Weir & Orifice Flow Comparison
Orifice flow equation
(Orifice Flow Equation)
Instructions:
  • Either Select catalog number (will automatically fill in Open Area and Perimeter) or enter your own values
  • Enter head value
  • Press CALCULATE

    The results will determine automatically if your situation falls into a Weir, Transitional or Orifice flow. Additionally, a pop-up window will offer Neenah grates which fall within the parameters chosen.
  • Weir equation
    (Weir Equation)
    Q = Capacity in CFS
    A = Free open area of grate in sq. ft.
    g = 32.2 (feet per sec/sec)
    h = Head in feet
    Q = Capacity in CFS
    P = Feet perimeter
    h = Head in feet
    Catalog number and grate type: Head in feet (h):
    Feet Perimeter (P):
    Free open area in sq. ft. (A):
    Weir capacity in cfs:
    Transitional flow in cfs:
    Orifice capacity in cfs:

    (Results assume no debris restriction.)
    NOTE: The above results do not account for the dome height of Beehive-type
    grates. Please take note of this when determining the Head (h) value.

              For additional information regarding Neenah Inlet Grate Capacities, please contact
              our Product Engineer, Steve Akkala, at 920-725-7000 or at sakkala@nfco.com.