Brookfield Dial Stepper Viscometer Manual de usuario descargar pdf (Pagina 13)

  

 

In taking viscosity measurements with the Dial Viscometer, there are two considerations which

pertain to the low viscosity limit of effective measurement.

1) Viscosity measurements should be accepted 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.

The rst consideration has to do with the accuracy of the instrument. All Dial Viscometers have

a full scale range precision of ± 1% for any spindle/speed combination. 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.

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.

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 34 35

Sin comentarios

Brookfield Dial Stepper Viscometer Manual de usuario Pagina 13