LIT194-Handbook of TII.pdf - Diamond Head Sprinkler Supply

Variables and UnitsSYMBOL DEFINITION ENGLISH UNITS SI UNITSa Cross-sectional area of pipe flow in. 2 mm 2A r Area of land ft. 2 acres m 2 , haA e Area of land ft. 2 m 2AW Available soil water in. cmBP Barometric pressure ft mC Hazen-Willimas friction coefficient none noneC u Christiansen’s coefficient of uniformity % %d Inside diameter of a pipe in. mmd v Difference between an observed value and the mean value in. 3 mLD t Diameter of throw of sprinkler ft. mDU Distribution uniformity % %E Elevation of a point ft. mEA Application Efficiency % %ET c Crop Evapotranspiration in./day mm/dayET o Reference Evapotranspiration in./day mm/dayH Energy head, usually sum of elevation and pressure ft. mI Electrical current amps AID Inside diameter of pipe in. mmh f Energy loss due to friction ft./ft. m/mK c Crop Coefficient % %kPa Kilopascals psi barsk s Constant used to compute sprinkler spacing none noneL Spacing between lateral lines ft. mMAD Management allowed depletion none noneMC Maximum coverage for single row sprinklers ft. mn Number of observations in a uniformity test none noneNPSHA Net positive suction head available ft. mNPSHR Net positive suction head required ft. mOD Outside diameter of pipe in. mmP Pressure of water lb./in. 2 (psi) kPa, barsPal Allowable loss in pressure lb./in. 2 (psi) kPa, barsPav Average pressure in a zone lb./in. 2 (psi) kPa, barsPET Potential evapotranspiration in./day mm/dayPSIPounds per square inchPR Precipitation rate in./h mm/hPL Pressure losses due to friction ft. mPo Sprinkler operating pressure psi kPa, barsPv Pressure Variation % %P s Static Pressure psi kPa, barsQ Flow of water in a pipe or from a sprinkler gal/min L/sq e Flow of water gal/min 1/min.,m 3 /hrR Electrical resistance ohmsRt Radius of throw of sprinkler ft. mRAW Readily available water in. mmS Sprinkler spacing ft. mSC Scheduling coefficient ratio ratioSD Scalloped distance ft. mt Time of application or other timed events h hTDH Total dynamic head ft. mv Average velocity of water in a pipe ft/s (fps) m/sV o Electrical voltage volts VVP Vapor pressure of water ft. mXMean of all values in C u eq.X LQMean of the lower one-fourth of the application values, D u eq.z Change in elevation between two points ft. m®Handbook of Technical Irrigation Information33