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Univeristy of Minnesota Non-Level Pressure Ditribution Worksheet 1. Enter each system lateral elevation and len th in order of highest to lowest elevation Lateral 1 Elevation 5.0 ft Length of pipe 37 ft Lateral 2 Elevation 3:9 ft. Length of pipe . 37 ft Lateral 3 Elevation ft Length of pipe ft Lateral 4 Elevation ft Length of. pipe ft Lateral 5 Elevation ft Length of pipel ft 2. Calculate change in elevation over the laterals. Highest elevation-lowest elevation: 5.0 - 3.9 = 1.1 feet 3. Calculate the Total Head=head at orifices(either 1 or 2 ft)+change in elevation(2) Elater 1 ft if design if for a single family home or 2 ft for anything else(min design pressure head at perforation) L_ 1 I ft + 1.1 ft = 2.1 feet This worksheet can not be used if greater than 5 feet. Design must be modified or valving must be used to equalize flow. 4. Calculate pressure head for each lateral 1. Highest Trench Elevation(E1)the Head=1 or 2 feet 2. For all other laterals the pressure head is calculated as 2 feet plus the change in elevation from Lateral 1, Lateral Elevation 5.0 1.0 ft Lateral 2 Elevation 3.9 1,: + [E1 `-E21. 1 3.9 ];= 2.1 ' ft. Lateral 3 Elevation 0.0 0 + [E1 - E3] = 0 + [ 5.0 0.0 ]= 0.0 ft Lateral 4 Elevation 0.0 0 . + [E1-E4) = 0.0 ft Lateral 5 Elevation 0.0 0 + [E1 -E5] = 0 + [ 5.0 0.0 ]= 0.0 ft 5. Determine flow rate per hole(See figure E-6). j Select a perforation diameter and the corresponding gallons per minute interpo/atin as needed. Lateral 1 Pres 1.0 Perf Diameter 13/16 = 0.42 gpm Lateral 2 Pres�2.1 Pert Qiameter 3/1;6 = 0.60 gpm _. Lateral 3 Pres 0.0 Pert Diameter = gpm Lateral 4 Pres 0.0 Perf. Diameter 9Pm Lateral 5 Pres 0.0 Pert Diameter = gpm 6. Calculate flow in gallons per minute for Lateral 1 -Select a spacing and enter in box. Number of perforations=[(length of ipe-2)/spacing]+1 [( 37 ft-2ft) / L 3 Jft]+1 = 12 perforations(Check figure E-4 to make sure it is ok) FI umber of perforations x flow rate 12 pert x 0.4 gpm = 5.0 gpm for Lateral 1 7. Calculate the gallons per minute per foot for Lateral 1 'b This value will then be used to make sure the gallon per minute per foot is equivalent in each lateral. Gallons/length= 5.0 gpm / 37 ft= 0.14 gpm/ft 1 E-6 Perforation Discharge in GPM E-4 Maximum Number of 114 inch perforations Pressure per lateral to guarantee<10%dischar a variation t Head Perforation Diameter in inches Perf feet 1/8 3/16 7/32 1/4 Spacing 1 0.18 0.42 0.56 0.74 feet 1 in 1.25 in 1.5 in 2.0 in 1.5 0.22 0:51 0.68-: 0.90. 2.5 8 14 18 28 C 2 0.26 0.59 0.80 1.04 3.-0,-,~ 8' . 13 17 26 2.5 029 0:65, 0,8,8 1.17` 3.3 7 12 16 25 3 0.32 0.72 0.98 1.28 4.0: 7''. 11 15 23 4 0.37 0.83 1.13 1:47:: 5.0 6 10 14 22 5 0.41 0.94 1.26 1.65 R Page 1 of 2