Place 30 mL of sample, completely clear and free of any suspended or entrained water (see 9.3), into a chemically clean,
dry 25-mm by 150-mm test tube and, within 1 min after completing the final preparation (polishing), slide the copper
strip into the sample tube. If more than one sample is to be analyzed at essentially the same time, it is permissible to
prepare each sample in the batch by stoppering each tube with a vented stopper, such as a vented cork before placing each tube in a bath maintained at 50 6 1°C (122 6 2°F), provided the elapsed time between the first and last sample prepared is kept to a minimum. Protect the contents of the test tube from strong light during the test. After 3 h 6 5 min in the bath, examine the strip as described in 11.4. For tests on fuel oil and diesel fuel, to specifications other than Specifications D396 and evaporation losses are apparent, it is recommended that the Pressure Vessel Procedure (see 11.2 and 11.2.3) be used. In addition, if the lab decides it wants to minimize or mitigate any evaporation losses associated with the analysis of automotive gasolines (even if the corresponding vapor pressure is ≤ 80 kPa), the option exists for the lab to test samples using the Pressure Vessel Procedure (see 11.2 and 11.2.3)