1、BS EN 938:2016Chemicals used for treatmentof water intended for humanconsumption SodiumchloriteBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 938:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 938:2016. It supersedes
2、 BS EN 938:2009 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CII/59, Chemicals for drinking water treatment.A list of organizations represented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 includ
3、e all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 86576 3 ICS 13.060.20; 71.100.80 Compliance with a British Standard cannot confer immunity from legal obligati
4、ons.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS EN 938:2016EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 938 May 2016 ICS 71.100.80 Supersede
5、s EN 938:2009English Version Chemicals used for treatment of water intended for human consumption - Sodium chlorite Produits chimiques utiliss pour le traitement de leau destine la consommation humaine - Chlorite de sodium Produkte zur Aufbereitung von Wasser fr den menschlichen Gebrauch - Natriumch
6、lorit This European Standard was approved by CEN on 18 March 2016. 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
7、 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
8、 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, Former Yugoslav Republic of Mac
9、edonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUR
10、OPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 938:2016 EBS EN 938:2016EN 938:2016 (E) 2 Contents Page European foreword . 4 Introdu
11、ction 5 1 Scope 6 2 Normative references 6 3 Description 6 3.1 Identification 6 3.1.1 Chemical name . 6 3.1.2 Synonym or common name . 6 3.1.3 Relative molecular mass . 6 3.1.4 Empirical formula . 6 3.1.5 Chemical formula 6 3.1.6 CAS Registry Number 6 3.1.7 EINECS reference 7 3.2 Commercial form . 7
12、 3.3 Physical properties . 7 3.3.1 Appearance 7 3.3.2 Density 7 3.3.3 Solubility in water . 7 3.3.4 Vapour pressure 7 3.3.5 Boiling point at 100 kPa . 7 3.3.6 Crystallization point . 7 3.3.7 Specific heat 8 3.3.8 Viscosity (dynamic) 8 3.3.9 Critical temperature 8 3.3.10 Critical pressure 8 3.3.11 Ph
13、ysical hardness . 8 3.4 Chemical properties . 8 4 Purity criteria . 8 4.1 General 8 4.2 Composition of commercial product 9 4.3 Impurities and main by-products . 9 4.4 Chemical parameters . 9 5 Test methods . 10 5.1 Sampling 10 5.1.1 General . 10 5.1.2 Sampling from drums and bottles 10 5.1.3 Sampli
14、ng from tanks and tankers 10 5.2 Analysis 11 5.2.1 Determination of sodium chlorite (main product) 11 5.2.2 Impurities . 12 5.2.3 Chemical parameters 15 6 Labelling - Transportation - Storage . 17 6.1 Means of delivery . 17 6.2 Labelling according to the EU Legislation 17 BS EN 938:2016EN 938:2016 (
15、E) 3 6.3 Transportation regulations and labelling . 17 6.4 Marking 18 6.5 Storage 18 6.5.1 General . 18 6.5.2 Long term stability . 18 6.5.3 Storage incompatibilities . 18 Annex A (informative) General information on sodium chlorite . 19 A.1 Origin 19 A.1.1 Raw materials 19 A.1.2 Manufacturing proce
16、ss . 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 20 A.3 Routine analyses . 20 A.3.1 Determination of sodium chlorite (NaClO2) . 20 A.3.2 Determination of chlorat
17、e ion (ClO3-) 22 A.3.3 Determination of chemical parameters . 23 Annex B (normative) General rules relating to safety . 24 B.1 Rules for safe handling and use . 24 B.2 Emergency procedures . 24 B.2.1 First aid 24 B.2.2 Spillage . 24 B.2.3 Fire . 24 Annex C (normative) Determination of arsenic, antim
18、ony and selenium (atomic absorption spectrometry hydride technique) 25 C.1 Safety precautions 25 C.2 General principle 25 C.3 Interferences 25 C.4 Reagents . 25 C.5 Apparatus 27 C.6 Procedure 29 C.6.1 Preparation of the apparatus . 29 C.6.2 Preparation of calibration solutions . 30 C.6.3 Preparation
19、 of test solutions and standard solutions . 30 C.6.4 Determination of arsenic with sodium borohydride . 30 C.6.5 Determination of selenium with sodium borohydride . 30 C.6.6 Determination of antimony with sodium borohydride 31 C.7 Calculation. 31 Bibliography . 32 BS EN 938:2016EN 938:2016 (E) 4 Eur
20、opean foreword This document (EN 938:2016) 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 late
21、st by November 2016, and conflicting national standards shall be withdrawn at the latest by November 2016. 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 not be held responsible for identifying any or all
22、 such patent rights. This document supersedes EN 938:2009. Significant technical differences between this edition and EN 938:2009 are as follows: a) deletion of reference to EU Directive 67/548/EEC of June 27, 1967 in order to take into account the latest Regulation in force (see 2); b) use of the c
23、hanged classification and labelling (see 2). According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Forme
24、r 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. BS EN 938:2016EN 938:2016 (E) 5 Introducti
25、on In respect 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 E
26、U 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 the standard does not confer or imply acceptance or approval of the pr
27、oduct 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. BS EN 938:2016EN 938:2016 (E) 6 1 Scope This European Standard is applicable to sodium chlorite used for treatment of water inten
28、ded for human consumption. It describes the characteristics of sodium chlorite and specifies the requirements and the corresponding test methods for sodium chlorite. It gives information on its use in water treatment. 2 Normative references The following documents, in whole or in part, are normative
29、ly 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 amendments) applies. EN ISO 3696, Water for analytical laboratory use Specification and
30、 test methods (ISO 3696) EN ISO 12846, Water quality Determination of mercury Method using atomic absorption spectrometry (AAS) with and without enrichment (ISO 12846) ISO 3165, Sampling of chemical products for industrial use Safety in sampling ISO 6206, Chemical products for industrial use Samplin
31、g Vocabulary ISO 8288, Water quality Determination of cobalt, nickel, copper, zinc, cadmium and lead Flame atomic absorption spectrometric methods ISO 9174, Water quality Determination of chromium Atomic absorption spectrometric methods 3 Description 3.1 Identification 3.1.1 Chemical name Sodium chl
32、orite. 3.1.2 Synonym or common name None. 3.1.3 Relative molecular mass 90,44. 3.1.4 Empirical formula NaClO2. 3.1.5 Chemical formula Na-O-Cl = O. 3.1.6 CAS Registry Number 1)7758-19-2. 1) Chemical Abstracts Service Registry Number. BS EN 938:2016EN 938:2016 (E) 7 3.1.7 EINECS reference 2)231-836-6.
33、 3.2 Commercial form The product is supplied as a powder or as an aqueous solution of sodium chlorite. 3.3 Physical properties 3.3.1 Appearance The products are either a white powder or a greenish-yellow aqueous solution. 3.3.2 Density The density of sodium chlorite solutions is given in Table 1. Ta
34、ble 1 Density of sodium chlorite solutions Aqueous solution concentration Density % (mass fraction) g/ml at 20 C 25 1,210 31 1,270 3.3.3 Solubility in water The solubility of sodium chlorite depending on temperature is given in Table 2. Table 2 Solubility of sodium chlorite Temperature Solubility C
35、g/l 5 340 17 390 30 460 45 530 60 550 3.3.4 Vapour pressure Not applicable. 3.3.5 Boiling point at 100 kPa 3)Not applicable. 3.3.6 Crystallization point The crystallization point of sodium chlorite depending on concentration is given in Table 3. 2) European Inventory of Existing Commercial Chemical
36、Substances. 3) 100 kPa = 1 bar. BS EN 938:2016EN 938:2016 (E) 8 Table 3 Crystallization point of sodium chlorite Aqueous solution concentration Crystallization point % (mass fraction) C 25 14,5 31 3 3.3.7 Specific heat Not known. 3.3.8 Viscosity (dynamic) The viscosity of sodium chlorite depending o
37、n concentration is given in Table 4. Table 4 Viscosity of sodium chlorite Aqueous solution concentration Viscosity % (mass fraction) mPa.s at 20 C 25 2,33 31 3,26 3.3.9 Critical temperature Not applicable. 3.3.10 Critical pressure Not applicable. 3.3.11 Physical hardness Not applicable. 3.4 Chemical
38、 properties Sodium chlorite is a strong oxidizing agent. It generates chlorine dioxide with acidic solutions or chlorine and reacts with organic compounds. 4 Purity criteria 4.1 General This European Standard specifies the minimum purity requirements for sodium chlorite used for the treatment of wat
39、er 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 the relevant authorities. Users of this
40、 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 product not stated in the produ
41、ct standard. 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 BS EN 938:2016EN 938:2016 (E) 9 or raw materials leads to significant quantities
42、 of impurities, by-products or additives being present, this shall be notified to the user. 4.2 Composition of commercial product The sodium chlorite is available as a powder or as an aqueous solution with sodium chlorite content of 7,5 percent by mass fraction to 35 percent by mass fraction. The co
43、ntent of sodium chlorite shall be equal to or greater than the manufacturers declared value. 4.3 Impurities and main by-products The product shall conform to the requirements specified in Table 5. Table 5 Impurities Impurity Limit g/kg sodium chlorite 100 % mass fraction Sodium chlorate (NaClO3) max
44、. 40 Sodium nitrate (NaNO3) max. 1 NOTE Sodium chlorate can be a by-product of the manufacturing process. 4.4 Chemical parameters NOTE For the purposes of this standard, “chemical parameters” are those defined in the EU Directive 98/83/EC of November 13, 1998 (see 1). The content of chemical paramet
45、ers shall conform to the requirements specified in Table 6. Table 6 Chemical parameters Parameter Limit mg/kg sodium chlorite 100 % mass fraction Type 1 Type 2 Arsenic (As) max. 1,1 7,5 Cadmium (Cd) max. 1,5 7,5 Chromium (Cr) max. 1,1 7,5 Mercury (Hg) max. 1,1 3,7 Nickel (Ni) max. 1,1 7,5 Lead (Pb)
46、max. 1,1 7,5 Antimony (Sb) max. 1,1 7,5 Selenium (Se) max. 1,1 7,5 NOTE Cyanide which does not exist in a strong oxidizing medium such as sodium chlorite is not a relevant chemical parameter. Pesticides and polycyclic aromatic hydrocarbons are not by-products of the manufacturing process. BS EN 938:
47、2016EN 938:2016 (E) 10 5 Test methods 5.1 Sampling 5.1.1 General Observe the general recommendations of ISO 3165 and take ISO 6206 into account. 5.1.2 Sampling from drums and bottles 5.1.2.1 General 5.1.2.1.1 Mix the contents of the container to be sampled by shaking the container, by rolling it or
48、by rocking it from side to side, taking care not to damage the container or spill any of the liquid. 5.1.2.1.2 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 thor
49、oughly mixed. Otherwise, proceed as described in 5.1.2.3. 5.1.2.1.3 Examine the surface of the liquid. If there are signs of surface contamination, take samples from the surface as described in 5.1.2.2; otherwise, take samples as described in 5.1.2.3. 5.1.2.2 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 just before it fills completely and allow any liquid adhering to the ladle to drain
