Vegetated Filter Strip System Design Manual
Design Guidelines of VFS System Components

Table 3.1 Orifice Discharge Capacity

Orifice
Diameter
(in) 		Orifice
Area
(ft2) 		Discharge Capacity at Specific Head (m)
1
(gal/min.) 		1.1
(gal/min.) 		1.2
(gal/min.) 		1.3
(gal/min.) 		1.4
(gal/min.)
0.39 0.00 4.91 5.15 5.38 5.60 5.81
0.79 0.00 19.65 20.60 21.52 22.40 23.25
1.18 0.01 44.20 46.36 48.42 50.40 52.30
1.57 0.01 78.58 82.42 86.08 89.60 92.98
1.97 0.02 122.79 128.78 134.51 140.00 145.28
2.36 0.03 176.81 185.44 193.69 201.60 209.21
2.76 0.04 240.66 252.41 263.63 274.40 284.76
3.15 0.05 314.33 329.68 344.34 358.40 371.93
3.54 0.07 397.83 417.25 435.80 453.60 470.72
3.94 0.08 491.15 515.12 538.03 559.99 581.13
4.33 0.10 594.29 623.30 651.01 677.59 703.17
4.72 0.12 707.25 741.77 774.76 806.39 836.83
5.12 0.14 830.04 870.55 909.26 946.39 982.12
5.51 0.17 962.65 1009.64 1054.53 1097.59 1139.02
5.91 0.19 1105.08 1159.02 1210.56 1259.99 1307.55
6.30 0.22 1257.34 1318.71 1377.35 1433.59 1487.70
6.69 0.24 1419.42 1488.70 1554.89 1618.38 1679.48
7.09 0.27 1591.32 1668.99 1743.20 1814.38 1882.87
7.48 0.31 1773.04 1859.58 1942.27 2021.58 2097.89
7.87 0.34 1964.59 2060.48 2152.10 2239.98 2324.54
8.27 0.37 2165.96 2271.68 2372.69 2469.58 2562.80
8.66 0.41 2377.16 2493.18 2604.04 2710.37 2812.69
9.06 0.45 2598.17 2724.99 2846.16 2962.37 3074.20
9.45 0.49 2829.01 2967.09 3099.03 3225.57 3347.33
9.84 0.53 3069.67 3219.50 3362.66 3499.97 3632.09
10.24 0.57 3320.16 3482.21 3637.05 3785.56 3928.47
10.63 0.62 3580.47 3755.23 3922.21 4082.36 4236.47
11.02 0.66 3850.60 4038.54 4218.12 4390.36 4556.09
11.42 0.71 4130.55 4332.16 4524.80 4709.56 4887.34
11.81 0.76 4420.33 4636.08 4842.23 5039.95 5230.21
12.20 0.81 4719.93 4950.31 5170.43 5381.55 5584.70
12.60 0.87 5029.35 5274.83 5509.38 5734.35 5950.81
12.99 0.92 5348.60 5609.66 5859.10 6098.34 6328.55
13.39 0.98 5677.67 5954.79 6219.58 6473.54 6717.91
13.78 1.04 6016.56 6310.22 6590.81 6859.94 7118.89
14.17 1.10 6365.28 6675.96 6972.81 7257.53 7531.50
14.57 1.16 6723.82 7052.00 7365.57 7666.33 7955.73
14.96 1.22 7092.18 7438.34 7769.09 8086.33 8391.58
15.35 1.29 7470.36 7834.98 8183.37 8517.52 8839.05
15.75 1.35 7858.37 8241.92 8608.41 8959.92 9298.15

Using equation Q = (C)(A)(2gh)0.5, with the following variables: Q = Orifice discharge, C = Orifice constant = 0.61 (varies by type of orifice, value considered conservative), A = Orifce Area m2, g = 9.8 m/s2, h = Head of Orifice m

Back to Calculating Orifice Size Based on Orifice Discharge Capacity

| Top of Page |


For more information:
Toll Free: 1-877-424-1300
Local: (519) 826-4047
E-mail: ag.info.omafra@ontario.ca
Author: Robert P. Stone, P. Eng., Engineer, Soil/OMAFRA
Creation Date: 04 July 2005
Last Reviewed: 20 June 2006