Brookfield DV1 User Manual

Brookeld Engineering Laboratories, Inc. Page 39 Manual No. M14-023
When taking viscosity measurements with the DV1 Viscometer, there are two considerations, which
pertain to the low viscosity limit of eective measurement.
1. Viscosity measurements should be taken within the equivalent % Torque Range from 10%
to 100% for any combination of spindle/speed rotation.
2. Viscosity measurements should be taken under laminar ow conditions, not under turbulent
ow conditions.
e rst consideration has to do with the accuracy of the instrument. All DV1 Viscometers have
a Full Scale Range allowable error of (+/-) 1% of any spindle/speed in use. We discourage taking
readings below 10% of range because the potential viscosity error of (+/-) 1% is a relatively high
number compared to the instrument reading.
e 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 cannot be analyzed with standard math models. is 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 to the onset of turbulent
ow occurs in the following situation:
1) No. 1 LV Spindle: 15 cP at 60 RPM
2) No 2 LV Spindle: 100 cP at 200 RPM
3) No. 1 RV Spindle: 100 cP at 50 RPM (optional spindle available from Brookeld)
4) UL Adapter: 0.85 cP at 60 RPM
Turbulent conditions may exist in these situations whenever the RPM/cP ratio exceeds the values
listed above. e viscosity at which turbulence starts is still at best a guess because it is a relationship
between viscous and inertial forces, and it can vary dramatically from uid to uid. Turbulence
starts as a small deviation or increase in viscosity for a Newtonian uid and grows quickly. Basically,
there is no specic shear that it starts at, only an approximate region of shear depending on the uid.

Brookfield DV1 Specifications

General

Speed Range	0.3 to 100 rpm
Display	LCD
Number of Speeds	18
Power Supply	100-240 VAC, 50/60 Hz
Viscosity Range	1 to 2, 000, 000 cP
Temperature Measurement	Optional
Accuracy	±1% of full scale range
Repeatability	+/- 0.2%