10. Cleaning Test Cell
10.1 The cleanliness of the test cell is of paramount importance when measuring loss characteristics because of the inherent susceptibility of most insulating liquids to contaminating influences of the most minute nature. For this reason, clean and dry the cell immediately prior to making the test, and strictly observe the procedures and precautions outlined in 10.2 to 10.5.
10.2 Dismantle the cell completely and wash all the component parts thoroughly with a technical grade of a suitable solvent(such as acetone, pentane, petroleumether, or heptane). Wash the component parts with a mild abrasive soap or detergent. Take care not to lay the electrodes on any surface. Rinse all parts thoroughly with hot tap water, then with cold tap water, followed by several rinses with distilled water. Take extreme care during the washing and rinsing of some test cells to prevent any moisture from entering the thermometer well in the inner electrode. As a precaution against this eventuality, use a suitable stopper to plug this opening prior to starting the cleaning operation.
10.3 After the surfaces of the measuring, guard, and high voltage electrodes have been washed, do not touch these surfaces during the rinsing or any subsequent operation.
10.4 Place the component parts of the test cell in an oven maintained at 110°C for a period of not less than 60min. Do not dry test cells made of Monel at this elevated temperature for more than 90 min as oxidation will take place causing erroneous results. Take care that the surfaces on which the component parts of the cell are placed in the oven are clean.
10.5 At the expiration of the drying period, assemble the cell using clean cotton gloves as protection for the hands and to prevent contamination from skin oils and salt.
