Functioning Of The Device; Capillary Viscometry - Xylem SI Analytics ViscoPump II Manual De Instrucciones

Basics ViscoPump II

1.4 Functioning of the device

The ViscoPump II Modul is used to perform flow-time measurements in capillary viscometers.
The available capillary viscometers enable viscosity measurements 0.35 of approx 5,000 mm²/s (cSt)
to be carried out at a measuring temperature of approx. 20 ... 25 °C.
The ViscoPump II Modul can be fitted out in two ways to be used for meniscus sensing. Connecting
TC viscometers to the ViscoPump II VZ 8512 module will also enable the measurement of black and
opaque liquids. As an alternative option it is possible to use viscometers in combination with the
light-optical ViscoPump II VZ 8511 module viscometers for meniscus sensing with the measurement
stand, e.g. the AVS®/S.
Time recording extends up to 9999.99 seconds with a resolution of 0.01 s. Serial data transmission is
used to transfer the time readings to the respective controller unit.
Prior to the measurement as such, the liquid to be measured is sucked upwards inside the capillary
viscometer though two measurement planes (N2 and N1) which are designed as light barriers or
thermistor sensors, depending on the viscometer type (fig. 1 and 2).
When using Ubbelohde viscometer, the design of the program ensures that the suspended spherical
level will form prior to the start of the measurement.

1.5 Capillary viscometry

Capillary viscometry is the most accurate method for the determination of the viscosity of liquids
with a Newtonian flowing behaviour. The measurement as such consists in a time measurement. The
time measured is that which a specific quantity of liquid requires to pass through a capillary having a
defined width and length. Conventionally, this process is watched with the human eye, and the flow
time is measured manually using a stop watch.
In the case of the AVS® 370 Viscosity Measuring Unit, as with all viscometry measuring devices
from SI Analytics GmbH, the liquid meniscus is captured on the measurement planes, either in an
optoelectronic manner by means of light barriers, or else on a thermo-resistivity basis by thermistors.
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