EN 937:2009

SLOVENSKI STANDARD
01-oktober-2009
1DGRPHãþD
SIST EN 937:2000
Kemikalije, ki se uporabljajo za pripravo pitne vode - Klor
Chemicals used for treatment of water intended for human consumption - Chlorine
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Chlor
Produits chimiques utilisés pour le traitement de l'eau destinée à la consommation
humaine - Chlore
Ta slovenski standard je istoveten z: EN 937:2009
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 .HPLNDOLMH]DþLãþHQMHYRGH Chemicals for purification of
water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 937
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2009
ICS 71.100.80 Supersedes EN 937:1999
English Version
Chemicals used for treatment of water intended for human
consumption - Chlorine
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Chlore menschlichen Gebrauch - Chlor
This European Standard was approved by CEN on 13 May 2009.
CEN 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 CEN Management Centre or to any CEN 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 CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 937:2009: E
worldwide for CEN national Members.

Contents Page
Foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Description . 6
3.1 Identification . 6
3.1.1 Chemical name . 6
3.1.2 Synonym or common name . 6
3.1.3 Relative molecular mass . 6
3.1.4 Empirical formula. 6
3.1.5 Chemical formula . 6
3.1.6 CAS Registry Number . 7
3.1.7 EINECS reference . 7
3.2 Commercial form . 7
3.3 Physical properties . 7
3.3.1 Appearance . 7
3.3.2 Density . 7
3.3.3 Solubility (in water) . 7
3.3.4 Vapour pressure . 7
3.3.5
Boiling point at 100 kPa . 7
3.3.6 Liquefaction point . 7
3.3.7 Specific heat . 8
3.3.8 Viscosity (dynamic) . 8
3.3.9 Critical temperature . 8
3.3.10 Critical pressure. 8
3.3.11 Physical hardness . 8
3.4 Chemical properties . 8
4 Purity criteria . 8
4.1 General . 8
4.2 Composition of commercial product . 9
4.3 Impurities and main by-products . 9
4.4 Chemical parameters . 9
5 Test methods . 10
5.1 General . 10
5.2 Sampling . 10
5.3 Analysis . 10
5.3.1 Determination of chlorine content . 10
5.3.2 Determination of water content . 10
5.3.3 Determination of nitrogen trichloride content . 10
6 Labelling - Transportation - Storage . 10
6.1 Means of delivery . 10
6.2 Risk and safety labelling in accordance with the EU directives . 10
6.3 Transportation regulations and labelling . 11
6.4 Marking . 11
6.5 Storage . 12
6.5.1 Storage conditions . 12
6.5.2 Long term stability . 12
6.5.3 Storage incompatibilities . 12
Annex A (informative) General information on chlorine . 13
A.1 Origin . 13
A.1.1 Raw materials . 13
A.1.2 Manufacturing process . 13
A.2 Use . 13
A.2.1 Function. 13
A.2.2 Form in which the product is used . 13
A.2.3 Treatment dose . 13
A.2.4 Means of application . 13
A.2.5 Secondary effects . 13
A.2.6 Removal of excess product . 13
Annex B (normative) General rules relating to safety . 14
B.1 Rules for safe handling and use . 14
B.2 Emergency procedures . 14
B.2.1 General . 14
B.2.2 First aid . 14
B.2.3 Spillage . 14
B.2.4 Fire . 14
Annex C (normative) Determination of nitrogen trichloride (molecular absorption spectrometry) . 15
C.1 General . 15
C.2 Principle. 15
C.3 Reaction. 15
C.4 Reagents. 15
C.5 Apparatus . 16
C.6 Sampling and samples . 17
C.7 Procedure . 17
C.7.1 Calibration solutions . 17
C.7.2 Discharge and evaporation (see Figure C.1) . 17
C.7.3 Test solution . 18
C.7.4 Determination . 19
C.7.5 Blank test determination . 19
C.8 Calculation and expression of the results . 21
C.8.1 Calibration graph (see Table C.1) . 21
C.8.2 Test solution . 21
Bibliography . 23

Foreword
This document (EN 937:2009) has been prepared by Technical Committee CEN/TC 164 “Water supply”, the
secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2009, and conflicting national standards shall be withdrawn
at the latest by December 2009.
This document supersedes EN 937:1999.
Differences between this edition and EN 937:1999 are mainly editorial to harmonize the text with other
standards in this series and more precisely as follows:
a) deletion of reference to EU Directive 80/778/EEC of July 15, 1980 in order to take into account the latest
Directive in force (see [1]);
b) deletion of Hg as Chemical Parameter in Table 1.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and United Kingdom.

Introduction
In respect of potential adverse effects on the quality of water intended for human consumption, caused by the
product covered by this European Standard:
a) this European Standard provides no information as to whether the product may be used without
restriction in any of the Member States of the EU or EFTA;
b) it should be noted that, while awaiting the adoption of verifiable European criteria, existing national
regulations concerning the use and/or the characteristics of this product remain in force.
NOTE Conformity with this European Standard does not confer or imply acceptance or approval of the product in any
of the Member States of the EU or EFTA. The use of the product covered by this European Standard is subject to
regulation or control by National Authorities.
1 Scope
This European Standard is applicable to chlorine used for treatment of water intended for human consumption.
It describes the characteristics of chlorine and specifies the requirements and the corresponding test methods
for chlorine. It gives information on its use in water treatment.
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.
EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696:1987)
ISO 1552, Liquid chlorine for industrial use — Method of sampling (for determining only the volumetric
chlorine content)
ISO 2120, Liquid chlorine for industrial use — Determination of the content of chlorine by volume in the
vaporized product
ISO 2121, Liquid chlorine for industrial use — Determination of water content — Gravimetric method
ISO 6206, Chemical products for industrial use — Sampling — Vocabulary
3 Description
3.1 Identification
3.1.1 Chemical name
Chlorine.
3.1.2 Synonym or common name
Liquid chlorine.
3.1.3 Relative molecular mass
70,91.
3.1.4 Empirical formula
Cl .
3.1.5 Chemical formula
Cl .
1)
3.1.6 CAS Registry Number
7782-50-5.
2)
3.1.7 EINECS reference
231-959-5.
3.2 Commercial form
Pressurized liquefied gas.
3.3 Physical properties
3.3.1 Appearance
Liquid chlorine is a clear, amber coloured liquid. Chlorine gas is greenish yellow, 2,5 times heavier than air. It
has a suffocating and characteristic odour.
3.3.2 Density
Liquid: 1,409 g/ml at 20 °C.
Gas:
 3,169 kg/m at 101.3 kPa at 0 °C;
 2,945 kg/m at 101.3 kPa at 20 °C.
3.3.3 Solubility (in water)
7,26 g/l at 20 °C and 100 kPa.
3.3.4 Vapour pressure
669 kPa at 20 °C.
3.3.5 3)
Boiling point at 100 kPa
- 34 °C.
3.3.6 Liquefaction point
- 101 °C at 100 kPa.
1)
Chemical Abstracts Service Registry Number.

2)
European Inventory of Existing Commercial Chemical Substances.

3)
100 kPa = 1 bar.
3.3.7 Specific heat
Liquid : 920 J/(kg.K) at - 34 °C.
Gas : 475 J/(kg.K) at 0 °C.
3.3.8 Viscosity (dynamic)
-8
Gas : 1 333 x 10 Pa.s at 20 °C.
-4
Liquid : 4,78 x 10 Pa.s at - 34 °C.
3.3.9 Critical temperature
144 °C.
3.3.10 Critical pressure
7 710,83 kPa.
3.3.11 Physical hardness
Not applicable.
3.4 Chemical properties
Chlorine is a very strong oxidizing agent and can react violently with some gases such as hydrogen. Almost all
metals form chlorides in the presence of chlorine. Organic compounds including mineral oils and greases
react very quickly with chlorine.
The standard redox potential of gaseous chlorine in neutral aqueous solution at 25 °C and 101.3 mbar is:
- -
Cl + 2e = 2 Cl E =+1,36 V (1)
(gas) (aq)
4 Purity criteria
4.1 General
This European Standard specifies the minimum purity requirements for chlorine used for the treatment of
water intended for human consumption. Limits are given for impurities commonly present in the product.
Depending on the raw material and the manufacturing process other impurities may be present and, if so, this
shall be notified to the user and when necessary to relevant authorities.
NOTE Users of this product should check the national regulations in order to clarify whether it is of appropriate purity
for treatment of water intended for human consumption, taking into account raw water quality, required dosage, contents
of other impurities and additives used in the product not stated in the product standard.
Limits have been given for impurities and chemicals parameters where these are likely to be present in
significant quantities from the current production process and raw materials. If the production process or raw
materials leads to significant quantities of impurities, by-products or additives being present, this shall be
notified to the user.
4.2 Composition of commercial product
The product shall contain at least a volume fraction of 99,5 % chlorine.
4.3 Impurities and main by-products
The product shall conform to the requirements specified in Table 1.
Table 1 — Impurities
Impurities Limit in mg/kg of product
Water (H0) 20
a
Nitrogen trichloride (NCl) 20
a
Valid for containers with a net mass of max. 1000 kg liquid chlorine.
For tanks with a higher capacity the limit shall be lowered to
10 mg/kg due to safety concerns (see [4] for further details).

NOTE 1 Other by-products consist of inert gases (nitrogen, oxygen, carbon dioxide, hydrogen) in variable proportion
which are not relevant for the purposes described in this European Standard.
NOTE 2 Carbon tetrachloride, which is used in some chlorine manufacturing plants as an auxiliary solvent in chlorine
processing, and other chlorinated hydrocarbons originating from rubberised or plastic piping might be present in traces in
chlorine, but are not relevant due to the low dosage of chlorine to water intended for human consumption. Chlorine can
also contain traces of bromine, depending on the purity of the salt used in the electrolytic process and the subsequent
chlorine processing.
4.4 Chemical parameters
Heavy metals, which might be present in traces in liquid chlorine, are no relevant chemical parameters for
gaseous chlorine that is applied in water treatment. Cyanide, pesticides and polycyclic aromatic hydrocarbons
are not by-products of the manufacturing process.
NOTE For the purpose of this standard, "chemical parameters" are those defined in the EU Directive 98/83/EC of
November 3, 1998 ([1]). For their parametric values in drinking water see [1].”
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