### Gross Estimated Runtimes for Small to Medium Turf Areas

Bill Carlos, Horticulturist, University of Nevada Cooperative Extension
John C. Guitjens Ph.D., Prof, Environmental Resource Science, University of Nevada College of Agriculture

The following suggested sprinkle runtimes and irrigation rates are for residential turf areas. Site specific runtimes will vary because of lawn shape and slope, nozzle size, and sprinkler head spacing. Runtimes are based on the manufacturer information and names of products are used for illustration purposes only. The impact rotor runtimes are longer because of a larger radius and, therefore, a larger area, and a smaller delivery rate.

Small Lawn Areas
Pop-up Toro 570
is based on 30 pounds per square inch (psi) of water pressure, a delivery rate of 3.60 gallons per minute (gpm) for a full circle nozzle, a sprinkler head of 15 ft, a spray radius of 15ft, and matched precipitation rates (MPR).
Please note: run times will vary with ET rates.

Runtime calculation
Reference evapotranspiration = Eto=0.35 inches per day = 0.029 ft per day of water depth
• Assume an irrigation efficiency = 85% (=0.85)
• The area used here is square and the sprinkler head spacing 15 ft x 15 ft = 225 ft2
• The conversion of cubic feet to gallons = 7.48 gal/ft3
• 0.029 ft/0.85 irrigation efficiency =0.034 ft of water application depth
• 0.034 ft x 225 ft2 = 7.65 ft3
• 7.65 ft3 x 7.48 gal/ ft3 = 57.2 gal
• 57.2 gal/3.60 gal/minute = 15.9 minutes per day (approx. 16 minutes per day)
Medium Lawn Area
RainBird Mini Paw, Impact Rotor Pop-Up Sprinkler
is based on 25 psi, a delivery rate of 2.60 gpm for a full circle rotor, a sprinkler spacing of 20ft, and a spray radius of 20 ft.

Runtime calculation:
Reference evapotranspiration = Eto=0.35 inches per day = 0.029 ft per day of water depth
• Assume an irrigation efficiency = 85% (=0.85)
• The area used here is square and the sprinkler head spacing 20 ft x 20 ft = 400 ft2
• The conversion of cubic feet to gallons = 7.48 gal/ft3
• 0.029 ft/0.85 irrigation efficiency =0.034 ft of water application depth
• 0.034 ft x 400 ft2 = 13.6 ft3
• 13.6 ft3 x 7.48 gal/ ft3 = 102 gal
• 102 gal/2.60 gal/minute = 39 minutes per day
Medium Turf Areas
Toro 340 Series Stream Rotors
is based on 35 psi, a delivery rate of 3.10 gpm for a full circle rotor, a sprinkler spacing of 15ft, and a spray radius of 15 ft.
Runtime calculation:
Reference evapotranspiration = Eto=0.35 inches per day = 0.029 ft per day of water depth
• Assume an irrigation efficiency = 85% (=0.85)
• The area used here is square and the sprinkler head spacing 15 ft x 15 ft = 225 ft2
• The conversion of cubic feet to gallons = 7.48 gal/ft3
• 0.029 ft/0.85 irrigation efficiency =0.034 ft of water application depth
• 0.034 ft x 225 ft2 = 7.65 ft3
• 7.65 ft3 x 7.48 gal/ ft3 = 57.2 gal
• 57.2 gal/3.10 gal/minute = 18.5 minutes per day (approx. 20 minutes per day)

Reference:

Rain Bird. 1999-2000 Catalog. Landscape Irrigation Products
Toro. 2000-2001, Irrigation Product Catalog