ASTM D3613 for Sampling Insulating Liquids for Gas Analysis and Water Analysis
ASTM D3613 Standard Practice for Sampling Insulating Liquids for Gas Analysis and Determination of Water Content
8. Collecting Samples Using Syringe
8.1 Perform the steps in Section 6. Attach the plastic tube to the syringe as shown in Fig. 1.
8.2 Adjust the equipment drain valve or the sample port valve for a gentle flow of fluid through the tubing with the syringe stopcock open (Fig. 1) to permit flushing of the stopcock. Position the handle toward the syringe.
8.2.1 The handle of the plastic stopcock always points to the closed port leaving the other two ports in open communication.
8.3 Turn the stopcock slowly to open the stopcock into the syringe (Fig. 2 handle in line with the flushing port). Allow the fluid to fill the syringe to maximum full mark (shown as 40 in Fig. 2). Immediately close the port into the syringe (Fig. 3 handle toward collection tube). Slowly depress the syringe piston until all the oil is evacuated from the syringe completing the first conditioning. Perform this condition procedure one more time.
8.3.1 If the quantity of oil in the apparatus is small and a visible change in level occurs when filling the syringe, the above conditioning steps may be omitted. A large variance from normal should be considered when evaluating the test results obtained when the syringe conditioning was not used.
8.3.2 If conditions warrant, the sample collection tubing may be removed from the syringe during the time the piston is depressed. In this case the flow of oil shall continue and should be directed into the flush container. Care shall be taken not to contaminate the syringe inlet port.
8.4 Turn the stopcock slowly to open the port to the syringe (Fig. 2 handle in line with the flushing port). Allow 10 mL of fluid to enter the syringe. Immediately close the port to the syringe (Fig. 3 handle toward collection tube).
8.5 With the syringe vertical (Fig. 3), the stopcock up, and the handle away from the syringe, eject any air bubbles and carefully depress the syringe piston far enough to leave 1 to 2 mL of fluid in the syringe. If all of the fluid is evacuated from the syringe, there is a greater chance of an air leak. Close the stopcock, with the handle toward the syringe.
8.6 To eliminate any possibility that air may be entrapped in the valve, let the fluid flow through the flushing port before the valve is turned to allow the syringe to be filled.
8.7 Open the stopcock (Fig. 2), with the handle in line with flushing port. Allow fluid pressure to push the piston back until the syringe is filled to approximately 80 % full. Do not pull the piston manually since this can result in bubble formation.
8.8 Close the stopcock (Fig. 4), with the handle toward syringe. Separate the syringe from the tubing and inspect for air bubbles. If air is present, discharge oil with the syringe vertical (stopcock up) and obtain another sample.
8.9 Remove the sample adapter, if used, and install the security plug with a non-hardening thread sealant.
9. Collecting Samples Using Stainless Steel Cylinder
9.1 Perform the steps in Section 6.
9.2 Hold the steel cylinder in a vertical position. Connect the oil-resistant tubing to the lower valve port on the steel cylinder and connect a short piece approximately 60 cm (24 in.) of clear oil-resistant tubing to the upper valve on the steel cylinder.
9.3 While keeping the cylinder in the vertical position, open the electrical apparatus drain valve or the sample port valve. Open the lower valve on the steel cylinder. Direct the short piece of plastic tubing towards the flush oil container and open the upper valve on the steel cylinder. With all three valves open and the cylinder held in a vertical position (see Fig. 5), flush the cylinder. 1.9 L (2 qt) of fluid should pass through the cylinder into the flush oil container.
9.4 If air bubbles are seen in the plastic tubing, the steel cylinder may be tapped lightly or shaken to dislodge any bubbles inside the cylinder. Flushing with oil should be continued until the flow out of the cylinder is free of any bubbles.
9.5 Tightly close the three valves in the following sequence: first close the upper cylinder valve tightly; then the bottom cylinder valve; followed by the electrical apparatus drain valve or sample port valve. Remove the sample adapter if used, and reinstall the security plug with a non-hardening thread sealant.
9.6 As a final check to determine that the cylinder has been properly filled, shake the cylinder and listen for the motion of the bubbles and the splashing of the oil. If any sound is heard, the cylinder should be drained and the sampling repeated.
10. Collecting Samples Using Flexible-Sided Metal Can
10.1 Perform the steps in Section 6.
10.2 When collecting the sample in a flexible-sided metal can, hold the sample container so that the fluid will run down the sides and limit aeration of the fluid. Partially fill the sample container several times and slosh the fluid around to warm (to prevent condensation). Rinse the container, and properly discard the fluid after each rinse. The flow of fluid should be gentle and not interrupted from the start of the flushing of the valve and container to the completion of the final filling of the sample container.
10.3 Obtain the sample by allowing the fluid to flow down the sides of the container or from the bottom up, filling the container to overflowing. Once the container is full, install the cap immediately.
10.4 Close the drain valve, remove the sample adapter, if used, and install the drain valve security plug with a non-hardening thread sealant. The tubing should not be reused. Clean the sample adapter before reusing on any other oil-filled compartments or apparatus.
