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1、BS EN 938:2009 ICS 13.060.20; 71.100.80 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Chemicals used for treatment of water intended for human consumption Sodium chlorite This British Standard was published under the authority of the Standards Policy and Str
2、ategy Committee on 30 June 2009. BSI 2009 ISBN 978 0 580 58599 9 Amendments/corrigenda issued since publication DateComments BS EN 938:2009 National foreword This British Standard is the UK implementation of EN 938:2009. It supersedes BS EN 938:2000 which is withdrawn. The UK participation in its pr
3、eparation 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 include all the necessary provisions of a contract. Users are respons
4、ible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. BS EN 938:2009 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 938 January 2009 ICS 71.100.80Supersedes EN 938:1999 English Version Chemicals used for treatment of water intended
5、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 - Natriumchlorit This European Standard was approved by CEN on 5 December 2008. CEN mem
6、bers 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 applicat
7、ion to the CEN 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 Management Centre has
8、the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Port
9、ugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CENAll rights of exploitation in any form and by any means
10、reserved worldwide for CEN national Members. Ref. No. EN 938:2009: E BS EN 938:2009 EN 938:2009 (E) 2 Contents Page Foreword 3 Introduction . 4 1 Scope 5 2 Normative references 5 3 Description . 5 3.1 Identification 5 3.2 Commercial form . 6 3.3 Physical properties 6 3.4 Chemical properties 7 4 Puri
11、ty criteria 8 4.1 General 8 4.2 Composition of commercial product . 8 4.3 Impurities and main by-products . 8 4.4 Chemical parameters 8 5 Test methods . 9 5.1 Sampling . 9 5.2 Analysis 10 6 Labelling - Transportation - Storage 20 6.1 Means of delivery . 20 6.2 Risk and safety labelling according to
12、the EU Directives 20 6.3 Transportation regulations and labelling 21 6.4 Marking . 21 6.5 Storage 21 Annex A (informative) General information on sodium chlorite . 22 Annex B (normative) General rules relating to safety . 27 Annex C (normative) Determination of arsenic, antimony and selenium (atomic
13、 absorption spectrometry hydride technique) . 28 Bibliography 34 w w w . b z f x w . c o m BS EN 938:2009 EN 938:2009 (E) 3 Foreword This document (EN 938:2009) has been prepared by Technical Committee CEN/TC 164 “Water supply”, the secretariat of which is held by AFNOR. This European Standard shall
14、 be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2009, and conflicting national standards shall be withdrawn at the latest by July 2009. Attention is drawn to the possibility that some of the elements of this document ma
15、y be 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 938:1999. The significant technical differences between this edition and EN 938:1999 are as follows: a) Deletion of reference to EU Directive
16、 80/778/EEC of July 15, 1980 in order to take into account the latest Directive in force (see 1). b) Replacement of ISO 5666-1 by EN 1483. Annex A is informative. Annexes B and C are normative. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following c
17、ountries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
18、Spain, Sweden, Switzerland and the United Kingdom. w w w . b z f x w . c o m BS EN 938:2009 EN 938:2009 (E) 4 Introduction In respect of potential adverse effects on the quality of water intended for human consumption, caused by the product covered by this Standard: 1) this Standard provides no info
19、rmation as to whether the product may be used without restriction in any of the Member States of the EU or EFTA; 2) 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
20、 in force. NOTE Conformity with the 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 European Standard is subject to regulation or control by National Authorities. w w w . b z f x w . c o m B
21、S EN 938:2009 EN 938:2009 (E) 5 1 Scope This European Standard is applicable to sodium chlorite used for treatment of water intended for human consumption. It describes the characteristics of sodium chlorite and specifies the requirements and the corresponding test methods for sodium chlorite. It gi
22、ves information on its use in water treatment. 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 edition of the referenced document (including any a
23、mendments) applies. EN 1483, Water quality - Determination of mercury - Method using atomic absorption spectrometry 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 62
24、06, Chemical products for industrial use - Sampling - Vocabulary ISO 8288:1986, Water quality - Determination of cobalt, nickel, copper, zinc, cadmium and lead - Flame atomic absorption spectrometric methods ISO 9174, Water quality - Determination of total chromium - Atomic absorption spectrometric
25、methods 3 Description 3.1 Identification 3.1.1 Chemical name Sodium chlorite. 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 NaClO2. w w w . b z f x w . c o m BS EN 938:2009 EN 938:2009 (E) 6 3.1.6 CAS Registry Number 1)
26、 7758-19-2. 3.1.7 EINECS reference 2) 231-836-6. 3.2 Commercial form The product is supplied as an aqueous solution of sodium chlorite 3.3 Physical properties 3.3.1 Appearance The products are greenish-yellow aqueous solution. 3.3.2 Density The density of sodium chlorite is given in Table 1. Table 1
27、 Density of sodium chlorite Aqueous solution concentration % (mass fraction) Density 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 C Solubility g/l 5 340 17 390
28、 30 460 45 530 60 550 3.3.4 Vapour pressure Not applicable. 1) Chemical Abstracts Service Registry Number 2) European Inventory of Existing Commercial Chemical Substances w w w . b z f x w . c o m BS EN 938:2009 EN 938:2009 (E) 7 3.3.5 Boiling point at 100 kPa 3) Not applicable. 3.3.6 Crystallizatio
29、n point The crystallization point of sodium chlorite depending on concentration is given in Table 3. Table 3 Crystallization point of sodium chlorite Aqueous solution concentration % (mass fraction) Crystallization point C 25 - 14,5 31 3 3.3.7 Specific heat Not known. 3.3.8 Viscosity (dynamic) The v
30、iscosity of sodium chlorite depending on concentration is given in Table 4. Table 4 Viscosity of sodium chlorite Aqueous solution concentration % (mass fraction) Viscosity 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 Physica
31、l hardness Not applicable. 3.4 Chemical properties Sodium chlorite is a strong oxidizing agent. It generates chlorine dioxide with acidic solutions or chlorine and reacts with organic compounds. 3) 100 kPa = 1 bar w w w . b z f x w . c o m BS EN 938:2009 EN 938:2009 (E) 8 4 Purity criteria 4.1 Gener
32、al This European Standard specifies the minimum purity requirements for Sodium chlorite 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
33、 present and, if so, this shall be notified to the user and when necessary to the relevant authorities. NOTE 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
34、raw water quality, required dosage, contents of other impurities and additives used in the product not stated in the product 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
35、 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 sodium chlorite is available as an aqueous solution with sodium chlorite con
36、tent of 24,5 percent by mass fraction to 35 percent by mass fraction. Solutions of 25 percent by mass fraction and 31 percent by mass fraction of sodium chlorite are the most commonly used. The content of sodium chlorite shall be equal to or greater than the manufacturers declared value. 4.3 Impurit
37、ies 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. 40 Sodium nitrate (NaNO3) max. 1 NOTE Sodium chlorate can be a by-product of the manufacturing process
38、. Sodium nitrate is used as a corrosion inhibitor in the sodium chlorite special grade for the textile industry. 4.4 Chemical parameters NOTE For the purpose 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 pa
39、rameters shall conform to the requirements specified in Table 6. BS EN 938:2009 EN 938:2009 (E) 9 Table 6 chemical parameters Parameter Limit in mg/kg of sodium chlorite 100 % of mass fraction Type 1Type 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
40、,1 3,7 Nickel (Ni) max.1,1 7,5 Lead (Pb) 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
41、 the manufacturing process. 5 Test methods 5.1 Sampling 5.1.1 General Observe the general recommendations of ISO 3165 and take account of ISO 6206. 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
42、or 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 t
43、horoughly 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. BS EN 938:2009 EN 938:2009 (E) 10 5.1.2.2 Sur
44、face 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 off. If necessary, repeat this o
45、peration 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. 5.1.2.3 Bottom sampling Take a sample using an open sampling tube, or a bottom-valve sampling tube, suited to the size of container and
46、 the viscosity of the liquid. When using an open sampling tube, close it at the top and then lower the bottom end to the bottom of the container. Open the tube and move it rapidly so that the bottom of the tube traverses the bottom of the container before the tube is filled. Close the tube, withdraw
47、 it from the container and allow any liquid adhering to the outside of the tube to drain off. When using a bottom-valve sampling tube, close the valve before lowering the tube into the container and then proceed in a similar manner to that when using an open sampling tube. 5.1.3 Sampling from tanks
48、and tankers From each access point, take samples as follows: a) from the surface of the liquid, using a ladle as described in 5.1.2.2; b) from the bottom of the tank or tanker, using a sampling tube as described in 5.1.2.3 or using a specially designed bottom-sampling apparatus; c) from one or more
49、positions, depending on the overall depth, between the bottom and the surface using a weighted sampling can. 5.2 Analysis 5.2.1 Determination of sodium chlorite (main product) 5.2.1.1 General This method applies to the measurements of sodium chlorite content in commercial sodium chlorite solutions and is specific for these species. 5.2.1.2 Principle Automated iodometric titration with an excess of sulfuric acid. This method is based on the reducing action of the iodide ion on the chlorite species and on the subsequent determination of iodine f