Fire hazard testing - Part 5-2: Corrosion damage effects of fire effluent - Summary and relevance of test methods

IEC TS 60695-5-2:2021 is available as IEC TS 60695-5-2:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC TS 60695-5-2:2021 gives a summary of the test methods that are used in the assessment of the corrosivity of fire effluent. It presents a brief summary of test methods in common use, either as international standards or national or industry standards. It includes special observations on their relevance, for electrotechnical products and their materials, to real fire scenarios and gives recommendations on their use.
One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. The requirements, test methods or test conditions of this publication will not apply unless specifically referred to or included in the relevant publications.
This third edition cancels and replaces the second edition published in 2002.
The main changes with respect to the previous edition are listed below:
– References to IEC TS 60695-5-3 (withdrawn in 2014) have been removed.
– ISO/TR 9122-1 has been revised by ISO 19706.
– References to ISO 11907-2 and ISO 11907-3 have been removed.
– Terms and definitions have been updated.
– Text in 5.4 has been updated.
– Text in 5.5.8 (5.7.8 in Ed. 2) has been updated.
– Text in Clause 6 (7 in Ed. 2) has been updated.
– Bibliographic references have been updated.
It has the status of a basic safety publication in accordance with IEC Guide 104 and ISO/IEC Guide 51.
This technical specification is to be read in conjunction with IEC 60695-5-1.

General Information

Status
Published
Publication Date
02-Jun-2021
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
03-Jun-2021
Ref Project

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IEC TS 60695-5-2
Edition 3.0 2021-06
TECHNICAL
SPECIFICATION
Fire hazard testing –
Part 5-2: Corrosion damage effects of fire effluent – Summary and relevance of
test methods
IEC TS 60695-5-2:2021-06(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 60695-5-2
Edition 3.0 2021-06
TECHNICAL
SPECIFICATION
Fire hazard testing –
Part 5-2: Corrosion damage effects of fire effluent – Summary and relevance of
test methods
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.220.99; 19.020; 29.020 ISBN 978-2-8322-9842-8

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 60695-5-2:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

4 Classification of test methods .......................................................................................... 9

4.1 General ................................................................................................................... 9

4.2 Test specimen ........................................................................................................ 9

4.2.1 Product testing ................................................................................................ 9

4.2.2 Material or composite sample testing ............................................................... 9

4.3 The physical fire model ........................................................................................... 9

4.4 The nature of the corrosivity measurement ............................................................. 9

4.4.1 Product as target ............................................................................................. 9

4.4.2 Simulated product as target ............................................................................. 9

4.4.3 Indirect assessment ....................................................................................... 11

5 Published test methods ................................................................................................. 11

5.1 General ................................................................................................................. 11

5.2 Tests for the determination of halogen acid in combustion gases .......................... 11

5.2.1 Standards ...................................................................................................... 11

5.2.2 Purpose and principle .................................................................................... 11

5.2.3 Test specimen ............................................................................................... 11

5.2.4 Test method .................................................................................................. 11

5.2.5 Repeatability and reproducibility .................................................................... 11

5.2.6 Relevance of test data to corrosion hazard assessment ................................. 12

5.3 Tests for the determination of the acidity and conductivity of combustion

gases dissolved in an aqueous solution ................................................................ 12

5.3.1 Standards ...................................................................................................... 12

5.3.2 Purpose and principle .................................................................................... 12

5.3.3 Test specimen ............................................................................................... 12

5.3.4 Test method .................................................................................................. 12

5.3.5 Repeatability and reproducibility .................................................................... 12

5.3.6 Relevance of test data to corrosion hazard assessment ................................. 13

5.4 Tests for the determination of corrosive gases by evaluation of copper

corrosion in ASTM D 2671 – Sections 89 to 95 [9] ................................................ 13

5.4.1 Purpose and principle .................................................................................... 13

5.4.2 Test specimen ............................................................................................... 13

5.4.3 Test methods ................................................................................................. 13

5.4.4 Special observations ..................................................................................... 13

5.4.5 Repeatability and reproducibility .................................................................... 13

5.4.6 Relevance of test data to corrosion hazard assessment ................................. 13

5.5 Cone corrosimeter method .................................................................................... 14

5.5.1 Standards ...................................................................................................... 14

5.5.2 Purpose and principle .................................................................................... 14

5.5.3 Test specimen ............................................................................................... 14

5.5.4 Corrosion target ............................................................................................. 14

5.5.5 Test method .................................................................................................. 14

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IEC TS 60695-5-2:2021 © IEC 2021 – 3 –

5.5.6 Special observation ....................................................................................... 15

5.5.7 Repeatability and reproducibility .................................................................... 15

5.5.8 Relevance of test data to corrosion hazard assessment ................................. 15

6 Overview of methods and relevance of data .................................................................. 15

Annex A (informative) Acidity and conductivity of aqueous solutions – Test methods .......... 18

Annex B (informative) Determination of repeatability and reproducibility –

Comparative tests of solutions of combustion gases ............................................................. 19

Bibliography .......................................................................................................................... 23

Figure 1 – Schematic drawing of a typical corrosion target of defined metal thickness .......... 15

Table 1 – Characteristics of fire stages (from Table 1 in ISO 19706:2011) ............................ 10

Table 2 – Overview of corrosivity test methods ..................................................................... 17

Table A.1 – Test methods for the measurement of acidity and conductivity of aqueous

solutions obtained after bubbling combustion effluent through water ..................................... 18

Table B.1 – Determination of repeatability and reproducibility – Comparative pH tests

on solutions of combustion gases ......................................................................................... 20

Table B.2 – Determination of repeatability and reproducibility – Comparative resistivity

tests on solutions of combustion gases ................................................................................. 21

Table B.3 – Results obtained on brominated polycarbonate .................................................. 22

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– 4 – IEC TS 60695-5-2:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 5-2: Corrosion damage effects of fire effluent –
Summary and relevance of test methods
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

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with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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6) All users should ensure that they have the latest edition of this publication.

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

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

IEC 60695-5-2, which is a technical specification, has been prepared by IEC technical

committee 89: Fire hazard testing.
This third edition cancels and replaces the second edition published in 2002.
The main changes with respect to the previous edition are listed below:
– References to IEC TS 60695-5-3 (withdrawn in 2014) have been removed.
– ISO/TR 9122-1 has been revised by ISO 19706.
– References to ISO 11907-2 and ISO 11907-3 have been removed.
– Terms and definitions have been updated.
– Text in 5.4 has been updated.
– Text in 5.5.8 (5.7.8 in Ed. 2) has been updated.
– Text in Clause 6 (7 in Ed. 2) has been updated.
---------------------- Page: 6 ----------------------
IEC TS 60695-5-2:2021 © IEC 2021 – 5 –
– Bibliographic references have been updated.

It has the status of a basic safety publication in accordance with IEC Guide 104 and

ISO/IEC Guide 51.
The text of this technical specification is based on the following documents:
Draft Report on voting
89/1473/DTS 89/1506/RVDTS

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.

The language used for the development of this Technical Specification is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,

available at www.iec.ch/members_experts/refdocs. The main document types developed by

IEC are described in greater detail at www.iec.ch/standardsdev/publications.
In this technical specification, the following print types are used:
Arial bold: terms referred to in Clause 3
This technical specification is to be read in conjunction with IEC 60695-5-1.

A list of all parts in the IEC 60695 series, published under the general title Fire hazard testing,

can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 7 ----------------------
– 6 – IEC TS 60695-5-2:2021 © IEC 2021
INTRODUCTION

In the design of an electrotechnical product the risk of fire and the potential hazards

associated with fire need to be considered. In this respect the objective of component, circuit

and equipment design, as well as the choice of materials, is to reduce the risk of fire to a

tolerable level even in the event of reasonably foreseeable (mis)use, malfunction or failure.

IEC 60695-1-10 [1] , IEC 60695-1-11 [2], and IEC 60695-1-12 [3] provide guidance on how

this is to be accomplished.

Fires involving electrotechnical products can also be initiated from external non-electrical

sources. Considerations of this nature are dealt with in an overall fire hazard assessment.

The aim of the IEC 60695 series is to save lives and property by reducing the number of fires

or reducing the consequences of the fire. This can be accomplished by:

• trying to prevent ignition caused by an electrically energised component part and, in the

event of ignition, to confine any resulting fire within the bounds of the enclosure of the

electrotechnical product.

• trying to minimise flame spread beyond the product’s enclosure and to minimise the

harmful effects of fire effluents including heat, smoke, and toxic or corrosive combustion

products.

All fire effluent is corrosive to some degree and the level of potential to corrode depends on

the nature of the fire, the combination of combustible materials involved in the fire, the nature

of the substrate under attack, and the temperature and relative humidity of the environment in

which the corrosion is taking place. There is no evidence that fire effluent from

electrotechnical products offers greater risk of corrosion damage than the fire effluent

from other products such as furnishings, building materials, etc.

The performance of electrical and electronic components can be adversely affected by

corrosion damage when subjected to fire effluent. A wide variety of combinations of small

quantities of effluent gases, smoke particles, moisture and temperature may provide

conditions for electrical component or system failures from breakage, overheating or shorting.

Evaluation of potential corrosion damage is particularly important for high value and safety-

related electrotechnical products and installations.

Technical committees responsible for the products will choose the test(s) and specify the level

of severity.

The study of corrosion damage requires an interdisciplinary approach involving chemistry,

electricity, physics, mechanical engineering, metallurgy and electrochemistry. In the

preparation of this part of IEC 60695, all of the above have been considered.

IEC 60695-5-1 defines the scope of the guidance and indicates the field of application.

IEC 60695-5-2 provides a summary of test methods including relevance and usefulness.

___________
Numbers in square brackets refer to the bibliography.
---------------------- Page: 8 ----------------------
IEC TS 60695-5-2:2021 © IEC 2021 – 7 –
FIRE HAZARD TESTING –
Part 5-2: Corrosion damage effects of fire effluent –
Summary and relevance of test methods
1 Scope

This part of IEC 60695, which is a technical specification, gives a summary of the test

methods that are used in the assessment of the corrosivity of fire effluent. It presents a brief

summary of test methods in common use, either as international standards or national or

industry standards. It includes special observations on their relevance, for electrotechnical

products and their materials, to real fire scenarios and gives recommendations on their use.

One of the responsibilities of a technical committee is, wherever applicable, to make use of

basic safety publications in the preparation of its publications. The requirements, test

methods or test conditions of this publication will not apply unless specifically referred to or

included in the relevant publications.
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.

IEC 60695-4:2012, Fire hazard testing – Part 4: Terminology concerning fire tests for

electrotechnical products

IEC 60695-5-1, Fire hazard testing – Part 5-1: Corrosion damage effects of fire effluent -

General guidance

IEC GUIDE 104, The preparation of safety publications and the use of basic safety

publications and group safety publications
ISO Guide 51, Safety aspects – Guidelines for their inclusion in standards
ISO 13943:2017, Fire safety – Vocabulary
ISO 19706:2011, Guidelines for assessing the fire threat to people
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60695-4:2012 and

ISO 13943:2017 (some of which are reproduced below), apply.
3.1
corrosion damage
physical and/or chemical damage or impaired function caused by chemical action
[SOURCE: ISO 13943:2017, 3.69]
---------------------- Page: 9 ----------------------
– 8 – IEC TS 60695-5-2:2021 © IEC 2021
3.2
corrosion target

sensor used to determine the degree of corrosion damage (3.1), under specified test

conditions

Note 1 to entry: This sensor may be a product, a component. It may also be a reference material or object used to

simulate the behaviour of a product or a component.
[SOURCE: ISO 13943:2017, 3.70]
3.3
fire effluent
all gases and aerosols, including suspended particles created by combustion or
pyrolysis (3.6) and emitted to the environment
[SOURCE: ISO 13943:2017, 3.123]
3.4
fire scenario

qualitative description of the course of a fire with respect to time, identifying key events that

characterize the studied fire and differentiate it from other possible fires

Note 1 to entry: See fire scenario cluster (ISO 13943:2017, 3.154) and representative fire scenario

(ISO 13943:2017, 3.153).

Note 2 to entry: It typically defines the ignition and fire growth processes, the fully developed fire stage, the fire

decay stage, and the environment and systems that will impact on the course of the fire.

Note 3 to entry: Unlike deterministic fire analysis, where fire scenarios are individually selected and used as

design fire scenarios, in fire risk assessment, fire scenarios are used as representative fire scenarios within fire

scenario clusters.
[SOURCE: ISO 13943:2017, 3.152]
3.5
physical fire model

laboratory process, including the apparatus, the environment and the fire test procedure

intended to represent a certain phase of a fire
[SOURCE: ISO 13943:2017, 3.298]
3.6
pyrolysis
chemical decomposition of a substance by the action of heat

Note 1 to entry: Pyrolysis is often used to refer to a stage of fire before flaming combustion has begun.

Note 2 to entry: In fire science, no assumption is made about the presence or absence of oxygen.

[SOURCE: ISO 13943:2017, 3.316]
3.7
smoke
visible part of a fire effluent (3.3)
[SOURCE: ISO 13943:2017, 3.347]
---------------------- Page: 10 ----------------------
IEC TS 60695-5-2:2021 © IEC 2021 – 9 –
4 Classification of test methods
4.1 General
Test methods can be classified according to three criteria:
a) the nature of the test specimen which is burned;
b) the physical fire model used in the test;
c) the nature of the measurement of corrosivity.
4.2 Test specimen
4.2.1 Product testing

The test specimen is a manufactured product or a representative portion of a product.

Examples include: a printed circuit board, a switchboard, a computer or a cable.
4.2.2 Material or composite sample testing

The test specimen is a basic material (solid or liquid), or composite of materials.

4.3 The physical fire model

Test methods use a wide variety of heat sources and geometries. The amount, the rate of

production and the corrosive nature of fire effluent released from a given material or product

is not an inherent property of that material or product, but is critically dependent on the

conditions under which that material or product is burnt. In a fire scenario or a fire test, the

chemical nature of the fuel, the decomposition temperature and the amount of ventilation are

the main variables which affect the composition of fire effluent.

It is critical to show that the test conditions defined in a standardized test method are relevant

to, and replicate, the desired stage of a real fire. ISO has published a general classification of

fire stages in ISO 19706, shown in Table 1. The important factors affecting effluent production

are oxygen concentration and irradiance/temperature.
4.4 The nature of the corrosivity measurement
4.4.1 Product as target

In these cases the corrosion target is a manufactured product or a representative portion of

a product. Examples include: printed wiring boards, switchboards, washing machines and

computers.
The corrosion damage effects of fire effluent on the product can be assessed by
degradation of function as determined by inspection or measurement.
4.4.2 Simulated product as target

When a simulated product is used as the target, the corrosion target is typically a reference

circuit, a thin sheet of metal or a metal mirror. The corrosion damage effects of fire effluent

on the target can be assessed by changes in appearance, mass or measurements of
mechanical, physical or electrical characteristics.
---------------------- Page: 11 ----------------------
– 10 – IEC TS 60695-5-2:2021 © IEC 2021
Table 1 – Characteristics of fire stages (from Table 1 in ISO 19706:2011)
Max. temperature Oxygen volume
Heat flux to
100×[CO2]
[CO]
fuel surface
°C % Fuel/air
([CO2]+[CO])
Fire stage equivalence
[CO2]
ratio (plume)
Fuel surface Upper layer Entrained Exhausted
kW/m
v/v
% efficiency
1 Non-flaming
a self-sustaining not
450 to 800 20 20 – 0,1 to 1 50 to 90
25 to 85
(smouldering) applicable
b oxidative pyrolysis
b c c
from externally applied – 300 to 600 a 20 20 < 1
radiation
c anaerobic pyrolysis
b c c
from externally applied – 100 to 500 0 0 >> 1
radiation
d e
0 to 60 350 to 650 50 to 500 ≈ 20 ≈ 20 < 1 > 95
2 Well-ventilated flaming < 0,05
3 Underventilated flaming
a small, localized fire,
generally in a poorly
0 to 30 50 to 500 15 to 20 5 to 10 > 1 0,2 to 0,4 70 to 80
300 to 600
ventilated
compartment
g h i
b post-flashover fire 50 to 150 > 600 < 15 < 5 70 to 90
350 to 650 > 1 0,1 to 0,4

The upper limit is lower than for well-ventilated flaming combustion of a given combustible.

The temperature in the upper layer of the fire room is most likely determined by the source of the externally applied radiation and room geometry.

There are few data, but for pyrolysis this ratio is expected to vary widely depending on the material chemistry and the local ventilation and thermal conditions.

The fire’s oxygen consumption is small compared to that in the room or the inflow, the flame tip is below the hot gas upper layer or the upper layer is not yet significantly

vitiated to increase the CO yield significantly, the flames are not truncated by contact with another object, and the burning rate is controlled by the availability of fuel.

The ratio can be up to an order of magnitude higher for materials that are fire-resistant. There is no significant increase in this ratio for equivalence ratios up to ≈ 0,75.

Between ≈ 0,75 and 1, some increase in this ratio may occur.

The fire’s oxygen demand is limited by the ventilation opening(s); the flames extend into the upper layer.

Assumed to be similar to well-ventilated flaming.

The plume equivalence ratio has not been measured; the use of a global equivalence ratio is inappropriate.

Instances of lower ratios have been measured. Generally, these result from secondary combustion outside the room vent.

---------------------- Page: 12 ----------------------
IEC TS 60695-5-2:2021 © IEC 2021 – 11 –
4.4.3 Indirect assessment

An indirect method of assessment is one that uses no corrosion target but measures a

characteristic of the gases and vapours evolved. For example, the amount of halogen acid

produced, or the pH and/or the conductivity of a solution in which the gases and vapours

evolved by combustion have been dissolved.
5 Published test methods
5.1 General

The test methods reviewed in this clause were selected on the basis that they are published

in international, national or industry standards, and are in common usage in the
electrotechnical field. It is not intended to review all possible test methods.

NOTE These summaries are intended as a brief outline of the test methods and as such not meant to be used

in place of full published standards.
5.2 Tests for the determination of halogen acid in combustion gases
5.2.1 Standards

International standard IEC 60754-1 [4], which is a test on cable materials, is based on the

method described in 5.2.2 to 5.2.6.
5.2.2 Purpose and principle

The standard specifies the procedure for the determination of the amount of halogen acid gas,

other than hydrofluoric acid, evolved during the combustion of compounds based on

halogenated polymers, and compounds containing halogenated additives
...

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