IEC 60734:2001

INTERNATIONAL IEC
STANDARD
Third edition
2001-12
Household electrical appliances –
Performance –
Hard water for testing
Appareils électrodomestiques –
Aptitude à la fonction –
Eau dure pour les essais
Reference number
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INTERNATIONAL IEC
STANDARD
Third edition
2001-12
Household electrical appliances –
Performance –
Hard water for testing
Appareils électrodomestiques –
Aptitude à la fonction –
Eau dure pour les essais
 IEC 2001  Copyright - all rights reserved
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– 2 – 60734  IEC:2001(E)
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Definitions .6
4 General .7
5 Composition and preparation of artificial hard waters.7
6 Storage of standardised hard water .11
7 Checking .11
Annex A (informative) Water hardness – Conversion table.12
Annex B (normative) Amounts of salts to be used for rehardening demineralised water .13
Annex C (informative) Amounts of waters to be mixed at various degrees of hardness
of the natural water according to methods C1 and C2 .14

60734  IEC:2001(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HOUSEHOLD ELECTRICAL APPLIANCES –
PERFORMANCE –
HARD WATER FOR TESTING
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International standard IEC 60734 has been prepared by subcommittee 59D: Home laundry
appliances, of IEC Technical Committee 59: Performance of household electrical appliances.
This third edition of IEC 60734 replaces the second edition published in 1993.
The text of this standard is based on the following documents:
FDIS Report on voting
59D/201/FDIS 59D/210/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 3.
Annex B forms an integral part of this standard.
Annexes A and C are for information only.
Words in bold in the text are defined in clause 3.

– 4 – 60734  IEC:2001(E)
The committee has decided that the contents of this publication will remain unchanged until
2006. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

60734  IEC:2001(E) – 5 –
INTRODUCTION
This publication describes several methods to prepare water of standardised hardness to be
used for testing household appliances in cases where the water quality is important for the
reproducibility of the test results.
It is based on the second edition of IEC 60734, which describes two methods, A and B, of
preparing water of three different water hardnesses. Experiences from application of the
methods have shown that they are unnecessarily rigid for some purposes and thus expensive
or not suited for the preparation of large quantities of water. Furthermore the hardness given
is not in line with those stated in some performance standards. Complementary methods C1
and C2 have been developed to be used in such cases. These allow the use of natural
instead of demineralised water.
Method A is used to prepare hard water of the correct total hardness. Preparation starts with
demineralised water in which hardening salts are dissolved by bubbling carbon dioxide though
the mixture.
Method B involves preparation in a similar way but with other salts, which are soluble without
addition of carbon dioxide. This method will result in excessive amounts of some ions
compared to method A. Both methods give water with specified temporary as well as
permanent hardness.
Method C1 starts with natural water with higher hardness than required, while method C2
starts with soft natural water, which is hardened. Depending on the composition of the natural
water, several other ions might be present. Restrictions regarding the amounts are given for
some ions, which may influence the cleaning results when testing washing machines and
dishwashers. No specification regarding temporary and permanent hardness is given.

– 6 – 60734  IEC:2001(E)
HOUSEHOLD ELECTRICAL APPLIANCES –
PERFORMANCE –
HARD WATER FOR TESTING
1 Scope
This International Standard describes the preparation of three types of water of different
hardness intended to be used for testing the performance of household appliances such as
washing machines, dishwashers, dryers, steam irons etc.
It defines the characteristics of these waters and establishes various methods to be used for
obtaining them.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
ISO 6059:1984, Water quality – Determination of the sum of calcium and magnesium – EDTA
titrimetric method
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1
water hardness
measurement, in degrees, indicating the quantity of alkaline earth salts (bicarbonates,
sulphates, chlorides etc.) present in the water
3.2
total hardness
the sum of calcium and magnesium ions in the water
3.3
temporary hardness
the fraction of the total hardness equivalent to the bicarbonate content
3.4
permanent hardness
the difference between the total and the temporary hardness

60734  IEC:2001(E) – 7 –
4 General
4.1 Principle
Hard water may be prepared according to different methods. Methods A and B may be used
both for large and small amounts of water. Methods C1 and C2, which give less well defined
hard waters, should only be used for large amounts.
Since natural waters are variable in character and hardness, the only procedure for the
preparation of hard water with a completely specified co mposition starts with completely
demineralised water according to 5.1, which is subsequently hardened to the right level. The
rehardening may be performed in two ways, resulting in either a water with exactly the
composition required in method A, according to 5.2, or a water with an excess of sodium,
chlorine and sulphate ions, as required in method B, according to 5.3.
The second method takes less time to perform and the composition is satisfactory if the
excess of ions is acceptable.
The third method, which does not allow exact control of the composition, gives water with the
required hardness but may contain unknown ions as well. It starts with natural water, which is
either diluted with demineralised water through method C1, according to 5.4.2, or rehardened
through method C2, according to 5.4.3, depending on the source and object. The ratio
between calcium and magnesium is kept within relatively wide limits. Some restrictions
regarding the levels of metal ions are set.
NOTE Depending on the appliance to be tested, the prepared water may have to be cooled down to the required
temperature.
4.2 Units
2+ 2+
Hardness is expressed in mmol/l for the ions Ca and Mg .
NOTE A table for conversion into other hardness units is given in annex A.
4.3 Levels of water hardness
This standard defines three different levels of water hardness:
2,5 mmol/l
1,5 mmol/l total hardness Ca + Mg
0,5 mmol/l
NOTE With these three values of water hardness it is possible to select one or more standardised hard waters,
which would approximate the local natural waters available. If any other hardness is needed, it can be prepared in
a similar way by interpolation of the given amounts of chemicals.
5 Composition and preparation of artificial hard waters
5.1 Demineralisation of natural water
Natural water is demineralised so that its specific resistance is 100 000 Ωcm or more (its
conductivity not more than 10 µS/cm). Water of this quality can be obtained using an
apparatus filled with a column of mixed cation and anion exchange resins or by equipment for
reverse osmosis.
NOTE When an ion exchange resin is new, the first one or two preparations should be discarded. This is not
necessary after each normal regeneration.

– 8 – 60734  IEC:2001(E)
5.2 Preparation of water method A
5.2.1 Composition of hard water prepared by method A
The temporary hardness component of the hard water consists of calcium hydrogen carbonate
(Ca(HCO ) ). The permanent hardness component is equally divided between calcium
3 2
chloride (CaCl ) and magnesium sulphate (MgSO ).
2 4
Table 1 – Composition of the hard water achieved with method A
Total hardness
mmol/l
Ions Mol. weight 0,5 1,5 2,5
Ion concentrations
mmol/l
2+
40,0 0,42 1,25 2,08
Ca
2+ 24,3 0,08 0,25 0,42
Mg
61,0 0,68 2,00 3,33
–
HCO
35,5 0,16 0,50 0,83
–
Cl
96,0 0,08 0,25 0,42
2–
SO
...