Chemicals used for treatment of water intended for human consumption - Sodium thiosulfate

This document is applicable to sodium thiosulfate used for treatment of water intended for human consumption. It describes the characteristics and specifies the requirements of sodium thiosulfate and refers to the corresponding analytical methods. It gives information for its use in water treatment.

Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Natriumthiosulfat

Dieses Dokument ist anzuwenden für Natriumthiosulfat zur Aufbereitung von Wasser für den menschlichen Gebrauch. Es beschreibt die Eigenschaften von Natriumthiosulfat, legt die Anforderungen an Natriumthiosulfat fest und verweist auf die entsprechenden Analysenverfahren. Es enthält Angaben zu dessen Anwendung in der Wasseraufbereitung.

Produits chimiques utilisés pour le traitement de l'eau destinée à la consommation humaine - Thiosulfate de sodium

Le présent document s’applique au thiosulfate de sodium utilisé pour le traitement de l’eau destinée à la consommation humaine. Il décrit les caractéristiques du thiosulfate de sodium, en spécifie les exigences ainsi que les méthodes d’analyse correspondantes. Il donne des informations pour son emploi dans le traitement de l’eau.

Kemikalije, ki se uporabljajo za pripravo pitne vode - Natrijev tiosulfat

Ta dokument obravnava natrijev tiosulfat, ki se uporablja za pripravo pitne vode. Opisuje značilnosti natrijevega tiosulfata in določa zahteve zanj ter se sklicuje na ustrezne analizne metode. Podaja informacije za njegovo uporabo pri pripravi pitne vode.

General Information

Status
Published
Publication Date
10-May-2022
Withdrawal Date
29-Nov-2022
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
11-May-2022
Due Date
04-Dec-2021
Completion Date
11-May-2022

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SLOVENSKI STANDARD
SIST EN 12125:2022
01-julij-2022
Nadomešča:
SIST EN 12125:2013
Kemikalije, ki se uporabljajo za pripravo pitne vode - Natrijev tiosulfat
Chemicals used for treatment of water intended for human consumption - Sodium
thiosulfate
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch -
Natriumthiosulfat
Produits chimiques utilisés pour le traitement de l'eau destinée à la consommation
humaine - Thiosulfate de sodium
Ta slovenski standard je istoveten z: EN 12125:2022
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
SIST EN 12125:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 12125:2022

---------------------- Page: 2 ----------------------
SIST EN 12125:2022


EN 12125
EUROPEAN STANDARD

NORME EUROPÉENNE

May 2022
EUROPÄISCHE NORM
ICS 71.100.80 Supersedes EN 12125:2012
English Version

Chemicals used for treatment of water intended for human
consumption - Sodium thiosulfate
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Thiosulfate de menschlichen Gebrauch - Natriumthiosulfat
sodium
This European Standard was approved by CEN on 27 March 2022.

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-CENELEC 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-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12125:2022 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
SIST EN 12125:2022
EN 12125:2022 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Description . 5
4.1 Identification . 5
4.2 Commercial form . 6
4.3 Physical properties . 6
4.4 Chemical properties . 7
5 Purity criteria . 7
5.1 General. 7
5.2 Composition of commercial product . 7
5.3 Impurities and main by-products . 7
5.4 Chemical parameters. 7
6 Test methods . 8
6.1 Sampling . 8
6.2 Analyses. 8
7 Labelling – Transportation – Storage . 14
7.1 Means of delivery . 14
7.2 Labelling according to the EU legislation . 14
7.3 Transportation regulations and labelling . 14
7.4 Marking . 14
7.5 Storage . 14
Annex A (informative) General information on sodium thiosulfate . 15
Annex B (normative) General rules relating to safety . 16
Bibliography . 17
2

---------------------- Page: 4 ----------------------
SIST EN 12125:2022
EN 12125:2022 (E)
European foreword
This document (EN 12125:2022) 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 November 2022, and conflicting national standards
shall be withdrawn at the latest by November 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12125:2012.
In comparison with the previous edition, the following technical modifications have been made:
a) Modification of 7.3 on transportation regulations and labelling, adding the sentence “The user must
be aware of the incompatibilities between transported products.”;
b) Modification of 7.4 on marking. The requirements of marking are also applied to the accompanying
documents.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
3

---------------------- Page: 5 ----------------------
SIST EN 12125:2022
EN 12125:2022 (E)
Introduction
In respect of potential adverse effects on the quality of water intended for human consumption caused
by the product covered by this document:
a) this document 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 document 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 document is subject to regulation
or control by National Authorities (see Annex A).
4

---------------------- Page: 6 ----------------------
SIST EN 12125:2022
EN 12125:2022 (E)
1 Scope
This document is applicable to sodium thiosulfate used for treatment of water intended for human
consumption. It describes the characteristics and specifies the requirements of sodium thiosulfate and
refers to the corresponding analytical methods. It gives information for its use in water treatment.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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)
ISO 3165, Sampling of chemical products for industrial use — Safety in sampling
ISO 5993, Sodium hydroxide for industrial use — Determination of mercury content — Flameless atomic
absorption spectrometric method
ISO 6206, Chemical products for industrial use — Sampling — Vocabulary
ISO 6353-1, Reagents for chemical analysis — Part 1: General test methods
ISO 8213, Chemical products for industrial use — Sampling techniques — Solid chemical products in the
form of particles varying from powders to coarse lumps
ISO 10636, Photography — Processing chemicals — Specifications for anhydrous sodium thiosulfate and
sodium thiosulfate pentahydrate
ISO 22743, Water quality — Determination of sulfates — Method by continuous flow analysis (CFA)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Description
4.1 Identification
4.1.1 Chemical name
Sodium thiosulfate.
4.1.2 Synonym or commons names
Sodium thiosulfate, sodium hyposulfite.
4.1.3 Relative molecular mass
158,11 (anhydrous).
5

---------------------- Page: 7 ----------------------
SIST EN 12125:2022
EN 12125:2022 (E)
4.1.4 Empirical formula
Na S O .
2 2 3
4.1.5 Chemical formula
Na S O .
2 2 3
1
4.1.6 CAS-Registry Number
7772-98-7 (anhydrous); 10102-17-7 (pentahydrate).
2
4.1.7 EINECS reference
231-867-5.
4.2 Commercial form
The product is a crystalline powder.
4.3 Physical properties
4.3.1 Appearance
The hydrated product is colourless crystal. The anhydrous product is a white powder.
4.3.2 Density
3 3
The particle density of the hydrated product is 1,69 g/cm to 1,73 g/cm at 20 °C.
4.3.3 Solubility in water
The solubility of the product in water is 700 g/l at 20 °C (anhydrous); for pentahydrate : 2 910 g/l
at 45 °C.
4.3.4 Vapour pressure
Not applicable.
3
4.3.5 Boiling point at 100 kPa
Not applicable.
4.3.6 Crystallization point
The product starts to decompose at 45 °C to 50 °C.
4.3.7 Specific heat
Not known.
4.3.8 Viscosity, dynamic
Not applicable.
4.3.9 Critical temperature
Not applicable.

1
Chemical Abstracts Service Registry Number.
2
European Inventory of Existing Commercial Chemical Substances.
3
100 kPa = 1 bar.
6

---------------------- Page: 8 ----------------------
SIST EN 12125:2022
EN 12125:2022 (E)
4.3.10 Critical pressure
Not applicable.
4.3.11 Physical hardness
Not applicable.
4.4 Chemical properties
The pH value of a diluted aqueous solution of sodium thiosulfate is approximately neutral (6,5 to 8).
Sodium thiosulfate dissolves silver halogenids and other silver salts.
At elevated temperatures (>50 °C), sulfur dioxide is generated.
Sodium thiosulfate releases sulfur dioxide when mixed with acids.
Sodium thiosulfate reacts violently with oxidising agents; e.g. with sodium hypochlorite or hydrogen
peroxide. It shall not come into contact with acids, iodine, lead and silver salts. For additional
information on Sodium thiosulfate, see Annex A.
5 Purity criteria
5.1 General
This document specifies the minimum purity requirements for sodium thiosulfate 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.
The national regulations allow users to clarify whether the product is of appropriate purity for the
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 and not stated in this document.
Limits have been given for impurities and chemical 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
...

SLOVENSKI STANDARD
oSIST prEN 12125:2020
01-julij-2020
Kemikalije, ki se uporabljajo za pripravo pitne vode - Natrijev tiosulfat
Chemicals used for treatment of water intended for human consumption - Sodium
thiosulfate
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch -
Natriumthiosulfat
Produits chimiques utilisés pour le traitement de l'eau destinée à la consommation
humaine - Thiosulfate de sodium
Ta slovenski standard je istoveten z: prEN 12125
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
oSIST prEN 12125:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN 12125:2020

---------------------- Page: 2 ----------------------
oSIST prEN 12125:2020


DRAFT
EUROPEAN STANDARD
prEN 12125
NORME EUROPÉENNE

EUROPÄISCHE NORM

May 2020
ICS 71.100.80 Will supersede EN 12125:2012
English Version

Chemicals used for treatment of water intended for human
consumption - Sodium thiosulfate
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Thiosulfate de menschlichen Gebrauch - Natriumthiosulfat
sodium
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 164.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12125:2020 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
oSIST prEN 12125:2020
prEN 12125:2020 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Description . 5
4.1 Identification . 5
4.2 Commercial form . 6
4.3 Physical properties . 6
4.4 Chemical properties . 7
5 Purity criteria . 7
5.1 General. 7
5.2 Composition of commercial product . 7
5.3 Impurities and main by-products . 7
5.4 Chemical parameters. 7
6 Test methods . 8
6.1 Sampling . 8
6.2 Analyses. 8
7 Labelling – Transportation – Storage . 14
7.1 Means of delivery . 14
7.2 Labelling according to the EU legislation . 14
7.3 Transportation regulations and labelling . 14
7.4 Marking . 14
7.5 Storage . 14
Annex A (informative) General information on sodium thiosulfate . 15
Bibliography . 17
2

---------------------- Page: 4 ----------------------
oSIST prEN 12125:2020
prEN 12125:2020 (E)
European foreword
This document (prEN 12125:2020) has been prepared by Technical Committee CEN/TC 164 “Water
supply”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12125:2012.
In comparison with the previous edition, the following technical modifications have been made:
a) Modification of 7.3 on transportation regulations and labelling, adding the sentence “The user must
be aware of the incompatibilities between transported products.”;
b) Modification of 7.4 on marking. The requirements of marking are also applied to the accompanying
documents.
3

---------------------- Page: 5 ----------------------
oSIST prEN 12125:2020
prEN 12125:2020 (E)
Introduction
In respect of potential adverse effects on the quality of water intended for human consumption caused
by the product covered by this document:
a) this document 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 document 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 document is subject to regulation
or control by National Authorities.
4

---------------------- Page: 6 ----------------------
oSIST prEN 12125:2020
prEN 12125:2020 (E)
1 Scope
This document is applicable to sodium thiosulfate used for treatment of water intended for human
consumption. It describes the characteristics and specifies the requirements of sodium thiosulfate and
refers to the corresponding analytical methods. It gives information for its use in water treatment.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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)
ISO 3165, Sampling of chemical products for industrial use — Safety in sampling
ISO 5993, Sodium hydroxide for industrial use — Determination of mercury content — Flameless atomic
absorption spectrometric method
ISO 6206, Chemical products for industrial use — Sampling — Vocabulary
ISO 6353-1, Reagents for chemical analysis — Part 1: General test methods
ISO 8213, Chemical products for industrial use — Sampling techniques — Solid chemical products in the
form of particles varying from powders to coarse lumps
ISO 10636, Photography — Processing chemicals — Specifications for anhydrous sodium thiosulfate and
sodium thiosulfate pentahydrate
ISO 22743, Water quality — Determination of sulfates — Method by continuous flow analysis (CFA)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Description
4.1 Identification
4.1.1 Chemical name
Sodium thiosulfate.
4.1.2 Synonym or commons names
Sodium thiosulfate, sodium hyposulfite.
4.1.3 Relative molecular mass
158,11 (anhydrous).
5

---------------------- Page: 7 ----------------------
oSIST prEN 12125:2020
prEN 12125:2020 (E)
4.1.4 Empirical formula
Na S O .
2 2 3
4.1.5 Chemical formula
Na S O .
2 2 3
1
4.1.6 CAS-Registry Number
7772-98-7 (anhydrous); 10102-17-7 (pentahydrate).
2
4.1.7 EINECS reference
231-867-5.
4.2 Commercial form
The product is a crystalline powder.
4.3 Physical properties
4.3.1 Appearance
The hydrated product is colourless crystal. The anhydrous product is a white powder.
4.3.2 Density
3 3
The particle density of the hydrated product is 1,69 g/cm to 1,73 g/cm at 20 °C.
4.3.3 Solubility in water
The solubility of the product in water is 700 g/l at 20 °C (anhydrous); for pentahydrate : 2 910 g/l
at 45 °C.
4.3.4 Vapour pressure
Not applicable.
3
4.3.5 Boiling point at 100 kPa
Not applicable.
4.3.6 Crystallization point
The product starts to decompose at 45 °C to 50 °C.
4.3.7 Specific heat
Not known.
4.3.8 Viscosity, dynamic
Not applicable.
4.3.9 Critical temperature
Not applicable.

1
Chemical Abstracts Service Registry Number.
2
European Inventory of Existing Commercial Chemical Substances.
3
100 kPa = 1 bar.
6

---------------------- Page: 8 ----------------------
oSIST prEN 12125:2020
prEN 12125:2020 (E)
4.3.10 Critical pressure
Not applicable.
4.3.11 Physical hardness
Not applicable.
4.4 Chemical properties
The pH value of a diluted aqueous solution of sodium thiosulfate is approximately neutral (6,5 to 8).
Sodium thiosulfate dissolves silver halogenids and other silver salts.
At elevated temperatures (>50 °C), sulfur dioxide is generated.
Sodium thiosulfate releases sulfur dioxide when mixed with acids.
Sodium thiosulfate reacts violently with oxidising agents; e.g. with sodium hypochlorite or hydrogen
peroxide. It shall not come into contact with acids, iodine, lead and silver salts. For additional
information on Sodium thiosulfate, see Annex A.
5 Purity criteria
5.1 General
This document specifies the minimum purity requirements for sodium thiosulfate 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.
The national regulations allow users to clarify whether the product is of appropriate purity for the
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 and not stated in this document.
Limits have been given for impurities and chemical 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.
5.2 Composition of commercial product
The concentration of sodium thiosulfate anhydrous shall not be less than a mass fraction of 95 %
of Na S O .
2 2 3
The concentration of sodium thiosulfate pentahydrate shall not be less than a mass fraction of 95 %
of Na S O .5 H O.
2 2 3 2
5.3 Impurities and main by-products
The content of sodium sulfate shall not exceed a mass fraction of 5
...

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