Tag Archives: discharge coefficient

Partially Contracted V-Notch Weir Excel Spreadsheets

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Where to Find a Partially Contracted V-Notch Weir Excel Spreadsheet

To obtain a Partially Contracted V-notch weir Excel spreadsheet for , click here to visit our spreadsheet store. Why use online calculators or hand calculations when you can buy a partially contracted V-notch weir spreadsheet for only $11.95.  Read on for information about Excel spreadsheets that can be used as v-notch weir open channel flow calculators for partially contracted flow.

For background on fully contracted v notch weir calculations, see the article, “V-Notch Weir Calculator Excel Spreadsheet.”   That article gives general information about V notch weirs and equations and conditions required for fully contracted v notch weir calculations.

Partially Contracted V Notch Weir Calculations for a 90o Notch Angle

Partially contracted v-notch weir excel spreadsheet diagram

The equation shown below is recommended by the U.S. Dept. of the Interior, Bureau of Reclamation in their Water Measurement Manual (ref #1 below) for calculations with a partially contracted, 90o, v notch, sharp crested weir with free flow conditions and 0.4 ft < H < 2 ft (0.05 m < H < 0.38 m).

In U. S. units:  Q = 4.28H2.48, where Q is discharge in cfs and H is head over the weir in ft.

In S.I. units:  Q = 1.36H2.48, where Q is discharge in  m3/s and H is head over the weir in m.

The conditions for the v notch weir to be fully contracted are:

H/P < 1.2,    H/B < 0.4,    P > 0.33 ft (0.1 m),   B > 2 ft (0.6 m)

The diagram above shows the parameters H, P, θ and B for a v notch weir as used for open channel flow rate measurement in a partially contracted v-notch weir excel spreadsheet.

Screenshot of a Partially Contracted V Notch Weir Excel Spreadsheet

The screenshot below shows a partially contracted v notch weir excel spreadsheet for making 90o, partially contracted v-notch weir calculations in U.S. units.  Based on specified values for H, P, & B (and a value for Ce from a graph on the spreadsheet), the spreadsheet checks on whether the required conditions for partially contracted flow are met and then calculates the flow rate, Q.  This Excel spreadsheet and others for v notch weir calculations are available in either U.S. or S.I. units at a very low cost (only $11.95)  in our spreadsheet store.

partially contracted v-notch weir spreadsheet screenshot

References:

1. U.S. Dept. of the Interior, Bureau of Reclamation, 2001 revised, 1997 third edition, Water Measurement Manual, available for online use or download at: http://www.usbr.gov/pmts/hydraulics_lab/pubs/wmm/index.htm.

2. Bengtson, Harlan H., “Sharp Crested Weirs for Open Channel Flow Measurement,” an Amazon Kindle ebook

3. Bengtson, Harlan H., Open Channel Flow III – Sharp Crested Weirs, an online continuing education course for PDH credit, http://www.online-pdh.com/engcourses/course/view.php?id=87

4. Munson, B. R., Young, D. F., & Okiishi, T. H., Fundamentals of Fluid Mechanics, 4th Ed., New York: John Wiley and Sons, Inc, 2002.

ISO 5167 Venturi Meter Calculations with Spreadsheets

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Where to Find ISO 5167 Venturi Meter Spreadsheets

For Excel spreadsheets to make ISO 5167 venturi meter calculations, click here to visit our spreadsheet store.  Obtain convenient, easy to use spreadsheets for ISO 5167 venturi meter calculations at reasonable prices. Read on for information about the use of Excel spreadsheets for venturi meter calculations.

How a Venturi Meter Works

Diagram for ISO 5167 Venturi meter calculationsVenturi meters function by sending pipe flow through a constricted area (the venturi throat), as shown in the diagram at the right.  Due to the increased fluid velocity passing through the constriction, there will be a decreased pressure at that location.   The pipe flow rate can then be calculated from the measured pressure difference between the undisturbed pipe flow and the flow through the constriction.

equation for ISO 5167 venturi meter calculationsA general equation for calculating flow rate through a venturi meter is shown at the left.  The parameters in the equation and their units are as shown below:

 

  • Q is the flow rate through the pipe and through the meter  (cfs – U.S. or m3/s – S.I.)
  • C is the discharge coefficient, which is dimensionless
  • A2 is the constricted area perpendicular to flow (calculated from the venturi throat diameter)  (ft2 – U.S. or m2 – S.I.)
  • P1 is the undisturbed upstream pressure in the pipe  (lb/ft2 – U.S. or N/m2 – S.I.)
  • P2 is the pressure in the pipe at the constricted area, Ao (lb/ft2 – U.S. or N/m2 – S.I.)
  • β = d/D = (diam. at A2/pipe diam.), which is dimensionless
  • ρ is the fluid density (slugs/ft3 – U.S. or kg/m3 – S.I.)

ISO 5167 Venturi Meter Guidelines

ISO 5167-4: 2003 provides discharge coefficient values for three venturi meter variations, subject to the venturi meeting a set of specifications and guidelines given in the publication.  The three venturi meter variations are i) “as cast” convergent section, ii) “machined” convergent section, and iii) “rough welded sheet iron” convergent section.  For each of these three variations, ISO 5167-4:2003 specifies a range for pipe diameter, diameter ratio (d/D), and Reynolds number in the pipe.

A Spreadsheet Screenshot for ISO 5167 Venturi Meter Calculations

The image below shows part of an Excel spreadsheet that can be used for ISO 5167 venturi meter calculations, such as flow rate calculation, discharge coefficient, pressure difference, or venturi throat diameter.  For this spreadsheet and other low cost, easy to use spreadsheets for gas flow or liquid flow ISO 5167 venturi meter calculations in S.I. or U.S. units, click here to visit our spreadsheet store.

screenshot of spreadsheet for ISO 5167 venturi meter calculations

 

References

1. Munson, B. R., Young, D. F., & Okiishi, T. H., Fundamentals of Fluid Mechanics, 4th Ed., New York: John Wiley and Sons, Inc, 2002.

2. U.S. Dept. of the Interior, Bureau of Reclamation, 2001 revised, 1997 third edition, Water Measurement Manual, available for on-line use or download at: http://www.usbr.gov/pmts/hydraulics_lab/pubs/wmm/index.htm

3. International Organization of Standards -Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full. Part 4, Reference number: ISO 5167-4:2003

4. Bengtson, Harlan H., “Orifice or Venturi Pipe Flow Meters: for Liquid Flow or Gas Flow,” an Amazon Kindle ebook.

5. Bengtson, Harlan H., “Flow Measurement in Pipes and Ducts,” an online, self-study, continuing education course for Professional Engineers at www.CEDengineering.com.

6. Bengtson, Harlan H., “Orifice and Venturi Meters Pipe Flow Meters – for Liquid and Gas Flow,” an online, self-study, continuing education course for Professional Engineers at www.suncam.com.