Insulating liquids - Methods for counting and sizing particles

Describes the sampling procedures and methods for the determination of particle concentration and size distribution. Three methods are specified. One uses an automatic particle size analyser, working on the light interruption principle. The other two use an optical microscope, in either the transmitted light or incident light mode, to count particles collected on the surface of a membrane filter. The optical microscope methods are described in ISO 4407. All three methods are applicable to both used and unused insulating liquids. Annex A contains an alternative sampling procedure using a syringe and Annex B reports a reference for the calibration of automatic particle counters. The significant technical changes with respect to the previous edition are as follows: - new calibration procedures for automated laser particle; - three figures contamination code; - new procedure of sample pre-treatment when automated laser counter method are used.

Isolierflüssigkeiten - Verfahren zur Bestimmung der Anzahl und Größen von Teilchen

Isolants liquides - Méthodes de détermination du nombre et de la taille des particules

Décrit les procédures de prélèvement et les méthodes pour déterminer la concentration des particules et la répartition selon leur taille. Trois méthodes sont recommandées. L'une d'entre elles utilise un analyseur automatique de particules, dont le principe repose sur l'interruption d'un faisceau lumineux. Les deux autres utilisent un microscope optique, en mode soit de lumière transmise soit de lumière incidente, pour compter les particules retenues à la surface d'une membrane filtrante. Les méthodes au microscope optique sont décrites dans l'ISO 4407. Ces trois méthodes sont applicables tant aux isolants liquides usagés qu'aux isolants liquides neufs. L'Annexe A comporte une autre procédure d'échantillonnage utilisant une seringue et l'Annexe B indique une référence pour l'étalonnage des compteurs automatiques de particules. Les principales modifications techniques par rapport à l'édition précédente sont les suivantes: - nouvelles procédures d'étalonnage pour les analyseurs automatiques de particules; - code de contamination à trois chiffres; - nouvelle procédure pour le pré-traitement d'échantillons quand la méthode des compteurs de particules automatisés est utilisée.

Izolacijske tekočine – Metode za štetje in ugotavljanje velikosti delcev (IEC 60970:2007)

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Insulating liquids - Methods for counting and sizing particles
Isolierflüssigkeiten - Verfahren zur Bestimmung der Anzahl und Größen von Teilchen
Isolants liquides - Méthodes de détermination du nombre et de la taille des particules
Ta slovenski standard je istoveten z: EN 60970:2007
17.220.99 Drugi standardi v zvezi z Other standards related to
elektriko in magnetizmom electricity and magnetism
29.040.01 Izolacijski fluidi na splošno Insulating fluids in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 60970
August 2007
ICS 17.220.99. 29.040.10
English version
Insulating liquids -
Methods for counting and sizing particles
(IEC 60970:2007)
Isolants liquides -  Isolierflüssigkeiten -
Méthodes de détermination du nombre Verfahren zur Bestimmung der Anzahl
et de la taille des particules und Größen von Teilchen
(CEI 60970:2007) (IEC 60970:2007)

This European Standard was approved by CENELEC on 2007-08-01. 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.

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 60970:2007 E
The text of document 10/695/FDIS, future edition 2 of IEC 60970, prepared by IEC TC 10, Fluids for
electrotechnical applications, was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 60970 on 2007-08-01.
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) 2008-05-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-08-01
Annex ZA has been added by CENELEC.
Endorsement notice
The text of the International Standard IEC 60970:2007 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60422 NOTE Harmonized as EN 60422:2006 (not modified).
ISO 4402 NOTE Harmonized as EN ISO 14402:1999 (not modified).
- 3 - EN 60970:2007
Annex ZA
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
Publication Year Title EN/HD Year
- - Insulating oil - Determination of fibre EN 50353 -
contamination by the counting method using
a microscope
IEC 60475 - Method of sampling liquid dielectrics - -

ISO 4406 - Hydraulic fluid power - Fluids - Method for - -
coding the level of contamination by solid
ISO 4407 - Hydraulic fluid power - Fluid contamination - - -
Determination of particulate contamination by
the counting method using an optical
ISO 5884 - Aerospace - Fluid systems and components - - -
Methods for system sampling and measuring
the solid particle contamination of hydraulic
Undated reference.
Second edition
Deuxième édition
Insulating liquids – Methods for counting and
sizing particles
Isolants liquides – Méthodes de détermination du
nombre et de la taille des particules
Commission Electrotechnique Internationale
International Electrotechnical Commission
For price, see current catalogue
Pour prix, voir catalogue en vigueur

– 2 – 60970 © IEC:2007

1 Scope.6
2 Normative references .6
3 General caution, health, safety and environmental protection .6
4 Significance.7
5 Comparison and limitation of the methods .7
6 Types and identification of particles.8
7 Sampling .8
7.1 General remarks.8
7.2 Sampling vessels .9
7.3 Cleaning of sampling bottles .9
7.4 General directions for sampling .9
7.5 Sampling procedure .10
7.6 Labelling of samples.10
7.6.1 Samples from tanks .10
7.6.2 Samples from electrical equipment .10
8 Preparation of the samples for analysis .10
9 Method A – Automatic particle size analyzer.11
9.1 Summary of method .11
9.2 Apparatus and auxiliary materials.11
9.3 Calibration procedures .11
9.4 Preparation of the apparatus for counting.12
9.5 Preparation of sample before counting .12
9.6 Preparation of sample for counting .12
9.7 Counting procedures .12
9.8 Report .13
9.9 Precision .13
9.10 Repeatability .13
9.11 Reproducibility .13
10 Method B – Optical microscopy .14
10.1 Principle.14
10.2 Procedure by transmitted light .14
10.3 Procedure by incident light .14

Annex A (informative) Use of syringes as sampling vessels .15
Annex B (informative) Calibration of the automatic particle counters .17


60970 © IEC:2007 – 3 –
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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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
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 60970 has been prepared by IEC technical committee 10: Fluids
for electrotechnical applications.
This second edition cancels and replaces the first edition published in 1989. This edition
constitutes a technical revision.
The significant technical changes with respect to the previous edition are as follows:
– new calibration procedures for automated laser particle;
– three figures contamination code;
– new procedure of sample pre-treatment when automated laser counter method are used.

– 4 – 60970 © IEC:2007
The text of this standard is based on the following documents:
FDIS Report on voting
10/695/FDIS 10/714/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.
The committee has decided that the contents of this publication will remain unchanged until

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