3C factor Pipe Material C Plastic (4-in diameter or larger) 150 Plastic (2- to 3-in diameter)140Aluminum (with couplers every 30 ft)130Galvanized steelEpoxy-coated steelPolyethylene lined steelSteel (new)Steel (15 years old)100Butyl rubber drop tubesRigid drop tubes145
5Multiple outlet factor Christiansen's equation for computing the reduction coefficient (F) for pipes with multiple, equally spaced outlets where the first outlet is Sl from the mainline is:F = Reduction factorN= number of sprinklersM= exponent depends on which friction equation is used
6Caveats For pipes that have no flow past the last outlet (sprinkler) Cannot be directly applied to the estimation of friction losses only partway down the lateral pipe.Assumes that each outlet has a constant discharge,Equations are for use with laterals having nearly constant discharge per outlet, such as for hand lines, wheel-lines, solid set (fixed), and linear-move systems.The value of F approaches 0.36 when N > 35, which is often the case with sprinkler laterals.
7Applying Irrigation Water in Circles (vs. squares) Why it’s a little trickier?In a circular system the areaincreases as the radius increasesHence, each sprinkler applieswater to a differently sized Area (A)In a rectangular system eachsprinkler applies water to anIdentically sized Area (A)1243Explain how area considerations affect nozzle sizing, spacing and possibly throw diameter1234A1 = A2 = A3 = A4A1 < A2 < A3 < A4
8Center pivot reduction factor Outlet discharge varies with distance from the center pivotFlow rate in the pipe decreases more slowly at the upstream endAverage velocity along the length of the lateral is higher.F value is higher on a center-pivot lateral than on laterals for other types of sprinkler systemsFor center pivot F = (> than 35 sprinklers)