ASTM D2170 standard test method for kinematic viscosity of asphalts (bitumens)
8. Procedure
8.1 The specific details of operation vary somewhat for the various types of viscometers. See the detailed descriptions of viscometers in Annex A2 for instructions for using the type viscometer selected. In all cases, however, follow the general procedure described in 8.2 to 8.8.
8.2 Maintain the bath at the test temperature within more or less 0.02°F (more or less 0.01°C) for test temperature of 140°F (60°C) and within more or less 0.05°F (more or less 0.03°C) for test temperature of 275°F (135°C). Apply the necessary corrections, if any, to all thermometer readings.
8.3 Select a clean, dry viscometer which will give an efflux time greater than 60 s and preheat to test temperature.
8.4 Charge the viscometer in the manner dictated by the design of the instrument, as prescribed in Annex A2.
8.5 Allow the charged viscometer to remain in the bath long enough to reach the test temperature, as prescribed in Annex A2.
8.6 Start the flow of asphalt in the viscometer as prescribed in Annex A2.
8.7 Measure to within 0.1 s, the time required for the leading edge of the meniscus to pass from the first timing mark to the second. If this efflux time is less than 60 s, select a viscometer of smaller capillary diameter and repeat the operation.
8.8 Upon completion of the test, clean the viscometer thoroughly by several rinsings with an appropriate solvent completely miscible with the sample, followed by a completely volatile solvent. Dry the tube by passing a slow stream of filtered dried air through the capillary for 2 min, or until the last trace of solvent is removed. Periodically clean the instrument with a strong acid cleaning solution to remove organic deposits, rinse thoroughly with distilled water and residue-free acetone, and dry with filtered dry air.
8.8.1 Chromic acid cleaning solution may be prepared by adding, with the usual precautions, 800 mL of concentrated sulphuric acid to a solution of 92 g of sodium dichromate in 458 mL of water. The use of similar commercially available sulphuric acid cleaning solutions is acceptable. Nonchromium- containing, strongly oxidizing acid cleaning solutions may be substituted so as to avoid the disposal problems of chromium-containing solutions.
8.8.2 Use of alkaline glass cleaning solutions may result in a change of viscometer calibration, and is not recommended.
