VNotch Weir Design Considerations. Minimum of 2. 4 inches or 0. 2 feet of head (water level above the crest). Maximum of 24 inches or 2. 0 feet of head (higher is0. 30 3. 60 0. 0914 0. 1232 55. 31 0. 0796 3. 490 12. 56 Sources: Skrenter, R. , Instrumentation Handbook Water and Wastewater Treatment Plants ASTM D (2001): Standard Test Method for Open Channel Flow Measurement of Water with ThinPlate Weirs Nappe may cling to downstream weir face 90 VNotch Weir Discharge Table 25 Accuracy 30 degree v notch weir table
Discharge Tables. The discharge tables here are for thinplate weirs in general. . Before relying on the full flow rates indicated on the tables below, compare the depths indicated in the tables
Weirs are structures consisting of an obstruction such as a dam or bulkhead placed across the open channel with a specially shaped opening or notch. The flow rate over a weir is a function of the head on the weir. Common weir constructions are the rectangular weir, the triangular or vnotch weir, and the broadcrested weir. For a V notch weir with a notch angle other than 90 degrees, the equation for calculation of the flow rate over the weir is given by the equation: Q 4. 28 Ce Tan(2)(H k) 52, where the effective discharge coefficient, Ce, and the head correction factor, k, are both functions of the notch angle, . The equations for Ce and k in terms of are: 30 degree v notch weir table A V Notch Weir Calculator Excel Spreadsheet for a 90 Degree Notch Angle 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 fully contracted, 90 o, v notch, sharp crested weir with free flow conditions and 0. 2 ft H 1. 25 ft.
Vnotch weirs Weir Angle GPM MGD CFS ls m3hr 22. 5 Degree 223 H2. 5 0. 321 H2. 5 0. 497 H2. 5 274 H2. 5 988 H2. 5 30 Degree 303 H2. 5 0. 437 H2. 5 0. 676 H2. 5 373 H2. 5 1304 H2. 5 Thin Plate FreeFlow Discharge Table Distributed B y: Aqua Technology Group 2 4 7 Sales and Support 30 degree v notch weir table 90 Triangular Notch Weirs. This calculator finds the flow rate of a 90 triangular notch weir. The opening to this weir is a 90 degree triangular notch. The bottom of the notch is the lowest point with the sides going up at 45 degree angles. Quick Ref Table for VNotch Weir, 0 to 64 ls 28oV Height Above Cease to Flow Point in mm Discharge in ls (Litres per Second) If the water level when measured is, say 65mm above the cease to flow level. Go to the left column, then come down the left column till you reach 60, then across to the right to the 5 column, your now at 60 5 65. Table A74. Discharge of 90 Vnotch weirs, in ft3sec, computed from the formula Q2. 49h 1 2. 48. Head Discharge Head Discharge Head Discharge Head Discharge H, ft Q, ftsec H, ft Q, ftsec H, ft Q, ftsec H, ft Q, ftsec 0. 20 0. 046 0. 65 0. 856 1. 10 3. 15 1. 55 7. 38 11. Fully Contracted Standard 90Degree VNotch Weir. The triangular or Vnotch, thinplate weir is an accurate flow measuring device particularly suited for small flows. (a) Traditional Equation for Standard 90Degree Contracted VNotch Weirs. The Cone equation is commonly used for 90degree Vnotch weirs.Rating: 4.66 / Views: 306