RheoVADR
®
Rheometer Instruction Manual
D00845847
Revision E, September 2014
40
Appendix B Viscosity Calculations
To calculate Newtonian viscosities in centipoise, use the following equation:
ƞ
N
= S x
θ
x f x C
where,
S is the speed factor, = 300
/
Test Speed
θ
is the dial reading
f is the spring factor (Refer to Table B-2)
C is the rotor-bob factor (Refer to Table B-1 Rotor-Bob Factor (C))
ƞ
N
is the Newtonian viscosity (cP)
Example: Using an R2-B1 combination at a speed of 600 rpm with an F5.0 spring,
and a dial deflects to 189, the viscosity is
ƞ
N
= 0.5 x 189 x 5 x 0.315 = 149 cP
Table B-1 Rotor-Bob Factor (C)
Rotor-Bob
Combination
R-B Factor
(C)
R1-B1
1.000
R1-B2
8.915
R1-B3
25.392
R1-B4
50.787
R1-B5
2.334
R2-B1
0.315
R2-B2
8.229
R2-B3
24.707
R2-B4
49.412
R2-B5
1.649
R3-B1
4.517
R3-B2
12.431
R3-B3
28.909
R3-B4
57.815
R3-B5
5.849