Brookfield R/S Coaxial Cylinder Rheometer - Manual (Page 71)

Brookfi eld Engineering Labs., Inc. Page 71 Manual No. M08-219-B1211
If you prefer to work in stress values, then these torques equate to the following for our standard
vanes:
Constant Rate Test Creep Test (recommended minimum
V30-15 121 Pa to 4040 Pa 303 Pa
V40-20 51 Pa to 1700 Pa 128 Pa
V80-40 6.4 Pa to 213 Pa 16 Pa
D.3.1 Vane selection
The fi rst consideration in vane selection is the working torque ranges just mentioned. The next
consideration relates to vane-to-container diameter ratios. The vane measuring method works best
when these ratios are lower than 0.75. Low vane/container ratios allow the measurement of samples
with large particulates to be dispersed throughout. You can also apply low strains to our sample while
still operating at angular displacements well within the instrument range.
Ideally, the vane should be immersed in a sample of a depth twice that of the vane height. This is,
however, very often not practical but the user should at least ensure ample clearance between the lower
end of the vane and the base of the container, especially when measuring large-particle suspensions.
D.3.2 Container Dimensions
For yield point measurements, the container dimensions are largely irrelevant. For creep tests and strain,
or modulus measurements in constant rate tests, the container diameter does come into effect, especially
with higher diameter ratios, and must, therefore be, entered into the measuring system setup details in
the Meas-Editor utility program. For diameter ratios of less than 0.2 for vane diameter to container
diameter, minor changes in the container size, design or positioning can be more or less ignored for
most applications.
D.3.3 Setting Up Vanes In Measuring System Editor
Before you can use a vane, its details must be set up in Meas-Editor.
Open Meas-Editor
Click New
Enter the name of the vane (eg V80-40) and select Type
→ Vane.
Enter the factors K-Gamma and Tau_Prom that were supplied with the vane.
Enter the radius of the vane ( Radius i ) and the radius of the container ( Radius o ).
Click Save.
Repeat as necessary and close Meas-Editor.
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