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Figure 3-46
Figure 3-47
Data averaging
The DVNext Rheometer offers two techniques to average data, Live Averaging and Post Test Averaging. Data
averaging can be useful when measuring samples with entrained air or suspended particles that cause some
variation in measurement results. Data averaging may not be useful when changes in measurement results are
caused by the rheological properties of the test sample such as thixotropy or pseudoplasticity (shear thinning).
Materials that exhibit thixotropy will show a steadily decreasing measured viscosity over time. Materials that exhibit
pseudoplasticity will show a changing viscosity as the spindle speed changes.
TIP: When averaging data for a thixotropic material, begin the Averaging Duration after the period of most
significant change in measured viscosity. This will reduce the variability in the averaged value.
TIP: When averaging data for a pseudoplastic material, do not average together (Test Averaging) data collected at
different speeds (or shear rates).
Live Averaging of data occurs during actual testing of a sample. Data can be collected as an average of readings
over a specific time interval; each data point saved in the file is an averaged value. This averaging is defined in the
Data Collection section of Configure Viscosity Test.
Single Point Averaging
Single Point Averaging requires a definition of Averaging Duration, the amount of time for which readings will be
averaged. This time parameter will be applied at the end of the End Condition. In this case a single data point will be
collected which represents the average of all data measured during the specified time period (Averaging Duration).
Multi-Point Averaging
Multi-point Averaging requires a definition of 1) Data Interval, the frequency of data collection and 2) Averaging
Duration, the amount of time for which readings will be averaged. These two parameters will work in conjunction to
generate multiple data points each of which represent the average of all data measured during the average duration
within the specified Data Interval.
Post Test Averaging
Post Test Averaging of data occurs after the test is complete, through the Results screen. Averages and standard
deviation values can be generated for data collected in a single step or across several steps. If the test used to
collect data utilized Live Averaging (described above), then the Post Test Averaging will produce an average value of
averaged data points. Post Test Averaging can be specified in the Report section of Configure Viscosity Test When
configured as part of the test, the average values will be displayed immediately upon test conclusion. If not specified
M19-2101 REVISION 2.0
D V N E X T R H E O M E T E R - O P E R AT I O N A L M A N U A L
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