Patent ID: 6257051
Filing Date: 2001-07-10
Classification: G01N

Abstract:
A viscometer for measuring or characterizing the stress required to shear a fluid at a given rate comprising a pair of members coaxially mounted for relative rotation wherein one of said members comprises a cup and the other of said members comprises a bob coaxially mounted within said cup with a separation between an inner end of said bob and a closed end of said cup that is between one half to five times the annular gap between said members, said bob having a longitudinal passage there through, whereby differential rotation of said bob and said cup causes fluid from a volume outside said bob to flow through said bob, through said separation between said bob and said cup and through said annular gap to a volume outside said cup, an annular gap between said members defining a flow path for the fluid, a driver for producing such differential rotation, means within said flow path for causing fluid to flow through said gap during such differential rotation that is a function of the differential rate of rotation between said members the viscosity of the fluid, and a sensor for measuring the torque or torque equivalent required to achieve such differential rotation between said members, and a pumping action of fluid through the viscometer.