BYK CAP 1000+ - Page 30

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Appendix C
VISCOMETER RELATED VARIABLES
• Mostuidviscositiesarefoundtobenon-Newtonian.Theyaredependent
onShearRateandthespindlegeometryconditions.Thespecicationsofthe
Viscometer cone and plate geometry will affect the viscosity readings. If one
reading is taken at 400 rpm, and a second at 1,000 rpm, the two viscosity values
produced may be different because the readings were made at different shear
rates. The faster the spindle speed, the higher the shear rate.
• Theshearrateofagivenmeasurementisdeterminedbytherotationalspeed
and the cone angle.
• Arepeatableviscositytestshouldcontrolorspecifythefollowing:
1. Viscometer model
2. Cone used
3. Test temperature
4. Test speed(s) [or the shear rate(s)]
5. Length of time to record viscosity
6.Samplevolumesufcienttocoverthefaceofthecone