Chemicals used for treatment of water intended for human consumption - Sodium hydrogen sulfite

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.

Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Natriumhydrogensulfit

Dieses Dokument gilt für Natriumhydrogensulfit zur Aufbereitung von Wasser für den menschlichen Ge-brauch. Es beschreibt die Eigenschaften von Natriumhydrogensulfit und legt die Anforderungen sowie die entsprechenden Prüfverfahren für Natriumhydrogensulfit fest. Es enthält Angaben zu dessen Anwendung in der Wasseraufbereitung.

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

Le présent document est applicable à l’hydrogénosulfite de sodium utilisé pour le traitement de l’eau destinée à la consommation humaine. Il décrit les caractéristiques de l’hydrogénosulfite de sodium et spécifie les exigences et les méthodes d’essai correspondant à l’hydrogénosulfite de sodium. Il donne des informations pour son emploi dans le traitement de l’eau.

Kemikalije, ki se uporabljajo za pripravo pitne vode - Natrijev hidrogen sulfit

General Information

Status
Published
Public Enquiry End Date
19-Jul-2020
Publication Date
11-May-2022
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
11-May-2022
Due Date
16-Jul-2022
Completion Date
12-May-2022

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SLOVENSKI STANDARD
SIST EN 12120:2022
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
SIST EN 12120:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 12120:2022
---------------------- Page: 2 ----------------------
SIST EN 12120:2022
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.
---------------------- Page: 3 ----------------------
SIST EN 12120:2022
EN 12120:2022 (E)
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

---------------------- Page: 4 ----------------------
SIST EN 12120:2022
EN 12120:2022 (E)

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

---------------------- Page: 5 ----------------------
SIST EN 12120:2022
EN 12120:2022 (E)
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.
---------------------- Page: 6 ----------------------
SIST EN 12120:2022
EN 12120:2022 (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 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).
---------------------- Page: 7 ----------------------
SIST EN 12120:2022
EN 12120:2022 (E)
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 .
---------------------- Page: 8 ----------------------
SIST EN 12120:2022
EN 12120:2022 (E)
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.
---------------------- Page: 9 ----------------------
SIST EN 12120:2022
EN 12120:2022 (E)
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
...

SLOVENSKI STANDARD
oSIST prEN 12120:2020
01-julij-2020
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: prEN 12120
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
oSIST prEN 12120:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN 12120:2020
---------------------- Page: 2 ----------------------
oSIST prEN 12120:2020
DRAFT
EUROPEAN STANDARD
prEN 12120
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2020
ICS 71.100.80 Will supersede 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 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 12120:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (E)
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......................................................................................................................... 11

7 Labelling, Transportation, Storage ............................................................................................... 16

---------------------- Page: 4 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (E)

7.1 Means of delivery ................................................................................................................................ 16

7.2 Labelling ................................................................................................................................................ 16

7.3 Transportation .................................................................................................................................... 16

7.4 Marking .................................................................................................................................................. 17

7.5 Storage .................................................................................................................................................... 17

7.5.1 Long term stability ............................................................................................................................. 17

7.5.2 Storage incompatibilities ................................................................................................................. 17

Annex A (informative) General information on sodium hydrogen sulfite .................................. 18

A.1 Origin ...................................................................................................................................................... 18

A.1.1 Raw materials ...................................................................................................................................... 18

A.1.2 Manufacturing process ..................................................................................................................... 18

A.2 Use ............................................................................................................................................................ 18

A.2.1 Function ................................................................................................................................................. 18

A.2.2 Form in which it is used ................................................................................................................... 18

A.2.3 Treatment dose ................................................................................................................................... 18

A.2.4 Means of application.......................................................................................................................... 18

A.2.5 Secondary effects ................................................................................................................................ 18

A.2.6 Removal of excess product .............................................................................................................. 18

A.3 Rules for safe handling and use ..................................................................................................... 18

A.4 Emergency procedures ..................................................................................................................... 18

A.4.1 First aid .................................................................................................................................................. 18

A.4.2 Spillage ................................................................................................................................................... 19

A.4.3 Fire ........................................................................................................................................................... 19

Bibliography ....................................................................................................................................................... 20

---------------------- Page: 5 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (E)
European foreword

This document (prEN 12120:2020) 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 12120:2012.

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 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 [4]).
---------------------- Page: 6 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (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 dcoument 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.
---------------------- Page: 7 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (E)
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 http://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 .
---------------------- Page: 8 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (E)
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 an 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.
---------------------- Page: 9 ----------------------
oSIST prEN 12120:2020
prEN 12120:2020 (E)
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 to the user and when necessary to relevant authorities.

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 products not stated in t

...

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