Soils 456 Irrigation and Drainage Answers to chapter 6 questions

7.1
Compute wall thickness of 1, 2, and 3 inch class 160 PVC, Determine dimension ratio.

1 inch = 1.3125/ (1.315-1.195)/ 2= 21.9
2. inch= 2.375/ (2.375- 2.193)/2= 26
3.inch= 3.5/(3.5-3.23)/2= 28

7.2
Determine the water velocity and presssure loss due to firction in 750 ft of 1 inch type K copper pipe Flow is 11 gal/min
loss 4.2psi/100*750= 30.24 psi v= 4.53 ft/sec.

7.3
Class200 pvc pip with sprinklers every 60 ft . Minimum pipe size for each section based on velocity if the zone has 6 sprinklers each discharging 4 gal/min

 

section flow pipe size inches
1 4 1
2 8 1
3 12 1
4 16 1
5 20 1.25
6 24 1.25

7.4

Size 300 ft of pipe line in problem 7.3 . Limit the POC water pressure so total loss in the zone cannot exceed 3 lb/in^2

Loss per 100 ft = 3*100/300= 1.0lb/in^2

section flow loss size loss/100 ft
         
1 4 0.24*0.6=0.14 1 0.24
2 8 .0.86*0.6=.51 1 0.86
3 12 0.59*0.6=0.35 1.25 0.59
4 16 1.0*.6=0.61 1.25 1.0
5 20 1.51*0.6=0.9 1.25 1.51
6 24 0.52*.6=0.31 1.5 0.52
  total 2.81