Brookfield DV2+Pro Viscometer - Manual (Page 89)

Brookfield Engineering Labs., Inc. Page 89 Manual No. M03-165-F0612
Appendix H - Communications
When using the Brookfield Computer Cable (Brookfield part # DVP-80), the DV-II+Pro 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+Pro uses the following 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+Pro.
Viscosity (cP) = 100 * TK * SMC * Torque
RPM
Shear Rate ( 1 /
Sec
) = RPM * SRC
Shear Stress ( Dynes /
Cm
2 ) = TK * SMC * SRC * Torque
Where:
RPM = Current Viscometer spindle speed in RPM
TK = Viscometer torque constant from Appendix D, Table D-2.
SMC = Current spindle multiplier constant from Appendix D, Table D-1.
SRC = Current spindle shear rate constant from Appendix D, Table D-1.
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
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 D-1 and D-2:
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
Shear Stress ( Dynes /
Cm
2 ) = TK * SMC * SRC * Torque
= 0.09373 * 32.0 * 0.34 * 62.3
= 63.5 Dynes /
Cm
2