E0608
Brookeld 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.
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