9. Method B
9.1 Prepare the test specimen as described in 8.1.
9.2 Promptly place the prepared copper strip in a clean 250-mL bottle to which has been added 220 mL of the oil to be tested. Place the bent copper strip standing on its long edge so that no flat surface lies along the glass bottom of the vessel. Bubble nitrogen through the oil in the bottle by means of a 1/16 in. inner diameter glass or stainless steel tube connected to the reduction or needle valve of the cylinder (rubber connections must be sulfur-free) for 5 min at a rate of 0.5 L/min. Quickly screw in the PFTE plug equipped with fluoro-elastomer o-ring.
9.3 Place the bottle in the oven at 150°C. After 15 min of heating at 150°C, partially unscrew the PFTE plug to release the pressure and then screw it back down so the bottle does not burst. Remove the bottle after heating for 48 h more or less 20 min at 150 more or less 2°C. Allow to cool. Carefully take the copper strip from the flask and wash with acetone or other suitable solvent to remove all of the oil and let air dry. Do not use pressurized air to dry copper strip.
9.4 To inspect, hold the test strip in such a manner that light reflected from it at an angle of approximately 45° will be observed. If a specimen is borderline or unclear, take a clean laboratory tissue and drag it across the surface with heavy pressure; if any of the deposited material is removed, the deposit is corrosive and is to be reported as such.
