ASTM D1662 Standard Test Method for Active Sulfur in Cutting Oils
8. Procedure
8.1 Determine the sulfur concentration of the sample to be tested in accordance with Test Method D129.
8.2 Place 50 more or less 2 g of sample in a 200-mL tall-form beaker, lower the stirrer to within 5 mm of the bottom of the beaker and add 5 more or less 0.25 g of copper powder and heat to 150 more or less 2°C (300 more or less 5°F) while stirring at 500 more or less 25 rpm. If a magnetic stirrer is used, rotate the stirring bar at 500 more or less 25 rpm. When 150 more or less 2°C (300 more or less 5°F) is reached, add an additional 5 more or less 0.25 g copper powder. Continue stirring at 150 more or less 2°C (300 more or less 5°F) for 30 more or less 1 min. At the end of this period, stop stirring and insert a copper strip prepared in accordance with Test Method D130 for 10 more or less 0.25 min. If there is any evidence of stain on the strip, recommence stirring and add an additional 5 more or less 0.25 g of copper powder. Continue stirring the mixture at 150 more or less 2°C for 30 more or less 1 min. Again, insert a copper strip as previously stated for 10 more or less 0.25 min. Repeat this procedure until the copper strip shows no stain, maintaining the temperature of the mixture at 150 more or less 2°C.
8.3 Filter the sample through filter paper at the end of the heating period. The filtration apparatus may be placed in an oven maintained at 100 more or less 1°C (212 more or less 2°F) for more rapid filtration.
NOTE 2 - A filter paper sufficiently fine to prevent passage of any particulate matter must be used, as the presence of copper sulfide in the filtrate will give erroneous results.
8.4 Determine the sulfur content of the filtered sample using Test Method D129.
9. Calculation
9.1 Calculate the active sulfur concentration of the sample as follows:
Active sulfur, wt % = A - B
where:
A = weight % sulfur of the untreated sample, and
B = weight % sulfur of the treated sample.
