1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 12120:2012Chemicals used for treatmentof water intended for humanconsumption Sodiumhydrogen sulfiteBS EN 12120:2012 BRITISH STANDARDNational forewordThis British Standard i
2、s the UK implementation of EN 12120:2012. It supersedes BS EN 12120:2005 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CII/59, Chemicals for drinking water treatment.A list of organizations represented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
3、its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013ISBN 978 0 580 77779 0 ICS 71.100.80 Compliance with a British Stan
4、dard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2013.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 12120:2012EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NO
5、RM EN 12120 November 2012 ICS 71.100.80 Supersedes EN 12120:2005English Version Chemicals used for treatment of water intended for human consumption - Sodium hydrogen sulfite Produits chimiques utiliss pour le traitement de leau destine la consommation humaine - Hydrognosulfite de sodium Produkte zu
6、r Aufbereitung von Wasser fr den menschlichen Gebrauch - Natriumhydrogensulfit 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 status of a n
7、ational 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, German). A
8、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, Croatia, Cypru
9、s, 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 United King
10、dom. 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 12120:2012: EBS EN
11、12120:2012EN 12120:2012 (E) 2 Contents Page Foreword 3Introduction . 41 Scope 52 Normative references 53 Description . 54 Purity criteria 75 Test methods 86 Labelling Transportation Storage . 15Annex A (informative) General information on sodium hydrogen sulfite . 17Bibliography 19BS EN 12120:2012EN
12、 12120:2012 (E) 3 Foreword This document (EN 12120:2012) 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 publication of an identical text or by endorsemen
13、t, 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 not be held responsible for identifying any or
14、 all such patent rights. This document supersedes EN 12120:2005. The significant technical differences between this edition and EN 12120:2005 are as follows: Modification of 6.2 on labelling, deletion of the reference to EU Directive 80/778/EEC of 15 July 1980 in order to take account of the latest
15、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, Estonia, Finland, Former Yugoslav Republic of Ma
16、cedonia, 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 12120:2012EN 12120:2012 (E) 4 Introduction In respect of pote
17、ntial 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) it shoul
18、d 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 product in any
19、 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 12120:2012EN 12120:2012 (E) 5 1 Scope This European Standard is applicable to sodium hydrogen sulfite used for treatment of water inten
20、ded for human consumption. It describes the characteristics of sodium hydrogen sulfite and specifies the requirements and the corresponding test methods for sodium hydrogen sulfite. It gives information on its use in water treatment. 2 Normative references The following documents, in whole or in par
21、t, 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 amendments) applies. EN ISO 3696, Water for analytical laboratory use S
22、pecification and test methods (ISO 3696) ISO 418, Photography Processing chemicals Specifications for anhydrous sodium sulfite 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
23、 absorption spectrometric method ISO 6206, Chemical products for industrial use Sampling Vocabulary ISO 6353-1, Reagents for chemical analysis Part 1: General test methods ISO 9297, Water quality Determination of chloride Silver nitrate titration with chromate indicator (Mohrs method) ISO 22743, Wat
24、er quality Determination of sulphates Method by continuous flow analysis (CFA) 3 Description 3.1 Identification 3.1.1 Chemical name Sodium hydrogen sulfite. 3.1.2 Synonym or commons name Sodium bisulfite. 3.1.3 Relative molecular mass 104,6. 3.1.4 Empirical formula NaHSO3. BS EN 12120:2012EN 12120:2
25、012 (E) 6 3.1.5 Chemical formula NaHSO3.3.1.6 CAS-Registry Number 1)7631-90-5. 3.1.7 EINECS reference 2)231-548-0. 3.2 Commercial form The product is an aqueous solution with an usual concentration of approximately a mass fraction of 40 % NaHSO3. This corresponds to 520 g NaHSO3per litre. 3.3 Physic
26、al properties 3.3.1 Appearance and odour The product is a yellowish liquid with a slight odour of sulfur dioxide. 3.3.2 Density The density of the product is 1,3 g/ml to 1,5 g/ml at 20 C. 3.3.3 Solubility (in water) The product is miscible with water. 3.3.4 Vapour pressure The vapour pressure of a s
27、olution of mass fraction of 40 % NaHSO3 is 4 kPa3) at 20 C. 3.3.5 Boiling point at 100 kPa 3)The product decomposes at 100 C. 3.3.6 Crystallisation point A solution of mass fraction of 40 % NaHSO3crystallises at 2 C. 3.3.7 Specific heat The specific heat of the product is 3,15 kJ/(kg K). 1) Chemical
28、 Abstracts Service Registry Number. 2) European Inventory of Existing Commercial Chemical Substances. 3)100 kPa = 1 bar. BS EN 12120:2012EN 12120:2012 (E) 7 3.3.8 Viscosity dynamic The viscosity of a solution of mass fraction of 40 % NaHSO3is 4 mPa.s at 25 C. 3.3.9 Critical temperature Not applicabl
29、e. 3.3.10 Critical pressure Not applicable. 3.3.11 Physical hardness Not applicable. 3.4 Chemical properties The solution is weakly acid. The pH value of a commercial solution of mass fraction of 40 % is between 4,5 and 5,0. NaHSO3exists in solution only; if the solution is evaporated the salt which
30、 is formed is sodium disulfite. At elevated temperatures ( 100C) sulfur dioxide is generated. Sodium hydrogen sulfite reacts violently with oxidising agents; e.g. with sodium hypochlorite or hydrogen peroxide. 4 Purity criteria 4.1 General This European Standard specifies the minimum purity requirem
31、ents for sodium hydrogen sulfite 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 present and, if so, this shall be notified to the user
32、 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 intended for human consumption, taking into account raw water quality, required dosage, contents of other impurities
33、 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 be present in significant quantities from the current production process and raw materials. If the production process or raw materials lead
34、s 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 commercial product has a concentration of NaHSO3of approximately 520 g/l, which relates to a content of mass fraction of 40 % NaHSO3, corre
35、sponding to a mass fraction of 25 % SO2. The concentration of sodium hydrogen sulfite shall be within 5 % of the manufacturers declared value. BS EN 12120:2012EN 12120:2012 (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
36、fraction of 5 % of the commercial product, i.e. solution of mass fraction of 40 % NaHSO3. 4.4 Chemical parameters The product shall conform to the requirements specified in Table 1. Table 1 Chemical parameters Parameter Limit mg/kg of commercial product (mass fraction of 40 % NaHSO3) Antimony (Sb) m
37、ax 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 indicator parameters are not relevant in sodium hydrogen sulfite because the raw materials used in the manufacturing process are
38、free of them. For parametric values of sodium hydrogen sulfite on trace metal content in drinking water, see 1. 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
39、the contents of each container to be sampled by shaking the container, by rolling it 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
40、 to use a sampling implement, take a sample by pouring after the contents have been thoroughly mixed. Otherwise, proceed as described in 5.1.2.1.3. BS EN 12120:2012EN 12120:2012 (E) 9 5.1.2.1.3 Examine the surface of the liquid. If there are signs of surface contamination, take samples from the surf
41、ace 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 comple
42、tely and allow any liquid adhering to the ladle to drain off. If necessary, repeat this operation 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
43、 open sampling tube, or a bottom-valve sampling tube, suited to the size of container and 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
44、traverses the bottom of the container before the tube is filled. Close the tube, withdraw 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
45、 in a similar manner to that when using an open sampling tube. 5.1.3 Sampling from tanks 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
46、 in 5.1.2.3 or using a specially designed bottom-sampling apparatus; c) from one or more positions, depending on the overall depth, between the bottom and the surface using a weighted sampling can. 5.2 Analyses 5.2.1 General All reagents shall be of a recognised analytical grade and the water used s
47、hall conform to the grade 3 specified in EN ISO 3696. 5.2.2 Main product 5.2.2.1 General The sodium hydrogen sulfite content shall be determined by the method for sodium sulfite described in ISO 418. NOTE Both methods, direct titration and back titration, can be used. BS EN 12120:2012EN 12120:2012 (
48、E) 10 5.2.2.2 Back titration method 5.2.2.2.1 Principle Sodium hydrogen sulfite 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 NaHSO3. 5.2.2.2.2 Calculation The sodium hydrogen sulfit
49、e content C1, expressed as a mass fraction in %, is given by the following formula: mcVcC)2()350(2,51= (1) where c3is the actual concentration, in moles per litre, of the iodine solution; c2is the actual concentration, in moles per litre, of the sodium thiosulfate solution; V is the volume, in millilitres, of the sodium thiosulfate solution used for the titration; 5,2 is a conversion factor for the mass of sodium hydrogen sulfite equivalent to 1 mole of iodine (i.e. 52,0) x the conversion fa
