SIST EN ISO 21178:2013

SLOVENSKI STANDARD
SIST EN ISO 21178:2013
01-junij-2013
1DGRPHãþD
SIST EN ISO 21178:2007
1DSUDYH]DNRQWLQXLUQLWUDQVSRUW/DKNLWUDNRYLWUDþQLKWUDQVSRUWHUMHY
8JRWDYOMDQMHHOHNWULþQLKXSRUQRVWL,62
Light conveyor belts - Determination of electrical resistances (ISO 21178:2013)
Courroies transporteuses légères - Détermination des résistances électriques (ISO
21178:2013)
Ta slovenski standard je istoveten z: EN ISO 21178:2013
ICS:
53.040.10 Transporterji Conveyors
53.040.20 Deli za transporterje Components for conveyors
SIST EN ISO 21178:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21178:2013

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SIST EN ISO 21178:2013


EUROPEAN STANDARD
EN ISO 21178

NORME EUROPÉENNE

EUROPÄISCHE NORM
April 2013
ICS 53.040.10 Supersedes EN ISO 21178:2006
English Version
Light conveyor belts - Determination of electrical resistances
(ISO 21178:2013)
Courroies transporteuses légères - Détermination des
résistances électriques (ISO 21178:2013)
This European Standard was approved by CEN on 4 March 2013.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21178:2013: E
worldwide for CEN national Members.

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SIST EN ISO 21178:2013
EN ISO 21178:2013 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 21178:2013
EN ISO 21178:2013 (E)
Foreword
This document (EN ISO 21178:2013) has been prepared by Technical Committee ISO/TC 41 "Pulleys and
belts (including veebelts)" in collaboration with Technical Committee CEN/TC 188 “Conveyor belts” the
secretariat of which is held by SNV.
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 October 2013, and conflicting national standards shall be withdrawn at
the latest by October 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 21178:2006.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 21178:2013 has been approved by CEN as EN ISO 21178:2013 without any modification.

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SIST EN ISO 21178:2013

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SIST EN ISO 21178:2013
INTERNATIONAL ISO
STANDARD 21178
Second edition
2013-03-15
Light conveyor belts — Determination
of electrical resistances
Courroies transporteuses légères — Détermination des résistances
électriques
Reference number
ISO 21178:2013(E)
©
ISO 2013

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SIST EN ISO 21178:2013
ISO 21178:2013(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

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SIST EN ISO 21178:2013
ISO 21178:2013(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Symbols . 1
4 Electrical surface resistances . 2
4.1 Method A: measurement of surface resistance R omni-directionally . 2
OA
4.2 Method B: measurement of surface resistance R in longitudinal and
OB
transverse direction . 5
5 Electrical surface resistivity ρ . 7
s
5.1 General . 7
5.2 Principle . 7
5.3 Apparatus . 7
5.4 Preparation and preservation of test pieces prior to testing . 9
5.5 Procedure . 9
5.6 Expression of results .10
5.7 Test report .10
6 Electrical volume resistances .10
6.1 Volume resistance R perpendicular to plane of belt .10
D
6.2 Volume resistance, R , in longitudinal and transverse direction parallel to plane of belt 15
Di
7 Electrical volume resistivity ρ .18
D
7.1 Procedure .18
7.2 Expression of results .18
7.3 Test report .18
Annex A (informative) Comparative values for electrical resistances .19
Bibliography .20
© ISO 2013 – All rights reserved iii

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SIST EN ISO 21178:2013
ISO 21178:2013(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 21178 was prepared by Technical Committee ISO/TC 41, Pulleys and belts (including veebelts),
Subcommittee SC 3, Conveyor belts.
This second edition cancels and replaces the first edition (ISO 21178:2005), of which it constitutes a
minor revision.
iv © ISO 2013 – All rights reserved

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SIST EN ISO 21178:2013
INTERNATIONAL STANDARD ISO 21178:2013(E)
Light conveyor belts — Determination of electrical
resistances
1 Scope
This International Standard specifies test methods for determining the electrical resistances of light
conveyor belts according to ISO 21183-1. The resistances are surface resistance, volume resistance
perpendicular to the belt plane, and longitudinal and transverse volume resistance parallel to the
belt plane. This International Standard also specifies two test methods for determining the surface
resistivity and the volume resistivity.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable to its application. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 18573, Conveyor belts — Test atmospheres and conditioning periods
3 Symbols
Symbol Quantity Unit
R Electrical surface resistance, method A Ω
OA
R Electrical surface resistance, method B Ω
OB
R Electrical surface resistance for the determination of ρ Ω
OG s
R Electrical volume resistance perpendicular to the plane of the belt Ω
D
R Electrical volume resistance in longitudinal and transverse direction parallel to the Ω
Di
plane of the belt
ρ Electrical surface resistivity Ω
s
ρ Electrical volume resistivity Ω⋅cm
D
d Diameter of electrode cm
1/2/3
d Middle of the gap diameter cm
m
g Width of the gap cm
2
A Surface of the electrode cm
h Thickness of test piece cm
NOTE The SI unit of surface resistivity, ρ , is the ohm (Ω). In practice, this is sometimes referred to as
s
“ohm/square” or “Ω/sq” or “Ω/⧠”. The size of the square is immaterial.
© ISO 2013 – All rights reserved 1

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SIST EN ISO 21178:2013
ISO 21178:2013(E)

4 Electrical surface resistances
4.1 Method A: measurement of surface resistance R omni-directionally
OA
4.1.1 Applicability
This method is applicable to belts which are electrically two-dimensionally isotropic in the plane of the belt.
4.1.2 Principle
An electric current of specified voltage is passed via electrodes through a suitably prepared test piece
taken from the belt.
4.1.3 Apparatus
4.1.3.1 Sheet of insulating material, a little larger than the test piece
4.1.3.2 Two cylindrical and coaxial brass electrodes, the base of one being circular and that of the
other annular. The dimensions and masses are given in Figure 2. The bases of these electrodes shall be
machined flat and polished.
4.1.3.3 Flexible insulated wire, connected to each electrode.
10
4.1.3.4 Ohmmeter, having a measuring range up to 10 Ω and accurate to within ±5 %.
4.1.3.5 Source of direct current, adjustable up to 500 V, and not permitting a current greater than 10 mA.
NOTE The source of current can be either an accumulator or a rectified, stabilized a.c. power supply.
4.1.4 Test piece
4.1.4.1 Material
Test piece material shall be new, unused (“virgin”), but shall not be tested sooner than five days after
manufacture. It shall be free from contamination and superficial damage.
4.1.4.2 Dimensions
The test pieces shall be square, 300 mm × 300 mm minimum, and shall be cut from the full thickness of
the belt.
4.1.4.3 Number
Three test pieces shall be taken. One test piece shall be taken from the middle of the belt, the other two
test pieces shall be taken 100 mm from each of the belt edges.
4.1.4.4 Cleaning
If necessary, clean both surfaces of the test pieces by rubbing with fuller’s earth (hydrated magnesium-
aluminium silicate), for example, using a clean cloth. After cleaning away all traces of the powder, wipe
the surface with a clean cloth moistened with distilled water and then dry with a clean cloth.
2 © ISO 2013 – All rights reserved

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SIST EN ISO 21178:2013
ISO 21178:2013(E)

4.1.4.5 Conditioning
Before testing, condition the test pieces in accordance with ISO 18573, Atmosphere B, for 24 h, except
that, if the light conveyor belt consists of materials with a high absorption of moisture, e.g. cotton or
polyamide, condition the test piece for 48 h.
4.1.4.6 Preparation
Prepare the test pieces in the following manner after conditioning according to 4.1.4.5.
To ensure good contact between electrodes and test piece a contact agent shall be used. The electrical
4
surface resistivity of the contact agent shall not be higher than 10 Ω. For checking this value, use the
same electrode arrangement as described in Clause 5.
NOTE A jelly having the following composition is suitable:
— anhydrous polyethylene glycol of molecular mass 600: 800 mg/g (mass fraction);
— water: 200 mg/g (mass fraction);
— potassium chloride: 10 mg/g (mass fraction);
— soft soap (pharmaceutical quality): 1 mg/g (mass fraction).
If the surface of the test piece is flat, paint the contact agent onto the bottom surface of the cleaned
electrodes. If the surface of the test piece is textured, paint two areas of the test piece as shown in
Figure 1. Take care to ensure the accuracy of the dimensions of the painted areas, although the symmetry
of the centre is not critical. Carry out the test immediately after painting. If silver lacquer is used as the
contact agent, carry out the test after evaporating the solvent.
4.1.5 Procedure
Measure the temperature and relative humidity in the test room.
Place the test piece on the sheet of insulating material, with the test surface upwards.
Paint the test piece or bottom surface of the cleaned electrodes with contact agent and let the solvent
evaporate, if necessary.
If necessary, clean the electrodes and place them on the test piece.
Apply the test voltage to the electrodes, starting with a low voltage to protect very fine antistatic layers
against damage.
Read the value of the electrical resistance 1 min after applying the test voltage.
© ISO 2013 – All rights reserved 3

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SIST EN ISO 21178:2013
ISO 21178:2013(E)

Dimensions in millimetres
Key
1 contact agent
Figure 1 — Design to be painted on the test piece
Dimensions in millimetres
Key
1 min. mass 115 g
2 min. mass 900 g
...