EN 27888:1993
(Main)Water quality - Determination of electrical conductivity (ISO 7888:1985)
Water quality - Determination of electrical conductivity (ISO 7888:1985)
Specifies a method for the measurement of all types of water. The quantity can be used to monitor the quality of surface waters, process waters in water supply and treatment plants, and waste waters. Interferences are given.
Wasserbeschaffenheit - Bestimmung der elektrischen Leitfähigkeit (ISO 7888:1985)
Qualité de l'eau - Détermination de la conductivité électrique (ISO 7888:1985)
La présente Norme internationale spécifie une méthode
de mesurage de la conductivité électrique de tous types d'eau.
La conductivité électrique peut être utilisée pour
contrôler la qualité
a) des eaux de surface ;
b) des eaux dans la distribution de l'eau et les stations de traitement ;
c) des eaux résiduaires.
L'analyse exhaustive des constituants ioniques de l'eau [1 à 3]
peut être vérifiée en utilisant cette méthode. Dans
certains cas, des valeurs absolues sont importantes, dans d'autres cas, seules
des variations relatives présentent de l'intérêt. Pour les
interférences, voir chapitre 9.
Kakovost vode - Določanje električne prevodnosti (ISO 7888:1985)
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Bestimmung der elektrischen Leitfähigkeit (ISO 7888:1985)Qualité de l'eau - Détermination de la conductivité électrique (ISO 7888:1985)Water quality - Determination of electrical conductivity (ISO 7888:1985)13.060.60Preiskava fizikalnih lastnosti vodeExamination of physical properties of waterICS:Ta slovenski standard je istoveten z:EN 27888:1993SIST EN 27888:1998en01-januar-1998SIST EN 27888:1998SLOVENSKI
STANDARD
International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION*MElK~YHAPOAHAR OPrAHM3AUMfl I-IO CTAHAAPTM3AL&lM.ORGANISATiON INTERNATIONALE DE NORMALISATION Water quality - Determination of electrical conductivity Qualit&’ de l’eau - Determination de Ia conduc tivitd blec trique First edition - 1985-05-15 UDC 543.3: 541.133 Ref. No. ISO 7888-1985 (E) Descriptors : water, quality, tests, determination, electrical properties, conductivity. Price based on 6 pages SIST EN 27888:1998
Foreword ISO (the International Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bedies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7888 was prepared by Technical Committee lSO/TC 147, Water quality. 0 International Organkation for Standardkation, 1985 Printed in Switzerland SIST EN 27888:1998
~- INTERNATIONAL STANDARD ISO 78884985 (E) Water 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 tan be used to monitor the quality of a) surface waters; b) process waters c) waste waters. in water supply and treatment plants; The completeness of analysis for ionic constituents[l 10 31 tan 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 Definitions 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 conductivity” and may be used as a measure of the concentration of ionizable solutes present in the Sample. (Definition taken from ISO 6107/2.) lt is expressed in Siemens per metre? NOTE - The Symbols 0 and K are also used for electrical conductivity (sec ISO 31/5). 2.2 cell constant, K: Quantity, in reciprocal metres, given by the equation 1 K=- A where I is the length, in metres, of an electrical conductor; A is the effective Cross-sectional area, in Square metres, of an electrical conductor. The cell constant results from the geometry of the cell; it tan be empirically determined. 2.3 temperature coefficient of electrical conductivity,*) a: The temperature coefficient of conductivity ae 25,M 51 r is given by the equation x 100 where 25 and 0 OC are the temperatures at which the electrical conductivities ~25 and ye respectively were measured. 2.4 temperature correction factors, f: Factors used to correct 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 25,0 OC, even if the temperature of the water Sample differs only slightly from that temperature. Conversions to the electrical conductivity at 25 OC, ~25, tan be made using the equation y25 = 1 + (a/lOO) (8 - 25) where a is the temperature coefficient of electrical conductivity; Yo is the electrical conductivity at the measured tem- perature, e ; 0 is the measuring temperature, in degrees Celsius, of the Sample. 1) 1 S/m = IO4 pS/cm = IO3 mS/m 2) The temperature coefficient of electrical conductivity tan be expressed in reciprocal kelvin or Yo per OC. 1 SIST EN 27888:1998
ISO 78884985 (El 3 Principle Table 1 - Electrical 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 kind”), and depends on a) the concentration of the ions; b) the nature of the ions; c) the temperature of the Solution; d) the viscosity of the Solution. Pure water as a result of its own dissociation has an electrical conductivity at 25 OC of 5,433 pS/m[61 (0,005 483 mS/m). 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade. 4.1 Water for preparing solutions and dilutions. Double distilled or de-ionized water; the electrical conductivity shall be Y25
ISO 7888-1985 (El 5.2 Electrodes. appropriate to the desired measuring range is fitted (sec table 2). The test Portion depends on the equipment used. Whenever platinum electrodes are used for precision measurements the electrodes shall be platinized (sec the note). Unplatinized electrodes laboratory testing. may be used only for field and routine NOTE -4 f Platinkation is necessary, the should be followed, or proceed as follows ma nufacturer’s instructions Platinize the electrodes of the cell with platinizing Solution (4.5). A suitable plating apparatus consists of a 6 V d.c. supply, a variable resistor, a milliammeter, and an eiectrode. The procedure for platiniz- ing is not critical. Good platinized coatings are obtained using from 1,5 to 3 C/cm* of electrode area. For example for an electrode having a total area (both sides) of IO cm*, the plating time at a current of 20 mA would be from 12,5 to 25 min. The current density may be from 1 to 4 mA/cm* of electrode area. Plate the electrodes one at a time with the aid of an extra electrode. During the plating, agitate the Solution gently. When not in use, fill the cells with water to prevent the drying out of the electrodes while in storage. 5.3 Thermometer, accurate to I!I 0,l OC, within the temperature range of measurement, shall be used for precise determinations. For routine measurements, a thermometer accurate to + 0,5 OC is satisfactory. 5.4 Thermostatic bath, capable of being maintained at 25,0 + 0,l OC. For routine measurements, a tolerante of & 0,5 OC is satisfactory. 6 Sampling and samples Collect the laboratory Sample in a polyethylene bottle com- pletely filled and tightly stoppered. Soda glass bottles shall not be used. Measurement of conductivity should be performed as soon as practicable, particularly when there is a possibility of an exchange of gases such as carbon dioxide or ammonia with the atmosphere, or a possibility of biological activity. Biological ac- tivity tan be reduced by storing the samples in the dark at 4 OC; 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 Proceduae 7.1 General Prepare the equipment for use as instructed by the manufac- turer and ensure that an electrode cell of known cell constant If the cell constant is not accurately known, determine the con- stant as given in clause 5 using the potassium chloride S
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