IEC 62021-2:2007

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
Reference number
Numéro de référence
IEC/CEI 62021-2:2007
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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
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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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
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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.
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 handled with due regard to
personal hygiene. Direct contact with eyes may cause slight irritation. In the case of eye
contact, irrigation with copious quantities of clean running water should be carried out and
medical advice sought.
Some of the tests specified in this standard involve the use of processes that could lead to a
hazardous situation. Attention is drawn to the relevant standard for guidance.
This standard involves mineral oils, chemicals and used sample containers. The disposal of
these items should be carried out in accordance with current national legislation with regard
to the impact on the environment. Every precaution should be taken to prevent the release
into the environment of mineral oil.

– 6 – 62021-2 © IEC:2007
INSULATING LIQUIDS –
DETERMINATION OF ACIDITY –
Part 2: Colourimetric titration

1 Scope
This part of IEC 62021 describes a procedure for determination of the acidity of unused and
used electrical mineral insulating oils.
NOTE 1 In unused and used mineral insulating oils, the constituents that may be considered to have acidic
characteristics include organic acids, phenolic compounds, some oxidation products, resins, organometallic salts
and additives.
The method may be used to indicate relative changes that occur in a mineral insulating oil
during use under oxidizing conditions that may or may not be shown by other properties of the
resulting mineral oil.
The acidity can be used in the quality control of unused mineral oil.
As a variety of oxidation products present in used mineral oil contribute to acidity and these
products vary widely in their corrosion properties, the test cannot be used to predict
corrosiveness of a mineral oil under service conditions.
NOTE 2 The acidity results obtained by this test method may or may not be numerically the same as those
obtained by potentiometric methods, but they are generally of the same magnitude. The potentiometric method
uses an endpoint at pH 11,3 to ensure titration of all species, whereas the colourimetric methods uses an indicator
changing colour at approximately pH 9,5. This may lead to slightly higher results for oils with acidities above
0,3 mg KOH/g oil when using the potentiometric method.
2 Normative references
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.
IEC 60475: Method of sampling liquid dielectrics
IEC 60567: Oil-filled electrical equipment – Sampling of gases and of oil for analysis of free
and dissolved gases – Guidance
ISO 5725: Accuracy (trueness and precision) of measurement methods and results
ISO 6619: Petroleum products and lubricants – Neutralization number – Potentiometric
titration method
62021-2 © IEC:2007 – 7 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acidity
quantity of base, expressed in milligrams of potassium hydroxide per gram of sample,
required to titrate colourimetrically a test portion in a specified solvent to the neutralization
point of Alkali Blue 6B
3.2
unused oil
mineral insulating oil that has not been used in, or been in contact with electrical equipment
4 Principle
The test portion is dissolved in a specified solvent and titrated colourimetrically with alcoholic
potassium hydroxide to a specified colour using Alkali Blue 6B indicator.
5 Reagents
Only reagents of recognized analytical grade and de-ionized water or water of equivalent
purity shall be used.
5.1 Titration reagent
Standard alcoholic solution 0,05 mol/l potassium hydroxide.
Add 3,0 g of potassium hydroxide to 1 000 ml ± 10 ml of 2-propanol. Boil gently for 10 min to
effect solution. Cool and stopper the flask.
Allow the solution to stand in the dark for 2 days and then filter the supernatant liquid through
a 5 μm membrane filter. Store in a suitable amber glass bottle.
The concentration of this solution is approximately 0,05 mol/l and shall be standardized as
described in 8.1. For periodic tests on equipment in service, faster titration may be achieved
by the use of 0,1 mol/l potassium hydroxide by agreement between the laboratory and the
equipment owner, although this may result in poorer precision and detection limit.
Commercial alcoholic potassium hydroxide solution may be used, if necessary diluting to
0,05 mol/l with 2-propanol. This shall be standardized as described in 8.1.
Store and use in such a manner that the solution is protected from atmospheric carbon
dioxide and in such a way that it does not come into contact with cork, rubber or saponifiable
stopcock grease. The solution may be protected by inert gas or by means of a guard tube
containing soda-lime absorbent.

– 8 – 62021-2 © IEC:2007
5.2 Titration solvent
2-propanol (isopropanol; IPA), pure.
5.3 Potassium hydrogen phthalate, primary standard
This should be dried before use for 2 h at 105 °C.
5.4 Standard hydrochloric acid solution
A 0,1 mol/l solution of hydrochloric acid in de-ionized water, prepared as in ISO 6619, may be
used. Other acids may be used, provided they are certified against a primary standard.
5.5 Alkali blue 6B indicator solution
Dissolve 2 g ± 0.1 g of alkali blue 6B in 100 ml of 2-propanol or azeotropic ethanol containing
1 ml of the hydrochloric acid solution. After 24 h, carry out a titration to check whether the
indicator has been sufficiently sensitized. The indicator is satisfactory if the colour changes
distinctly from blue to red comparable to that of a 10 % solution of cobalt nitrate. If
sensitization is insufficient, repeat the addition of the hydrochloric acid solution and check
again after 24 h. Continue until sensitization is satisfactory. Filter and store in a brown bottle
in the dark.
Commercial alkali blue 6B solution may be used as an alternative if the concentration is within
the range 0,05 % to 5 %. If the concentration is not 2 %, the amount added to the solvent in
8.2 and 8.3 should be adjusted to maintain the same ultimate concentration.
5.6 Cobalt nitrate solution
Co(NO ) .6H O solution, 10 % in water.
3 2 2
6 Apparatus
6.1 Titration vessel
This should be as small as possible, sufficient to contain the solvent, sample and stirrer and
be inert to the reagents. Glass conical vessels are preferred.
6.2 Stirrer
Stirring may be manual by swirling the solution on the titration vessel, or mechanically using a
variable speed stirrer fitted with a propeller, paddle or magnetic bar of chemically inert
surface material.
6.3 Burette
A burette or syringe capable of adding aliquots of 0,001 ml shall be used.
7 Sampling
Samples shall be taken following the procedure given in IEC 60475 and/or IEC 60567.
Ensure that the test portion is representative by thoroughly mixing, as any sediment present
may be acidic or have adsorbed acidic material from the liquid phase.

62021-2 © IEC:2007 – 9 –
8 Procedure
Rinse and fill the burette with 0,05 mol/l alcoholic potassium hydroxide solution (5.1).
Standardize the alcoholic potassium hydroxide solution at least every two weeks against
potassium hydrogen phthalate (5.3) or certified standard 0,1 mol/l acid.
Carry out a blank titration on the solvent (5.2) each day and after changing to a fresh batch of
solvent.
8.1 Standardization of alcoholic potassium hydroxide solution
Standardize the alcoholic potassium hydroxide solution, using a suitable indicator, against
0,1 g to 0,16 g of potassium hydrogen phthalate, weighed to an accuracy of 0,000 2 g and
dissolved in approximately 100 ml of carbon dioxide free water.
Alternatively the standardization can be performed by potentiometric titration.
Calculate the molarity M to the nearest 0,000 5 using Equation (1):
1 000 × m × p
Molarity = (1)
204,23 ×V
where
m is the mass of potassium hydrogen phthalate, in grams;
p is the percent purity of the potassium hydrogen phthalate;
V is the volume of potassium hydroxide solution, in millilitres.
Alternatively, certified standard 0,1 mol/l acid may be used to standardize the alcoholic
potassium hydroxide solution.
Calculate the molarity M to the nearest 0,000 5 using Equation (2):
V × M
1 A
Molarity = (2)
V
where
V is the volume of 0,1 mol/l standard acid used to titrate the solution, in millilitres;
M is the molarity of the standard hydrochloric acid;
A
V is the volume of potassium hydroxide solution, in millilitres.
8.2 Blank titration
Perform a blank titration at a temperature not above 25 °C on 10 ml ± 0,1 ml aliquots of the
solvent containing 0,5 % of alkali blue 6B indicator solution (5.5) using the standardized
alcoholic potassium hydroxide solution. The endpoint shall be as soon as a colour change
from blue to a red colour comparable to that of the cobalt nitrate solution (5.6) is obtained and
persists for at least 15 s.
Carry out triplicate titrations and calculate the mean result, in millilitres to the nearest
0,001 ml, as the blank value V .
– 10 – 62021-2 © IEC:2007
Protect the solvent from atmospheric carbon dioxide and use within 8 h.
8.3 Sample titration
Weigh 5 g of sample to the nearest 0,01 g into the titration vessel. Add 10 ml ± 0,1 ml of the
solvent solution containing 0,5 % of alkali blue 6B indicator solution (5.5). Swirl to dissolve
the oil and immediately titrate at a temperature not above 25 °C with the standardized
potassium hydroxide solution. A typical end point is as described in 8.2. However, since the
colour change may vary for different oils, pre-titration may be necessary to establish this. In
such cases, the endpoint shall be reached as soon as a stable colour change, which persists
for at least 15 s, is obtained.
NOTE Before titrating, the colour may vary from blue to green and at the endpoint from red to light orange to dark
yellow-brown, depending on the original colour of the oil.
Carry out determinations for each oil sample and note the result, in millilitres, to the nearest
0,001 ml, as the titration value V .
9 Calculation of results
Calculate, for each determination, the acidity to the nearest 0,005, expressed as mg KOH/g of
oil, using Equation (3):
()V −V × M × 56,1
1 0
Acidity = (3)
m
where
V is the volume of alcoholic KOH solution used to titrate the test sample, in millilitres;
V is the mean volume of alcoholic KOH solution used for the blank titration, in millilitres;
M is the molarity of alcoholic KOH solution;
m is the mass of the test portion used, in grams.
10 Precision
The repeatability and reproducibility limits were established in accordance with ISO 5725.
10.1 Repeatability
The difference between successive test results obtained by the same operator with the same
apparatus under constant operating conditions on identical test material would, in the long run,
in the normal and correct operation of the test method, exceed the values shown below only in
one case in 20:
− unused oils –15 %;
− used oils –10 %.
NOTE The repeatability values for unused oils only apply where the result is significantly above the quantification
limit, which has been established as 0,01 mg KOH/g oil.

62021-2 © IEC:2007 – 11 –
10.2 Reproducibility
The difference between two single and independent results obtained by different operators
working in different laboratories on identical test material would, in the long run, in the normal
and correct operation of the test method, exceed the values shown below only in one case
in 20:
− unused oils – 35 %;
− used oils – 20 %.
NOTE The reproducibility values for unused oils only apply where the result is significantly above the
quantification limit, which has been established as 0,01 mg KOH/g oil.
11 Report
The test report shall contain at least the following information.
– The type and identification of the product tested.
– A reference to this International Standard.
– The result of the test (see Clause 9) expressed to the nearest 0,01 mg KOH/g of oil.
– Any deviation, by agreement or otherwise, from the procedure specified.
– The date of the test.
– 12 – 62021-2 © IEC:2007
Annex A
(informative)
Determination of acidity in electrical insulating oils
by photometric titration
A.1 Principle
A sample of new or used oil is dissolved in a mixture of toluene and 2-propanol containing a
small amount of water. The solution is titrated at ambient temperature with alcoholic
potassium hydroxide. The neutralization of acid components in oil is detected by the colour
change of the added para-naphtolbenzein indicator, using a photometric sensor at 660 nm.
A.2 Reagents and solvents
– Para-naphtolbenzein indicator (1 % in alcoholic solution)
– Potassium hydroxide solution in 2-propanol (1 mol/l)
– Potassium hydrogen phthalate
– 2-Propanol, anhydrous, HPLC grade
– Toluene, HPLC grade
– Demineralized water, conductivity < 0,1 μS/cm
– Methanol, HPLC grade
– CO absorbing agent, 8-20 mesh
– Water absorbing agent, 10-20 mesh
NOTE It is recommended to filter all solvents, solutions and oil samples prior to use.
A.2.1 Preparation of titration solutions and solvents
A.2.1.1 Potassium hydroxide alcoholic solution (0,05 mol/l)
Introduce 50 ml of the potassium hydroxide solution in 2-propanol (1 mol/l) into a volumetric
vessel of 1 l. Make up to 1,0 l with 2-propanol.
A.2.1.2 Potassium hydrogen phthalate solution (0,05 mol/l)
Crush 10 g of potassium hydrogen phthalate in a mortar and dry at 120 °C for 1 h, then cool in
a desiccator containing a water-absorbing agent. Weigh about 5 g of dried potassium
hydrogen phthalate precisely in a scoop and introduce it in a volumetric vessel of 500 ml.
Wash the scoop several times with small amounts of water into the volumetric vessel. Make
up to 500,0 ml with demineralised water.
Calculate the molarity to the nearest 0,000 5 using following Equation (A.1):
m
Molarity (M KPH) =   (A.1)
204,23 × 0,5
where m is the mass of potassium hydrogen phthalate, in gram.

62021-2 © IEC:2007 – 13 –
A.2.1.3 Titration solvent
The composition of the titration solvent in % volume/volume is: 50 % toluene, 49,5 %
2-propanol, 0,5 % demineralized water. 500 μl of para-naphtolbenzein indicator solution is
added per 100 ml of titration solvent.
A.3 Apparatus
A.3.1 Volumetric titrator
The apparatus shall be equipped with an automatic burette of 5 ml capacity with a dispensing
accuracy of ±0,01ml. A guard tube containing the water and carbon dioxide absorbing agents
is necessary for the reservoir for the alcoholic potassium hydroxide solution.
A.3.2 Titration vessel
The titration vessel shall have a 100 ml capacity and be inert to the reagents.
NOTE The vessel volume should be such that the photometer probe is covered by liquid during the titration.
A.3.3 Titration stand
A suitable stand shall be provided to support the titration vessel, stirrer, automatic burette and
photometric sensor.
A.3.4 Stirrer
The stirrer shall be mechanical or electrical, having variable speed.
A.3.5 Recorder/printer
A device shall be required to record/print out the data coming from the titrator and
photometric sensor.
NOTE 1 Installing the titration apparatus in a fume hood will eliminate solvent vapours from the laboratory
environment.
NOTE 2 An automatic sampler may be used to increase the productivity of analyses.
A.3.6 Photometric sensor
A suitable sensor is equipped with a glass-fibre light guide probe measuring the transmission
of light in the visible region, equipped with a filter allowing measurements to be made in a
bandwidth of less than 10 nm at any visible wavelength.
The molecular structures of para-naphtolbenzein indicator in acidic and basic media are
indicated in Figure A.1. The UV transmission rate is maximum at 660 nm in acidic media,
giving the solution an orange colour (Figure A.2). It is minimum at 660 nm in basic media,
changing the solution to green colour. The wavelength of the photometric sensor therefore is
set at 660 nm.
NOTE Phenolphthalein indicator may also be used at 550 nm.
A.4 Procedure
A.4.1 Preparation and maintenance of the titration system
It is necessary to clean the titration vessel, stirrer and photometric sensor with methanol and
to air-dry them before each use.

– 14 – 62021-2 © IEC:2007
NOTE If the photometer and its controller cannot be set to achieve the manufacturer’s recommended parameters,
this may be an indication that the photometer is dirty and should be cleaned more thoroughly.
A.4.2 Determination of acidity of the titration solvent
Install the photometric sensor on the titration stand and connect it to the titrator. Flush the
automatic burette 3 times into a beaker using the KOH solution. The tubes carrying the KOH
solution should not contain bubbles after these operations. Fix a cleaned titration vessel to
the titration stand.
Introduce 50 ml ± 0,1 ml of titration solvent into the titration vessel. Start the stirrer. Place the
tip of the automatic burette in the centre of the solution, at about 2,5 cm from the stirrer. The
optical path of the photometric sensor should be void of any bubbles. If there are bubbles,
adjust stirring speed to eliminate them. Set the voltage on the photometric sensor at 1 000 mV.
Start titrating with the potassium hydroxide alcoholic solution (0,05 mol/l) and the automatic
burette. The printer will print the titration curve (in mV vs. ml), the first derivative of the
titration curve (in mV/ml vs. ml) and the volume of KOH solution used (in ml). Note volume of
KOH used for neutralization of titration solvent as V .
NOTE The above procedure should be carried out daily.
A.4.3 Determination of molarity of the potassium hydroxide alcoholic solution
(0,05 mol/l)
Proceed as follows:
a) fix a cleaned titration vessel to the titration stand;
b) introduce 1 ml ± 0,01 of potassium hydrogen phthalate water solution (0,05 mol/l) into the
titration vessel. Add 50 ml of titration solvent;
c) titrate as in A.4.2.
Calculate the molarity of the KOH solution to the nearest 0,000 5 using the following Equation
(A:2):
1× M
KHP
Molarity =   (A.2)
V
where
M is molarity of potassium hydrogen phthalate;
KHP
V is volume of potassium hydroxide solution, in millilitres.
Calculate the final value of molarity as the average of 3 determinations.
NOTE Procedure A.4.3 need only be carried out each month. The potassium hydroxide alcoholic solution has
been found quite stable with time when suitably stored; see 5.1.
A.4.4 Titration of soluble acidity in the oil sample
Proceed as follows:
a) fix a cleaned titration vessel to the titration stand;
b) for new oils or only slightly used oils, introduce 20 g ± 0,01 g of oil in the titration vessel.
For highly used oils, introduce 5 g ± 0,01 g of oil;
c) add 50 ml ± 0,1 ml of titration solvent and titrate as in A.4.2.

62021-2 © IEC:2007 – 15 –
Calculate the acidity of the oil sample KOH to the nearest 0,000 5, using the following
Equation (A.3):
()V −V × M × 56,1
1 0
Acidity =  (A.3)
m
where
V is the volume of alcoholic KOH solution used to titrate the test sample, in millilitres;
V is the mean volume of alcoholic KOH solution used for the blank titration (titration
solvent), in millilitres;
M is the molarity of alcoholic KOH solution;
m is the mass of the test portion used, in grams.
NOTE On modern equipment, data measured in A.4.2, A.4.3 and A.4.4 may be stored in the memory of the
equipment to automate calculations.

–+
OH O K
KHO
C HO C
H O
–+
O O K
IEC  681/07
Figure A.1 – Molecular structure of para-naphtolbenzein indicator
in (I) acidic media and (II) basic media

– 16 – 62021-2 © IEC:2007
b
a
350 450 550 650
Wavelength  nm
IEC  682/07
Figure A.2 – UV spectra of para-naphthol-benzein indicator in toluene/2-propanol/water
solution in (a) acidic media, (b) basic media
____________
Transmission  %
– 18 – 62021-2 © CEI:2007
SOMMAIRE
AVANT-PROPOS.19
INTRODUCTION.21

1 Domaine d’application .22
2 Références normatives.22
3 Termes et définitions .23
4 Principe.23
5 Réactifs.23
5.1 Réactif titrant.23
5.2 Solvant titrant.24
5.3 Hydrogénophthalate de potassium, étalon primaire .24
5.4 Solution d’acide chlorhydrique normalisée.24
5.5 Solution indicatrice de Bleu Alcalin 6B.24
5.6 Solution de nitrate de cobalt.24
6 Appareillage .24
6.1 Récipient de titrage .24
6.2 Agitateur .24
6.3 Burette .24
7 Échantillonnage.24
8 Mode opératoire .25
8.1 Détermination du titre de la solution alcoolique d’hydroxyde de potassium .25
8.2 Titrage à blanc .25
8.3 Titrage d’échantillons .26
9 Calcul des résultats .26
10 Précision .26
10.1 Répétabilité.26
10.2 Reproductibilité .27
11 Rapport .27

Annexe A (informative) Détermination de l’acidité dans les huiles isolantes électriques
par titrage photométrique.28

Figure A.1 – Structure moléculaire d'indicateur de para-naphtol-benzene dans les
supports acides (I) et de base (II) .31
Figure A.2 – Spectres UV de l’indicateur de para-naphtol-benzène dans la solution
aqueuse toluène/2-propanol dans les supports acides (a) et de base (b) . .32

62021-2 © CEI:2007 – 19 –
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
___________
LIQUIDES ISOLANTS –
DÉTERMINATION DE L’ACIDITÉ –
Partie 2: Titrage colorimétrique

AVANT-PROPOS
1) La Commission Electrotechnique Internationale (CEI) est une organisation mondiale de normalisation
composée de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI). La CEI a
pour objet de favoriser la coopération internationale pour toutes les questions de normalisation dans les
domaines de l'électricité et de l'électronique. A cet effet, la CEI – entre autres activités – publie des Normes
internationales, des Spécifications techniques, des Rapports techniques, des Spécifications accessibles au
public (PAS) et des Guides (ci-après dénommés "Publication(s) de la CEI"). Leur élaboration est confiée à des
comités techniques – tous les comités nationaux de la CEI qui sont intéressés par le sujet traité peuvent
participer à ces travaux d’élaboration. Des organisations internationales, gouvernementales et non
gouvernementales peuvent également participer à ces travaux en liaison avec la CEI. La CEI collabore
étroitement avec l'Organisation Internationale de Normalisation (ISO), selon des conditions fixées par accord
entre les deux organisations.
2) Les décisions ou accords officiels de la CEI concernant les questions techniques représentent, dans la mesure
du possible, un accord international sur les sujets étudiés, étant donné que les Comités nationaux de la CEI
intéressés sont représentés dans chaque comité d’études.
3) Les Publications de la CEI se présentent sous la forme de recommandations internationales et sont agréées
comme telles par les Comités nationaux de la CEI. Tous les efforts raisonnables sont entrepris afin que la CEI
s'assure de l'exactitude du contenu technique de ses publications; la CEI ne peut pas être tenue responsable
de l'éventuelle mauvaise utilisation ou interprétation qui en est faite par un quelconque utilisateur final.
4) Dans le but d'encourager l'unification internationale, les Comités nationaux de la CEI s'engagent à appliquer de
façon transparente, dans toute la mesure possible, les normes internationales de la CEI dans leurs normes
nationales et régionales. Toute divergence entre toute Publication de la CEI et toute publication nationale ou
régionale correspondante doit être indiquée en termes clairs dans cette dernière.
5) La CEI n’a prévu aucune procédure de marquage valant indication d’approbation et n'engage pas sa
responsabilité pour les équipements déclarés conformes à une de ses Publications.
6) Tous les utilisateurs doivent s'assurer qu'ils sont en possession de la dernière édition de cette publication.
7) Aucune responsabilité ne doit être imputée à la CEI, à ses administrateurs, employés, auxiliaires ou
mandataires, y compris ses experts particuliers et les membres de ses comités d'études et des Comités
nationaux de la CEI, pour tout préjudice causé en cas de dommages corporels et matériels, ou de tout autre
dommage de quelque nature que ce soit, directe ou indirecte, ou pour supporter les coûts (y compris les frais
de justice) et les dépenses découlant de la publication ou de l'utilisation de cette Publication de la CEI ou de
toute autre Publication de la CEI, ou au crédit qui lui est accordé.
8) L'attention est attirée sur les références normatives citées dans cette publication. L'utilisation de publications
référencées est obligatoire pour une application correcte de la présente publication.
9) L’attention est attirée sur le fait que certains des éléments de la présente Publication de la CEI peuvent faire
l’objet de droits de propriété intellectuelle ou de droits analogues. La CEI ne saurait être tenue pour
responsable de ne pas avoir identifié de tels droits de propriété et de ne pas avoir signalé leur existence.
La Norme internationale CEI 62021-2 a été établie par le comité d’études 10 de la CEI:
Fluides pour applications électrotechniques.
Le texte de cette norme est issu des documents suivants:
FDIS Rapport de vote
10/692/FDIS 10/696/RVD
Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant
abouti à l'approbation de cette norme.
Cette publication a été rédigée selon les Directives ISO/CEI, Partie 2.

– 20 – 62021-2 © CEI:2007
Une liste de toutes les parties de la série CEI 62021, présentées sous le titre général
Liquides isolants – Détermination de l’acidité peut être consultée sur le site web de la CEI.
Le comité a décidé que le contenu de cette publication ne sera pas modifié avant la date de
maintenance indiquée sur le site web de la CEI sous «http://webstore.iec.ch» dans les
données relatives à la publication recherchée. A cette date, la publication sera
• reconduite;
• supprimée;
• remplacée par une édition révisée, ou
• amendée.
62021-2 © CEI:2007 – 21 –
INTRODUCTION
La méthode normalisée existante dans la CEI 62021-1 est la méthode de mesure de l’acidité
dans les huiles minérales neuves et usagées et il s'agit d'un titrage potentiométrique
nécessitant des appareils de mesure spéciaux en vue de la mesure de l’acidité.
Historiquement, l’acidité des huiles isolantes a été mesurée par titrage colorimétrique comme
décrit dans la CEI 60296, édition 1982. Avec la révision de la CEI 60296, le titrage
colorimétrique a été supprimé parce quecette méthode utilisait de grands volumes
d’échant
...