit (ISO 8031:2020)

In diesem Dokument werden Verfahren zur elektrischen Prüfung von Gummi  und Kunststoffschläuchen mit und ohne Einlagen und von Schlauchleitungen festgelegt, um den Widerstand von leitfähigen, antistatischen und nicht leitfähigen Schläuchen und den elektrischen Durchgang oder die elektrische Unterbrechung zwischen Metall Endarmaturen zu bestimmen.
Alle in diesem Dokument für Gummischläuche beschriebenen Prüfverfahren können auch auf Kunststoffschläuche angewendet werden.

Tuyaux et flexibles en caoutchouc et en plastique - Détermination de la résistance et de la conductivité électriques (ISO 8031:2020)

Le présent document spécifie des méthodes d'essais électriques des tuyaux, tubes et flexibles en caoutchouc et en plastique pour déterminer la résistance des tuyaux conducteurs, antistatiques et non conducteurs et la continuité ou la discontinuité électrique entre extrémités de raccordement métalliques.
Toutes les méthodes d'essai pour les tuyaux en caoutchouc détaillées dans le présent document peuvent être également appliquées aux tuyaux en plastique.

Gumene in polimerne cevi ter cevni priključki - Ugotavljanje električne upornosti in prevodnosti (ISO 8031:2020)

General Information

Status
Published
Public Enquiry End Date
30-Apr-2020
Publication Date
27-Jul-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
23-Jul-2020
Due Date
27-Sep-2020
Completion Date
28-Jul-2020

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SLOVENSKI STANDARD
SIST EN ISO 8031:2020
01-oktober-2020
Nadomešča:
SIST EN ISO 8031:2010

Gumene in polimerne cevi ter cevni priključki - Ugotavljanje električne upornosti in

prevodnosti (ISO 8031:2020)

Rubber and plastics hoses and hose assemblies - Determination of electrical resistance

and conductivity (ISO 8031:2020)

Gummi- und Kunststoffschläuche und Schlauchleitungen - Bestimmung des elektrischen

Widerstands und der elektrischen Leitfähigkeit (ISO 8031:2020)

Tuyaux et flexibles en caoutchouc et en plastique - Détermination de la résistance et de

la conductivité électriques (ISO 8031:2020)
Ta slovenski standard je istoveten z: EN ISO 8031:2020
ICS:
23.040.70 Gumene cevi in armature Hoses and hose assemblies
83.140.40 Gumene cevi Hoses
SIST EN ISO 8031:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 8031:2020
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SIST EN ISO 8031:2020
EN ISO 8031
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2020
EUROPÄISCHE NORM
ICS 23.040.70 Supersedes EN ISO 8031:2009
English Version
Rubber and plastics hoses and hose assemblies -
Determination of electrical resistance and conductivity
(ISO 8031:2020)

Tuyaux et flexibles en caoutchouc et en plastique - Gummi- und Kunststoffschläuche und

Détermination de la résistance et de la conductivité Schlauchleitungen - Bestimmung des elektrischen

électriques (ISO 8031:2020) Widerstands und der elektrischen Leitfähigkeit (ISO
8031:2020)
This European Standard was approved by CEN on 12 June 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8031:2020 E

worldwide for CEN national Members.
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SIST EN ISO 8031:2020
EN ISO 8031:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 8031:2020
EN ISO 8031:2020 (E)
European foreword

This document (EN ISO 8031:2020) has been prepared by Technical Committee ISO/TC 45 "Rubber and

rubber products" in collaboration with Technical Committee CEN/TC 218 “Rubber and plastics hoses

and hose assemblies” the secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by January 2021, and conflicting national standards shall

be withdrawn at the latest by January 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 8031:2009.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 8031:2020 has been approved by CEN as EN ISO 8031:2020 without any modification.

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SIST EN ISO 8031:2020
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SIST EN ISO 8031:2020
INTERNATIONAL ISO
STANDARD 8031
Fourth edition
2020-06
Rubber and plastics hoses and hose
assemblies — Determination of
electrical resistance and conductivity
Tuyaux et flexibles en caoutchouc et en plastique — Détermination de
la résistance et de la conductivité électriques
Reference number
ISO 8031:2020(E)
ISO 2020
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SIST EN ISO 8031:2020
ISO 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

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 2020 – All rights reserved
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SIST EN ISO 8031:2020
ISO 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

© ISO 2020 – All rights reserved iii
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SIST EN ISO 8031:2020
ISO 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 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 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.
iv © ISO 2020 – All rights reserved
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SIST EN ISO 8031:2020
ISO 8031:2020(E)
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.
© ISO 2020 – All rights reserved v
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SIST EN ISO 8031:2020
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SIST EN ISO 8031:2020
INTERNATIONAL STANDARD ISO 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 non-conductive 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

4.2.1.1 To determine the resistance of conductive, antistatic and non-conductive 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.
© ISO 2020 – All rights reserved 1
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SIST EN ISO 8031:2020
ISO 8031:2020(E)

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

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.

Electrodes shall be formed on the surface as bands 25 mm wide around the circumference by

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.

2 © ISO 2020 – All rights reserved
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SIST EN ISO 8031:2020
ISO 8031:2020(E)
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 sheet-metal 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.
© ISO 2020 – All rights reserved 3
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SIST EN ISO 8031:2020
ISO 8031:2020(E)
a) Outer electrode for all sizes b) Inner electrode for bore sizes >50 mm
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

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.

4 © ISO 2020 – All rights reserved
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SIST EN ISO 8031:2020
ISO 8031:2020(E)
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

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

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.

© ISO 2020 – All rights reserved 5
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SIST EN ISO 8031:2020
ISO 8031:2020(E)
Apply the test voltage and measure the resistance (5 ± 1) s after the appli
...

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