ASTM D1545 for Viscosity of Transparent Liquids by Bubble Time Method
3. Apparatus
3.1 Constant-Temperature Bath - Any suitable bath capable of maintaining temperature at 25 +/- 0.1°C with water as the bath medium.
3.2 Standard Viscosity Tubes, of clear glass and with flat bottoms, 10.65 +/- 0.025 mm in inside diameter; 114 +/- 1 mm in outside length. Plainly legible lines shall be located as follows (Note 1):
27 +/- 0.5 mm
100 +/- 0.5 mm
108 +/- 0.5 mm
The distance between the first and second lines shall be 73 +/- 0.5 mm.
NOTE 1 - All distances shall be measured from the outside bottom of the tube.
3.3 Reference Standards - A series of standard viscosity tubes (3.2) filled with transparent liquids having predetermined viscosities in stokes and bubble seconds and spaced in logarithmically even increments of about 26 % (log 1.260 5 0.100), as listed in Table 1. The standards shall be marked alphabetically or numerically as shown in Table 1 without reference to stokes or bubble time (Note 2). Also listed in Table 1, for general and historical reference only, is the long established series of Gardner-Holdt letter standards, in tubes that do not have the three lines and are shorter than the standard viscosity tubes described in 3.2.
NOTE 2 - For convenience, the reference standards can be divided in three series: light series, 15 tubes marked 0.22 to 8.0; heavy series, 14 tubes marked 10 to 200; and very heavy series, 7 tubes, marked 250 to 1000.
3.4 Timing Device - Stopwatch or electric stop clock capable of being read to a precision of 0.1 s.
3.5 Tube Racks, capable of inverting one or more viscosity tubes 180° to within 1° of a vertical position while rack and tubes are immersed in the constant temperature bath.
3.6 Viscosity Tube Corks, No. 2 short.
