V notch formula for discharge. V notch weirs are computed using this equation. Notch weir is typically installed in open channels to measure the dischargeflow rate. Cfs 2500 h ft.
Example discharge over a rectangular notch problem a rectangular notch 05m wide has constant head of 400 mm. For a triangular or v notch weir the flow rate can be expressed as. 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.
A right angled v notch was used to measure the discharge of a centrifugal pump. 25 gpm 1122 h ft. If the depth of water at v notch is 200mm calculate the discharge over the notch in liters per minute.
O v notch angle. Also you can make use of the related calculator designed based on the v notch weir discharge formula to verify your results. Ls 1380 h m.
Formulas h in feet. 25 mgd 1616 h ft. Assume coefficient of discharge as 062.
V notch weir is a type of flow gauge used in measuring water flow especially for v shaped or triangular shaped open channel. It is especially useful in measuring low flow rate and its denoted by symbol q. It is especially good for measuring a low flow rate because the area of flow through the v notch becomes quite small while the head over the v notch is still a measurable value.
Q discharge over weir cfs o angle of v notch degrees h head on apex of v notch ft adjustment for submerged weirs. It doesnt matter how thick the weir is except where water flows over the weir through the v the weir should be between 003 and 008 inches 08 to 2 mm thick in the v. Q 815 c d 2 g 12 tano2 h 52 2 where.
Find the discharge over the notch in liters per second if the coefficient of discharge for the notch is 062. Use our v notch weir calculator to perform. Quick ref table for v notch 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.
Formulas h in meters. The v notch weir is widely used to measure open channel flow rate. Head h should be measured at a distance of at least 4h upstream of the weir.
When a v notch weir is used to meter flow the weir equation q 249 h248 can be used to calculate q the flow rate over the weir and through the. The triangular or v notch thin plate weir is an accurate flow measuring device particularly suited for small flows. Usbr 1997 suggests using the v notch weir equations for the following conditions.