Design of Agricultural Irrigation Systems in Florida standards are included in the list of references in this publication (1, 12, 13, 36). Copies of these standards are available from the developing agency. Computer software has been developed by the University of Florida to help with the design and management of Florida irrigation systems. Water management utilities were published by Zazueta et al. (69) and continue to be developed. A complete list of available software is published in the IFAS Microcomputer Software Catalog (64). Major components of irrigation systems must often be designed in groups for compatibility and efficiency. This publication discusses the major component groups of 1) control equipment; 2) water conveyance system; 3) water distribution system; and 4) pumping system. Selection of operating conditions (flow rates and pressures) is also discussed. This publication references many other publications which provide more information on specific aspects of irrigation system design in Florida. SYSTEM COMPONENT GROUPS Control Equipment The objective of control equipment design is to specify components that will enable the irrigation system to be efficiently and safely managed and monitored in order to optimize crop production, conserve water and preserve water quality. Control equipment consists of the components required to regulate and monitor water and chemical applications to an irrigation system, and safety equipment required to protect the water supply from contamination. These include valves, pressure regulators, flow meters, backflow prevention systems, filters, pressure gauges, chemical injection equipment, and irrigation controllers. Valves Valves are required to control the filling of irrigation systems at pump startup, to control flows to the desired subunits of a system, and to allow flushing of irrigation pipes. Only properly pressure-rated irrigation valves must be used to avoid failures due to system pressure and hydraulic shock (water hammer) problems. Valve materials and components must be resistent to corrosion by the irrigation water and any chemicals injected during irrigation. I o I SC IECE LIBRARY Page 2 Valves must be properly sized to avoid excessive pressure losses. Normally, valves should be the same size as the pipeline in which they are installed. Installing smaller valves to save initial costs will result in higher operating costs for the life of the system due to friction losses. Automatically-controlled irrigation systems will require the use of automatic valves. These may be controlled by electric solenoids or hydraulic pressures, depending upon the type of timer/controller used. Like manual valves, automatic valves should be selected based on friction loss and water hammer considerations. For more information on valve types and selection, see IFAS Ext. Cir. 824, Valves in Irrigation Systems (19). For information on estimating and controlling hydraulic shock, see IFAS Ext. Cir. 828, Water Hammer in Irigation Systems (7). Pressure Regulators Pressure regulators may be required to maintain the desired operating pressure in pipe flow systems. These valves are required when it is necessary to manage changing pumping conditions such as those due to changes in the water source or flow requirements to subunits of the irrigation system. Regulators are also required if some subsections of a system operate at different pressures than others. Pressure regulators are often installed at either the irrigation pump outlet, the entrances to subunits, or at both locations. Pressure regulators may include slow opening and check valve features. The slow opening feature will allow an irrigation system to fill slowly upon pump startup, thus avoiding water hammer problems. The check valve feature will help to prevent backflow to the water source, thus helping to protect the water supply from contamination. Because of their cost and the pressure losses which occur through them, pressure regulators should be used only when absolutely necessary. The system subunits should be designed to have as nearly the same pressure and flow rate requirements as possible to minimize the number of regulators. In some cases, field sizes, layouts, or slopes will not permit the same flow rate and pressure to be used for all subunits. Then, pressure regulators will be necessary. For more information on pressure regulating valves, see IFAS Ext. Cir. 824, Valves in Irigation Systems (19).