ASTM D6514 Standard Test Method for High Temperature Universal Oxidation Test for Turbine Oils
8. Corrosion Standards
8.1 ASTM Oxidation Cell Varnish Standards (ADJD6514) consist of reproductions in color of typical oxidation cell internal surfaces representing increasing degrees of staining, the reproductions being encased in plastic in the form of a plaque.
8.1.1 Keep the plastic-encased printed ASTM Oxidation Cell Varnish Standards (ADJD6514) protected from light to avoid the possibility offading. Inspect for fading by comparing two different plaques, one of which has been carefully protected from light (new). Observe both sets in diffuse daylight (or equivalent) first from a point directly above and then from an angle of 45°. When any evidence of fading is observed, particularly at the left-hand of the plaque, it is suggested that the one that is more faded with respect to the other be discarded.
8.1.1.1 Alternatively, place a 20 mm (3/4 in.) opaque strip (masking tape) across the top of the colored portion of the plaque when initially purchased. At intervals, remove the opaque strip and observe. When there is any evidence of fading of the exposed portion, it is suggested that the standards be replaced.
8.1.2 If the surface of the plastic cover shows excessive scratching, it is suggested that the plaque be replaced.
9. Sampling
9.1 Samples for this test can come from laboratory blends, tanks, drums, small containers, or operating equipment. Therefore, use the applicable apparatus and techniques described in Practice D4057 or IP 2546 to obtain suitable samples.
9.2 Special precautions to preserve the integrity of a sample will not normally be required. It is good practice to avoid undue exposure of samples to sunlight or strong direct light. Fluid samples which are not homogeneous on visual inspection shall be rejected and fresh samples obtained.
10. Preparation of Apparatus
10.1 Cleaning Glassware:
10.1.1 Clean new glassware by washing with a hot detergent solution (using a bristle brush) and rinse thoroughly with tap water. If any visible deposits remain, soaking with a hot detergent solution has proven helpful. After final cleaning, by 24-h soak at room temperature with cleaning reagent, rinse thoroughly with tap water, then distilled water and allow to dry at room temperature or in an oven. Following the final distilled water rinse, an iso-propyl alcohol or acetone rinse will hasten drying at room temperature.
10.1.2 Used glassware should be cleaned immediately following the end of a test. Drain the used oil completely. Rinse all glassware with heptane to remove traces of oil. Then clean the glassware by the procedure described in 9.1.1 before later use.
10.2 Cleaning Catalyst:
10.2.1 Clean equal lengths (0.50 +/- 0.01 m) of iron and copper wire with wads of absorbed cotton wet with heptane or isooctane. Follow by abrasion with silicon carbide cloth until fresh metal surfaces are exposed. Then wipe with dry absorbent cotton until all loose particles of metal and abrasive have been removed. In following operations, handle the catalyst with clean gloves (cotton, rubber, or plastic) to prevent contact with the skin.
NOTE 2 - One procedure for preparing clean catalyst wire is to cut 0.50 +/- 0.01 m lengths of wire. Hold one end of the wire tightly with a pair of clean pliers or in a vise while cleaning with the abrasive cloth. Reverse ends of the wire and repeat. Alternatively, clean a longer length of wire (3 to 5 m) and then cut 0.50 6 0.01 m lengths from the clean wire.
10.3 Preparation of Catalyst Coil:
10.3.1 Twist the iron and copper wires tightly together at one end for three twists. With the two wires parallel, wind the wires around a cylindrical mandrel to produce a single coil 16 mm in inside diameter. The mandrel described in Test Method D943 is satisfactory, but other cylindrical metal or wood stock may be used. Remove the coil from the mandrel and secure the free ends with three twists. Bend the twisted ends to conform to the shape of the spiral coil. Stretch the coil to produce a finished coil with an overall length of 80 +/- 8 mm.
10.3.2 Store the catalyst coil in a dry, inert atmosphere until use. For storage up to 24 h, the coil can be stored in heptane. Before use, inspect stored coils to ensure that no corrosion products or contaminating materials are present.
10.4 Use a fresh catalyst coil for each test. Do not reuse coils.
