EN 15938:2010

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kraftstoffe für Kraftfahrzeuge - Ethanol Mischungskomponent und Ethanolkraftstoff (E85) - Bestimmung der elektrischen LeitfähigkeitCarburants pour automobiles - Ethanol comme base de mélange à l'essence et carburant éthanol (E85) - Détermination de la conductivité électriqueAutomotive fuels - Ethanol blending component and ethanol (E85) fuel - Determination of electrical conductivity75.160.20Liquid fuels71.080.60Alkoholi. EtriAlcohols. EthersICS:Ta slovenski standard je istoveten z:EN 15938:2010SIST EN 15938:2010en,de01-november-2010SIST EN 15938:2010SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 15938
September 2010 ICS 75.160.20 English Version
Automotive fuels - Ethanol blending component and ethanol (E85) automotive fuel - Determination of electrical conductivity
Carburants pour automobiles - Éthanol comme base de mélange à l'essence et carburant éthanol (E85) pour automobiles - Détermination de la conductivité électrique
Kraftstoffe für Kraftfahrzeuge - Ethanol als Blendkomponente und Ethanolkraftstoff (E85) - Bestimmung der elektrischen Leitfähigkeit This European Standard was approved by CEN on 7 August 2010.
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 without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.
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A is the effective cross-section of the measuring cell, in m2 or, following the respective unit conversion, in cm2, with 1 m2 = 104 cm2; K is the cell constant of the measuring cell in m–1 or, following the respective unit conversion, in cm–1, with
1 m–1 = 0,01 cm–1. NOTE 2 The electrical conductivity of a solution depends on the temperature; therefore the temperature is given together with the measurement value. Hence, the electrical conductivity, which is mostly determined at 25 °C, is designated as σ25. NOTE 3 The electrical conductivity depends on ion concentration, ion type, temperature and viscosity of the solution. Therefore its measurement range can be large. "Ultrapure" (deionized and demineralised) water for example, due to its self-dissociation at 25 °C, has an electrical conductivity of 0,054 83 µS cm-1 (5,483 µS m-1). 3.4 cell constant K geometrical dimension of the measuring cell used to form one value NOTE The electrical conductivity σ (3.3) cannot be calculated simply from the electrical resistance R (3.2) and the geometrical cell dimensions because its functional relationship to the cell dimensions is very complex, especially in cases where the geometry is not cubical. Therefore, the measuring cell is calibrated by means of a calibration solution of known electrical conductivity σ*. The cell constant K is determined in accordance with Equation (3) from the measured electrical conductance G* caused by the calibration solution and its known electrical conductivity σ*. *25*25GKσ= (3) where: K is the cell constant of the measuring cell in m–1 or, following the respective unit conversion, in cm–1 (1 m-1 = 0,01 cm–1); *25G is the measured electrical conductance at 25 °C in the measuring cell filled with the calibration solution, expressed in S; *25σ is the electrical conductivity of the calibration solution at 25 °C, in S m-1 or µS cm-1 (1 S m-1 = 104 µS cm-1). 4 Principle The determination of the electrical conductivity in ethanol or ethanol fuel is carried out by means of a direct conductometer (6.1) measurement, using a measuring cell (6.2) suitable for a measurement range of approximately (0,01 to 5) µS cm-1. The measurement is carried out at a sample temperature of (25 ± 0,1) °C. As electrical conductivity is strongly depending on temperature, selection of another measurement SIST EN 15938:2010

5.3 Water, deionized or distilled with a maximum conductivity of 1 µS cm-1, for cleaning and rinsing the sample vessel (6.4) and the measuring cell (6.2). 6 Apparatus 6.1 Conductometer, suitable of being operated with measuring cells (6.2) having a cell constant of approximately (0,1 to 1) cm–1, with an alternating voltage of a frequency between 50 Hz and 500 Hz in the measuring cell (6.2), directly displaying the measured conductivity to the nearest 0,01 µS cm-1 at least. A single-point calibration using a single KCl calibration solution (5.2) is sufficient. 6.2 Measuring cell, manufactured from a material inert to ethanol or ethanol fuel, for example high-grade steel. The cell constant should be in the range (0,1 and 1) cm–1, preferably close to 0,1 cm–1. The measuring cell is introduced from above into the sample vessel (6.4), through a cover, and fixed in a way it is completely immersed in the solution to be measured. 6.3 Temperature sensor, with an accuracy of ± 0,1 °C or better, suitable for recording the temperature of the solution subjected to measurement at approximately 25 °C. This sensor can also be integrated in the measuring cell (6.2). The temperature signal is indicated on a display to the nearest ± 0,1 °C. 6.4 Thermostatable glass sample vessel, having a capacity of 20 ml to 500 ml, into which the sample to be measured is filled.
The sample vessel may be designed as a double-walled glass vessel, for example, which is thermostated by means of a circulating liquid. Alternatively, a thermostatable flow-through vessel may be used, provided it is ensured that the substance to be measured can be maintained at a temperature of (25 ± 0,1) °C, the measuring cell (6.2) is completely immersed, and all requirements for cleaning are also complied with. 6.5 Thermostat with thermometer, suitable for thermostating the sample vessel (6.4) to (25 ± 0,1) °C . 6.6 S
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