Manual Measuring Operation; Automated Measuring Operation; Example Of Manual Measuring Operation - Schott Instruments 567 Mode D'emploi

7

Manual measuring operation

Apply vacuum to venting tube (2), closing venting tube (2) by a finger or rubber stopper. This will cause
the successive filling of the reference level vessel (5), the capillary tube (1), the measuring sphere (8), and
the pre-run sphere (9). In case of the micro viscometer, follow the same procedure and fill to approx.
10 mm above the upper timing mark M 1 .
Now suction is discontinued and the venting tube (2) opened again. This causes the liquid column to
separate at the lower end of the capillary (7) and to form the suspended level at the dome-shaped top
part (6). What is measured in the time interval (flow time t) it takes the leading edge of the meniscus of the
sample to descend from the upper edge of the upper timing mark M 1 to the upper edge of the lower timing
mark M 2 .
Note: When measuring highly viscous samples with capillary No. IV, Ivc, IVa and V, it is advisable, after
opening of venting tube (2), to keep capillary tube (1) closed long enough for reference level vessel (5) to
run empty and the suspended level to form. If, during measurement, venting tube (2) should be clogged
by a drop of liquid, the measuring operation must be repeated. In the event of renewed clogging, the
vertical axis of the capillary may be slightly modified.
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Automated measuring operation

The automated viscosity-measuring instruments by SCHOTT Instruments GmbH (see catalogue) replace
the above described manual operation of viscosity measurement. Subjective measuring errors are
eliminated, and the efflux times measured appear as a 6-digit print-out with sample identification. Accord-
ing to the type and number of samples to be measured, an optimum measuring device may be assembled
which can be expanded to an automatic sampler. Rinsing and filling of Ubbelohde viscometers and Ubbe-
lohde micro viscometers and measuring of sample with subsequent changing of sample is performed
automatically. The timing marks required for manual measuring are replaced by light b
All Ubbelohde viscometers and Ubbelohde micro viscometers of SCHOTT Instruments GmbH can be
used in the AVS automatic viscosity measuring instruments by SCHOTT Instruments GmbH.
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Example of manual measuring operation

Required accuracy of measurement
for test temperatures 10 ... 30 °C:
Accuracy of thermostat
Accuracy of reading thermometer
Equilibration time
Allowable deviation from vertical suspension of viscometer
Permissable parallax in viewing viscometer marking
1
Minimum flow time )
in capillary I
in capillary II
in capillary III
Maximum permissable time measurement error
Number of single measurements required
Allowable deviations between measurements
The accuracy obtained with the AVS automated measuring system is greater since certain parameters
such as errors in reading, clock errors, etc. are eliminated.
Chosen so that the uncertainty inherent in the kinetic energy correction (HC) does not exceed the
1)
error allowed for time measurement.
13
[%]
[°C]
[°C]
[min]
[°]
[°]
[s]
[%]
[%]
[%]
arriers.
± 1 ± 0.5 ± 0.1
± 0.1 ± 0.05 ± 0.01
± 0.05 ± 0.03 ± 0.005
15 15 15
4.5 3.3 1.5
10 5
250 350 650
100 135 240
100 100 100
± 0.33 ± 0.17 ± 0.03
4 4
± 1 ± 0.5 ± 0.1
1
4