Brookfield DV-II+ Programmable Viscometer - Manual (Page 62)

Brookfield Engineering Labs., Inc. Page 62 Manual No. M/97-164-F1102
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 follow-
ing RS-232 parameters to output these strings:
Baud Rate 9600
Data Bits 8
Stop Bits 1
Parity None
Handshake 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 = Current Viscometer spindle speed in RPM
TK = Viscometer torque constant from Appendix D, Table D2.
SMC = Current spindle multiplier constant from Appendix D, Table D1.
SRC = Current spindle shear rate constant from Appendix D, Table D1.
Torque = 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 cur-
rently 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 = 30 from the example statement.
TK = 0.09373 from Appendix D for an LV Viscometer.
SMC = 32.0 from Appendix D for a type SC4-31 spindle.
SRC = 0.34 from Appendix D for a type SC4-31 spindle.
Torque = 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