Functioning Of The Device; Capillary Viscometry - Xylem SI Analytics AVS 370 Manual De Instrucciones

42
1.4

Functioning of the device

®
The AVS 370 is used to perform flow-time measurements in capillary viscometers in combination with
the WinVisco 370 PC software. It is operated via a Personal Computer. The WinVisco 370 software
can be used to display the time readings. The results of a measurement series can be stored on the
PC.
When using up to four different modular ViscoPump II units, the AVS
ways to beused for meniscus sensing.
The available capillary viscometers enable viscosity measurements 0.35 of approx 5,000 mm
to be carried out at a measuring temperature of approx. 20 ... 25 °C.
TC viscometers can also be used to handle colour-less and transparent liquids just as easily.
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
Time recording extends up to 9999.99 seconds with a resolution of 0.01 s.
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).
The pumping pressure is controlled automatically by the AVS
When using Ubbelohde viscometer, the design of the program ensures that the suspended spherical
level will form prior to the start of the measurement.
®
The AVS 370 is equipped with two RS-232-C interfaces for data transfer; these interfaces also allow
several units to be chained.
The number of devices which can be connected to the computer depends on the software being used
(presently it is limited to two AVS
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
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.
®
/S.
®
370, with 4 ViscoPump II modules each).
®
370, as with all viscometry measuring devices from SI Analytics
®
370 can be upgraded in two
®
370 via the ViscoPump II module.
2
/s (cSt)
®
, the liquid