Appendix A: Gap Settings Procedure For The Rso Rheometer - Ametek BROOKFIELD RSO Operating Instructions Manual

Appendix A: Gap Settings Procedure for the RSO Rheometer
"The gap" refers to the gap between a truncated-cone or plate spindle and the measuring bottom
plate. Cones are truncated to prevent contact between the cone spindle and the measuring bottom
plate. The cone spindle gap height is the distance between the truncated flat and the theoretical tip
of the cone. This value is indicated on the cone spindle datasheet as the cone truncation value. The
gap height for plate spindles is usually determined by the largest particle size in the material. The best
practice is to use a gap height 5 to 10 times greater than the largest particle diameter (For example, if
the largest particle in the substance is 0.010 mm, then the gap height should be 0.050 to 0.10 mm). If
the material does not have large particles, but is highly viscous, experiment with various gap heights
to determine what will give the most repeatable viscosity measurements.
Any time a spindle is changed, the gap needs to be set.
Ensure that the spindle and measuring the bottom plate are clean. There should be no sample
material on the plate. The rheometer head should be in the raised position. It is also important
that the correct spindle is selected at the beginning of the program because the automatic gap
control uses the spindle information to adjust to the correct gap height. Spindles with the same
basic geometry may still have unique cone truncation heights.
The rheometer head will then automatically move down to the zero-gap position. The hit point is the
point at which the spindle touches the bottom measuring plate.
If operating at a temperature greater than +40°C (+104°F), the touchscreen will instruct the
user to wait for the spindle to temper for 10 minutes before continuing the gap settings process.
Allowing the spindle to temper accounts for any thermal expansion of the spindle which could
otherwise result in faulty measurement or damage to the measurement system.
The rheometer head will automatically move to the filling position, and the gap will automatically be
adjusted as shown in the figure.
The next screen instructs the user to place the sample material on the plate. Follow the instructions
provided in section
M19-230-REV.B
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