1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 12125:2012Chemicals used for treatmentof water intended for humanconsumption SodiumthiosulfateCopyright European Committee for Standardization Provided by IHS under license
2、 with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 12125:2012. Itsupersedes BS EN 12125:2005 which is withdrawn.The UK participation in its preparation was
3、entrusted to TechnicalCommittee CII/59, Chemicals for drinking water treatment.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correc
4、tapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 77785 1ICS 13.060.20; 71.100.80Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and
5、 Strategy Committee on 31 January 2013.Amendments issued since publicationDate Text affectedCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EUROPEAN STANDARD NORM
6、E EUROPENNE EUROPISCHE NORM EN 12125 November 2012 ICS 71.100.80 Supersedes EN 12125:2005English Version Chemicals used for treatment of water intended for human consumption - Sodium thiosulfate Produits chimiques utiliss pour le traitement de leau destine la consommation humaine - Thiosulfate de so
7、dium Produkte zur Aufbereitung von Wasser fr den menschlichen Gebrauch - Natriumthiosulfat This European Standard was approved by CEN on 23 September 2012. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the s
8、tatus 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,
9、 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, Cr
10、oatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
11、 United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12125:2
12、012: ECopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Description .5
13、4 Purity criteria 75 Test methods 86 Labelling Transportation Storage . 14Annex A (informative) General information on sodium thiosulfate . 15Bibliography . 17Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted
14、without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 3 Foreword This document (EN 12125:2012) 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 pu
15、blication of an identical text or by endorsement, at the latest by May 2013, and conflicting national standards shall be withdrawn at the latest by May 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall
16、 not be held responsible for identifying any or all such patent rights. This document supersedes EN 12125:2005. The significant technical differences between this edition and EN 12125:2005 are as follows: Modification of 6.2 on labelling, deletion of the reference to EU Directive 80/778/EEC of 15 Ju
17、ly 1980 in order to take account of the latest Directive in force. 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, E
18、stonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Copyright European C
19、ommittee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 4 Introduction In respect of potential adverse effects on the quality of water intended for human consumption caused
20、 by the product covered by this European Standard: a) this European Standard provides no information as to whether the product may be used without restriction in any of the Member States of the EU or EFTA; b) it should be noted that, while awaiting the adoption of verifiable European criteria, exist
21、ing national regulations concerning the use and/or the characteristics of this product remain in force. NOTE Conformity with this European Standard does not confer or imply acceptance or approval of the product in any of the Member States of the EU or EFTA. The use of the product covered by this Eur
22、opean Standard is subject to regulation or control by National Authorities. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 5 1 Scope This Europ
23、ean Standard 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.
24、2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amend
25、ments) 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 spectrom
26、etric 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 l
27、umps 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 Description 3.1 Identification 3.1.1 Chemical name Sodium thiosulfate. 3.
28、1.2 Synonym or commons names Sodium thiosulfate, sodium hyposulfite. 3.1.3 Relative molecular mass 158,11 (anhydrous). 3.1.4 Empirical formula Na2S2O3. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without
29、 license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 6 3.1.5 Chemical formula Na2S2O3. 3.1.6 CAS-Registry Number 1)7772-98-7 (anhydrous); 10102-17-7 (pentahydrate). 3.1.7 EINECS reference 2)231-867-5. 3.2 Commercial form The product is a crystalline powder. 3.3 Physical properties 3.3.1 Appearanc
30、e The hydrated product is colourless crystal. The anhydrous product is a white powder. 3.3.2 Density The particle density of the hydrated product is 1,69 g/cm3to 1,73 g/cm3at 20 C. 3.3.3 Solubility in water The solubility of the product in water is 700 g/l at 20 C (anhydrous); for pentahydrate : 291
31、0 g/l at 45 C. 3.3.4 Vapour pressure Not applicable. 3.3.5 Boiling point at 100 kPa 3)Not applicable. 3.3.6 Crystallisation point The product starts to decompose at 45 C to 50 C. 3.3.7 Specific heat Not known. 1) Chemical Abstracts Service Registry Number. 2) European Inventory of Existing Commercia
32、l Chemical Substances. 3) 100 kPa = 1 bar. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 7 3.3.8 Viscosity, dynamic Not applicable. 3.3.9 Crit
33、ical temperature Not applicable. 3.3.10 Critical pressure Not applicable. 3.3.11 Physical hardness Not applicable. 3.4 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 si
34、lver 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, iodin
35、e, lead and silver salts. 4 Purity criteria 4.1 General This European Standard 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 materi
36、al 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 inten
37、ded for human consumption, taking into account raw water quality, required dosage, contents of other impurities and additives used in the product not stated in this product standard. Limits have been given for impurities and chemical parameters where these are likely to be present in significant qua
38、ntities from the current production process and raw materials. If the production process or raw materials leads to significant quantities of impurities, by-products or additives being present, this shall be notified to the user. 4.2 Composition of commercial product The concentration of sodium thios
39、ulfate anhydrous shall not be less than a mass fraction of 95 % of Na2S2O3. The concentration of sodium thiosulfate pentahydrate shall not be less than a mass fraction of 95% of Na2S2O3.5 H2O. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo rep
40、roduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 8 4.3 Impurities and main by-products The content of sodium sulfate shall not exceed a mass fraction of 5 % . 4.4 Chemical parameters The product shall conform to the requirements specified in Table 1. T
41、able 1 Chemical parameters Parameter Limitmg/kg of commercial product Antimony (Sb) max 2 Arsenic (As) max 0,5 Cadmium (Cd) max 0,1 Chromium (Cr) max 5 Lead (Pb) max 5 Mercury (Hg) max 0,1 Nickel (Ni) max 5 Selenium (Se) max 2 NOTE Pesticides and polycyclic aromatic hydrocarbons and cyanides (CN ) a
42、re not relevant in sodium thiosulfate because the raw materials used in the manufacturing are free of them. For parametric values of sodium thiosulfate on trace metal content in drinking water, see 1. 5 Test methods 5.1 Sampling Observe the general recommendations of ISO 3165 and take account of ISO
43、 6206. Prepare the laboratory sample(s) required by the relevant procedure described in ISO 8213. 5.2 Analyses 5.2.1 Main product The sodium thiosulfate content shall be determined in accordance with ISO 10636. 5.2.2 Impurities 5.2.2.1 Sulfate The content of sodium sulfate (Na2SO4) shall be determin
44、ed in accordance with ISO 22743. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12125:2012EN 12125:2012 (E) 9 5.2.3 Chemical parameters 5.2.3.1 General The content of chem
45、ical parameters shall be determined using the procedures specified in Table 2: Table 2 Procedures for the determination of chemical parameters Element Reference Method Wavelength (nm) Flame As see 5.2.3.3 Hydride AAS 193,7 n.a.Sb see 5.2.3.3 Hydride AAS 217,6 n.a. Cd ISO 6353-1 GM 29see 5.2.3.2 AAS
46、228,8 air-acetylene Cr ISO 6353-1 GM 29see 5.2.3.2 AAS 357,8 air-acetylene Pb ISO 6353-1 GM 29see 5.2.3.2 AAS 217,0 or 283,3 air-acetylene Ni ISO 6353-1 GM 29see 5.2.3.2 AAS 232,0 oxidising acetylene-air Se see 5.2.3.3 Hydride AAS 196,0 n.a.Hg in accordance withISO 5993 flameless AAS 253,6 n.a. AAS
47、= Atomic Absorption Spectroscopy. n.a. = not applicable. 5.2.3.2 Determination of cadmium (Cd), chromium (Cr), lead (Pb) and nickel (Ni) 5.2.3.2.1 Principle The elements cadmium (Cd), chromium (Cr), lead (Pb) and nickel (Ni) are determined using atomic absorption spectrometry with the standard addit
48、ions technique. 5.2.3.2.2 Reagents All reagents shall be of a recognised analytical grade and the water used shall conform to the grade 3 specified in EN ISO 3696. 5.2.3.2.2.1 Standard solution (100 g/l Cd, Cr ,Pb or Ni) The standard solution shall be freshly prepared on the day of use by individual dilution of a stock solution. This stock solution with a Cd, Cr, Pb or Ni content of at least 1 mg/l shall be made by dilution of standard solutions of Cd, Cr, Pb and Ni which are available from all major supplie
