ASTM D2171 Test Method for Viscosity of Asphalts by Vacuum Capillary Viscometer
6. Apparatus
6.1 Viscometers, capillary-type, made of borosilicate glass, annealed, suitable for this test are as follows:
6.1.1 Cannon-Manning Vacuum Viscometer (CMVV), as described in Appendix X1.
6.1.2 Asphalt Institute Vacuum Viscometer (AIVV), as described in Appendix X2.
6.1.3 Modified Koppers Vacuum Viscometer (MKVV), as described in Appendix X3. Calibrated viscometers are available from commercial suppliers. Details regarding calibration of viscometers are given in Appendix X4.
NOTE 3 - The viscosity measured in a CMVV may be from 1 to 5 % lower than either the AIVV or MKVV having the same viscosity range. This difference, when encountered, may be the result of non-Newtonian flow.
6.2 Thermometers - Calibrated liquid-in-glass thermometers (see Table X5.1) of an accuracy after correction of 0.02°C (0.04°F) can be used or any other thermometric device of equal accuracy. ASTM Kinematic Viscosity Thermometers 47°C and 47°F are suitable for the most commonly used temperature of 60°C (140°F).
6.2.1 The specified thermometers are standardized at "total immersion", which means immersion to the top of the mercury column with the remainder of the stem and the expansion chamber at the top of the thermometer exposed to room temperature. The practice of completely submerging the thermometer is not recommended. When thermometers are completely submerged, corrections for each individual thermometer based on calibration under conditions of complete submergence must be determined and applied. If the thermometer is completely submerged in the bath during use, the pressure of the gas in the expansion chamber will be higher or lower than during standardization, and may cause high or low readings on the thermometer.
6.2.2 It is essential that liquid-in-glass thermometers be calibrated periodically using the technique given in Test Method E 77 (see Appendix X5).
6.3 Bath - A bath suitable for immersion of the viscometer so that the liquid reservoir or the top of the capillary, whichever is uppermost, is at least 20 mm below the upper surface of the bath liquid and with provisions for visibility of the viscometer and the thermometer. Firm supports for the viscometer shall be provided. The efficiency of the stirring and the balance between heat losses and heat input must be such that the temperature of the bath medium does not vary by more than more or less 0.03°C (more or less 0.05°F) over the length of the viscometer, or from viscometer to viscometer in the various bath positions.
6.4 Vacuum System - A vacuum system capable of maintaining a vacuum to within more or less 0.5 mm of the desired level up to and including 40.0 kPa 300 mm Hg. The essential system is shown schematically in Fig. 1. Glass tubing of 6.35-mm (1/4-in.) inside diameter should be used, and all glass joints should be airtight so that when the system is closed, no loss of vacuum is indicated by the open-end mercury manometer having 1-mm graduations. A vacuum or aspirator pump is suitable for the vacuum source.
6.5 Timer - A stop watch or other timing device graduated in divisions of 0.1 s or less and accurate to within 0.05 % when tested over intervals of not less than 15 min.
6.6 Electrical Timing Devices may be used only on electrical circuits, the frequencies of which are controlled to an accuracy of 0.05 % or better.
6.6.1 Alternating currents, the frequencies of which are intermittently and not continuously controlled, as provided by some public power systems, can cause large errors, particularly over short timing intervals, when used to actuate electrical timing devices.
7. Sample Preparations
7.1 Heat the sample with care to prevent local overheating until it has become sufficiently fluid to pour, occasionally stirring the sample to aid heat transfer and to assure uniformity.
7.2 Transfer a minimum of 20 mL into a suitable container and heat to 135 more or less 5.5°C (275 more or less 10°F), stirring occasionally to prevent local overheating and taking care to avoid the entrapment of air.
NOTE 4 - If it is suspected that the sample may contain solid material, strain the melted sample into the container through a No. 50 (300-µm) sieve conforming to No. 50 Specification E 11.
