Abstract: A transducer for inline process control of highly viscous fluids at high pressure and high temperature having a torsionally oscillating sensor tip supported by a pressure resistant threaded body portion. The sensor tip, which includes a thermocouple to measure fluid temperature, is driven by a crossarm which oscillates with a constant angular amplitude, the power required to maintain that amplitude despite the viscous resistance offered by the fluid being a measure of the viscosity-density product of the fluid. The crossarm driver and detector electromagnetic coils are oriented at right angles to each other to reduce crosstalk and transducer housing diameter. The associated electronic control unit includes means to compensate for the effects of fluid flow rate and fluid pressure which were found to be encountered with the vibratory viscometer method of measurement when inline measurements are made on high viscosity fluids.

Abstract: A viscosity measuring transducer especially useful for process control of fluids. The transducer oscillates an immersed blade sensor in the direction of the plane of the blade in order to maximize generation of shear waves and to minimize generation of compression waves. The transducer includes a bar which penetrates and is secured and peripheral sealed to an isolation plate which serves to protect the oscillation driver and pickup adjacent one end of the bar from the sensor blade to be immersed in a fluid adjacent the other end of the bar. Either the bar is relatively rigid and the isolation plate is relatively compliant, or vice versa. In the former case the isolation plate acts as an intrinsic flexible member of the oscillating system of the transducer; and in both cases the isolation plate constitutes a strong impermeable seal between the fluid and the driver/pickup mechanism.