Ubbelohde viscometer

Both are u-shaped pieces of glassware with a reservoir on one side and a measuring bulb with a capillary on the other.

The Ubbelohde device has a third arm extending from the end of the capillary and open to the atmosphere.

In this way the pressure head only depends on a fixed height and no longer on the total volume of liquid.

The determination of viscosity is based on Poiseuille's law: where t is the time it takes for a volume V to elute.

depends on R as the capillary radius, on the average applied pressure P, on its length L and on the dynamic viscosity η.

Ubbelohde viscometer. 1)Filling tube 2)Venting Tube 3)Capillary Tube 4)Feeder Bulb 5)Measuring Bulb 6)Capillary 7)Level Bulb 8)Reservoir A-B)Timing Marks C-D)Max/Min Marks [ 1 ]