TOFG-all

Irrigation—Principles & Practices

Part 1 – 262 | Unit 1.5

Appendix 13: Sample Sprinkler & Drip Tape

Application Rate Calculations

Appendix 13: Sample Sprinkler & Drip Tape Application Rate

Sample sprinkler application rate
calculation

You determine your sprinkler risers put out

3.5 gpm (gallons per minute) at 60 psi

30 x 30 spacing = 64 risers per acre

64 risers x 3.5 gpm = 227.5 gpm

227.5 gpm x 60 = 13,650 gph (gallons per

hour)

There are 27,154 gallons of water

per acre inch

27,154 divided by 2 = 13,577 gallons

So, 13,650 gallons per hour =

approximately .5 inch application

rate per hour

If your application uniformity is 80% then

your application rate is closer to .4 inches

per hour (.5 x 80%)

Sample drip application rate

calculation

Flow rate: .75 gpm per 100 feet @ 8 psi

(from label)

Bed spacing 2 feet

Bed length 100 feet

218 beds per acre

218 beds x 100 feet = 21,800 bed feet

per acre

Total bed feet divided by 100 = 218

100-foot sections per acre

218 sections x .75 gpm (per 100 feet) =

163.5 gpm

163.5 gpm x 60 minutes per hour =

9,810 gph

9,810 gph = 2.76 hours to apply

one acre inch

27,154 gallons per acre inch divided by

9,810 gph = 2.76 hours