Download BROOKFIELD DV-II+ PROGRAMMABLE VISCOMETER Operating

Appendix G - Communications
When using the Brookfield Computer Cable (Brookfield part # DVP-80), the DV-II+ will output a
data string at a rate of approximately 3 times per second. When using the Brookfield Printer Cable
(Brookfield Part No. DVP-81), the output rate is 1.0 times per second. The DV-II+ uses the following RS-232 parameters to output these strings:
Baud Rate
Data Bits
Stop Bits
Parity
Handshake
9600
8
1
None
None
The following formulas should be used to calculate and display the Viscometer data after each
packet of data is obtained from the DV-II+.
Viscosity (cP)
= 100 * TK * SMC * Torque
RPM
Shear Rate (1/Sec)
= RPM * SRC
Shear Stress (Dynes/Cm2)
= TK * SMC * SRC * Torque
Where:
RPM
TK
SMC
SRC
Torque
=
=
=
=
=
Current Viscometer spindle speed in RPM
Viscometer torque constant from Appendix D, Table D2.
Current spindle multiplier constant from Appendix D, Table D1.
Current spindle shear rate constant from Appendix D, Table D1.
Current Viscometer torque (%) expressed as a number between 0 and 100.
As an example, consider an LV Viscometer using an SC4-31 spindle, running at 30 RPM and currently displaying a Torque of 62.3 (%). First we list all of the given data and include model and
spindle constants from Appendix D, Tables D1 and D2:
RPM
TK
SMC
SRC
Torque
=
=
=
=
=
30 from the example statement.
0.09373 from Appendix D for an LV Viscometer.
32.0 from Appendix D for a type SC4-31 spindle.
0.34 from Appendix D for a type SC4-31 spindle.
62.3 from the example statement.
Applying this data to the above equations yields:
Viscosity (cP)
= 100 * TK * SMC * Torque
RPM
= 100 * 0.09373 * 32.0 * 62.3
30
= 622.9 cP
Shear Rate (1/Sec)
= RPM * SRC
= 30 * 0.34
= 10.2 1/Sec
Brookfield Engineering Labs., Inc.
Page 60
Manual No. M/97-164-D1000