The Avs 470 Viscosity Measuring Unit; Functioning Of The Device - Fisher AVS 470 Manual De Instrucciones

Chapter1 The AVS470 Viscosity Measuring Unit
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1 The AVS 470 Viscosity Measuring Unit

The AVS 470 is an measurement instrument for determining absolute and relative viscosity. It is
operated using either the built-in membrane keyboard at the front or the TZ 2835 PS2 keyboard. Cal-
culation of the results on the basis of the determined values is done by the built-in computing unit. The
readings can be shown on the display or documented on the optional TZ 3460 printer.
1.1

Functioning of the device

The AVS 470 Viscosity Measuring Unit 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). This piece of information refers to the measurement temperature. The viscosity of "heavy
fuel oil", for instance, is above 50,000 mm²/s (cSt) at ambient temperature; as a result, no measurement
would be possible at temperatures between 20-25°C. But if one increases the temperature to 100°C or
more, viscosity will drop under the measurement limit, so that a measurement is now possible again. The
filling of the appropriate viscometer is the only problematic point in this regard, but this problem is also
present with manual measurements, i.e. it is not specific to an automated measurement unit.
The AVS 470 Viscosity Measuring Unit 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. TC viscometers can also be used to handle colour-less and transparent liquids
just as easily. 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. The individual results of a
measurement series can either be presented on the display using an up/down function, but it is also
possible to document them on the printer which is available as an option.
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 470 Viscosity Measuring Unit via the
ViscoPump II module.
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 measured flow time is shown on the display. Up to 99 measurements of a measurement series (i.e.
successive flow time readings taken one and the same viscometer) will be stored and evaluated.