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 | |||