Brookfield CP-52 - Page 13

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Brookeld Engineering Laboratories, Inc. Page 13 Manual No. M00-151-I0614
The second consideration involves the mechanics of uid ow. All rheological measurements of
uid ow properties should be made under laminar ow conditions. Laminar ow is ow wherein
all particle movement is in layers directed by the shearing force. For rotational systems, this means
all uid movement must be circumferential. When the inertial forces on the uid become too great,
the uid can break into turbulent ow wherein the movement of uid particles becomes random
and the ow can not be analyzed with standard math models. This turbulence creates a falsely high
viscometer reading with the degree of non-linear increase in reading being directly related to the
degree of turbulence in the uid.
For the following geometries, we have found that an approximate transition point to turbulent ow
occurs as follows:
1) No. 61 LV Spindle: 15 cP at 60 RPM
2) No. LV-2 Spindle: 100 cP at 200 RPM
3) No. 1 RV Spindle: 100 cP at 50 RPM
4) UL Adapter: 0.85 cP at 60 RPM
5) SC4-18/13R: 1.25 cP at around 240 RPM
Turbulent conditions will exist in these situations whenever the RPM/cP ratio exceeds the values
listed above.