ISO 20615:2018

INTERNATIONAL ISO
STANDARD 20615
First edition
2018-10
Fibre ropes — Electrostatic surface
potential measuring method
Cordages en fibres — Méthode de mesurage du potentiel
électrostatique de surface
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Test atmosphere. 1
6 Apparatus . 2
7 Preparation of specimens . 4
7.1 Specimen diameter . 4
7.2 Cutting . 4
7.3 Splicing rope specimen . 4
7.4 Conditioning of specimen . 5
8 Testing procedure . 5
8.1 Rope specimen setting . 5
8.2 Measurement of surface potential generated by tribocharging . 5
9 Test report . 6
Annex A (normative) Verification procedure and correction factor . 7
Annex B (informative) Example of test results.10
Annex C (informative) Information on the effect of parameters .12
Annex D (informative) Interlaboratory test .14
Bibliography .17
Foreword
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electrotechnical standardization.
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This document was prepared jointly by Technical Committee ISO/TC 38, Textiles, and Technical
Committee IEC/TC 101, Electrostatics. The draft was circulated for voting to the national bodies of both
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iv © ISO 2018 – All rights reserved

Introduction
Heavy duty ropes can be made from metal wire or synthetic fibre or a combination of these two.
Historically, fibre ropes were commonly made of natural fibres such as cotton, flax, etc. Recently,
synthetic fibres have been used to make heavy duty ropes. Synthetic fibre ropes are lighter and stronger
than steel wire ropes and natural fibre ropes.
However, synthetic fibre can acquire electrostatic charge more easily compared to metal wire ropes or
natural fibre ropes.
To overcome this disadvantage, different methods have been applied to the manufacture of synthetic
fibre ropes, such as combining them with steel wire or blending with conductive yarn, etc. The
development of such ropes has taken place without a standard procedure for evaluating their
electrostatic propensity.
This document describes a test method that is used to determine tribocharging of fibre ropes by a
specified charging mechanism.
This testing method may not be representative of all possible charging mechanisms that are found in use.
INTERNATIONAL STANDARD ISO 20615:2018(E)
Fibre ropes — Electrostatic surface potential measuring
method
1 Scope
This document specifies a method for determining the electrostatic charging propensity of fibre ropes
by measuring the surface potential generated by tribocharging.
This document is not intended to be used to evaluate the safety of ropes for use in explosive atmospheres
as safety also depends on application conditions.
The test method described in this document is only applicable to fibre ropes of diameter between
12 mm and 20 mm.
The result obtained using this test method is valid only for the charging mechanism and parameters
described in the test method. Charging can be different in end-use applications.
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 630-1, Structural steels — Part 1: General technical delivery conditions for hot-rolled products
ISO 1968, Fibre ropes and cordage — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1968 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 Principle
A fibre rope specimen is cut to a designated length and both ends spliced by the short splice method
to make an endless loop. The rope specimen loop is mounted in a rope driving apparatus and passes
around friction cylinders and a non-contacting electrostatic voltmeter. As the rope makes contact with
the friction cylinders, rollers and pulleys, it becomes electrostatically charged. The resulting surface
potential is measured by the non-contacting electrostatic voltmeter.
5 Test atmosphere
Unless otherwise agreed or specified, the atmosphere for conditioning and testing shall be a
temperature of (23 ± 2) °C and a relative humidity of (25 ± 5) %.
A different temperature or relative humidity may be used as appropriate for different geographical
regions, but in any case, the atmosphere for conditioning and testing shall include the lowest relative
humidity expected in use.
6 Apparatus
6.1 Apparatus for tribocharging and measuring surface potential
One possible test apparatus is shown in Figure 1 as an example. Other apparatus capable of measuring
surface potential generated by tribocharging and recording such measurements over a period of time
may also be used after appropriate validation. For the validation, test a rope made of high modulus
polyethylene (HMPE) and compare the data with the example shown in Annex B.
The apparatus should be earthed. National electrical codes can be applicable.
Dimensions in millimetres with tolerance of ±4,0 mm
Key
1 rope specimen
2 friction cylinder (no rotation)
3 friction cylinder (no rotation)
4 loading roller
5 load
6 driving pulley
7 electrostatic voltmeter
8 motor
9 recording device
Figure 1 — Diagram of an example of the test apparatus
6.1.1 Friction cylinders, consisting of two friction cylinders (see Figure 1, key items 2 and 3), which
are fixed without rotation, and the rope specimen winds around the cylinders. The dimension of each
2 © ISO 2018 – All rights reserved

cylinder is 140 mm ± 3 mm in diameter and 180 mm ± 3 mm between flanges. The material is E275A
prescribed in ISO 630-1 and polishing roughness is an arithmetic mean roughness of 6,3 μm.
E275A represents a typical material in many applications. However, there can be other materials in
other applications that have different triboelectric charging characteristics.
If the application for ropes requires testing using other friction materials, such as polyamide resin for
example, other material for the friction cylinders may be used and shall be recorded in the test report.
6.1.2 Loading roller, hanging freely in the rope path (Figure 1, key item 4) and loaded with a mass
of 2,4 kg ± 0,3 kg (Figure 1 key item 5). The diameter of the roller is 46 mm ± 3 mm. The material is the
same as the friction cylinder material.
If a different load is used, record it in the test report.
6.1.3 Driving pulley, for driving the rope specimen in this testing apparatus along the rope path
(Figure 1, key item 6). The material is the same as the friction cylinder material.
6.1.4 Electrostatic potential measuring instrument, non-contacting electrostatic voltmeter as
shown in Figure 2, which may be either an electrostatic field meter calibrated to read surface voltage
using a known target geometry, or a direct reading electrostatic voltmeter (e.g. vibrating reed type).
— Range: 0 kV to 20 kV, both positive and negative polarity.
— Response time (0 % to 90 % full scale): ≤10 ms.
Verification shall be performed, and the correction factors shall be calculated according to Annex A.
Key
1 non-contacting electrostatic voltmeter
2 sensing point
3 rope specimen
4 mounting base
Figure 2 — Electrostatic voltmeter
6.1.5 Driving motor, with speed controlled by an inverter system. The rope running speed for this
measurement is 0,6 m/s ± 0,1 m/s.
If a different rope speed is used, record it in the test report.
...