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<br />Non-uniform heads: <br /> <br />· A mixed zone refers to a zone that has multiple types of sprinkler heads on one <br />zone (i.e. rotor, spray, or drip) Fixed spray heads are designed to emit an average <br />of 50% more water than rotor heads. Since watering times can only be controlled <br />zone by zone and not by individual heads, the areas being watered by fixed sprays <br />will be receiving an average of 50% more water than the areas being watered by <br />rotors. The optimal operating pressure levels for fixed sprays versus rotors are <br />very different. Fixed spray heads are designed to operate best between 20 and 30 <br />psi, while rotors are designed to operate best between 40 and 70 psi. Therefore, if <br />the time and pressure is correct for one type of head, it will inherently be wrong <br />for the other type of head. For the above reasons, sprays and rotors should never <br />be located on the same zone. A direct result of this type of design is turf that has <br />spots of overly wet and/or overly dry areas. <br /> <br />· Each rotor type/brand is manufactured to have a different precipitation rate as <br />well as a different oscillating speed. Therefore, it is inefficient to have different <br />types of rotors on the same zone. <br /> <br />· Drip irrigation should never be attached to a zone containing different types of <br />sprinl<ler heads (i.e. rotor or spray heads) This is an extremely inefficient design <br />that has the potential to create serious problems. As noted above, sprays and <br />rotors have different precipitation rates and are also designed to operate at <br />different pressure levels. Similarly, drip lines are designed not only to have <br />different precipitation rates and different operational pressure levels than sprays <br />and rotors, but are also designed specifically to water non-turf material. The <br />precipitation rate for sprays and rotors is significantly higher than for drip system <br />and is measured in gallons per minute versus gallons per hour for drip. Therefore, <br />zones with rotors and sprays usually run for shorter periods of time. Conversely, <br />it is not abnormal for a drip system to run for one to two hours at a time. Also, <br />turf only needs to be watered two to three times a week, while many plants need <br />to be watered every day. Therefore, if they are being controlled by the same zone, <br />either the watering schedule for the turf or the watering schedule for the plants <br />will be incorrect. Additionally, the desired pressure level for sprays is between <br />20-30 psi and the desired pressure level for rotors is between 40-70 psi. Drip <br />systems on the other hand, should operate at a maximum of 20 psi. When a drip <br />system is operating at too high of pressure, it will result in the emitters being <br />continually blown off and will also result in the system prematurely wearing out. <br />The zones containing both rotors/sprays and drip should be broken up so that each <br />zone would contain either all drip or all rotors/sprays. <br /> <br />· Generally, switching the type of head will necessitate either adding additional <br />heads or removing existing heads,. this has the potential to greatly influence the <br />entire irrigation system design. A certified irrigation professional should be <br />consulted and/or utilized when addressing these types of problems. <br /> <br />22 <br />