Rubber, vulcanized or thermoplastic — Determination of volume and/or surface resistivity

This document specifies a method for the determination of the volume and the surface resistivity of vulcanized or thermoplastic rubbers. The method can be applied to materials with a resistivity from 101 Ω⋅m to 1017 Ω⋅m.

Caoutchouc vulcanisé ou thermoplastique — Détermination de la résistivité transversale et/ou superficielle

General Information

Status
Published
Publication Date
02-Jul-2019
Current Stage
6060 - International Standard published
Start Date
03-Jul-2019
Completion Date
03-Jul-2019
Ref Project

RELATIONS

Buy Standard

Standard
REDLINE ISO 14309:2019 - Rubber, vulcanized or thermoplastic — Determination of volume and/or surface resistivity Released:7/3/2019
English language
18 pages
sale 15% off
Preview
sale 15% off
Preview
Standard
ISO 14309:2019 - Rubber, vulcanized or thermoplastic -- Determination of volume and/or surface resistivity
English language
18 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

ISO 14309:2019(E)
INTERNATIONAL STANDARD
Deleted: /FDIS
ISO
14309
Second edition
2019‐07
Rubber, vulcanized or thermoplastic — Determination of
volume and/or surface resistivity

Caoutchouc vulcanisé ou thermoplastique — Détermination de la résistivité transversale et/ou

superficielle
© ISO 2019 – All rights reserved i
---------------------- Page: 1 ----------------------
ISO 14309:2019(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 on 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 the following

URL: www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,

Subcommittee SC 2, Testing and analysis.

This second edition cancels and replaces the first edition (ISO 14309:2011), which has been technically

revised.
The main changes compared to the previous edition are as follows:

— A detailed explanation on the requirement for the electrode gap for volume resistivity has been

added in 5.4.2.
— The typical dimension for D2 has been changed to (60 ± 0,5) mm in 5.4.2.

— To calculate the volume resistivity, the effective area of the main electrode is now derived from

D + B in 11.1, and the information on B has been newly included as Annex D.
1 g g

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.
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14309:2019(E)
Introduction

Rubber materials are widely used in many industries, either as the major material or forming a part of

the product, because of their unique physical properties which can be tailored by compounding to

match the particular requirements of the product specification. Although rubbers are generally

regarded as insulating materials, they can be made electrically conductive or dissipative by

compounding with a certain amount of carbon black or ionizable ingredients. Hence, the range of

electrical resistance to be measured is very wide. It is difficult, however, to obtain high accuracy for

measurements in the high‐resistance range due to a number of factors.

In this document, the guarded‐electrode system is used to determine the resistivity of rubber test

pieces since it is considered a good compromise between minimizing the errors by shunting away stray

currents and using more unwieldy measurement instruments (see also IEC 62631‐3‐1).

ISO 1853, on the other hand, covers rubber materials with medium to low resistance, i.e. resistivities of

10 Ω⋅m or below. It specifies three methods for determining volume resistivity which minimize or

eliminate contact resistance.

The methods specified in this document were originally designed for the determination of both surface

and volume resistivity of insulating rubber materials, but their use can be extended to cover the range

from high to low resistivity.

It is known that the test results are sensitive to the test conditions, such as temperature and humidity,

and to heat and strain history.
© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 14309:2019(E)
Rubber, vulcanized or thermoplastic — Determination of volume
and/or surface resistivity

WARNING 1 — Persons using this document should be familiar with normal laboratory practice. This

document does not purport to address all of the safety problems, if any, associated with its use. It is the

responsibility of the user to establish appropriate safety and health practices and to determine the

applicability of any other restrictions.

WARNING 2 — Certain procedures specified in this document might involve the use or generation of

substances, or the generation of waste, that could constitute a local environmental hazard. Reference

should be made to appropriate documentation on safe handling and disposal after use.

1 Scope

This document specifies a method for the determination of the volume and the surface resistivity of

vulcanized or thermoplastic rubbers. The method can be applied to materials with a resistivity from

1 17
10 Ω⋅m to 10 Ω⋅m.
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 1382, Rubber — Vocabulary
ISO 18899:2013, Rubber — Guide to the calibration of test equipment

ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical test

methods
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1382 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
volume resistance

quotient of a direct‐current voltage applied between two electrodes in contact with opposite faces of a

test piece and the current between the electrodes, excluding current along the surface

Note 1 to entry: It is expressed in ohms (Ω).
3.2
surface resistance
© ISO 2019 – All rights reserved 1
---------------------- Page: 4 ----------------------
ISO 14309:2019(E)

quotient of a direct‐current voltage applied between two electrodes on the same surface of a test piece

and the current between the electrodes
Note 1 to entry: It is expressed in ohms (Ω).
3.3
volume resistivity
measured volume resistance calculated to apply to a cube of unit side
Note 1 to entry: It is expressed in ohm metres (Ω⋅m).
3.4
surface resistivity
measured surface resistance calculated to apply to a square

Note 1 to entry: It is expressed in ohms (Ω) and the size of the square is immaterial.

3.5
guarded-electrode system

electrode system composed of three electrodes, a guard, and a guarded and an unguarded electrode to

reduce measurement errors by protecting the current‐measuring electrode from the interfering

influences of voltages other than the test voltage, and of stray conductances

Note 1 to entry: Guarding depends on interposing, in all critical insulated parts, guard electrodes which intercept

all stray currents that might otherwise cause errors. The guard electrodes are connected together, constituting the

guard system and forming with the measurement terminals a three‐terminal network. When suitable connections

are made, stray currents from spurious external voltages are shunted away from the measurement circuit by the

guard system, the insulation resistance from either measurement terminal to the guard system shunts a circuit

element which should be of very much lower resistance, and the specimen resistance constitutes the only direct

path between the measurement terminals. By this technique, the probability of error is considerably reduced (see

5.3.2 of IEC 62631‐3‐1:2016 for more details).
4 Principle

The volume and surface resistances of a rubber test piece are determined, using a suitable arrangement

of electrodes, from the current flowing when a voltage is applied. The volume and surface resistivities

are calculated from the measured resistances, which include the contact resistance.

5 Apparatus

The test equipment consists of a power supply, current‐measuring equipment and electrodes:

5.1 Stabilized direct-current power supply, capable of applying a voltage of 1 V to 1 000 V to the

test piece.

5.2 Voltmeter, capable of measuring the applied voltage with an accuracy of ±2 %.

5.3 Ammeter or other current-measuring device, capable of measuring a current of 0,01 pA to

100 mA, depending on the resistivity of the test piece to be measured. The accuracy of the current‐

measuring device shall be better than 5 %.
5.4 Electrodes
2 © ISO 2019 – All rights reserved
---------------------- Page: 5 ----------------------
ISO 14309:2019(E)
5.4.1 Guarded-electrode system
Three electrodes shall be applied to the test piece:
— a main electrode (circular);
— a ring electrode (annular);
— an opposed electrode (circular).
5.4.2 Shapes and dimensions of electrodes

The main (smallest) electrode is circular and is surrounded by the ring electrode. The third electrode is

circular and placed on the opposite side of the test piece to the main electrode. The arrangement of the

electrodes is shown schematically in Figure 1.
A typical example
D1 (50 ± 0,5) mm
D (60 ± 0,5) mm
D (80 ± 0,5) mm
D (83 ± 2) mm
g 5 mm
h 2 mm
Key
1 main electrode
2 ring electrode
3 opposed electrode
4 test piece
© ISO 2019 – All rights reserved 3
---------------------- Page: 6 ----------------------
ISO 14309:2019(E)
Figure 1 — Arrangement of electrodes
The dimensions of the electrodes shall comply with following requirements:

— The diameter D1 of the main electrode shall be at least ten times the test piece thickness h.

— The gap g between the main electrode and the ring electrode shall be uniform in width. For the

measurement of volume resistivity, the gap needs to be such as to give a balance between fringing

and current leakage. Fringing is current flowing in a curved path near the electrode and is more

prevalent with a wide gap. Leakage current between the main and ring electrodes will be greater

with a narrow gap. Gaps between 1 mm and 15 mm have been used depending on the range of

resistivity to be measured.

For the measurement of surface resistivity, the gap g shall be at least twice the test piece thickness so

that the effect of the volume resistance can be ignored.

— The width of the ring electrode shall be greater than the test piece thickness h.

— The diameter D4 of the opposed electrode shall be greater than the outer diameter D3 of the ring

electrode.

NOTE The measured volume or surface resistance might depend strongly on the test piece and electrode

dimensions. For comparative determinations, the same size of test piece and electrodes need to be used.

5.4.3 Electrode materials

Electrodes shall be of a conducting material capable of being intimately applied to the test piece. If they

are applied before conditioning, the material shall be moisture‐permeable. Electrodes other than of

rigid metal shall be supplemented by rigid metal backing plates.
NOTE Suitable electrode materials are considered in Annex A.
5.4.4 Electrical circuits
Suitable circuits for testing are shown in Figures 2 and 3.
4 © ISO 2019 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 14309:2019(E)
Key
1 guarded electrode (main electrode)
2 guard electrode (ring electrode)
3 test piece
4 unguarded electrode (opposed electrode)
5 direct‐current supply
6 switch
7 connection for short‐circuiting electrodes (to discharge test piece)
8 connection for measurement circuit
9 ammeter
10 earth
11 measurement current
12 guard current
Figure 2 — Circuit configuration for volume resistivity
© ISO 2019 – All rights reserved 5
---------------------- Page: 8 ----------------------
ISO 14309:2019(E)
Key
1 guarded electrode (main electrode)
2 unguarded electrode (ring electrode)
3 test piece
4 guard electrode (opposed electrode)
5 direct‐current supply
6 switch
7 connection for short‐circuiting electrodes (to discharge test piece)
8 connection for measurement circuit
9 ammeter
10 earth
11 measurement current
12 guard current
Figure 3 — Circuit configuration for surface resistivity
6 Calibration
The requirements for calibration of the test apparatus are given in Annex C.
7 Test pieces
7.1 Form

The test piece shall be a flat, smooth sheet of sufficient size that the annular electrode does not reach its

edges. The surfaces of the sheet shall not be buffed.

The nominal thickness of the test piece shall be in the range 0,5 mm to 5 mm. Recommended thickness

is 1 mm or 2 mm.

The thickness of the test piece shall be measured at several points distributed uniformly over the area

covered by the main electrode to the nearest 0,01 mm. The average value shall be used as the test piece

6 © ISO 2019 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 14309:2019(E)

thickness. The variation in thickness within a given test piece shall not exceed 10 % of the mean value.

Test pieces used for comparative tests shall be, as nearly as practicable, of the same thickness.

7.2 Number of test pieces
Three test pieces shall be used.
8 Conditioning

The time interval between vulcanization and testing shall be in accordance with ISO 23529.

Samples and test pieces shall be stored in accordance with ISO 23529 during the interval between

vulcanization and testing.

The material shall be conditioned before testing for a minimum of 16 h at standard laboratory

temperature and humidity as specified in ISO 23529.

Metal foil, liquid and conductive elastomeric electrodes shall be applied after conditioning. This shall be

carried out either in the conditioning atmosphere or as soon as possible after removal from the

conditioning atmosphere. Moisture‐permeable electrodes can be applied before conditioning.

9 Test conditions
9.1 Temperature and humidity

Tests are normally performed at a standard laboratory temperature as defined in ISO 23529, although

elevated or subnormal temperatures can be used. In the latter case, the test temperature shall be

selected from the list in ISO 23529.

With materials for which the results are known to be sensitive to humidity, the test shall be carried out

under standard laboratory conditions (temperature and humidity) as defined in ISO 23529.

NOTE An influence of humidity has been observed with polyurethane rubbers and other rubbers containing

hydrophilic fillers.
9.2 Applied voltage

The test voltage applied to the test piece shall be in the range 1 V to 1 000 V. The voltage shall be

selected in consideration of the resistivity of the test piece and rated current of the ammeter. The power

dissipated in the test piece shall not exceed 0,1 W, in order to minimize heat generation. Recommended

voltages are 1 V, 10 V, 100 V, 500 V and 1 000 V. Suitable test conditions are given in Annex B.

NOTE Setting the dissipation of electric power at less than 0,1 W is based on the estimation of the heat

generated. Assuming that dissipation of electric power within a test pi
...

INTERNATIONAL ISO
STANDARD 14309
Second edition
2019-07
Rubber, vulcanized or
thermoplastic — Determination of
volume and/or surface resistivity
Caoutchouc vulcanisé ou thermoplastique — Détermination de la
résistivité transversale et/ou superficielle
Reference number
ISO 14309:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 14309:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14309:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Apparatus ..................................................................................................................................................................................................................... 2

6 Calibration .................................................................................................................................................................................................................. 6

7 Test pieces ................................................................................................................................................................................................................... 6

7.1 Form ................................................................................................................................................................................................................. 6

7.2 Number of test pieces ....................................................................................................................................................................... 7

8 Conditioning .............................................................................................................................................................................................................. 7

9 Test conditions ....................................................................................................................................................................................................... 7

9.1 Temperature and humidity .......................................................................................................................................................... 7

9.2 Applied voltage ....................................................................................................................................................................................... 7

10 Test procedure ........................................................................................................................................................................................................ 7

11 Expression of results ........................................................................................................................................................................................ 8

11.1 Volume resistivity ................................................................................................................................................................................. 8

11.2 Surface resistivity ................................................................................................................................................................................. 8

12 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Electrode materials ................................................................................................................................................10

Annex B (informative) Suitable range of test conditions ..............................................................................................................11

Annex C (normative) Calibration schedule .................................................................................................................................................13

Annex D (informative) Effective area of guarded electrode ......................................................................................................15

Bibliography .............................................................................................................................................................................................................................18

© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 14309:2019(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 on 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 the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,

Subcommittee SC 2, Testing and analysis.

This second edition cancels and replaces the first edition (ISO 14309:2011), which has been technically

revised.
The main changes compared to the previous edition are as follows:

— A detailed explanation on the requirement for the electrode gap for volume resistivity has been

added in 5.4.2.
— The typical dimension for D has been changed to (60 ± 0,5) mm in 5.4.2.

— To calculate the volume resistivity, the effective area of the main electrode is now derived from

D + B in 11.1, and the information on B has been newly included as Annex D.
1 g g

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 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 14309:2019(E)
Introduction

Rubber materials are widely used in many industries, either as the major material or forming a part of

the product, because of their unique physical properties which can be tailored by compounding to match

the particular requirements of the product specification. Although rubbers are generally regarded as

insulating materials, they can be made electrically conductive or dissipative by compounding with a

certain amount of carbon black or ionizable ingredients. Hence, the range of electrical resistance to be

measured is very wide. It is difficult, however, to obtain high accuracy for measurements in the high-

resistance range due to a number of factors.

In this document, the guarded-electrode system is used to determine the resistivity of rubber test

pieces since it is considered a good compromise between minimizing the errors by shunting away stray

currents and using more unwieldy measurement instruments (see also IEC 62631-3-1).

ISO 1853, on the other hand, covers rubber materials with medium to low resistance, i.e. resistivities

of 10 Ω⋅m or below. It specifies three methods for determining volume resistivity which minimize or

eliminate contact resistance.

The methods specified in this document were originally designed for the determination of both surface

and volume resistivity of insulating rubber materials, but their use can be extended to cover the range

from high to low resistivity.

It is known that the test results are sensitive to the test conditions, such as temperature and humidity,

and to heat and strain history.
© ISO 2019 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 14309:2019(E)
Rubber, vulcanized or thermoplastic — Determination of
volume and/or surface resistivity

WARNING 1 — Persons using this document should be familiar with normal laboratory practice.

This document does not purport to address all of the safety problems, if any, associated with its

use. It is the responsibility of the user to establish appropriate safety and health practices and to

determine the applicability of any other restrictions.

WARNING 2 — Certain procedures specified in this document might involve the use or generation

of substances, or the generation of waste, that could constitute a local environmental hazard.

Reference should be made to appropriate documentation on safe handling and disposal after use.

1 Scope

This document specifies a method for the determination of the volume and the surface resistivity of

vulcanized or thermoplastic rubbers. The method can be applied to materials with a resistivity from

1 17
10 Ω⋅m to 10 Ω⋅m.
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 1382, Rubber — Vocabulary
ISO 18899:2013, Rubber — Guide to the calibration of test equipment

ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical test methods

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1382 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
volume resistance

quotient of a direct-current voltage applied between two electrodes in contact with opposite faces of a

test piece and the current between the electrodes, excluding current along the surface

Note 1 to entry: It is expressed in ohms (Ω).
3.2
surface resistance

quotient of a direct-current voltage applied between two electrodes on the same surface of a test piece

and the current between the electrodes
Note 1 to entry: It is expressed in ohms (Ω).
© ISO 2019 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 14309:2019(E)
3.3
volume resistivity
measured volume resistance calculated to apply to a cube of unit side
Note 1 to entry: It is expressed in ohm metres (Ω⋅m).
3.4
surface resistivity
measured surface resistance calculated to apply to a square

Note 1 to entry: It is expressed in ohms (Ω) and the size of the square is immaterial.

3.5
guarded-electrode system

electrode system composed of three electrodes, a guard, and a guarded and an unguarded electrode

to reduce measurement errors by protecting the current-measuring electrode from the interfering

influences of voltages other than the test voltage, and of stray conductances

Note 1 to entry: Guarding depends on interposing, in all critical insulated parts, guard electrodes which intercept

all stray currents that might otherwise cause errors. The guard electrodes are connected together, constituting

the guard system and forming with the measurement terminals a three-terminal network. When suitable

connections are made, stray currents from spurious external voltages are shunted away from the measurement

circuit by the guard system, the insulation resistance from either measurement terminal to the guard system

shunts a circuit element which should be of very much lower resistance, and the specimen resistance constitutes

the only direct path between the measurement terminals. By this technique, the probability of error is

considerably reduced (see 5.3.2 of IEC 62631-3-1:2016 for more details).
4 Principle

The volume and surface resistances of a rubber test piece are determined, using a suitable arrangement

of electrodes, from the current flowing when a voltage is applied. The volume and surface resistivities

are calculated from the measured resistances, which include the contact resistance.

5 Apparatus

The test equipment consists of a power supply, current-measuring equipment and electrodes:

5.1 Stabilized direct-current power supply, capable of applying a voltage of 1 V to 1 000 V to the

test piece.

5.2 Voltmeter, capable of measuring the applied voltage with an accuracy of ±2 %.

5.3 Ammeter or other current-measuring device, capable of measuring a current of 0,01 pA to

100 mA, depending on the resistivity of the test piece to be measured. The accuracy of the current-

measuring device shall be better than 5 %.
5.4 Electrodes
5.4.1 Guarded-electrode system
Three electrodes shall be applied to the test piece:
— a main electrode (circular);
— a ring electrode (annular);
2 © ISO 2019 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 14309:2019(E)
— an opposed electrode (circular).
5.4.2 Shapes and dimensions of electrodes

The main (smallest) electrode is circular and is surrounded by the ring electrode. The third electrode is

circular and placed on the opposite side of the test piece to the main electrode. The arrangement of the

electrodes is shown schematically in Figure 1.
A typical example
D (50 ± 0,5) mm
D (60 ± 0,5) mm
D (80 ± 0,5) mm
D (83 ± 2) mm
g 5 mm
h 2 mm
Key
1 main electrode
2 ring electrode
3 opposed electrode
4 test piece
Figure 1 — Arrangement of electrodes
The dimensions of the electrodes shall comply with following requirements:

— The diameter D of the main electrode shall be at least ten times the test piece thickness h.

— The gap g between the main electrode and the ring electrode shall be uniform in width. For the

measurement of volume resistivity, the gap needs to be such as to give a balance between fringing

and current leakage. Fringing is current flowing in a curved path near the electrode and is more

prevalent with a wide gap. Leakage current between the main and ring electrodes will be greater

© ISO 2019 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 14309:2019(E)

with a narrow gap. Gaps between 1 mm and 15 mm have been used depending on the range of

resistivity to be measured.

For the measurement of surface resistivity, the gap g shall be at least twice the test piece thickness so

that the effect of the volume resistance can be ignored.

— The width of the ring electrode shall be greater than the test piece thickness h.

— The diameter D of the opposed electrode shall be greater than the outer diameter D of the ring

4 3
electrode.

NOTE The measured volume or surface resistance might depend strongly on the test piece and electrode

dimensions. For comparative determinations, the same size of test piece and electrodes need to be used.

5.4.3 Electrode materials

Electrodes shall be of a conducting material capable of being intimately applied to the test piece. If they

are applied before conditioning, the material shall be moisture-permeable. Electrodes other than of

rigid metal shall be supplemented by rigid metal backing plates.
NOTE Suitable electrode materials are considered in Annex A.
5.4.4 Electrical circuits
Suitable circuits for testing are shown in Figures 2 and 3.
4 © ISO 2019 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 14309:2019(E)
Key
1 guarded electrode (main electrode)
2 guard electrode (ring electrode)
3 test piece
4 unguarded electrode (opposed electrode)
5 direct-current supply
6 switch
7 connection for short-circuiting electrodes (to discharge test piece)
8 connection for measurement circuit
9 ammeter
10 earth
11 measurement current
12 guard current
Figure 2 — Circuit configuration for volume resistivity
© ISO 2019 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 14309:2019(E)
Key
1 guarded electrode (main electrode)
2 unguarded electrode (ring electrode)
3 test piece
4 guard electrode
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.