Connection Of The Vz 8552 Overflow Guard; Transparent Thermostats - Fisher AVS 470 Manual De Instrucciones

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2.3.4

Connection of the VZ 8552 overflow guard

We urgently recommend the connection of the VZ 8552 overflow guard (available as an option) for the
suction-mode operation of the ViscoPump II module. The connection of the VZ 8552 overflow guard
(capacitive sensor for the safety bottle) excludes over-pumping in suction mode (contamination of the
ViscoPump II module). The holder on the safety bottle accommodates the capacitive sensor.
When using the ViscoPump II module VZ 8511 (meniscus sensing by light barriers) the holder for the safety
bottle is to be attached to the measurement stand, e.g. the AVS/S.
When using the ViscoPump II module VZ 8512 (thermo-resistive measurement) the holder for the safety
bottle is to be attached to the "viscometer gallows" provided for the TC viscometer 5732.
Should any liquid be over-pumped into the safety bottle, the safety sensor will trigger a stop. After emptying
the safety bottle, the lateral LED on the capacitive sensor will go out. You may continue with the
measurements.
The electrical connection of the VZ 8552 overflow guard is made using DIN plugs on the front side of the
respective module of the ViscoPump II.
Please note: The sensitivity of the capacitive sensor has to be adapted to the medium being used.
To do so, please use the enclosed screw driver to adjust the lateral set screw in such a manner that the
capacitive sensor in the built-in condition (i.e. without medium) are just close from responding (i.e. the LED
is off).
2.3.5

Transparent thermostats

Viscosity depends on the temperature of the sample liquid. This means that the viscometers must always be
thermostated during the measurement. The measurement temperature has to be kept constant in order to
achieve an accurate result.
This is possible on the AVS 470 Viscosity Measuring Unit. The transparent thermostats from Schott
Instruments which were developed especially for capillary viscometry meet the requirements imposed on
precision and constancy. The CT 53, CT 54 thermostats, for instance, guarantee a temperature constancy of
± 0.01 K at a command temperature in the range of 10° to 40°C, and a maximum fluctuation of the ambient
temperature of ± 3 K. As a rule of thumb, you may suppose that the temperature deviation, expressed in
degrees, multiplied with a factor of 10 will correspond to the deviation from the result in terms of %. This
means that a deviation of 0.05 K corresponds to a possible error of 0.5%.
In principle, two different transparent thermostats can be used on the AVS 470 Viscosity Measuring Unit: for
measurements at different temperatures, the CT 53, CT 54 transparent thermostats are available. These
thermostats can be equipped with two or four viscometers including other equipment, for instance the AVS/S
measurement stands.
Please note: The transparent thermostats have to be selected on the basis of the required application, for
instance, CT 53 HR, CT 53 TT, or CT 53 HT.
Please read the separate operating instructions of the transparent thermostats as well.
Chapter 2 initial operation