EN 27888-1993 en Water Quality - Determination of Electrical Conductivity《水质 电导率的测定(ISO 7888-1985)》.pdf

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1、CEN EN+27888 93 9 3404589 0052814 2Tb 9 EUROPEAN STANDARD EUROPISCHE NORM NORME EUROPENNE EN 27888 September 1993 UDC 628.U.3 : 620.1 : 643.3 : 641.133 Descriptors: Water tests, water, quality, electrical properties, resistance English version Water quality - Determination of electrical conductivity

2、 (IS0 7888 : 1985) Qualit de leau - Dtermination de la conductivit lectrique elektrischen Leitfhigkeit (IS0 7888 : 1985) Wasserbeschaffenheit - Bestimmung der (IS0 7888 : 1985) This European Standard was approved by CEN on 1993-09-10. CEN members are bound to comply with the CENKENELEC Internal Regu

3、lations 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 CEN member. This E

4、uropean 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 members are the n

5、ational electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches

6、 Komitee fr Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels O 1993 Copyright reserved to CEN members Ref. No. EN 27888 : 1993 E CEN ENk27888 93 3909589 0052815 132 W Page 2 EN 27888 : 1993 Foreword This European Standard has been taken over by CEN/TC 230 Water analysis from the wprk

7、 of ISOfIC 147 Water quality of the Internqtional Organization for Standardization (ISO). It was decided by the Resolution EYE3 3 35/1990 to submit the Final Draft to the CEN members for voting by Unique Acceptance Procedure (UM). The result of the Unique Acceptance Proedure was positive. This Europ

8、ean Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 1994, and conflicting national standards shall be withdrawn at the latest by March 1994. In accordance with the CENKENELEC Irp-nal Regulations, the foll

9、owing countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portqpl, Spain, Sweden, Switzerland and United mgdom. CEN ENS27888 93 m 3404589 0052836 079 m Page 3 EN 27888 : 1993 W

10、ater quality - Determination of electrical conductivity 1 Scope and field of application This International Standard specifies a method for the measurement of the electrical conductivity of all types of water. Electrical conductivity can be used to monitor the quality of a) surface waters; b) proces

11、s waters in water supply and treatment plants; CI waste waters. The completeness of analysis for ionic constituentsl to 31 can be checked using this method. In some cases absolute values are important, in other cases only relative changes are of concern. For interferences, see clause 9. 2 Definition

12、s 2.1 specific conductance; electrical conductivity, y: The reciprocal of the resistance, measured under specified con- ditions, between the opposite faces of a unit cube of defined dimensions of an aqueous solution. For water quality examina- tion, this is often expressed as “electrical conductivit

13、y“ and may be used as a measure of the concentration of ionizable solutes present in the sample. (Definition taken from IS0 6107/2.) It is expressed in siemens per metre.) NOTE - The symbols u and K are also used for electrical conductivity (see IS0 31 /5). 2.2 by the equation cell constant, K : Qua

14、ntiw, in reciprocal metres, given I K=- A where I is the length, in metres, of an electrical conductor; A an electrical conductor. is the effective cross-sectional area, in square metres, of The cell constant results from the geometry of the cell; it can be empirically determined. 2.3 temperature co

15、efficient of electrical conductivity, a: The temperature coefficient of conductivity ae,z,4, 51 is given by the equation where 25 and 8 OC are the temperatures at which the electrical conductivities y% and Ye respectively were measured. 2.4 temperature correction factors, f: Factors used to correct

16、for the temperature dependence of electrical conduc- tivity. In order to make comparisons, it is essential that measurements are corrected to a chosen reference temperature, usually 25,O OC, even if the temperature of the water sample differs only slightly from that temperature. Conversions to the e

17、lectrical conductivity at 25 OC, y=, can be made using the equation Ye y25 = i + (a/100) (8 - 25) where a is the temperature coefficient of electrical conductivity; ye is the electrical conductivity at the measured tem- perature, 8; 8 is the measuring temperature, in degrees Celsius, of the sample.

18、i 1 S/m = io4 HS/cm = d mS/m 2) The temperature coefficient of electrical conductivity can be expressed in reciprocal kelvin or % per OC. CEN ENlr27888 0.000 5 0.001 0,005 0.01 0.02 0.05 o. 1 0.2 93 3404589 0052817 TO5 7.4 14.7 72 141 277 670 1290 2480 Page 4 EN 27888 : 1993 3 Principle Table 1 - El

19、ectrical conductivity of potassium chloride solutions Direct determination, using an appropriate instrument, of the electrical conductivity of aqueous solutions. The electrical con- ductivity is a measure of the current conducted by ions present in the water (“phenomenon of conductors of the second

20、kind“), and depends on I I Concentration of potassium 1 chloride, ciKCI) Electrical conductivity at 25 OC. YB I mol/l I mS/m I a) the concentration of the ions; b) the nature of the ions; c) the temperature of the solution; d) the viscosity of the solution. 4.5 Platinizing solution. Pure water as a

21、result of its own dissociation has an electrical conductivity at 25 OC of 5,483 pS/mIQ (0,005 483 mS/m). Dissolve 1.5 g of hydrogen hexachloroplatinate(1V) hexa- hydrate (H2PtClrGHfl) in 50 ml of water containing 0,012 5 g of lead(1l) acetate Pb(C the electrical conductivity shall be ya c0,l mS/m. T

22、he instrument may be of either of the following types: 4.2 Potassium chloride standard solution A, pl c(KCI) = 0,l mol/l. a) instrument equipped with a flow- or dip-type conduc- tivity cell fitted with two or more electrodes; b) instrument fitted with electrodes of the induction type. Dry a few gram

23、s of potassium chloride at 106 OC for 2 h, and dissahre 7,458 g in water (4.1). Dilute to 1 o00 ml. Preferably instruments should be capable of discrete and con- tinuous measurement both in the laboratory and in the field. The conductivity of this solution at 25 OC, YE, is 1 290 mS/m. A flow-type co

24、nductivity cell from which air is excluded is essential for measurements of conductivities of less than 1 mS/m. 4.3 Potassium chloride standard solution E, c(KCI) = 0.01 l/l. Dilute 100 ml of solution A (4.2) with water (4.1) to 1 O00 ml. The recommended electrode cell constant can be chosen from ta

25、ble 2 for each measuring range. The conductivity of this solution at 25 OC, y=, is 141 mS/m. 4.4 c(KCI) = 0,001 mol/l. Potassium chloride standard solution C, Table 2 - Recommended cell constants for different ranges of electrical conductivity 1- Measuring range Recommended cell constant I Dilute 10

26、0 ml of solution B (4.31 with water (4.1) to 1 O00 ml. Immediately before preparing this solution the water shall be freed from carbon dioxide by purging with pure nitrogen or by boiling. During work with these solutions any contact with the atmosphere shall be minimized. -+-p- 0,1y20 1 ym 10 y 2x10

27、3 100 y20x103 5000 Prepare this solution shortly before use. The conductivity of this solution at 25 OC, ya, is 14,7 mS/m. Some instruments are equipped with a cell constant control. If this is not the case, the reading must be multiplied by the cell constant. NOTE - Table 1 gives altemative concent

28、rations of potassium chloride that can be used as standards of conductivity. however, samples shall be brought to equilibrium at the reference temperature of 25 OC before the conductivity is measured. No suitable preservative is known for samples taken for conductivity measurements. 7 Procedure 7.1

29、General Prepare the equipment for use as instructed by the manufac- turer and ensure that an electrode cell of known cell constant Page 5 EN 27888 : 1993 appropriate to the desired measuring range is fitted (see table 2). The test portion depends on the equipment used. If the cell constant is not ac

30、curately known, determine the con- stant as given in clause 5 using the potassium chloride standard solutions (4.2 to 4.4) appropriate to each desired measuring range. Check the cell constant at least once every 6 months. Many instruments incorporate cell constant correction as an in- tegral functio

31、n and thus a direct reading of electrical conduc- tivity is obtained. Otherwise multiply the conductance value obtained by the cell constant to obtain electrical conductivity. For high precision work, carry out the measurement of elec- trical conductivity when the sample and apparatus in direct cont

32、act with it has attained equilibrium at 25,O I 0,l OC. Thus all sources of error that may arise from the use of temperature compensators, or from mathematical correction techniques, are eliminated. 7.2 Temperature correction If measurement at 25,O f 0,l OC is not possible, for example in field or pl

33、ant work, measure the electrical conductivity of the sample at a known temperature, e OC. Many instruments are fitted with temperature compensation devices, and with reference to the temperature coefficient of samples, may automatically correct measurements obtained over a range of temperatures to e

34、lectrical conductivity at 25,O “C. Such in- struments shall be calibrated strictly in accordance with the manufacturers instructions. If the temperature coefficient of the sample is not known, it may be derived by substituting electrical conductivity values experimentally determined at 25,O I 0.1 OC

35、 and temperatures e i o,i oc (see 2.3). Where instruments do not incorporate a temperature compen- sation device, the electrical conductivity measured at 0 OC shall be corrected to 25.0 OC using the appropriate correction factor taken from table 3. Whichever form of temperature compensation is appli

36、ed to the measurement of electrical conductivity at 8 OC, the result will be less accurate than that actually measured at the reference temperature of 25,O OC. In some aspects of routine field work, it may not be necessary to transpose values measured at 8 OC to 25,O OC. However, such measurements s

37、hould be interpreted with great care and comparison with other values may be difficult or even mean- ingless. CEN EN*27888 93 = 3404589 0052839 888 = we 6 EN 27888 : 1993 Table 3 - Temperature correction factor, fz, for the conversion of conductivity values of natural waters from 8 OC to 25 OC51 e I

38、 f5 OC ,O .1 .2 .3 84 .5 ,6 .7 ,8 3 O 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 I 1,918 1,857 1,800 1,745 1,693 1.643 1,586 1,551 1,508 1,467 1.428 1,390 1,354 1,320 1.287 1.256 1,225 1,196 1,168 1,141 1,116 1.091 1,067 1,044 1,021 1 .o00 0,979 0

39、.959 0,940 0,921 0,903 0,886 0,869 0,853 0,837 0,822 1,912 1,851 1.794 1,740 1.688 1.638 1,591 1,547 1,504 1.463 1,424 1.387 1,351 1,317 1,284 1.253 1.222 1,193 1,166 1,139 1,113 1,088 1,064 1,041 1,019 0.998 0,977 0,957 0,938 0,920 0,902 0.884 0.867 0.851 0,835 1.908 1,846 1.788 1 .m 1,683 1,834 1.

40、587 1.542 1.500 1,459 1,383 1,347 1,313 1.281 1,249 1,219 1,191 1,163 1,lS 1,111 1,086 1,062 1,039 1,017 0.996 0,975 0.956 0,936 0,918 0.900 0.883 0.868 0,850 0,834 i ,420 1,- 1.840 1.783 1,729 1,678 1.629 1.582 1.538 1.498 1,456 1,416 1.379 1,344 1,310 1,278 1,246 1,216 1,188 1,160 1,134 1.108 1.08

41、3 1 ,O0 1,037 1,015 0,994 0,973 0,953 0,934 0,916 0.898 0,881 0,- 0.848 0,832 0,819 0,817 1,893 1.834 1.777 1,724 1.673 1,624 1,578 1.534 1,491 1,451 1,413 1,376 1,341 1,307 1,274 1,243 1,214 1,185 1,157 1,131 1.105 1.081 1.057 1,035 1,013 0,992 0,971 0,952 0,933 0,914 0,896 0,879 0,863 0,846 0.831

42、0,816 1,829 1,772 1,719 1,668 1,619 1.573 1,529 1.487 1,447 1,409 1.372 1,337 1,303 1,271 1,240 1,211 1,182 1,155 1,128 1,103 1,079 1,056 1,032 1,011 0,990 0,969 0.950 0,931 0,912 0.895 0.877 0.861 0,845 0,829 0,814 1,881 1.822 1,766 1,713 1,663 1,615 1.569 1,525 1.483 1.443 1.406 1.369 1,334 1.300

43、1,268 1,237 1,208 1,179 1,152 1,126 1,101 1,076 1.053 1.030 1,008 0,987 0,967 0,948 0,929 0.91 1 0,893 0,876 0.859 0.843 0.828 0,813 _ 1,875 1,817 1,761 1,708 1.658 1,610 1.564 1,521 1,479 1.439 1.401 1.365 1.330 1,297 1,285 1,234 1,205 1,177 1,149 1,123 1,098 1,074 1,051 1.028 1,006 O. 985 0,946 0,

44、927 0,909 0.891 0,874 0.858 0,842 0,826 0.81 1 1 .= 1,811 1,756 1,703 1.653 1.605 1.560 1,516 1,475 1,436 1,398 1,362 1,327 1.294 1,262 1,231 1.202 1,174 1,147 1,121 1,098 1,071 1.048 1,026 1,004 0.983 0.963 0,944 0,925 0,907 0.889 0,872 0,856 0,840 0,825 0,810 1,863 1,805 1,750 1.698 1.64 1,601 1,5

45、55 1,512 1,471 1,432 1.394 1.358 1,323 1,290 1.259 1,228 1,199 1,171 1,144 1.118 1.093 1,069 1,046 1,024 1,002 0,981 0,961 0,942 0.923 0.906 0,888 0.871 0.854 0,839 0,823 0.808 NOTES TO TABLE 3 1 The values of the temperature correction factors given are the mean values of measurements of a number o

46、f natural waters. Note that they are only applicable for measurements of those waters having a of about 6 to 100 mSlm and a composition comparable to natural ground, well, or surface waters. Catlons Anions Predominant Ca2+ HCO; Minor Mg 2+ SO:-, CI-, NO; 2 Note especially that they are not applicabl

47、e to potassium chloride solutions used for the calibration of conductivity cells. Therefore the calibration must always be carried out ai the reference temperature 25.0 f 0.1 oc. 3 The temperature correction factors, fz, are calculated by the equations fis =I) - al i a (:)“I x 1,116 where q is the v

48、iscosity of the solution; is the temperature of the solution at which measurements were made. Values of the constants a= 0,962144 n = 0.965078 A = -0.198058 B = -1,992186 C = 231,17628 D = 86.39123 exp is the exponential function e = 2,718 28 ibase of natural logarithmsll 4 In the past electrical co

49、nductivity was often quoted as yN. If the water composition is comparable to that in note 1, it is possible to con- vert all such values to the present reference temperature of 25 OC using the temperature correction factor of 1,116 given in table 3. - and - le =A + exp ( B +- OL) q25 8 Expression of results Mean conductivity 8.1 Calculation Within batch (Repeatability Between standard batch deviation) Total The result is read directly from the instrument and shall be ex- pressed with reference to this International Standard as yZ, in millisiemens p