ISO 2160 Petroleum products - Corrosiveness to copper - Copper strip test
8 Procedure
8.1 General
There are a variety of test conditions which are broadly specific to given classes of product, but within certain classes, more than one condition of time and/or temperature may apply. In general, aviation fuels shall be tested in a pressure vessel at 100 °C, and natural gasolines at 40 °C. Other liquid products shall be tested in a test tube at 50 °C, 100 °C or even higher temperatures.
NOTE - These conditions apply to the most commonly used specifications, but other conditions may be set by specification bodies or agreement between parties.
8.2 Pressure vessel procedure
Place a 30 ml test portion, completely clear and free of any suspended or entrained water (see the note in 6.4) in a chemically clean, dry test tube (5.3). Within 1 min after completing the final polishing, slide the copper strip into the test portion in the test tube. Carefully slide the test tube into the pressure vessel (5.2) and screw the lid on tight. Completely immerse the pressure vessel in the liquid bath (5.4.2) maintained at the test temperature +/- 1 °C. At the end of the specified test period +/- 5 min, withdraw the pressure vessel from the liquid bath and immerse it for a few minutes in cool water. Open the pressure vessel, withdraw the test tube, and follow the procedure in 8.4.
8.3 Test tube procedure
Place a 30 ml test portion, completely clear and free from any suspended or entrained water (see the note in 6.4) in a chemically clean, dry test tube (5.3). Within 1 min after completing final polishing, slide the copper strip into the test portion in the test tube. Stopper with a vented cork, and place the test tube in the test bath (5.4.2) maintained at the test temperature +/- 1 °C. At the end of the specified test period +/- 5 min, remove the test tube and follow the procedure in 8.4. If, at the end of the test period, the level of the liquid in the test tube has fallen below any portion of the copper strip, discard, and repeat the test using a 35 ml test portion.
NOTE - Some automotive gasolines with vapour pressures above 80 kPa at 37.8 °C have exhibited evaporation losses in excess of 10 % of their volume.
8.4 Strip examination
Empty the contents of the test tube into a suitably-sized beaker, such as a 150 ml tall-form, letting the copper strip slide in gently so as to avoid breaking the beaker. Immediately withdraw the strip with the forceps (5.8) and immerse it in wash solvent (4.1). Withdraw the strip at once, dry with quantitative filter paper (by blotting and not by wiping), and inspect for evidence of tarnishing or corrosion by comparison with the corrosion standards (5.9). Hold both the test strip and the standards in such a manner that light reflected from them at an angle of approximately 45° will be observed.
NOTE - In handling the test strip during the inspection and comparison, the danger of marking or staining can be avoided if it is inserted in the viewing tube (5.7), which is stoppered with absorbent cotton (4.2.3).
