http://www.infoeach.com http://bbs.infoeach.com 7888 International Standard (TSO INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAA OPTAHW3ALMR IO CTAHAAPTW3ALWWMORGANISATION INTERNATIONALE DE NORMALISATION Water quality --- Determination of electrical conductivity Qualite de I'eau - Determination de la conductivite électrique First edition - 1985-05-15 UDC 543.3:541.133 Ref. No. 1S 7888-1985 (E) SO 7888-1985 (E) Descriptors : water, quality, tests, determination, electrical properties, conductivity. Price based on 6 pages Copyright internatioal Organization for Standardization http://www.infoeach.com http://bbs.infoeach.com Not for Resale http://www.infoeach.com http://bbs.infoeach.com Foreword Iso (the International Organization for Standardization) is a worldwide federation 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 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 ISO/TC 147, Water quality. ? International Organization for Standardization, 1985 Printed in Switzerland http://www.infoeach.com http://bbs.infoeach.com orking permitted without license from IHS Not for Resale http://www.infoeach.com http://bbs.infoeach.com INTERNATIONAL STANDARD ISO 7888-1985 (E) Water quality - Determination of electrical conductivity Scope and field of application where 1 This International Standard specifies a method for the I is the length, in metres, of an electrical conductor; measurement of the electrical conductivity of all types of water. Ais the effective cross-sectional area, in square metres, of Electrical conductivity can be used to monitor the quality of an electrical conductor: a) surface waters; The cell constant results from the geometry of the cell; it can be empirically determined. b) process waters in water supply and treatment plants; 2.3_ temperature coefficient of electrical conductivity,2) c) waste waters. α: The temperature coefficient of conductivity αg,25,[4,'5] is given by the equation The completeness of analysis for ionic constituents[1 to 3] can be checked using this method. (e-25 1 ×100 αo,25 θ- 25 In some cases absolute values are important, in .other cases 25 only relative changes are of concern. where 25 and oC are the temperatures at which the electrical conductivities Y25 and yo respectively were measured. For interferences, see clause 9. temperature correction factors, f: Factors used to 2.4 2 Definitions correct for the temperature dependence of electrical conduc- tivity. 2.1 specific conductance; electrical conductivity, y: In order to make comparisons, it is essential that measurements The reciprocal of the resistance, measured under specified con- are corrected to a chosen reference temperature, usually ditions, between the opposite faces of a unit cube of defined 25,o °C, even if the temperature of the water sample differs dimensions of an aqueous solution. For water quality examina- only slightly from that temperature. tion, this is often expressed as "electrical conductivity" and may be used as a measure of the concentration of ionizable Conversions to the electrical conductivity at 25 °C, Y25, can be solutespresent inthe sample. made using the equation (Definition taken from ISO 6107/2.) Ye It is expressed in siemens per metre.1) NOTE --. The symbols g and k are also used for electrical conductivity where (see ISO 31/5). is the temperature coefficient of electrical conductivity; 2.2 cell consta