ASTM D88 standard test method for Saybolt viscosity
10. Procedure
10.1 Establish and control the bath temperature at the selected test temperature.
10.1.1 Standard test temperatures for measuring Saybolt Universal viscosities are 21.1, 37.8, 54.4, and 98.9°C (70, 100, 130, and 210°F).
10.1.2 Standard test temperatures for measuring Saybolt Furol viscosities are 25.0, 37.8, 50.0, and 98.9°C (77, 100, 122, and 210°F).
10.1.3 Other standard test temperatures in use include 60.0 and 82.2°C (140 and 180°F).
10.2 Insert a cork stopper, having a cord attached for its easy removal, into the air chamber at the bottom of the viscometer. The cork shall fit tightly enough to prevent the escape of air, as evidenced by the absence of oil on the cork when it is withdrawn later as described.
10.3 If the selected test temperature is above room temperature, the test may be expedited by preheating the sample in its original container to not more than 1.7°C (3.0°F) above the test temperature. Never preheat any sample to within 28°C (50°F) of its flash point (see Test Methods D93), because volatility losses might alter its composition.
10.4 Stir the sample well; then strain it through the 150-µm (No. 100) wire cloth in the filter funnel directly into the viscometer until the level is above the overflow rim.
10.5 The viscosities of steam-refined cylinder oils, black lubricating oils, residual fuel oils, and similar waxy products can be affected by their thermal histories. Use the following preheating procedure with such products to obtain uniform results at temperatures below 93°C (200°F):
10.5.1 Heat the sample in its original container to about 50°C (122°F), with stirring and shaking to dissolve and blend waxy materials. Probe the bottom of the container with a stirring rod to be certain that all waxy materials are in solution, and mix well.
10.5.2 Pour about 100 mL into a 125-mL Erlenmeyer flask. Stopper loosely with a cork or rubber stopper.
10.5.3 Immerse the flask in a bath of boiling water for 30 min.
10.5.4 Mix well, remove the sample from the boiling water bath, wipe the outside of the flask dry, and strain the sample through the 75-µm (No. 200) wire cloth in the filter funnel directly into the viscometer until the level is above the overflow rim.
10.6 Stir the sample in the viscometer with the appropriate viscosity thermometer equipped with the thermometer support (Fig. 3). Use a circular motion at 30 to 50 rpm in a horizontal plane. When the sample temperature remains constant within 0.03°C (0.05°F) of the test temperature during 1 min of continuous stirring, remove the thermometer.
NOTE 4 - Never attempt to adjust the temperature by immersing hot or cold bodies in the sample. Such thermal treatment might affect the sample and the precision of the test.
10.7 Immediately place the tip of the withdrawal tube (Fig. 2) in the gallery at one point, and apply suction to remove oil until its level in the gallery is below the overflow rim. Do not touch the overflow rim with the withdrawal tube; the effective liquid head of the sample would be reduced.
10.8 Check to be sure that the receiving flask is in proper position; then snap the cork from the viscometer using the attached cord, and start the timer at the same instant.
10.9 Stop the timer the instant the bottom of the oil meniscus reaches the graduation mark on the receiving flask. Record the efflux time in seconds to the nearest 0.1 s.
