Abstract: A fluidic oil viscometer for determining the degradation of machinery lubating oils compares the viscosity of the machinery oil with the viscosity of another fluid, such as air. Both the viscosity of the air and the viscosity of the oil are sensed, using capillary-orifice combination sensors, and the air viscosity reading is amplified using a series of laminar proportional amplifiers to equalize its change in viscosity with that of oil. The outputs of the capillary orifice combination sensors are applied to two different pressure gauges, the difference between these two pressure gauges represents the viscosity breakdown. This difference will be independent of temperature.

Abstract: A device for measuring the fugacity of a material, without requiring a separate device to measure temperature, is disclosed, wherein the device is a solid electrolyte probe, with the probe having a passageway therein, and metallic conductor leads on the outside of the probe and on the inside of the probe in the passageway. The metallic conductor leads are in contact with an E.M.F. measuring circuit, with the reference fluid being passed through the passageway. The passageway also includes a capillary restriction therein, and measuring devices are provided to measure the pressure drop of the reference fluid when flowing through the capillary, thereby permitting determination of temperature. The temperature determination combined with the E.M.F. measurement permit determination of the fugacity of the material.

Abstract: The temperature sensors shown utilize a constant frequency fluidic oscillr to excite resonance tubes, whose frequency response is a function of temperature. The outputs of these sensors control a fluidic amplifier, whose output is rectified and filtered to produce a D.C. fluid signal which is a function of the sensed temperature. Different embodiments utilize resonance tubes excited in phase or 180.degree. out of phase to sense the difference between two temperatures or to provide increased sensitivity.