Abstract: An apparatus for measuring the flow rate and/or viscous characteristics of a fluid comprises a casing, having a fluid passage which is elongated in cross-section with two parallel, opposed sides and has a flared entry portion leading to a portion of constant cross-section. Formulae are given, using substantially pure water as a standard, from which a suitable geometry for the flared entry portion can be deduced. Fluid pressure detectors are provided for detecting a fluid pressure differential in the fluid passage such that the fluid characteristic to be measured may be deduced from the pressure differential when laminar flow is maintained in the passage. When laminar flow is maintained the apparatus is capable of measuring a wide range of flow rates and/or viscosities of an extensive variety of fluids in a consistent and deducible manner with minimal pressure loss.

Abstract: An apparatus for regulating the flow rate of a fluid, comprising a casing having an annular or cone-shaped fluid passage, for radial flow (inwardly or outwardly) between an inlet and outlet which are spaced radially and form unobstructed flow paths to the whole of the fluid passage. The geometry of the fluid passage is defined for a compressible and incompressible fluid so that laminar flow is achieved in the fluid passage. The apparatus further provides a very rapid dynamic response, essentially free of hysteresis, and substantially no internal generation of fluid flow turbulence resulting in a minimum of noise and freedom from cavitation. In an adjustable configuration the apparatus provides a proportional fluid valving function. In a nonadjustable configuration the apparatus provides a laminar flow restriction.

Abstract: An apparatus for measuring the flow rate and/or viscous characteristics of a fluid comprising a casing having a fluid passage, a fluid inlet cavity and a fluid outlet cavity, fluid pressure detecting means preferably at spaced positions along the passage, and fluid pressure indicating means for indicating the or each characteristic to be measured in terms of the fluid pressure differential between the detecting means positions. The fluid inlet cavity provides a substantially unobstructed flow path to the fluid passage and the fluid outlet cavity provides a substantially unobstructed flow path therefrom. The fluid passage cross-sectional area decreases in the fluid flow direction in order to maintain laminar flow of the fluid therealong and wall boundary induced viscous shear therealong, over an extended range of Reynolds number within the fluid passage and formulae are given, using substantially pure water as a standard fluid, from which the limits of fluid passage geometry can be defined.