Abstract: A flow measuring device for measuring the flow rate of a fluid in a partially filled conduit comprises sequentially disposed inlet transition and converging sections and means for determining the level of the fluid in the converging section. The inlet section has a substantially circular cross-sectional configuration, and the converging section has a substantially rectangular cross-sectional configuration, although it has a gradually reducing width in its longitudinal extent to the downstream end thereof. The transition section has an interior configuration which provides a substantially smooth transition between the circular inlet section and the rectangular converging section to avoid introducing turbulence and irregular flow patterns into a fluid passing through the device. A second embodiment of the device includes removable inserts which further reduce the width of the converging section adjacent the downstream end thereof to adapt the device to operate under reduced flow conditions.

Abstract: A flow measuring device comprises a flow tube having sequentially disposed inlet, converging and throat sections and first and second pressure sensing assemblies for sensing the pressures in the inlet and throat sections, respectively. Each of the pressure sensing assemblies includes a tubular housing portion which extends outwardly from the flow tube and communicates with the interior of the adjacent section thereof, a cylindrical diaphragm-type pressure sensing element which is slidably received in the housing portion, and a gate valve having a gate which is receivable in the housing portion thereof when the sensing element therein is in an outwardly disposed position in the housing portion. Each of the housing portions has a manometer tap formed therein which is disposed outwardly at the gate valve therein.

Abstract: A flow metering device of the type operative for producing a pressure differential comprises a shaped tubular member having sequentially disposed inlet, converging, and throat sections, and a downstream diverging section for energy recovery. Inner annular recesses, preferably having substantially sharp leading edges, are provided in the interior of the device in or adjacent the inlet and throat sections, and pressure taps for sensing the fluid pressures in the inlet and throat sections communicate with the interior of the device through the recesses. The taps are preferably positioned adjacent the leading edges of the respective recesses so that they are shielded from the direct flow of fluid in the device to provide true static pressure readings which are unaffected by the configurations of the inner ends of the taps. Accordingly, highly accurate operations can be effected with the device using bench calibrated discharge coefficients.

Abstract: A venturi-type fluid flow metering device is operative with minimum fluid energy losses and is adapted for construction in reduced lengths. The device comprises inlet, converging, throat and downstream diverging sections, and pressure sensing taps are provided which communicate with the inlet and throat sections for sensing static fluid pressures therein. The converging section comprises an inlet cone portion which extends angularly inwardly in a downstream direction relative to the inlet section and a throat cone portion which extends angularly inwardly in a downstream direction from the inlet cone portion to the throat section, the throat cone portion being at a reduced angle with respect to the inlet section compared to the inlet cone portion. The intersections between the inlet cone portion and the throat cone portion and between the throat cone portion and the throat section are of rounded configurations to prevent the formation of vena contractas in the device so that energy losses are minimized.