Brookfield DV-III Ultra Rheometer - Manual (Page 110)

Brookfield Engineering Laboratories, Inc. Page 110 Manual No. M98-211-E0912
Two constants are required:
a) SMC (Spindle Multiplier Constant) which is used to calculate cP value.
b) SRC (Shear Rate Constant) which is used to calculate Shear Rate and Shear Stress.
If SRC=0 (Example, LV #1-4, RV,HA,HB #1-7 spindles), Shear Rate and Shear Stress values are
not calculated and can not be displayed.
The SMC value for a spindle may be calculated as follows:
a) For new spindle conditions you calculate the SMC using a Newtonian fluid of known
viscosity (Brookfield Viscosity Standard). This is done in the container with the new
dimensions at the controlled temperature specified for the viscosity standard fluid.
b) The new full scale viscosity range is calculated for a selected RPM:
R1 = 100 n
Y
Where:
R1 = The new full scale viscosity range
n = The viscosity (in cP) of the Newtonian fluid
Y = The Torque % reading at the selected RPM
c) The SMC Value is then calculated:
SMC =
[Full Scale Viscosity Range (cP)] * [Selected RPM]
TK * 10,000
Where:
TK
= DV-III Ultra Torque Constant from Table D-2
The SRC value may be calculated for cylindrical spindle geometry using the following equation:
Shear Rate (1/sec) = ________________
c
2 2w R
b R 2
2 2 ] c χ [R
_
2
b
R
Where:
R
c
= Radius of the container (in centimeters)
R
b
= Radius of the spindle (in centimeters)
χ = Radius at which the shear rate is to be calculated (normally the same value as
R
b
; in centimeters)
w
= Angular velocity of the spindle (Rad/Sec)
w = *N
N = Spindle speed in RPM
SMC and SRC values are entered in RHEOCALC software. See the HELP file for details.
2≠ _____
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