EN 62021-2:2007

SLOVENSKI STANDARD
01-november-2007
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Insulating liquids - Determination of acidity -- Part 2: Colourimetric titration (IEC 62021-
2:2007)
Isolierflüssigkeiten - Bestimmung des Säuregehaltes -- Teil 2: Kolorimetrische Titration
(IEC 62021-2:2007)
Liquides isolants - Détermination de l’acidité -- Partie 2: Titrage colorimétrique (IEC
62021-2:2007)
Ta slovenski standard je istoveten z: EN 62021-2:2007
ICS:
29.040.10 Izolacijska olja Insulating oils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62021-2
NORME EUROPÉENNE
July 2007
EUROPÄISCHE NORM
ICS 29.040.10
English version
Insulating liquids -
Determination of acidity -
Part 2: Colourimetric titration
(IEC 62021-2:2007)
Liquides isolants -  Isolierflüssigkeiten -
Détermination de l’acidité - Bestimmung des Säuregehaltes -
Partie 2: Titrage colorimétrique Teil 2: Kolorimetrische Titration
(CEI 62021-2:2007) (IEC 62021-2:2007)

This European Standard was approved by CENELEC on 2007-07-01. CENELEC 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 Central Secretariat or to any CENELEC 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 CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62021-2:2007 E
Foreword
The text of document 10/692/FDIS, future edition 1 of IEC 62021-2, prepared by IEC TC 10, Fluids for
electrotechnical applications, was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 62021-2 on 2007-07-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-04-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-07-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62021-2:2007 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 62021-2:2007
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application 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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year
1)
IEC 60475 - Method of sampling liquid dielectrics -
-
1) 2)
IEC 60567 - Oil-filled electrical equipment - Sampling of EN 60567 2005
gases and of oil for analysis of free and
dissolved gases - Guidance
ISO 5725 Series Accuracy (trueness and precision) of - -
measurement methods and results

1)
ISO 6619 - Petroleum products and lubricants - - -
Neutralization number - Potentiometric
titration method
1)
Undated reference.
2)
Valid edition at date of issue.

INTERNATIONAL IEC
STANDARD
CEI
62021-2
NORME
First edition
INTERNATIONALE
Première édition
2007-05
Insulating liquids –
Determination of acidity
Part 2:
Colourimetric titration
Liquides isolants –
Détermination de l’acidité
Partie 2:
Titrage colorimétrique
PRICE CODE
P
CODE PRIX
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
Pour prix, voir catalogue en vigueur

– 2 – 62021-2 © IEC:2007
CONTENTS
FOREWORD.3
INTRODUCTION.5

1 Scope.6
2 Normative references .6
3 Terms and definitions .7
4 Principle .7
5 Reagents.7
5.1 Titration reagent.7
5.2 Titration solvent.8
5.3 Potassium hydrogen phthalate, primary standard .8
5.4 Standard hydrochloric acid solution .8
5.5 Alkali Blue 6B indicator solution .8
5.6 Cobalt nitrate solution .8
6 Apparatus.8
6.1 Titration vessel.8
6.2 Stirrer.8
6.3 Burette .8
7 Sampling .8
8 Procedure .9
8.1 Standardization of alcoholic potassium hydroxide solution.9
8.2 Blank titration .9
8.3 Sample titration .10
9 Calculation of results .10
10 Precision .10
10.1 Repeatability .10
10.2 Reproducibility .11
11 Report .11

Annex A (informative) Determination of acidity in electrical insulating oils by
photometric titration .12

Figure A.1 – Molecular structure of para-naphtolbenzein indicator in (I) acidic media
and (II) basic media .15
Figure A.2 – UV spectra of para-naphthol-benzein indicator in toluene/2-
propanol/water solution in (a) acidic media, (b) basic media .16

62021-2 © IEC:2007 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
INSULATING LIQUIDS –
DETERMINATION OF ACIDITY –
Part 2: Colourimetric titration

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,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
International Standard IEC 62021-2 has been prepared by IEC technical committee 10: Fluids
for electrotechnical applications.
The text of this standard is based on the following documents:
FDIS Report on voting
10/692/FDIS 10/696/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 62021-2 © IEC:2007
A list of all parts of IEC 62021 series, under the general title Insulating liquids – Determination
of acidity can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
62021-2 © IEC:2007 – 5 –
INTRODUCTION
The standardized method given in IEC 62021-1 is a method for measurement of acidity in
used and unused mineral oil and is a potentiometric titration requiring special instrumentation
for measurement of acidity. Historically, acidity of insulating oil was measured by
colourimetric titration as described in IEC 60296, 1982 edition. With the revision of IEC 60296,
the colourimetric titration was deleted as that method used high volumes of sample and
solvent, generating undesirable volumes of waste.
However, there is still a market requirement for having colourimetric titration as many labs
use this method.
Health and safety
This International Standard does not purport to address all the safety problems associated
with its use. It is the responsibility of the user of the Standard to establish appropriate health
and safety practices and determine the applicability of regulatory limitations prior to use.
The mineral oils which are the subject of this standard should be
...