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1、BRITISH STANDARD BS EN 12121:2005 Chemicals used for treatment of water intended for human consumption Sodium disulfite The European Standard EN 12121:2005 has the status of a British Standard ICS 71.100.80 ? Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolle
2、d Copy, (c) BSI BS EN 12121:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 April 2006 BSI 2006 ISBN 0 580 47479 8 National foreword This British Standard is the official English language version of EN 12121:2005. It supersedes BS EN
3、12121:1999 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee CII/59, Chemicals for drinking water treatment, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. The United K
4、ingdom, as a member of CEN, is obliged to publish EN 12121 as a British Standard. However, attention is drawn to the fact that the United Kingdom voted against the approval of EN 12121. The main reasons for this disapproval were as follows. a) In the opinion of the UK committee, the limit on the sum
5、 of the contents of sodium sulfate and sodium chloride, quoted in 4.3, is unnecessary. b) No information has been provided on the preparation of test solutions or the calculation of results for the determinations of sulfate and chloride, in order to apply the methods referred to in 5.2.3 which are i
6、ntended for the analysis of water. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility
7、 of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. a
8、id enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This
9、document comprises a front cover, an inside front cover, the EN title page, pages 2 to 18, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy:
10、sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12121 June 2005 ICS 71.100.80 Supersedes EN 12121:1998 English version Chemicals used for treatment of water intended for human consumption - Sodium disulf
11、ite Produits chimiques utiliss pour le traitement de leau destine la consommation humaine - Disulfite de sodium Produkt zue Aufbereitung von Wasser den menschlichen Gebrauch - Natriumdisulfit This European Standard was approved by CEN on 12 May 2005. CEN members are bound to comply with the CEN/CENE
12、LEC 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 Central Secretariat or to any C
13、EN 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 Central Secretariat has the same status as the official versions. CEN
14、members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and
15、 United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12121
16、:2005: E Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 2 Contents Foreword3 Introduction.4 1 Scope 5 2 Normative references5 3 Description.5 4 Purity criteria7 Table 1 Chemical parameters .8 5 Test methods8 Table 2 Proced
17、ures for the determination of chemical parameters .10 Figure 1 Calculation of the element concentration in the test solution.11 Figure 2 Calculation of the element concentration in the blank solution12 Table 3 Standard solution .13 6 Labelling - Transportation - Storage14 Annex A (informative) Gener
18、al information on sodium disulfite16 Annex B (normative) General rules relating to safety17 Bibliography18 Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 3 Foreword This European Standard (EN 12121:2005) has been prepared
19、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 December 2005, and conflicting national standards shall
20、 be withdrawn at the latest by December 2005. This document supersedes EN 12121:1998. Significant technical differences between this edition and EN 12121:1998 are as follows: deletion of this reference to EU Directive 80/778/EEC of July, 15 1980 in order to take into account the latest Directive in
21、force (see 1). According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, It
22、aly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 4 Introduction In respect
23、of potential adverse effects on the 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)
24、 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 European Standard does not confer or imply acceptance or approval of the produ
25、ct in any of the Member States of the EU or EFTA. The use of the product covered by this European Standard is subject to regulation or control by National Authorities. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 5 1 Sco
26、pe 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. It gives information on its use in wate
27、r treatment. It also determines the rules relating to safe handling and use (see Annex B). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest editio
28、n of the referenced document (including any amendments) applies. EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696:1987) ISO 3165, Sampling of chemical products for industrial use - Safety in sampling ISO 3629, Photography-Processing chemicals- Specification
29、s 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 ISO 6353-1, Reagents for chemical analysis. Part 1: General test meth
30、ods 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 with chromate indicator (Mohrs method) ISO 22743 (in preparation)
31、Water quality - Determination of sulfates 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 mass 190,10. 3.1.4 Empirical formula Na2S2O5. Licensed
32、Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 6 3.1.5 Chemical formula Na2S2O5. 3.1.6 CAS-Registry Number1) 7681-57-4. 3.1.7 EINECS reference2) 231-673-0. 3.2 Commercial form The product is a crystalline powder. 3.3 Physical prope
33、rties 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 product is 2,7 g/cm3 at 20 C. The bulk density is approximately 1,3 g/cm3 at 20 C. 3.3.3 Solubility (in water) The solubility of the p
34、roduct in water is 540 g/l at 20 C. 3.3.4 Vapour pressure Not applicable. 3.3.5 Boiling point at 100 kPa3 Not applicable. 3.3.6 Crystallisation point The product decomposes above 150 C. 3.3.7 Specific heat Not known. 1) Chemical Abstracts Service Registry Number. 2) European Inventory of Existing Co
35、mmercial Chemical Substances. 3) 100 kPa = 1 bar. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 7 3.3.8 Viscosity dynamic Not applicable. 3.3.9 Critical temperature Not applicable. 3.3.10 Critical pressure Not applicable.
36、 3.3.11 Physical hardness Not applicable. 3.4 Chemical properties The solution is weakly acid. 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
37、 with acids sulfur dioxide is generated. Sodium disulfite reacts violently with oxidizing agents ; 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 i
38、ntended 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. NOTE Users of this pr
39、oduct 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 produc
40、t standard. Limits have been given for impurities and chemical 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 leads to significant quantities of impurities, by-products or add
41、itives being present, this shall be notified to the user. 4.2 Composition of commercial product The 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. 4.3 Impurities and
42、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. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 8 4.4 Chemical parameters The p
43、roduct shall conform 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 O
44、ther chemical parameters and 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 gene
45、ral recommendations of ISO 3165 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 recognized analytical grade and the water used shall conform to grade 3 specified in EN ISO 3
46、696. 5.2.2 Main product 5.2.2.1 General The sodium disulfite content shall be determined by the method for potassium disulfite described in ISO 3629. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 05:48:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12121:2005 (E) 9 5.2.2.2 Principle Sodiu
47、m disulfite is oxidized 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 omitted for the purpose of this determination. 5.2.2.3
48、 Calculation The equation given in ISO 3629 for potassium disulfite has to be adapted for sodium disulfite. The sodium disulfite content C1, expressed as a mass fraction in %, is given by the following equation: C1 = 4,76 () ()()100 32 ccV m (1) where: c2 is the actual concentration, in moles per li
49、tre, of the sodium thiosulfate solution; c3 is 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 used 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 percenta
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