These are reverse flow type mostly used with dark samples that would obscure the timing lines of other tube configurations. Since the sample is timed as it ascends to the timing marks, it is possible to test very dark samples. Approximately 11ml of sample is suctioned into the reservoir bulb while the tube is inverted, and then the stem is returned to upright position and equilibrated in the bath. After equilibration, the stopper is removed and sample flows downward into first bulb, then upward into two timing bulbs where two timings may be done on the same sample. The certificate on this serialized tube contains calibrated Constants for both the Lower and Upper bulbs, so that dual viscosity data may be secured by multiplying the two timings with their respective constants.
Best GG-17 high borosilicate glass as the material, 80% more borosilicate content.
Linear expansion coefficient 3.3× 10-6K-1, highly stable, constant feature.
Size |
Approx. constant, mm 2 /s 2 (cSt/s) |
Kinematic Viscosity Range mm 2 /s(cSt) |
25* |
0.002 |
0.5 - 2 |
50 |
0.004 |
0.8 - 4 |
75 |
0.008 |
1.6 - 8 |
100 |
0.015 |
3 - 15 |
150 |
0.035 |
7 - 35 |
200 |
0.1 |
20 - 100 |
300 |
0.25 |
50 - 250 |
350 |
0.5 |
100 - 500 |
400 |
1.2 |
240 - 1200 |
450 |
2.5 |
500 - 2500 |
500 |
8 |
1600 - 8000 |
600 |
20 |
4000 - 20000 |
650 |
45 |
9000 - 45000 |
700 |
100 |
20000 - 100000 |