58d6d3 storm water inlet design curb inlets us units

Storm Water Inlet Design - Curb Inlet - U.S. units

1. Orifice Equation

Inputs Calculations

Design Storm Water 0.333 ft

3.4 cfs

0.500 ft

4 in

Storm Water Depth above

6 in 0.3333 ft

0.67 Width of Curb

3.3 ft

2. Weir Equation

Inputs Calculations

Design Storm Water 0.333 ft

1.6 cfs

Width of Curb

4 in 3.6 ft

2.3

Height of Curb Opening, h =

Flow Rate, Q =

Depth of Storm Water, d =

Height of Curb Opening, h =

Depth of Storm Water, d = Orifice Centroid, de =

Orifice Coeff., Co =

Opening, L =

Depth of Storm Water, d =

Flow Rate, Q =

Depth of Storm Water, d = Opening, L =

Orifice Coeff., Cw =

Equations for Curb Inlet Design using the Orifice Equation

Where: Q = design storm water flow rate through inlet, cfs

h = height of the curb opening, ft

d = depth of storm water at curb opening, ft

L = width of the curb opening, ft

Equation for Curb Inlet Design using the Weir Equation

Where: Q, L, and d are as defined above

Q = Co h L ( 2g de )1/2 { L = Q/[Coh(2gde)1/2] }

de = d - h/2

g = 32.2 ft/sec2

Co = orifice coefficient, dimensionless ( typically Co = 0.67 )

Q = Cw L d1.5 [ L = Q/(Cwd1.5) ]

Cw = wier coefficient, dimensionless ( typically Cw = 2.3 )