13
U
SING
YOUR
V
ISCOMETER
R
3.3 Starting a measurement
1. Press [START] to start the measurement.
Stable flow conditions are reached quickly and the viscosity readings on the display of the
Viscometer can be considered correct within a few seconds (depending on the selected speed
and the viscosity of the sample).
If the viscosity reading exceeds the optimum measuring range (<10% and >90% of selected
full scale), the instrument will give a warning beep.
The message ‘ERROR’ appearing on the screen indicates that the maximum viscosity value
has been exceeded. In this case, the speed should be reduced or a higher range spindle
should be used.
2. When you are satisfied that the reading is stable, press [STOP] to stop the motor. The motor
will slow down smoothly until 0 rpm is reached; this protects the delicate parts of the
instrument.
The last viscosity reading will be retained on the display.
On pressing [START] again, the Viscometer will restart at the preset speed.
If you are using an RV2 Viscometer
The information shown on the display of an RV2 Viscometer is identical to that shown on an RV1
Viscometer unless the optional accessories are being used.
If the Adaptor for Small Sample Volumes or the Adaptor for Low Viscosity Materials is being used,
the bottom two lines of the display will show the Shear Rate (S.R.) and the Shear Stress (S.S.).
Changing spindle rotation speed and spindle type
To modify the spindle rotation speed and spindle type, while the motor is running, press [ENTER]
to return to the data screen.
3.4 Viscosity measurement problems
Unstable viscosity readings may be caused by changes in the temperature of the sample or by the
behaviour of the product itself.
If the readings obtained are not stable, the temperature of the sample should be controlled and
stabilised. If the readings remain unstable once the temperature has been controlled, the instability
is due to the interaction between the product sample and the movement of the spindle.
In this instance, the product is called ‘Non-Newtonian’ and the behaviour of the product can be
described as thixotropic, rheopexy, dilatant, pseudoplastic, etc. The same settings (spindle, speed
rpm
60
R5
mPas
5080
50.8%
temp
20.5
o
C
range
10000 mPas
rpm
60
LCP
mPas
4.05
40.9%
1/sec 73.38
20.5
o
C
N/m2 3.12
2300_TMA_0377_00_01.book Page 13 Thursday, March 29, 2007 1:32 PM
