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1
Description
The viscometers basically consist of the four tube sections, the capillary tube (1), the venting tube (2), the
filling tube (3), the reservoir (4), the reference level vessel (5), the capillary (7) with the measuring
sphere (8), the pre-run sphere (9) and the cleaning tube (10). Above and below the timing bulb (8) are
printed on the capillary tube (1) the timing marks M
marks not only define the flow-through volume of the sample, but also the mean hydrostatic head h. The
capillary (7) ends in the upper part (6) shaped as a spherical cap of the lower reservoir (5). The sample
runs down from the capillary (7) as a thin film over this spherical cap (6) (suspended level bulb).
The cleaning tube (10) is for connection to the Automatic Viscometer Cleaner AVS 24 from SI Analytics
GmbH. The cable is plugged and screwed into the plug-in screw cap (11) for connection of the TC sensors
(Ubbelohde Viscometer with TC sensors) to the AVS measuring systems from SI Analytics GmbH.
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Preparation of sample
Low-viscosity samples should be passed through a SCHOTT glass filter (10 ... 100 µm) before measuring;
high-viscosity samples through a strainer of 0.3 mm mesh (test strainer 0.2, DIN 4188). Samples whose
setting point according to DIN 51 583 or pour point according to DIN 51 597 is not at least 30 °C below
the test temperature, must be heated up to 50 °C before measuring.
3
Selection of capillary
The diameter of the capillary should be selected so that the uncertainty inherent in the kinetic energy
correction (HC = Hagenbach-Couette correction) does not exceed the error allowed for time measurement
(see table). Therefore, for precision measurements, efflux times whose correction seconds are stated in
parentheses should not be applied. A selection of a viscometer with a smaller capillary diameter is
suggested.
4 Cleaning of viscometer
Before first use clean with 15 % H
It must be completely dry and dust-free before it is put to use for either manual or automatic measuring.
5
Filling of viscometer
About 20 ml (in case of Ubbelohde viscometers with TC sensors, about 22 ml) of the filtered sample are
filled by means of a one-way syringe through the part of the so-called Luer-Lok coupling which is facing
the viscometer or sucked in by means of the suction via the Automatic Viscometer Cleaner AVS 26.
12
and M
1
O
and 15 % HCl. Thereafter rinse viscometer with a suitable solvent.
2
2
or the TC sensors TC
2
and TC
. These
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