How to use a Ubstrom viscometer?

An Ubbelohde-type viscometer is an instrument that measures viscosity using a capillary-based method. This particular type is recommended for measuring highly viscous solutions as it obtains values ​​separate from the overall volume. It was invented by Leo Ubbelohde (1877-1964) and is named after him. The viscosity of a fluid is a measure of its ability to resist deformation. For example, when water overflows from a jug, it changes shape. Honey would do the same thing, but more gradually. So, for example, water has a much higher viscosity than honey. For liquids, viscosity refers to "thickness". There are many different types of glass capillary viscometers, as no one measuring instrument is suitable for all viscosities.  

However, Ubbelohde viscometers are all U-shaped glass vessels with a reservoir on one side and a measuring cup with a capillary on the other. Individual analysts have a preference as to which analyst to use. Once you have an instrument that suits your needs, follow the instructions below on how to use an Ubbelohde viscometer. 

first step

First, load the viscometer with the liquid you want to determine. Put it into the first big tube: the water storage tank. Make sure it is between the two wires of the light tube so that the filling liquid does not block the air tube during use. 

second step

Next, connect clean, dry rubber tubing to the timing and air tubing, and place the viscometer in a temperature-controlled liquid bath. Here, the capillary needs to be vertical. The sample solution needs to reach the same temperature in the bath, which takes about 20 minutes.  

third step

Next, seal the rubber tubing attached to the air tube and gently suck it into the timing tube until the fluid reaches about 5mm above the upper timing mark. Keep the liquid at this level by sealing the tube. Make sure this point is at least 2cm below the level of the bath fluid. 

the fourth step

Now, loosen the air tube so that the liquid falls from the bottom of the capillary. If the feed has a high viscosity, it may be necessary to apply pressure to the air line to force the liquid to fall from the bottom of the capillary. 

the fifth step

Next, loosen the timing tube and let the fluid flow. Measure the flow time in seconds for the base of the meniscus to flow from the top edge of the top marking line to the top edge of the marking line below it. The time it takes a liquid to pass the two calibration marks is a measure of viscosity.  

Note that the device also has a third arm that extends from the end of the capillary and is vented to atmosphere. In this way, the pressure head is only dependent on a fixed height and not on the total volume of the liquid, making this instrument the best measurement choice.