BS EN 15938:2010 pdf download
BS EN 15938:2010 pdf download.Automotive fuels – Ethanol blending component and ethanol (E85) automotive fuel – Determination of electrical conductivity.
5 Reagents
5.1 Ethanol, absolute, of analytical grade or a simdar quality, fox cleaning and nnsing the measunrig cell (6.2), the sample vessel (6.4) and all the other vesselsicontainers with which the sample can come into contact.
5.2 Calibration solution. KCI solution having a conductivity a2 of n,ax.100 pS cm1.
5.3 Water, deionized or distilled with a maximum conductivity of 1 iS cm”, for cleaning and rinsing the
sample vessel (64) 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) cnr1, 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 pS cm-i at least.
A single-point calibration using a single KCI catoration 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)cmt, preferably dose 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 measLvlng 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 wh the sample to be measured is filled.
The sample vessel may be designed as a double-walled glass vessel, for example, which Is therrnostated by means of a circulating liquid. Alternatively, a thermostatable flow-through vessel may be used, provided Ills ensured that the substance to be measured can be maintained at a temperature of (25 ± 0.1) C. the measuring cal (6.2) is completely Immersed, and all requirements for deaning are also complied with,
6.5 Thermostat with thermometer, suitable fox thermostating the sample vessel (6.4) to (25 ± 0,1) C.
6.6 Stirrer for ensuring a homogeneous temperature in the sample by stimng it with a magnetic stirrer and
a polytetrafluorethytene-coated stirring magnet.
7 Sampling
Unless specified otherwise, samples shall be taken ii accordance with EN ISO 3170 or EN ISO 3171 and the requirements of national standards regarding the sampling of fuels.
8 Procedure
8.1 PreparatIon of the measuring device
8.1.1 General
The device manufacturer’s Instructions shall be folowed for the preparation and operation of the conductometer (6.1) and the measuring cell (6.2). The thermostat (6.5) Is connected with the sample vessel (6.4) and set to achieve a temperature of (25 ± 0.1) C in the sample vessel.
8.1.2 Cleaning of the sample vessel
Before the measurement, the sample vessel (6.4) is rinsed several times with ethanol (5.1). The rest of the ethanol used for rinsing shall be dnpped off.
If the sample vessel (6.4) has been used before for saline samples, it shall additionally be cleaned thoroughly with water (5.3) prior to using it for ethanol or ethanol fuel. Subsequently, it is dried in the drying oven at mm, 80C. Afterwards it is rinsed once more using ethanol (5.1), It there are any visle contaminations (e.g. stains) on the inner glass surface of the sample vessel (6.4). the vessel shall not be used.
8.1.3 Cleaning of the measuring cell
The measuring cel (6.2) is also cleaned by rinsing It thoroughly with ethanol (5.1). If the measuring cell (6.2) had been used before for saline samples, It shall be cleaned thoroughly with water (5.3) prior to using It for ethanol or ethanol fuel. Subsequently, It Is thoroughly rinsed with ethanol (5.1). If there are any visible contaminations (e.g. stains) on the inner surface 01 the measunng cell (6.2), the cell shall not be used.
8.1.4 FillIng the sample into the sample vessel
The sample is filled into the sample vessel (6.4) by pouring it directly from the sample container into the vesseL Should an intermediate vessel be required for transferring, this vessel shall first be cleaned thoroughly using water (5.3). and dried in the drying oven at mm. so ‘C. Before the intermediate vessel is used, it is rinsed with ethanol (5.1). Subsequently it shall be dripped off. Rubbing its inside with a fibrous cloth shall be avoided. The size of the intermediate vessel shall be chosen such that it is filled up to at least half its height. If there are any visible contaminations (e.g. stains) at the surface of the glass on the inside of the vessel, the vessel shall not be used.
8.2 Calibration
8.2.1 Interferences
The measurement values of the electrical conductivity can very strongly be influenced by contaminations in the sample as well as by pollutions of the measuring cell (6.2) (suspended matter, grease or oil). Such interferences cannot easily be detected in routine operation; therefore, the cell constant should regularly be checked by means of a reference solution or the cal,ration solution (52).
