Portable wastewater flow meter

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under fill pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

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Claims

1. In the process of metering the flow of liquid which is flowing by gravity in an elongated pipe that is open to atmosphere, wherein:

tubular venturi metering device is installed in the pipe, 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 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 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 head in 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 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 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 head 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 pressure heads 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,
the improvement wherein:
arranging the device in the pipe with its axis and the top of its throat horizontal thus leveling the device,
the bore having an axially outwardly tapered exit section adjacent the downstream end thereof which diverges from the axis of the bore in vertical planes paralleling the axis of the bore relatively toward the end of the bore that is normally downstream,
providing means whereby the static pressure head of the liquid in the throat of the device and in both the entrance section and the exit section can be determined, so that the difference between the static pressure heads in the entrance section and in the exit section can be used to determine the direction of flow and, hence, the actual upstream end of the device, and, during the less than full condition, an appropriate correction factor for metering the flow rate, and so that the difference between the throat pressure head and the actual upstream pressure head can be determined to meter the flow in the pipe for the full condition thereof.

2. The process in claim 1 wherein the cross-sectional area of the throat is configured relative to the entrance section of the bore and the exit section of the bore to cause simultaneous filling of the throat and the section of the bore that is actually upstream before the modular limit of the device is reached when the device is installed in a pipe of minimum slope.

3. In the combination wherein there are:

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 of 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 head 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 rises therein, and
there being second means for determining static pressure head of the liquid in the throat of the device and in 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 pressure heads 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,
the improvement comprising
means for leveling the device,
an axially outwardly tapered exit section adjacent the downstream end of the bore which diverges from the axis of the bore in vertical planes paralleling the axis of the bore relatively toward the end of the bore that is normally downstream,
means for determining the static pressure head of the liquid in the throat of the device and both in the entrance section and in the exit section whereby the difference between the static pressure heads in the entrance section and the exit section can be used to determine the direction of flow and, hence, the actual upstream end of the device, and during the less than full condition an appropriate correction factor for metering flow rate and whereby the difference between the throat pressure head and the actual upstream pressure head can be determined to meter the flow in the pipe for the full condition thereof.

5. The combination in claim 4 wherein means for determining the static pressure head of the liquid in the entrance section and in the exit section comprise tubes that discharge bubbles into the liquid in the annular space between the outside surface of the device and the inside surface of the pipe.

6. The combination in claim 4 wherein means for determining the static pressure head of the liquid in the entrance section and in the exit section comprise tubes that discharge bubbles into the liquid as it flows through the interior of the device..Iadd.

7. A process of metering the flow of liquid which is flowing in an elongated pipe that is open to the atmosphere, wherein a closed conduit venturi metering device is installed in the pipe, which device has an open-ended bore therethrough extending end-to-end thereof, the bore having an entrance section adjacent a first end thereof, an exit section adjacent the second end thereof, and intermediate the entrance and exit sections, a throat having a top and bottom and a smaller cross-sectional area than the entrance and exit sections, comprising the steps of:

arranging the device in the pipe to accept flow into the entrance from the pipe and otherwise to substantially block the pipe, and
configuring the cross-sectional area of the throat, relative to that of the entrance section, including constricting the throat across the bore at the throat top or bottom, or both so that the throat will fill with liquid substantially simultaneously with the entrance section, when liquid depth rises in the entrance section, and
providing means for determining the head of the liquid in said entrance section, in said throat and, in said exit section, for use at least to determine direction of flow in the device and flow both in less than full and in full flow through the device..Iaddend..Iadd.

8. The process of claim 7 in which the throat is also configured to impart critical flow depth to liquid flowing through the throat in less than full flow..Iaddend..Iadd.9. The process of claim 8 further comprising,

comparing the heads of liquid in said entrance and exit sections of the device flowing in less than full flow or in full flow, and
determining therefrom the direction of flow in said device..Iaddend..Iadd.10. The process of claim 9 further comprising,
determining from said head comparisons the percent submergence of the device when the liquid is flowing less than full, and
applying a correction factor to flow rate in less than full flow condition when the percent submergence exceeds the maximum submergence of the device..Iaddend..Iadd.11. The process of claim 8 further comprising,
comparing the heads of liquid in said entrance and exit sections of the device flowing in less than full flow,
determining therefrom the percent submergence of the device, and
applying a correction factor to flow rate in less than full condition when the percent submergence exceeds the maximum submergence of the device.

.Iaddend..Iadd.12. The process of claim 8 in which the cross-sectional area of the throat is configured, relative to that of the entrance section, to cause the throat and entrance sections to fill simultaneously below the modular limits of the device, when liquid depth rises in the entrance section..Iaddend..Iadd.13. The process in claim 12 wherein the device is arranged in a pipe which at least flows full at an average velocity of about 2 feet/second..Iaddend..Iadd.14. A process of metering the flow of liquid which is flowing by gravity in an elongated pipe that is open to the atmosphere, wherein a tubular venturi metering device is installed in the pipe, which device has an open-ended bore therethrough having an axis extending end-to-end thereof, the bore having an entrance section adjacent a first end thereof which converges toward the second 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 said second end, the bore having an exit section adjacent said second end which diverges from the bore toward said second end, comprising the steps of:

arranging the device in the pipe to accept flow into said entrance and otherwise to substantially block the pipe,
configuring the cross-sectional area of the throat, relative to that of the entrance section, so that the critical flow depth is imparted to liquid flowing through the throat in less than full flow and so that the throat will fill with liquid substantially simultaneously with the entrance section, when the liquid depth rises in the entrance section,
providing means for determining the head of the liquid in said entrance section, in said throat and in said exit section,
comparing the heads of liquid in said entrance and exit sections of the device flowing in less than full flow or in full flow, and
determining the direction of flow..Iaddend..Iadd.15. The process of claim 14 further comprising,
determining from said head comparisons the percent submergence of the device when the liquid is flowing less than full, and
applying a correction factor to flow rate in less than full flow condition when the percent submergence exceeds the maximum submergence of the

device..Iaddend..Iadd.16. The process of claim 14 in which the cross-sectional area of the throat is configured, relative to that of the entrance section, to cause the throat and entrance sections to fill simultaneously below the modular limit of the device, when liquid depth rises in the entrance section..Iaddend..Iadd.17. The process of claim 16 wherein the device is arranged in a pipe which at least flows full at an average velocity of about 2 feet/second..Iaddend..Iadd.18. The process of claim 14 wherein said step of configuring includes constricting said throat horizontally across said bore at the throat top or bottom, or both..Iaddend..Iadd.19. The process of claim 16 wherein said step of configuring includes constricting said throat horizontally across said

bore at the throat top or bottom, or both..Iaddend..Iadd.20. Apparatus for metering flow of liquid which is flowing in an elongated pipe which is open to the atmosphere, comprising:

a closed conduit venturi metering device installed in the pipe and having an open-ended bore therethrough extending end-to-end thereof, said bore having an entrance section adjacent a first end thereof, an exit section adjacent the second end thereof, and intermediate the entrance and exit sections, a throat having a top and bottom and a smaller cross-sectional area than the entrance and exit sections,
said device being arranged in said pipe to accept flow into said entrance from the pipe and otherwise to substantially block the pipe,
the cross-sectional area of the throat, relative to that of the entrance section, being configured, including a throat constriction across the bore at the throat top or bottom, or both, such that the throat will fill with liquid substantially simultaneously with the entrance section, when liquid depth rises in the entrance section, and
means for determining the head of the liquid in said entrance section, in said throat, and in said exit section, for use at least to determine direction of flow in the device and flow both in less than full and in

full flow through the device..Iaddend..Iadd.21. The apparatus of claim 20 in which said throat also is configured to impart critical flow depth to liquid flowing through the throat in less than full flow..Iaddend..Iadd.22. The apparatus of claim 21, further including means for comparing heads of liquid in said entrance and exit sections in less than full flow or in full flow, and for determining therefrom the direction of flow in said device..Iaddend..Iadd.23. The apparatus of claim 21, further comprising means for determining the percent submergence of the device in less than full flow, and for applying a correction factor to flow rate in less than full flow condition when the percent submergence exceeds the maximum submergence of the device..Iaddend..Iadd.24. The apparatus of claim 21 in which said cross-sectional area of the throat is configured relative to that of the entrance section to cause the throat and entrance sections to fill simultaneously below the modular limit of the device,

when liquid depth arises in the entrance section..Iaddend..Iadd.25. The process of claim 24 in which said device is arranged in a pipe which at least flows full at an average velocity of about 2 feet/second..Iaddend..Iadd.26. Apparatus for metering the flow of liquid which is flowing by gravity in an elongated pipe that is open to the atmosphere, comprising:

a tubular venturi metering device arranged in the pipe, which device has an open-ended bore therethrough having an axis end-to-end thereof, said bore having an entrance section adjacent a first end thereof which converges toward the second 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 said second end, such bore having an exit section adjacent said second end which diverges from the bore toward that second end,
said device being arranged in the pipe to accept flow into said entrance from the pipe and otherwise to substantially block the pipe,
the cross-sectional entrance of a throat being configured relative to that of the entrance section, so that a throat will fill with liquid substantially simultaneously with the entrance section below the modular limit of the device, when the liquid depth rises in the entrance section, and
means for determining the head of liquid in said entrance section and in said throat..Iaddend..Iadd.27. The apparatus of claim 26, further comprising means for comparing the heads of liquids in said entrance and exit sections of the device flowing in less than full flow or in full flow, and for determining the direction of flow..Iaddend..Iadd.28. The apparatus of claim 27 further comprising means for determining the percent submergence of the device from said head comparisons in less than full flow, and for applying a correction factor to flow rate in less than full flow conditions when the percent submergence exceeds the maximum

submergence of the device..Iaddend..Iadd.29. The apparatus of claim 28 wherein said device is arranged in a pipe which at least flows full at an average velocity of about 2 feet/second..Iaddend..Iadd.30. The apparatus of claim 26 wherein said configuration of said throat includes a constriction of said throat horizontally across said throat at the throat top or bottom, or both..Iaddend..Iadd.31. The apparatus of claim 28 wherein said configuration of said throat includes a constriction of said throat horizontally across said throat at the throat top or bottom, or both..Iaddend.

Referenced Cited
U.S. Patent Documents
2283906 May 1942 Bennett
2872810 February 1959 Shaffer
3427878 February 1969 Gerlitz et al.
3719081 March 1973 Lynn et al.
3774645 November 1973 Pompa
3859853 January 1975 Khuzaie
4083246 April 11, 1978 Marsh
4095466 June 20, 1978 Schontzler et al.
4279148 July 21, 1981 Fitzgerald
Foreign Patent Documents
1260808 February 1968 DEX
Other references
  • BIF Industries Technical Bulletin 110-P1, Aug. 1958, p. 17. Harry G. Wenzel, Jr.--"Meter for Sewer Flow Measurement" From Journal of the Hydraulics Division, Jan. 1975, pp. 115-133. Floyd A. Nagler--"New Flow Meter Uses Side Contractions Only". George F. Smoot--"A Rainfall--Runoff Quantity-Quality Data Collection System" From Proceedings of a Research Conference, Aug. 1974.
Patent History
Patent number: RE36069
Type: Grant
Filed: Jan 29, 1992
Date of Patent: Feb 2, 1999
Inventor: Robert M. Hunter (Bozeman, MT)
Primary Examiner: Richard Chilcot
Assistant Examiner: Elizabeth L. Dougherty
Application Number: 7/828,528
Classifications
Current U.S. Class: Weir Type (73/215); 73/86163
International Classification: G01N 120;