EN 12120:2022

SLOVENSKI STANDARD
01-junij-2022
Nadomešča:
SIST EN 12120:2013
Kemikalije, ki se uporabljajo za pripravo pitne vode - Natrijev hidrogen sulfit
Chemicals used for treatment of water intended for human consumption - Sodium
hydrogen sulfite
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch -
Natriumhydrogensulfit
Produits chimiques utilisés pour le traitement de l’eau destinée à la consommation
humaine - Hydrogénosulfite de sodium
Ta slovenski standard je istoveten z: EN 12120:2022
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 12120
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2022
EUROPÄISCHE NORM
ICS 71.100.80 Supersedes EN 12120:2012
English Version
Chemicals used for treatment of water intended for human
consumption - Sodium hydrogen sulfite
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - menschlichen Gebrauch - Natriumhydrogensulfit
Hydrogénosulfite de sodium
This European Standard was approved by CEN on 13 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 12120:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Description . 6
4.1 Identification . 6
4.1.1 Chemical name . 6
4.1.2 Synonym or commons name . 6
4.1.3 Relative molecular mass . 6
4.1.4 Empirical formula . 6
4.1.5 Chemical formula . 7
4.1.6 CAS-Registry Number . 7
4.1.7 EINECS reference . 7
4.2 Commercial form . 7
4.3 Physical properties . 7
4.3.1 Appearance and odour . 7
4.3.2 Density . 7
4.3.3 Solubility (in water) . 7
4.3.4 Vapour pressure . 7
4.3.5 Boiling point at 100 kPa . 7
4.3.6 Crystallization point . 7
4.3.7 Specific heat . 7
4.3.8 Viscosity dynamic . 7
4.3.9 Critical temperature . 7
4.3.10 Critical pressure . 8
4.3.11 Physical hardness . 8
4.4 Chemical properties . 8
5 Purity criteria . 8
5.1 General. 8
5.2 Composition of commercial product . 8
5.3 Impurities and main by-products . 8
5.4 Chemical parameters. 8
6 Test methods . 9
6.1 Sampling . 9
6.1.1 General. 9
6.1.2 Sampling from drums and bottles . 9
6.1.3 Sampling from tanks and tankers . 10
6.2 Analyses. 10
6.2.1 General. 10
6.2.2 Main product . 10
6.2.3 Impurities . 11
6.2.4 Chemical parameters. 12
7 Labelling, transportation, storage . 17
7.1 Means of delivery . 17
7.2 Labelling . 17
7.3 Transportation labelling . 17
7.4 Marking . 18
7.5 Storage . 18
7.5.1 Long term stability . 18
7.5.2 Storage incompatibilities . 18
Annex A (informative) General information on sodium hydrogen sulfite . 19
A.1 Origin . 19
A.1.1 Raw materials . 19
A.1.2 Manufacturing process . 19
A.2 Use . 19
A.2.1 Function . 19
A.2.2 Form in which it is used . 19
A.2.3 Treatment dose . 19
A.2.4 Means of application. 19
A.2.5 Secondary effects . 19
A.2.6 Removal of excess product . 19
Annex B (normative) General rules relating to safety . 20
B.1 Rules for safe handling and use . 20
B.2 Emergency procedures . 20
B.2.1 First aid . 20
B.2.2 Spillage . 20
B.2.3 Fire . 20
Bibliography . 21
European foreword
This document (EN 12120:2022) 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 October 2022, and conflicting national standards shall
be withdrawn at the latest by October 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 12120:2012.
In comparison with the previous edition EN 12120:2012, the following technical modifications have been
made:
a) modification of 7.3 on transportation regulations and labelling, adding the sentence “The user shall
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;
c) use of the changed classification and labelling (see 7.2).
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.
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 a 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).
1 Scope
This document is applicable to sodium hydrogen sulfite used for treatment of water intended for human
consumption. It describes the characteristics of sodium hydrogen sulfite and specifies the requirements
and the corresponding test methods for sodium hydrogen sulfite. It gives information on 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 418, Photography — Processing chemicals — Specifications for anhydrous sodium sulfite
ISO 5993, Sodium hydroxide for industrial use — Determination of mercury content — Flameless atomic
absorption spectrometric method
ISO 6353-1, Reagents for chemical analysis — Part 1: General test methods
ISO 9297, Water quality — Determination of chloride — Silver nitrate titration with chromate indicator
(Mohr's method)
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 hydrogen sulfite.
4.1.2 Synonym or commons name
Sodium bisulfite.
4.1.3 Relative molecular mass
104,6.
4.1.4 Empirical formula
NaHSO .
4.1.5 Chemical formula
NaHSO .
4.1.6 CAS-Registry Number
7631-90-5.
4.1.7 EINECS reference
231-548-0.
4.2 Commercial form
The product is an aqueous solution with a usual concentration of approximately a mass fraction of 40 %
NaHSO . This corresponds to 520 g NaHSO per litre.
3 3
4.3 Physical properties
4.3.1 Appearance and odour
The product is a yellowish liquid with a slight odour of sulfur dioxide.
4.3.2 Density
The density of the product is 1,3 g/ml to 1,5 g/ml at 20 °C.
4.3.3 Solubility (in water)
The product is miscible with water.
4.3.4 Vapour pressure
The vapour pressure of a solution of mass fraction of 40 % NaHSO is 4 kPa at 20 °C.
4.3.5 Boiling point at 100 kPa
The product decomposes at 100 °C.
4.3.6 Crystallization point
A solution of mass fraction of 40 % NaHSO crystallizes at 2 °C.
4.3.7 Specific heat
The specific heat of the product is 3,15 kJ/(kg K).
4.3.8 Viscosity dynamic
.
The viscosity of a solution of mass fraction of 40 % NaHSO is 4 mPa s at 25 °C.
4.3.9 Critical temperature
Not applicable.
Chemical Abstracts Service Registry Number.
European Inventory of Existing Commercial Chemical Substances.
100 kPa = 1 bar.
4.3.10 Critical pressure
Not applicable.
4.3.11 Physical hardness
Not applicable.
4.4 Chemical properties
The solution is weakly acid. The pH value of a commercial solution of mass fraction of 40 % is between 4,5
and 5,0.
NaHSO exists in solution only; if the solution is evaporated the salt which is formed is sodium disulfite.
At elevated temperatures (>100 °C) sulfur dioxide is generated.
Sodium hydrogen sulfite reacts violently with oxidising agents; e.g. with sodium hypochlorite or
hydrogen peroxide.
5 Purity criteria
5.1 General
This document specifies the minimum purity requirements for sodium hydrogen sulfite 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 could be
present and, if so, this shall be notified
...