Rust-preventing characteristics of inhibited mineral oil in the presence of water
9. Procedure A for Distilled Water
9.1 Clean the beaker in accordance with good laboratory
procedure, wash with distilled water, and dry in an oven. Clean glass beaker cover and a glass stirrer by the same procedure. To clean a stainless steel stirrer and a PMMA cover, use ASTM precipitation naphtha or isooctane or IP 60/80 petroleum spirit, wash thoroughly with hot water and finally with distilled water, and dry in an oven at a temperature not over 65°C (150°F). Pour 300 mL of the oil to be tested (see Practice D 4057) into the beaker and place the beaker in the oil bath held at a temperature that will maintain the oil sample at 60 more or less 1°C (140 more or less 2°F). Insert the beaker into a hole of the bath cover and suspend in the hole with the beaker rim resting on the bath cover. The oil level in the bath shall not be below the oil level in the test beaker. Cover the beaker with the beaker cover with the stirrer in position in the proper opening. Adjust the stirrer so that the shaft is 6 mm (0.24 in.) off center in the beaker containing the oil sample and the blade is not more than 2 mm (0.08 in.) from the bottom of the beaker. Then suspend a temperature measuring device (see Note 11) through the hole in the cover intended for that purpose so that it is immersed to a depth of about 56 mm (2.2 in.). Start the stirrer and when the temperature reading reaches 60 more or less 1°C (140 more or less 2°F), insert the steel test rod prepared in accordance with Section 8.
9.2 Insert the test rod assembly through the test rod hole in the beaker cover and suspend so that its lower end is 13 to 15 mm (0.51 to 0.59 in.) from the bottom of the beaker. Either type of plastic test rod holder (see Fig. 3) may be used. The hole through which the test rod is suspended shall be unobstructed (see Note 13).
NOTE 11 - When analyzing multiple samples of a similar nature that are introduced into a thermostatically controlled bath at approximately the same time (that is, individual samples being analyzed as a batch), data collected has shown that it is not necessary to suspend a temperature measuring device through the hole in the cover intended for that purpose in each of the samples, since a thermostatically controlled bath is capable of maintaining the proper bath temperature within the allowed limits at each of the sample beaker locations. As such, it is permissible to suspend a temperature measuring device through the hole in the cover intended for that purpose in as few as one of the samples being analyzed, immersed to a depth of about 56 mm (2.2 in.). The temperature reading measured in the sample beaker location selected is the basis for determining when the temperature reaches 60 more or less 1°C (140 more or less 2°F) in order to begin stirring each of the beakers and inserting the steel test rods.
NOTE 12 - In order not to disturb the thermal equilibrium in the oil bath once stirring of the samples has begun, no additional samples are to be added to the oil bath.
NOTE 13 - Fig. 1 shows the arrangement of the apparatus.
9.3 Continue stirring for 30 min to ensure complete wetting of the steel test rod. With the stirrer in motion, remove the temperature measuring device (if applicable, see Note 11) temporarily and add 30 mL of distilled water through this hole, discharging the water on the bottom of the beaker, and replace the temperature measuring device (if applicable). Continue stirring at a speed of 1000 more or less 50 rpm for 4 h (see Note 14) from the time water was added, maintaining the temperature of the oil-water mixture at 60 more or less 1°C (140 more or less 2°F). Stop stirring at the end of the 4-h period, remove the test rod, allow to drain, and then wash with ASTM precipitation naphtha or isooctane, or IP 60/80 petroleum spirit. If desired, the test rod may be preserved by lacquering.
NOTE 14 - It is recommended to run the test for 4 h; however, the test period may, at the discretion of the contracting parties, be for a shorter or longer period.
