Inlet Design Coefficients

Coefficients for Inlet Control Design Equations

					Unsubmerged		Submerged
Chart No.	Shape and Material	Nomograph Scale	Inlet edge description	FORM	K	M	C	Y
1	Circular Concrete	1	Square edge with headwall	1	0.0098	2	0.0398	0.67
		2	Groove end with head wall	1	0.0018	2	0.0292	0.74
		3	Groove end projecting	1	0.0045	2	0.0317	0.69
2	Circular CMP	1	Headwall	1	0.0078	2	0.0379	0.69
		2	Mitered to slope	1	0.021	1.33	0.0463	0.75
		3	Projecting	1	0.034	1.5	0.0553	0.54
3	Circular	A	Beveled ring, 45˚ bevels	1	0.0018	2.5	0.0300	0.74
		B	Beveled ring, 33.7˚ bevels	1	0.0018	2.5	0.0243	0.83
8	Rectangular Box	1	30˚ to 75˚ wingwall flares	1	0.026	1	0.0347	0.81
		2	90˚ to 15˚ wingwall flares	1	0.061	0.75	0.0400	0.8
		3	0˚ wingwall flares	1	0.061	0.75	0.0423	0.82
9	Rectangular Box	1	45˚ Wingwall flare, d=.0430	2	0.51	0.667	0.0309	0.80
		2	18˚-33.7˚ wingwall flare, d=.0830	2	0.486	0.667	0.0249	0.83
10	Rectangular Box	1	90˚ headwall with chamfers	2	0.515	0.667	0.0375	0.79
		2	90˚ headwall with 45˚ bevels	2	0.495	0.667	0.0314	0.82
		3	90˚ headwall with 33.7˚ bevels	2	0.486	0.667	0.0252	0.865
11	Rectangular Box	1	chamfers; 45˚ skewed headwall	2	0.545	0.667	0.0505	0.73
		2	chamfers; 30˚ skewed headwall	2	0.533	0.667	0.0425	0.705
		3	chamfers; 15˚ skewed headwall	2	0.522	0.667	0.0402	0.68
		4	45˚ bevels; skewed headwall	2	0.498	0.667	0.0327	0.75
12	Rectangular Box - Chamfers	1	45˚ non-offset wingwall flares	2	0.497	0.667	0.0339	0.803
		2	18.4˚ non-offset wingwall flares	2	0.493	0.667	0.0361	0.806
		3	18.4˚ non-offset wingwall flares, 30˚ skewed barrel	2	0.495	0.667	0.0386	0.71
13	Rectangular Box - Top Bevels	1	45˚ wingwall flares - offset	2	0.497	0.667	0.0302	0.835
		2	33.7˚ wingwall flares - offset	2	0.495	0.667	0.0252	0.881
		3	18.4˚ wingwall flares - offset	2	0.493	0.667	0.0227	0.887
16-19	C M Boxes	2	90˚ headwall	1	0.0083	2	0.0379	0.69
		3	Thick wall projecting	1	0.0145	1.75	0.0419	0.64
		5	Thin wall projecting	1	0.034	1.5	0.0496	0.57
29	Horizontal Ellipse - Concrete	1	Square edge with headwall	1	0.01	2	0.0398	0.67
		2	Groove end with head wall	1	0.0018	2.5	0.0292	0.74
		3	Groove end projecting	1	0.0045	2	0.0317	0.69
30	Vertical Ellipse - Concrete	1	Square edge with headwall	1	0.01	2	0.0398	0.67
		2	Groove end with head wall	1	0.0018	2.5	0.0292	0.74
		3	Groove end projecting	1	0.0095	2	0.0317	0.69
34	Pipe Arch 18" Corner Radius CM	1	90˚ headwall	1	0.0083	2	0.0379	0.69
		2	Mitered to slope	1	0.03	1	0.0463	0.75
		3	Projecting	1	0.034	1.5	0.0496	0.57
35	Pipe Arch 18" Corner Radius CM	1	Projecting	1	0.0300	1.5	0.0496	0.57
		2	No Bevels	1	0.0088	2	0.0368	0.68
		3	33.7˚ bevels	1	0.003	2	0.0269	0.77
36	Pipe Arch 31" Corner Radius CM	1	Projecting	1	0.0300	1.5	0.0496	0.57
		2	No Bevels	1	0.0088	2	0.0368	0.68
		3	33.7˚ bevels	1	0.003	2	0.0269	0.77
40-42	Arch CM	1	90˚ headwall	1	0.0083	2	0.0379	0.69
		2	Mitered to slope	1	0.03	1	0.0463	0.75
		3	Thin wall projecting	1	0.034	1.5	0.0496	0.57
55	Circular	1	Smooth tapered inlet throat	2	0.534	0.555	0.0196	0.90
		2	Rough tapered inlet throat	2	0.519	0.64	0.0210	0.90
56	Elliptical Inlet Face	1	Tapered inlet - beveled edges	2	0.536	0.622	0.0368	0.83
		2	Tapered inlet - square edges	2	0.5035	0.719	0.0478	0.8
		3	Tapered inlet - thin edge projecting	2	0.547	0.8	0.0598	0.75
57	Rectangular	1	Tapered inlet throat	2	0.475	0.667	0.0179	0.97
58	Rectangular Concrete	1	Side tapered - less favorable edges	2	0.56	0.667	0.0466	0.85
		2	Side tapered - more favorable edges	2	0.56	0.667	0.0378	0.87
59	Rectangular Concrete	1	Slope tapered - less favorable edges	2	0.5	0.667	0.0466	0.65
		2	Slope tapered - more favorable edges	2	0.5	0.667	0.0378	0.71