SIST EN 12175:2022
(Main)Chemicals used for treatment of water intended for human consumption - Hexafluorosilicic acid
Chemicals used for treatment of water intended for human consumption - Hexafluorosilicic acid
This document is applicable to hexafluorosilicic acid used for treatment of water intended for human consumption. It describes the characteristics of hexafluorosilicic acid and specifies the requirements and the corresponding test methods for hexafluorosilicic acid. It gives information on its use in water treatment. It also determines the rules relating to safe handling and use of hexafluorosilicic acid (see Annex B).
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Hexafluorkieselsäure
Dieses Dokument gilt für Hexafluorkieselsäure zur Aufbereitung von Wasser für den menschlichen Gebrauch. Es beschreibt die Eigenschaften von Hexafluorkieselsäure und legt die Anforderungen sowie die entsprechenden Prüfverfahren für Hexafluorkieselsäure fest. Es enthält Angaben zu deren Anwendung in der Wasseraufbereitung. Es legt darüber hinaus Regeln für die sichere Handhabung und Verwendung von Hexafluorkieselsäure fest (siehe Anhang B).
Produits chimiques utilisés pour le traitement de l’eau destinée à la consommation humaine - Acide hexafluorosilicique
Le présent document est applicable à l’acide hexafluorosilicique utilisé pour le traitement de l’eau destinée à la consommation humaine. Il décrit les caractéristiques de l’acide hexafluorosilicique et spécifie les exigences et les méthodes d’essai relatives à l’acide hexafluorosilicique. Il donne des informations pour son emploi dans le traitement de l’eau. Il fixe également les règles relatives à la sécurité d’emploi et de manipulation de l’acide hexafluorosilicique (voir Annexe B).
Kemikalije, ki se uporabljajo za pripravo pitne vode - Heksafluorosilicijeva kislina
Ta dokument obravnava heksafluorosilicijevo kislino, ki se uporablja za pripravo pitne vode. Opisuje značilnosti heksafluorosilicijeve kisline ter določa zahteve in ustrezne preskusne metode zanjo. Podaja informacije za njeno uporabo pri pripravi vode. Določa tudi pravila za varno ravnanje s heksafluorosilicijevo kislino in njeno uporabo (glej dodatek B).
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 12175:2022
01-julij-2022
Nadomešča:
SIST EN 12175:2014
Kemikalije, ki se uporabljajo za pripravo pitne vode - Heksafluorosilicijeva kislina
Chemicals used for treatment of water intended for human consumption -
Hexafluorosilicic acid
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch -
Hexafluorkieselsäure
Produits chimiques utilisés pour le traitement de l’eau destinée à la consommation
humaine - Acide hexafluorosilicique
Ta slovenski standard je istoveten z: EN 12175:2022
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
SIST EN 12175:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 12175:2022
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SIST EN 12175:2022
EN 12175
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2022
EUROPÄISCHE NORM
ICS 71.100.80 Supersedes EN 12175:2013
English Version
Chemicals used for treatment of water intended for human
consumption - Hexafluorosilicic acid
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Acide menschlichen Gebrauch - Hexafluorkieselsäure
hexafluorosilicique
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 12175:2022 E
worldwide for CEN national Members.
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SIST EN 12175:2022
EN 12175:2022 (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. 8
6 Test methods . 8
6.1 General. 8
6.2 Sampling . 9
6.3 Analyses. 10
7 Labelling - Transportation - Storage . 17
7.1 Means of delivery . 17
7.2 Labelling . 17
7.3 Transportation regulations and labelling . 18
7.4 Marking . 18
7.5 Storage . 18
Annex A (informative) General information on hexafluorosilicic acid . 19
Annex B (normative) General rules relating to safety . 20
Bibliography . 21
2
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SIST EN 12175:2022
EN 12175:2022 (E)
European foreword
This document (EN 12175:2022) 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 12175:2013.
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
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SIST EN 12175:2022
EN 12175:2022 (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
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SIST EN 12175:2022
EN 12175:2022 (E)
1 Scope
This document is applicable to hexafluorosilicic acid used for treatment of water intended for human
consumption. It describes the characteristics of hexafluorosilicic acid and specifies the requirements
and the corresponding test methods for hexafluorosilicic acid. It gives information on its use in water
treatment. It also determines the rules relating to safe handling and use of hexafluorosilicic acid (see
Annex B).
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 5440, Sodium hexafluorosilicate for industrial use — Determination of phosphate content —
Molybdovanadate spectrophotometric method
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
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
Hexafluorosilicic acid.
4.1.2 Synonym or common name
Hydrofluosilicic acid.
Silicate-hexafluoro–dihydrogen.
Fluorosilicic acid.
HFSA.
5
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SIST EN 12175:2022
EN 12175:2022 (E)
4.1.3 Relative molecular mass
144,09.
4.1.4 Empirical formula
H SiF .
2 6
4.1.5 Chemical formula
H SiF .
2 6
1
4.1.6 CAS-Registry Number
16961-83-4.
2
4.1.7 EINECS reference
241-034-8.
4.2 Commercial form
The product is an aqueous solution.
4.3 Physical properties
4.3.1 Appearance and odour
The product is a clear, colourless liquid with a pungent odour.
4.3.2 Density
The density of a mass fraction 35 % solution at 25 °C is 1,35 g/mL.
The density of a mass fraction 20 % solution at 25 °C is 1,18 g/mL.
4.3.3 Solubility (in water)
The product is miscible in any proportion.
4.3.4 Vapour pressure
3
The vapour pressure at 20 °C is approximately 3 kPa .
4.3.5 Boiling point at 100 kPa
The product boils and decomposes at 110 °C.
4.3.6 Crystallization point
A solution of mass fraction of 35 % crystallizes at −30 °C and of a mass fraction of 20 % crystallizes at
−11,6 °C.
4.3.7 Specific heat
Not known.
1
Chemical Abstracts Service Registry Number.
2
European Inventory of Existing Commercial Chemical Substances.
3
100 kPa = 1 bar.
6
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SIST EN 12175:2022
EN 12175:2022 (E)
4.3.8 Viscosity dynamic
A solution of a mass fraction of 20 % has a dynamic viscosity of 1,4 MPa.s at 25 °C.
4.3.9 Critical temperature
Not applicable.
4.3.10 Critical pressure
Not applicable.
4.3.11 Physical hardness
Not applicable.
4.4 Chemical properties
Hexafluorosilicic acid is only stable in an aqueous solution. On evaporation, it decomposes to hydrogen
fluoride (HF) and silicon tetrafluoride (SiF ).
4
It produces hydrogen on contact with steel and metals (e.g. nickel and aluminium). It is a strong acid
and reacts violently with alkalis. It forms hydrogen fluoride (HF) on contact with concentrated acids. It
attacks glass.
5 Purity criteria
5.1 General
This document specifies the minimum purity requirements for hexafluorosilicic acid 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.
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 this document.
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 lead 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 product shall contain between a mass fraction of 10 % and 47 % hexafluorosilicic acid, the
remainder being water.
The concentration of hexafluorosilicic acid shall be within ± 5 % of the manufacturer's declared value.
5.3 Impurities and main by-products
Impurities must not exceed the requirements specified in Table 1.
7
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SIST EN 12175:2022
EN 12175:2022 (E)
Table 1 — Impurities
Impurity Limit
in mass fraction in % of
commercial product
Phosphate as P O max. 0,75
2 5
Free hydrogen fluoride as HF max. 1,5
5.4 Chemical parameters
The product shall conform to the requirements specified in Table 2.
Table 2 — Chemical parameters
Parameter Limit
mg/kg H SiF (100 %)
2 6
Antimony (Sb) max. 80
Arsenic (As) max. 400
Cadmium (Cd) max. 40
Chromium (Cr) max. 400
Lead (Pb) max. 400
Mercury (Hg) max. 10
Nickel (Ni) max. 400
Selenium (Se) max. 80
NOTE Other chemical parameters and indicator parameters
are not relevant in hexafluorosilicic acid because the raw
materials used in the manufacturing process are free of
them. For parametric values of hexafluorosilicic acid on
trace metal content in drinking water, see [1].
6 Test methods
6.1 General
SAFETY PRECAUTIONS Hexafluorosilicic acid shall be handled with extreme care, see B.1.
All equipment in contact with hexafluorosilicic acid shall be made of plastics (for example polyethylene
or polytetrafluoroethylene (PTFE)); avoid contact with glass.
8
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SIST EN 12175:2022
EN 12175:2022 (E)
6.2 Sampling
6.2.1 General
Observe the general recommendations of ISO 3165 and take account of ISO 6206.
The sampling is carried out at the premises of the manufacturer of the hexafluorosilicic acid unless the
customer has adequate facilities to carry out this operation safely at his own premises.
6.2.2 Sampling from drums and bottles
6.2.2.1 General
6.2.2.1.1 Mix the contents of each container to be sampled by shaking the container, by rolling it or by
rocking it from side to side, taking care not to damage the container or spill any of the liquid.
6.2.2.1.2 If the design of the container is such (for example, a narrow-necked bottle) that it is
impracticable to use a sampling implement, take a sample by pouring after the contents have been
thoroughly mixed. Otherwise, proceed as described in 6.2.2.1.3.
6.2.2.1.3 Examine the surface of the liquid. If there are signs of surface contamination, take samples
from the surface as described in 6.2.2.2; otherwise, take samples as described in 6.2.2.3.
6.2.2.2 Surface sampling
Take a sample using a suitable ladle. Lower the ladle into the liquid until the rim is just below the
surface, so that the surface layer runs into it. Withdraw the ladle before it fills completely and allow any
liquid adhering to the ladle to drain off. If necessary, repeat this operation so that, when the other
selected containers have been sampled, in a similar manner, the total volume of sample required for
subsequent analysis is obtained.
6.2.2.3 Procedure of sampling from a container
The samples for testing the hexafluorosilicic acid shall be taken by means of a sampling tube, for
example. A tube made of polytetrafluoroethylene (PTFE), approximately 1 500 mm long, with 14,5 mm
inside diameter and 1,25 mm wall thickness tapering to an inside diameter of approximately 5 mm at
one end, may be used for this; fit a rubber tube approximately 200 mm long which can be closed by
means of a pinch clip, to the other end. When taking the samples, insert the sampling tube as far as
possible into the acid to be tested with the clip released.
Do this slowly so that the levels of liquid in the sampling tube and in the acid container are the same.
Close the clip, withdraw the sampling tube from the acid, allow any liquid adhering at the outside of the
tube to drain off, and by releasing the clip discharge the contents of the sampling tube into a
polytetrafluoroethylene (PTFE) bottle of 1 000 ml nominal capacity provided with a ground PTFE
stopper. Stopper the bottle immediately after filling each with the content of the sampling tube. After
shaking thoroughly, fill from the collective sample three
...
SLOVENSKI STANDARD
oSIST prEN 12175:2020
01-september-2020
Kemikalije, ki se uporabljajo za pripravo pitne vode - Heksafluorosilicijeva kislina
Chemicals used for treatment of water intended for human consumption -
Hexafluorosilicic acid
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch -
Hexafluorkieselsäure
Produits chimiques utilisés pour le traitement de l’eau destinée à la consommation
humaine - Acide hexafluorosilicique
Ta slovenski standard je istoveten z: prEN 12175
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
oSIST prEN 12175:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 12175:2020
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oSIST prEN 12175:2020
DRAFT
EUROPEAN STANDARD
prEN 12175
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2020
ICS 71.100.80 Will supersede EN 12175:2013
English Version
Chemicals used for treatment of water intended for human
consumption - Hexafluorosilicic acid
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Acide menschlichen Gebrauch - Hexafluorkieselsäure
hexafluorosilicique
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 12175:2020 E
worldwide for CEN national Members.
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oSIST prEN 12175:2020
prEN 12175:2020 (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 . 8
5.4 Chemical parameters. 8
6 Test methods . 8
6.1 General. 8
6.2 Sampling . 8
6.3 Analyses. 10
7 Labelling - Transportation - Storage . 16
7.1 Means of delivery . 16
7.2 Labelling . 16
7.3 Transportation regulations and labelling . 17
7.4 Marking . 17
7.5 Storage . 18
Annex A (informative) General information on hexafluorosilicic acid . 19
Annex B (normative) General rules relating to safety . 20
Bibliography . 21
2
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oSIST prEN 12175:2020
prEN 12175:2020 (E)
European foreword
This document (prEN 12175:2020) 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 12175:2013.
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
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oSIST prEN 12175:2020
prEN 12175:2020 (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
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oSIST prEN 12175:2020
prEN 12175:2020 (E)
1 Scope
This document is applicable to hexafluorosilicic acid used for treatment of water intended for human
consumption. It describes the characteristics of hexafluorosilicic acid and specifies the requirements
and the corresponding test methods for hexafluorosilicic acid. It gives information on its use in water
treatment. It also determines the rules relating to safe handling and use of hexafluorosilicic acid (see
Annex B).
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 5440, Sodium hexafluorosilicate for industrial use — Determination of phosphate content —
Molybdovanadate spectrophotometric method
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
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
Hexafluorosilicic acid.
4.1.2 Synonym or commons name
Hydrofluosilicic acid.
Silicate-hexafluoro–dihydrogen.
Fluorosilicic acid.
HFSA.
5
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oSIST prEN 12175:2020
prEN 12175:2020 (E)
4.1.3 Relative molecular mass
144,09.
4.1.4 Empirical formula
H SiF .
2 6
4.1.5 Chemical formula
H SiF .
2 6
1
4.1.6 CAS-Registry Number
16961-83-4.
2
4.1.7 EINECS reference
241-034-8.
4.2 Commercial form
The product is an aqueous solution.
4.3 Physical properties
4.3.1 Appearance and odour
The product is a clear, colourless liquid with a pungent odour.
4.3.2 Density
The density of a mass fraction 35 % solution at 25 °C is 1,35 g/ml.
The density of a mass fraction 20 % solution at 25 °C is 1,18 g/ml.
4.3.3 Solubility (in water)
The product is miscible in any proportion.
4.3.4 Vapour pressure
3
The vapour pressure at 20 °C is approximately 3 kPa .
4.3.5 Boiling point at 100 kPa
The product boils and decomposes at 110 °C.
4.3.6 Crystallization point
A solution of mass fraction of 35 % crystallizes at −30 °C and of a mass fraction of 20 % crystallizes at
−11,6 °C.
4.3.7 Specific heat
Not known.
1
Chemical Abstracts Service Registry Number.
2
European Inventory of Existing Commercial Chemical Substances.
3
100 kPa = 1 bar.
6
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oSIST prEN 12175:2020
prEN 12175:2020 (E)
4.3.8 Viscosity dynamic
A solution of a mass fraction of 20 % has a dynamic viscosity of 1,4 MPa.s at 25 °C.
4.3.9 Critical temperature
Not applicable.
4.3.10 Critical pressure
Not applicable.
4.3.11 Physical hardness
Not applicable.
4.4 Chemical properties
Hexafluorosilicic acid is only stable in an aqueous solution. On evaporation, it decomposes to hydrogen
fluoride (HF) and silicon tetrafluoride (SiF ).
4
It produces hydrogen on contact with metals, e.g. steel, nickel and aluminium. It is a strong acid and
reacts violently with alkalis. It forms hydrogen fluoride (HF) on contact with concentrated acids. It
attacks glass.
5 Purity criteria
5.1 General
This document specifies the minimum purity requirements for hexafluorosilicic acid 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.
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 this document.
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 lead 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 product shall contain between a mass fraction of 20 % and 40 % hexafluorosilicic acid, the
remainder being water.
The concentration of hexafluorosilicic acid shall be within ± 5 % of the manufacturer's declared value.
7
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oSIST prEN 12175:2020
prEN 12175:2020 (E)
5.3 Impurities and main by-products
Table 1 — Impurities
Impurity Limit
in mass fraction in % of
commercial product
Phosphate as P O max. 0,75
2 5
Free hydrogen fluoride as HF max. 1,5
5.4 Chemical parameters
The product shall conform to the requirements specified in Table 2.
Table 2 — Chemical parameters
Parameter Limit
mg/kg H SiF (100 %)
2 6
Antimony (Sb) max. 80
Arsenic (As) max. 400
Cadmium (Cd) max. 40
Chromium (Cr) max. 400
Lead (Pb) max. 400
Mercury (Hg) max. 10
Nickel (Ni) max. 400
Selenium (Se) max. 80
NOTE Other chemical parameters and indicator
parameters are not relevant in hexafluorosilicic acid
because the raw materials used in the manufacturing
process are free of them. For parametric values of
hexafluorosilicic acid on trace metal content in drinking
water, see [1].
6 Test methods
6.1 General
SAFETY PRECAUTIONS Hexafluorosilicic acid shall be handled with extreme care, see B.1.
All equipment in contact with hexafluorosilicic acid shall be made of plastics (for example polyethylene
or polytetrafluoroethylene (PTFE); avoid contact with glass.
6.2 Sampling
6.2.1 General
Observe the general recommendations of ISO 3165 and take account of ISO 6206.
The sampling is carried out at the premises of the manufacturer of the hexafluorosilicic acid unless the
customer has adequate facilities to carry out this operation safely at his own premises.
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oSIST prEN 12175:2020
prEN 12175:2020 (E)
6.2.2 Sampling from drums and bottles
6.2.2.1 General
6.2.2.1.1 Mix the contents of each container to be sampled by shaking the container, by rolling it or by
rocking it from side to side, taking care not to damage the container or spill any of the liquid.
6.2.2.1.2 If the design of the container is such (for example, a narrow-necked bottle) that it is
impracticable to use a sampling implement, take a sample by pouring after the contents have been
thoroughly mixed. Otherwise, proceed as described in 6.2.2.1.3.
6.2.2.1.3 Examine the surface of the liquid. If there are signs of surface contamination, take samples
from the surface as described in 6.2.2.2; otherwise, take samples as described in 6.2.2.3.
6.2.2.2 Surface sampling
Take a sample using a suitable ladle. Lower the ladle into the liquid until the rim is just below the
surface, so that the surface layer runs into it. Withdraw the ladle before it fills completely and allow any
liquid adhering to the ladle to drain off. If necessary, repeat this operation so that, when the other
selected containers have been sampled, in a similar manner, the total volume of sample required for
subsequent analysis is obtained.
6.2.2.3 Procedure of sampling from a container
The samples for testing the hexafluorosilicic acid shall be taken by means of a sampling tube, for
example. A tube made of polytetrafluoroethylene (PTFE), approximately 1 500 mm long, with 14,5 mm
inside diameter and 1,25 mm wall thickness tapering to an inside diameter of approximately 5 mm at
one end, may be used for this; fit a rubber tube approximately 200 mm long which can be closed by
means of a pinch clip, to the other end. When taking the samples, insert the sampling tube as far as
possible into the acid to be tested with the clip released.
Do this slowly so that the levels of liquid in the sampling tube and in the acid container are the same.
Close the clip, withdraw the sampling tube from the acid, allow any liquid adhering at the outside of the
tube to drain off, and by releasing the clip discharge the contents of the sampling tube into a
polytetrafluoroethylene (PTFE) bottle of 1 000 ml nominal capacity provided with a ground PTFE
stopper. Stopper the bottle immediately after filling each with the content of the sampling tube. After
shaking thoroughly, fill from the collective sample three PTFE bottles, each with a volume of
approximately 250 ml and provided with a ground PTFE stopper. Stopper, seal and label the bottles.
One of these samples is to be tested by the consignee; the other two shall be kept in case subsequent
complaint requires further testing to be carried out.
6.2.3 Sampling from tanks and tankers
From e
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