1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 12121:2012Chemicals used for treatmentof water intended for humanconsumption SodiumdisulfiteCopyright European Committee for Standardization Provided by IHS under license w
2、ith CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12121:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 12121:2012. It supersedes BS EN 12121:2005 which is withdrawn.The UK participation in its preparation was e
3、ntrusted to Technical Committee CII/59, Chemicals for drinking water treatment.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its corr
4、ect application. The British Standards Institution 2013. Published by BSI Standards Limited 2013ISBN 978 0 580 77780 6 ICS 71.100.80 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and St
5、rategy Committee on 28 February 2013.Amendments issued since publicationDate T e x t a f f e c t e dCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12121:2012EUROPEAN STAND
6、ARD NORME EUROPENNE EUROPISCHE NORM EN 12121 November 2012 ICS 71.100.80 Supersedes EN 12121:2005English Version Chemicals used for treatment of water intended for human consumption - Sodium disulfite Produits chimiques utiliss pour le traitement de leau destine la consommation humaine - Disulfite d
7、e sodiumProdukte zur Aufbereitung von Wasser fr den menschlichen Gebrauch - Natriumdisulfit 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
8、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
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, C
10、roatia, 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 an
11、d 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 12121:
12、2012: ECopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12121:2012EN 12121:2012 (E) 2 Contents Page Foreword 3Introduction . 41 Scope 52 Normative references 53 Description
13、. 54 Purity criteria 75 Test methods 86 Labelling Transportation Storage . 14Annex A (informative) General information on sodium disulfite 17Annex B (normative) General rules relating to safety . 18Bibliography 19Copyright European Committee for Standardization Provided by IHS under license with CEN
14、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12121:2012EN 12121:2012 (E) 3 Foreword This document (EN 12121:2012) has been prepared by Technical Committee CEN/TC 164 “Water supply”, the secretariat of which is held by AFNOR. This European Standard shall be
15、 given the status of a national standard, either by publication 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
16、the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 12121:2005. The significant technical differences between this edition and EN 12121:2005 are as follows: Modification of 6.2 on labelling, deletio
17、n of the reference to EU Directive 80/778/EEC of 15 July 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,
18、 Bulgaria, Croatia, 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, Switzerlan
19、d, Turkey and the United Kingdom. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12121:2012EN 12121:2012 (E) 4 Introduction In respect of potential adverse effects on the
20、quality of water intended for human consumption caused 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 awaiti
21、ng 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 European Standard does not confer or imply acceptance or approval of the product in any of the Member States of the
22、EU or EFTA. The use of the product covered by this European 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-,-,-
23、BS EN 12121:2012EN 12121:2012 (E) 5 1 Scope This European Standard is applicable to sodium disulfite used for treatment of water intended for human consumption. It describes the characteristics of sodium disulfite and specifies the requirements and the corresponding test methods for sodium disulfite
24、. It gives information on its use in water treatment. It also determines the rules relating to safe handling and use (see Annex B). 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 re
25、ferences, 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 Sa
26、fety in sampling ISO 3629, Photography Processing chemicals Specifications for potassium metabisulfite 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 IS
27、O 6353-1, Reagents for chemical analysis Part 1: General test methods ISO 8213, Chemical products for industrial use Sampling techniques Solid chemical products in the form of particles varying from powders to coarse lumps ISO 9297, Water quality Determination of chloride Silver nitrate titration wi
28、th chromate indicator (Mohrs method) ISO 22743, Water quality Determination of sulfates Method by continuous flow analysis (CFA) 3 Description 3.1 Identification 3.1.1 Chemical name Sodium disulfite. 3.1.2 Synonym or commons names Sodium metabisulfite, sodium pyrosulfite. 3.1.3 Relative molecular ma
29、ss 190,10. 3.1.4 Empirical formula Na2S2O5. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 12121:2012EN 12121:2012 (E) 6 3.1.5 Chemical formula Na2S2O5.3.1.6 CAS-Registry
30、Number 1)7681-57-4. 3.1.7 EINECS reference 2)231-673-0. 3.2 Commercial form The product is a crystalline powder.3.3 Physical properties 3.3.1 Appearance and odour The product is a white, free-flowing fine crystalline powder with a slight odour of sulfur dioxide. 3.3.2 Density The density of the prod
31、uct is 2,7 g/cm3at 20 C. The bulk density is approximately 1,3 g/cm3at 20 C. 3.3.3 Solubility (in water) The solubility of the product in water is 540 g/l at 20 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 decompose
32、s above 150 C. 3.3.7 Specific heat Not known. 1) Chemical Abstracts Service Registry Number. 2)European Inventory of Existing Commercial Chemical Substances. 3)100 kPa = 1 bar. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or net
33、working permitted without license from IHS-,-,-BS EN 12121:2012EN 12121:2012 (E) 7 3.3.8 Viscosity dynamic Not applicable. 3.3.9 Critical temperature Not applicable. 3.3.10 Critical pressure Not applicable. 3.3.11 Physical hardness Not applicable. 3.4 Chemical properties The solution is weakly acid.
34、 The pH value of a saturated aqueous solution of sodium disulfite is between 4,5 and 5,0. Sodium disulfite dissolves in water forming sodium hydrogen sulfite. At elevated temperatures ( 150 C) or on contact with acids sulfur dioxide is generated. Sodium disulfite reacts violently with oxidising agen
35、ts; e.g. with sodium hypochlorite or hydrogen peroxide. 4 Purity criteria 4.1 General This European Standard specifies the minimum purity requirements for sodium disulfite used for the treatment of water intended for human consumption. Limits are given for impurities commonly present in the product.
36、 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
37、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 product standard. Limits have been given for impurities and chemical parameters where these are likely to
38、be present in significant quantities from the current production process and raw materials. If the production process or raw materials leads to significant quantities of impurities, by-products or additives being present, this shall be notified to the user. 4.2 Composition of commercial product The
39、content of sodium disulfite shall not be less than a mass fraction of 95 % (Na2S2O5). The concentration of sodium disulfite shall be within 5 % of the manufacturers declared value. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or
40、 networking permitted without license from IHS-,-,-BS EN 12121:2012EN 12121:2012 (E) 8 4.3 Impurities and main by-products The sum of the content of sodium sulfate and sodium chloride shall not exceed a mass fraction of 5 % of the commercial product. 4.4 Chemical parameters The product shall conform
41、 to the requirements specified in Table 1. Table 1 Chemical parameters Parameter Limit mg/kg of commercial product Antimony (Sb) max 1 Arsenic (As) max 1 Cadmium (Cd) max 1 Chromium (Cr) max 1 Lead (Pb) max 5 Mercury (Hg) max 1 Nickel (Ni) max 1 Selenium (Se) max 1 NOTE Other chemical parameters and
42、 indicator parameters are not relevant in sodium disulfite because the raw materials used in the manufacturing process are free of them. For parametric values of sodium disulfite on trace metal content in drinking water, see 1. 5 Test methods 5.1 Sampling Observe the general recommendations of ISO 3
43、165 and take account of ISO 6206. Prepare the laboratory sample(s) required by the relevant procedure described in ISO 8213. 5.2 Analyses 5.2.1 General All reagents shall be of a recognised analytical grade and the water used shall conform to the grade 3 specified in EN ISO 3696. 5.2.2 Main product
44、5.2.2.1 General The sodium disulfite content shall be determined by the method for potassium disulfite described in ISO 3629. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS E
45、N 12121:2012EN 12121:2012 (E) 9 5.2.2.2 Principle Sodium disulfite is oxidised with a fixed volume of iodine. The excess of added iodine is titrated with sodium thiosulfate. The determination includes other sulfites in addition to Na2S2O5, therefore the second titration, as described in ISO 3629, is
46、 omitted for the purpose of this determination. 5.2.2.3 Calculation The formula given in ISO 3629 for potassium disulfite has to be adapted for sodium disulfite. The sodium disulfite content CB1B, expressed as a mass fraction in %, is given by the following formula: CB1= 4,76 ()()10032ccVm(1) where
47、c2is the actual concentration, in moles per litre, of the sodium thiosulfate solution; c3is the actual concentration, in moles per litre, of the iodine solution; V is the volume, in millilitres, of the sodium thiosulfate solution used for the titration; m is the mass, in grams, of the test portion u
48、sed for the titration; 4,76 is a conversion factor for the mass of sodium disulfite equivalent to 1 mole of iodine (i.e. 47,6) X the conversion factor for millilitres to litres (i.e. 0,001) X 100 (for percentage); 100 is the volume, in millilitres of iodine solution added for total oxidation. 5.2.3 Impurities 5.2.3.1 Sulfate The sulfate content shall be determined in accordance with ISO 22743. 5.2.3.2 Chloride The chloride content shall be determined in accordance with ISO 9297. 5.2.4 Chemical param
