Brookfield Spiral Adapter - Manual (Page 10)

Brookfield Engineering Labs., Inc. Page 10 Manual No. M93-270-D0812
V. OPERATION
V.1 Theory
The Spiral Adapter has an inner, threaded spindle surrounded by a concentric outer cylinder, as
shown previously in Figure 1. This combination causes the sample to be continuously pumped
up through the gap between the rotating spindle and the outer cylinder. The material reaches a
steady state of flow during which viscosity is measured.
At its various rotating speeds, the Brookfield Viscometer/Rheometer with the Spiral Adapter
provides viscosity data at different shear rates. The resulting rheogram from an up/down speed
ramp supplies important information on the pseudoplastic and thixotropic behavior of the test
material which may correlate with actual use in a process. In addition, the measurement method
may be less sensitive to sample handling and minor material variations than other viscosity
measuring methods.
V.2 Test Procedure
Ensure that the test material has been prepared properly in accordance with your prescribed
procedure. Lower the Spiral Adapter into the test fluid as shown in Figure 1.
Start the Viscometer/Rheometer and allow it to run at high speed for quick flooding of the
chamber. This speed will vary with the nature of the test fluid, but will typically be between 20
and 60 RPM for 2 to 10 minutes. The speed and time of the flood cycle may be an important
part of the test procedure. This is because the fluid in the chamber will experience a shear
history before the start of the test.
When the chamber is flooded, you will observe test fluid covering the top of the spindle. Stop
the Viscometer/Rheometer and allow a settling period per your defined procedure. Run the
viscosity test and record the data. An example of a test procedure is as follows:
Speed
Duration
50 RPM 6 min.
0 RPM 2 min.
5 RPM 1 min.
10 RPM 1 min.
15 RPM 1 min.
20 RPM 1 min.
30 RPM 1 min.
A strip chart recorder can be used with digital Brookfield Viscometers/Rheometers during the
above procedure. An example of data output is shown in Figure 3.