For liquid viscosity measurements recently a computer controlled system around a commercial Ubbelohde viscosimeter (Schott KPG Ubbelohde viscosimeter) was developed. The viscosimeter is arranged in a double wall glas cylinder. Thermostating takes place with a commercial circulating thermostat. To pump the liquid in the capillary a membran air pump controlled with valves is connected to the viscosimeter. The flowtime of the liquid is measured by photoelectric beams. A high precision thermometer (Pt 100) is attached for temperature measurement.
The complete control of the measurement system is carried out with the help of the Windows program "ViscoMeasurement". The control program is connected to the pure component databank of the Dortmund Data Bank (DDB-PCP). Automatic temperature programs for high precision viscosity measurements up to 353 K (limited up to now by the thermostat) and a viscosity range from 0.3 to 100 mm²/s (cSt) can be run.
A scheme of the setup is shown in the following figure:
Typical results of a measurement are plotted in the following diagram together with data from literature.
The main window of the control program contains all important input and the current status of the measurement: