Brookfield Engineering Labs., Inc.
Page 48
Manual No. M13-167-A0415
IV.3 Selecting a Spindle/Speed
The DV3T has the capability of measuring yield stress over an extremely wide range. For example,
the DV3TRV can measure fluids within the range of 0.5-400 Pa. This range is achieved through
the use of several vane spindles over many speeds. See Appendix B for details.
The process of selecting a spindle and speed for an unknown fluid is normally trial and error.
An
appropriate selection will result in measurements made between 10-100 on the instrument %
torque scale.
There are two general rules will help in the trial and error process:
1) Viscosity range is inversely proportional to the size of the spindle.
2) Viscosity range is inversely proportional to the rotational speed.
In other words: to measure high yield, choose a small spindle and/or a slow speed. If the chosen
spindle/speed results in a reading above 100%, then reduce the speed or choose a smaller spindle.
Experimentation may reveal that several spindle/speed combinations will produce satisfactory
results between 10-100%. When this circumstance occurs, any of the spindles may be selected.
When yield data must be compared, be sure to use the same test methodology: namely the
same instrument, spindle, speed, container, temperature and test time.
Vane spindles are optional equipment and are not part of the standard DV3T package. DV3TLV
Rheometers are provided with a set of four spindles and a narrow guardleg; DV3TRV Rheometers
come with a set of six spindles and a wider guardleg; DV3THA and DV3THB Rheometers come
with a set of six spindles and
no guardleg
. (See Appendix G for more information on the guardleg.)
Do not use the guard leg with vane spindles.
The spindles are attached to the rheometer by screwing them onto the coupling nut on the lower
shaft (see Figure IV-1). Note that the spindles have a left-hand thread. The lower shaft should
be secured and slightly lifted with one hand while screwing the spindle to the left. The face of
the spindle nut and the matching surface on the lower shaft should be smooth and clean to prevent
eccentric rotation of the spindle. Spindles can be identified by the number on the side of the spindle
coupling nut.
If your instrument has the EZ-Lock
system, the spindles are attached as
follows:
With one hand hold the spindle, while
gently raising the spring-loaded outer
sleeve to its highest position with
the other hand, as shown in Figure
IV-2. Insert the EZ-Lock Spindle
Coupling so that the bottom of the
coupling is flush with the bottom of
the shaft, and lower the sleeve. The
sleeve should easily slide back down
to hold the spindle/coupling assembly
The motor should
be OFF whenever
spindles are being
removed or attached.
Figure IV-1
Figure IV-2
