BS EN ISO 5814-2012 Water quality Determination of dissolved oxygen Electrochemical probe method《水质 溶解氧的测定 电化学探头法》.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 5814:2012Water quality Determinationof dissolved oxygen Electrochemical probe method(ISO 5814:2012)BS EN ISO 5814:2012 BRITISH STANDARDNational forewordThis British Sta

2、ndard is the UK implementation of EN ISO 5814:2012.It supersedes BS EN 25814:1992 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee EH/3/2, Physical chemical and biochemical methods.A list of organizations represented on this committee can beobtained on r

3、equest to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsLimited 2012 ISBN 978 0 580 66225 6 ICS 13.060.50 Compliance with a Brit

4、ish Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 November 2012. Amendments issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO

5、 5814 October 2012 ICS 13.060.50 Supersedes EN 25814:1992English Version Water quality - Determination of dissolved oxygen - Electrochemical probe method (ISO 5814:2012) Qualit de leau - Dosage de loxygne dissous - Mthode lectrochimique la sonde (ISO 5814:2012) Wasserbeschaffenheit - Bestimmung des

6、gelsten Sauerstoffs - Elektrochemisches Verfahren (ISO 5814:2012) This European Standard was approved by CEN on 4 August 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 national standard

7、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 version in any ot

8、her 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, Cyprus, Czech Republic

9、, 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 Kingdom. EUROPEAN COM

10、MITTEE 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 ISO 5814:2012: EBS EN ISO 5814:2012E

11、N ISO 5814:2012 (E) 3 Foreword This document (EN ISO 5814:2012) has been prepared by Technical Committee ISO/TC 147 “Water quality” in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of which is held by DIN. This European Standard shall be given the status of a nat

12、ional standard, either by publication of an identical text or by endorsement, at the latest by April 2013, and conflicting national standards shall be withdrawn at the latest by April 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

13、rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 25814:1992. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Stan

14、dard: Austria, Belgium, 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, Sp

15、ain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 5814:2012 has been approved by CEN as a EN ISO 5814:2012 without any modification. BS EN ISO 5814:2012ISO 5814:2012(E) ISO 2012 All rights reserved iiiContents PageForeword iv1 Scope 12 Normative references .

16、 13 Principle . 14 Interferences . 25 Reagents 26 Apparatus 27 Sampling and analysis procedure 37.1 Sampling 37.2 Measuring technique and precautions to be taken 37.3 Calibration . 47.4 Determination . 48 Calculation and expression of results . 58.1 Dissolved oxygen concentration 58.2 Dissolved oxyg

17、en expressed as percentage saturation . 59 Test report . 5Annex A (informative) Physicochemical data for oxygen in water 6Annex B (informative) Performance data .12Bibliography .14BS EN ISO 5814:2012ISO 5814:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide feder

18、ation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that commit

19、tee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance

20、 with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires app

21、roval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 5814 was prepared by Technical Committe

22、e ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods.This third edition cancels and replaces the second edition (ISO 5814:1990), which has been technically revised.The main changes compared to the second edition are:a) a calibration procedure using water-saturat

23、ed air is specified;b) the calibration procedure using air-saturated water is omitted.iv ISO 2012 All rights reservedBS EN ISO 5814:2012INTERNATIONAL STANDARD ISO 5814:2012(E)Water quality Determination of dissolved oxygen Electrochemical probe methodWARNING Persons using this International Standard

24、 should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory

25、conditions.IMPORTANT It is absolutely essential that tests conducted according to this International Standard be carried out by suitably trained staff.1 ScopeThis International Standard specifies an electrochemical method for the determination of dissolved oxygen in water by means of an electrochemi

26、cal cell which is isolated from the sample by a gas permeable membrane.Measurement can be made either as a concentration of oxygen in milligrams per litre, percentage saturation (% dissolved oxygen) or both. The method measures oxygen in water corresponding to 1 % to 100 % saturation. However, most

27、instruments permit measurement of values higher than 100 %, i.e. supersaturation.NOTE Supersaturation is possible when the partial pressure of oxygen is higher than in air. Especially when strong algal growth is present, supersaturation of up to 200 % and above can occur.The method measures oxygen i

28、n water with a saturation higher than 100 %, when special arrangements to prevent the outgassing of oxygen during the handling and measurement of the sample are made.The method is suitable for measurements made in the field and for continuous monitoring of dissolved oxygen, as well as measurements m

29、ade in the laboratory. It is the preferred method for highly coloured and turbid waters, and also for analysis of waters not suitable for the Winkler titration method because of iron- and iodine-fixing substances, which can interfere in the iodometric method specified in ISO 58131.The method is suit

30、able for drinking waters, natural waters, waste waters, and saline waters. If used for saline waters, such as sea or estuarine waters, a correction for salinity is essential.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indisp

31、ensable 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.ISO 3696, Water for analytical laboratory use Specification and test methods3 PrincipleImmersion of a probe, con

32、sisting of a cell enclosed by a selective membrane and containing the electrolyte and at least two metallic electrodes, in the water to be analysed.NOTE The membrane is effectively impermeable to water and ionic dissolved matter, but is permeable to oxygen and a certain number of other gases.One of

33、the electrodes is made of a noble metal like gold or platinum. Oxygen is reduced at its surface by an electrochemical process. In order to make this process possible, a suitable electrochemical potential is established at this electrode. For polarographic probes, this is achieved by applying an exte

34、rnal voltage related to a second electrode. Galvanic probes are able to build up the potential by themselves. ISO 2012 All rights reserved 1BS EN ISO 5814:2012ISO 5814:2012(E)The current resulting from the reduction of oxygen is directly proportional to the rate of transport of oxygen through the me

35、mbrane and the layer of electrolyte, and hence to the partial pressure of the oxygen in the sample at a given temperature.Temperature has two different influences. The first relates to the variation of gas permeability of the membrane with temperature. So the primary signal of the probe has to be co

36、mpensated with a built-in temperature sensor. Meters manufactured recently are able to do this automatically. The second is the temperature effect on the electrode reactions.To calculate the percentage of saturation of samples in contact with an atmosphere, it is necessary to include the effective p

37、ressure. This can be performed manually or by implementing a pressure sensor for automatic compensation. Salinity can also be an influence.4 InterferencesGases and vapors such as chlorine, hydrogen sulfide, amines, ammonia, bromine, and iodine which diffuse through the membrane can interfere, if pre

38、sent, by affecting the measured current.Other substances present in the sample can interfere with the measured current by causing obstruction, deterioration of the membrane or corrosion of the electrodes. These include solvents, oils, sulfides, carbonates, and biofilms.5 ReagentsDuring analysis, use

39、 only reagents of recognized analytical grade.5.1 Water, grade 2, as specified in ISO 3696, optionally from commercial sources.5.2 Sodium sulfite, anhydrous, Na2SO3or heptahydrate, Na2SO37H2O.5.3 Cobalt(II) salt, for example cobalt(II) chloride hexahydrate, CoCl26H2O.5.4 Nitrogen gas, N2, purity 99,

40、995 % volume fraction or better.6 Apparatus6.1 Measuring instrument, comprising the components specified in 6.1.1 and 6.1.2.6.1.1 Measuring probe, either of the galvanic type (e.g. lead/silver) or the polarographic type (e.g. silver/gold) with, if required, a temperature-sensitive compensating devic

41、e.6.1.2 Meter, graduated to show the concentrations of dissolved oxygen directly, and/or percentage saturation with oxygen.6.2 Thermometer, graduated in at least 0,5 C divisions.NOTE Commonly a temperature sensor is integrated into the instrument (6.1).6.3 Barometer, graduated to 1 hPa.NOTE Usually

42、the barometer is integrated into the instrument (6.1).2 ISO 2012 All rights reservedBS EN ISO 5814:2012ISO 5814:2012(E)7 Sampling and analysis procedure7.1 Sampling7.1.1 GeneralSamples should always be handled so that transfer of oxygen between water sample and air is inhibited.As a matter of princi

43、ple, the oxygen concentration shall be measured directly on site in the water body to be analysed.If direct measurement in the water body is not possible, the measurement can also be taken in a gas-tight connected flow-through device or immediately after sampling as a discrete sample.Any discrete sa

44、mpling procedure results in a higher measurement uncertainty.While filling the sample vessel during sampling, oxygen uptake or oxygen stripping shall be minimized. Sample transfer shall occur without any turbulence, i.e. by maintaining a laminar flow.7.1.2 Dip-sampling (e.g. surface waters)Take the

45、sample by carefully and slowly dipping the sample vessel.7.1.3 Sampling from tapsConnect an inert sampling tube, in a gas-tight fashion, to the tap and insert the sampling tube all the way down to the bottom of the sampling vessel. Ensure that the volume of water allowed to overflow is at least thre

46、e times the capacity of the vessel.7.1.4 Sampling with pumpsOnly water-displacing submersible pumps should be used. Pumps that function according to the principle of air displacement are not suitable. Fill the sample vessel from the bottom, using a sampling tube, and allow the water to overflow. Dur

47、ing sample transfer, the volume flow rate shall be controlled in order to guarantee a mainly laminar flow. Ensure that the volume of water allowed to overflow is at least three times the capacity of the vessel.7.2 Measuring technique and precautions to be takenThe measuring system shall be in a prop

48、er state as specified in the manufacturers instructions. For example: ensure the membrane is not damaged; allow an adequate polarization time; calibrate the system when necessary.When a measurement is performed, ensure that the sample flows past the membrane with sufficient velocity according to the

49、 manufacturers instructions. This can be achieved by natural streaming, movement of the sensor or stirring, e.g. with a magnetic stirrer. This is necessary to prevent loss of signal because of consumption of oxygen by the sensor.Take care that there is no exchange of oxygen from a gas reservoir to the sample or vice versa. Therefore, avoid formation of any air bubbles in the samples that are measured in a vessel. When measuring on-site, do not generate any air bubbles, which may affect the signal.For storing and maintenance of the prob