Apparatus and technique for metering liquid flow
First Claim
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1. A method of metering the flow of liquid which is flowing by gravity in an elongated pipe that is open to atmosphere, comprising:
- installing in the pipe a tubular venturi metering device which has an open-ended bore therethrough having an axis extending end-to-end thereof,arranging the device in the pipe so that the axis of the bore is disposed substantially parallel to the longitudinal axis of the pipe and the bore thus has an end which is normally oriented upstream of the liquid flow in the pipe and an end which is normally oriented downstream of the liquid flow of the pipe,the bore having an axially inwardly tapered entrance section adjacent the upstream end thereof which converges toward the axis of the bore in vertical planes paralleling the axis of the bore relatively toward the downstream end of the bore but terminates short of the axis of the bore so that a throat is formed in the bore which opens to the downstream end thereof,forming a liquid seal between the device and the pipe at the outer periphery of the device so that the liquid in that section of the pipe disposed upstream from the upstream end of the bore of the device, is constrained to flow through the bore of the device, relatively toward the downstream end thereof,determining the static pressure of the liquid in the aforesaid upstream section of the pipe when the liquid is flowing in the pipe at a depth less than that adapted to fill the upstream section of the pipe, to meter the flow in the pipe for the less-than-full condition thereof,configuring the cross-sectional area of the throat, relative to that of the upstream section of the pipe, transverse the respective axes thereof, so that the throat will fill with liquid substantially simultaneously with the upstream section of the pipe, when the liquid depth rises therein, andproviding means whereby the static pressure of the liquid in the throat of the device and the upstream section of the pipe can be determined when both the upstream section of the pipe and the throat are filled, so that the difference between the latter two pressures can be determined to meter the flow in the pipe for the full condition thereof, and thereby enable the flow in the pipe to be metered for the full condition thereof as well as the less-than-full condition thereof and the transition therebetween.
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Abstract
The gravity flow of a liquid in an open pipe is metered during open channel flow, during surcharged flow, and during the transition between the two. A tubular venturi metering device is employed, and when during open channel flow, the liquid depth rises in the section of the pipe upstream from the device, the throat of the device fills with liquid substantially simultaneously with the upstream section of the pipe, so that during the transition, the device continues to provide a flow determination.
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Citations
23 Claims
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1. A method of metering the flow of liquid which is flowing by gravity in an elongated pipe that is open to atmosphere, comprising:
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installing in the pipe a tubular venturi metering device which has an open-ended bore therethrough having an axis extending end-to-end thereof, arranging the device in the pipe so that the axis of the bore is disposed substantially parallel to the longitudinal axis of the pipe and the bore thus has an end which is normally oriented upstream of the liquid flow in the pipe and an end which is normally oriented downstream of the liquid flow of the pipe, the bore having an axially inwardly tapered entrance section adjacent the upstream end thereof which converges toward the axis of the bore in vertical planes paralleling the axis of the bore relatively toward the downstream end of the bore but terminates short of the axis of the bore so that a throat is formed in the bore which opens to the downstream end thereof, forming a liquid seal between the device and the pipe at the outer periphery of the device so that the liquid in that section of the pipe disposed upstream from the upstream end of the bore of the device, is constrained to flow through the bore of the device, relatively toward the downstream end thereof, determining the static pressure of the liquid in the aforesaid upstream section of the pipe when the liquid is flowing in the pipe at a depth less than that adapted to fill the upstream section of the pipe, to meter the flow in the pipe for the less-than-full condition thereof, configuring the cross-sectional area of the throat, relative to that of the upstream section of the pipe, transverse the respective axes thereof, so that the throat will fill with liquid substantially simultaneously with the upstream section of the pipe, when the liquid depth rises therein, and providing means whereby the static pressure of the liquid in the throat of the device and the upstream section of the pipe can be determined when both the upstream section of the pipe and the throat are filled, so that the difference between the latter two pressures can be determined to meter the flow in the pipe for the full condition thereof, and thereby enable the flow in the pipe to be metered for the full condition thereof as well as the less-than-full condition thereof and the transition therebetween. - View Dependent Claims (2, 3)
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4. In combination,
an elongated pipe which is open to atmosphere and adapted for the flow of liquid by gravity therein, a tubular venturi metering device installed in the pipe and having an open-ended bore therethrough which has an axis extending end-to-end thereof, the device being arranged in the pipe so that the axis of the bore is disposed substantially parallel to the longitudinal axis of the pipe and the bore thus has an end which is normally oriented upstream of the liquid flow in the pipe and an end which is normally oriented downstream of the liquid flow in the pipe, the bore having an axially inwardly tapered entrance section adjacent the upstream end thereof, which converges toward the axis of the bore in vertical planes paralleling the axis of the bore and in that axial direction of the bore relatively toward the downstream end of the bore, but terminates short of the axis of the bore so that a throat is formed in the bore which opens to the downstream end thereof, means for forming a liquid seal between the device and the pipe at the outer periphery of the device so that the liquid in that section of the pipe disposed upstream from the upstream end of the bore of the device, is constrained to flow through the bore of the device, relatively toward the downstream end thereof, and first means for determining the static pressure of the liquid in the aforesaid upstream section of the pipe when the liquid is flowing in the pipe at a depth less than that adapted to fill the upstream section of the pipe, to meter the flow in the pipe for the less-than-full condition thereof, the cross-sectional area of the throat being configured relative to that of the upstream section of the pipe, transverse the respective axes thereof, so that the throat will fill with liquid substantially simultaneously with the upstream section of the pipe, when the liquid depth rises therein, and there being second means for determining the static pressure of the liquid in the throat of the device and the upstream section of the pipe when both the upstream section of the pipe and the throat are filled, so that the difference between the latter two pressures can be determined to meter the flow in the pipe for the full condition thereof, and thereby enable the flow in the pipe to be metered for the full condition thereof, as well as the less-than-full condition thereof and the transition therebetween.
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20. Apparatus for metering the flow of liquid which is flowing by gravity in an elongated pipe that is open to atmosphere, both for the condition wherein the pipe is less than filled with the liquid, and the condition wherein the pipe is filled with the liquid, comprising, in combination,
a cylindrical member having end portions disposed at substantially the same elevation and an inner surface forming a tubular venturi-type device which in turn has an entrance section and a throat section, means circumposed about the cylindrical member and operable to form a fluid tight connection between the member and the internal wall of the pipe when the member is substantially coaxially inserted therein, whereby the liquid in that section of the pipe upstream from the member is constrained to flow through the entrance and throat sections of the venturi-type device, means for sensing the pressure of the liquid at the crest of the throat section of said tubular venturi-type device, and means for sensing the pressure of the liquid at the invert of the entrance section of said tubular venturi-type device.
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22. A device for metering fluid flow comprising a cylindrical member having open ends, at least a portion of the outer surface of said cylindrical member configured substantially to fit inside the contour of an entrance pipe to a sewer manhole, a single tubular venturi-type member having an entrance section a throat section and an exit section mounted in said cylindrical member in such a manner that all of the liquid that flows through the open ends of said cylindrical member must pass through said tubular venturi-type member, means for securing said cylindrical member in said entrance pipe attached to said cylindrical member whereby a seal is established between the inside contour of said entrance pipe and an annular portion of the outer surface of said cylindrical member, means attached to the invert of the entrance section of said tubular venturi-type member to sense the pressure of the liquid therein, means attached to the crest of said throat section to sense the pressure of the liquid therein, conductor means attached to each of said pressure sensor means to conduct pressure signals therefrom, and means attached to said conductor means to convert said pressure signals into flow rates and store in said flow rate data.
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23. A device for metering liquid flow in a substantially cylindrical entrance pipe to a sewer manhole, said entrance pipe flowing either partially filled or filled with liquid, said device comprising, in combination, a cylindrical member, the inner surface of which forms a tubular venturi-type member having an entrance section and a throat section therein, the outer surface of which member is dimensioned substantially to fit the inside contour of said substantially cylindrical entrance pipe, means for securing said cylindrical member in said entrance pipe and for forming a closed connection between the outer surface of said cylindrical member and the inner surface of said substantially cylindrical entrance pipe, means attached to the invert of the entrance section of said tubular venturi-type member to sense the pressure of the liquid therein, means attached to the crest of the throat section of said venturi-type member to sense the pressure of the liquid therein, conductor means attached to each of said pressure sensor means to conduct pressure signals therefrom, and means attached to said conductor means to convert said pressure signals into flow rates and store said flow rate data.
Specification