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Basic Irrigation Terminology Part 6 Adapted from Information by Rain Bird Corporation and Washington State University P Precipitation Rate - The rate a sprinkler system applies water. Abbreviated as PR, it is expressed in depth of water per hours of operation (inches/centimeters per hour). Pressure - The measurement of force within a system. This is the force which moves water through pipes, sprinklers, and emitters. Static pressure is measured when no water is flowing, and dynamic pressure is measured when water is flow- ing. Pressure and flow are affected by each other. Pressure Loss - The amount of pressure lost as water flows through a system, also called friction loss. Pressure Regulator - A device which maintains constant downstream oper- ating pressure which is lower than the upstream operating pressure. Program - The watering plan or sched- ule which tells the controller exactly when and how long to run each set of sprin- klers. Some controllers offer multiple programs. Puddling - Typically caused by low head drainage, over irrigation, or slow soil in- filtration, puddling is when water gathers in one location. Pump - A device that raises, transfers, delivers fluid by suction or pressure or both. Centrifugal pumps are the most common type used for irrigation. Pump Efficiency - Ratio of the water power produced by the pump to the power delivered to the pump by the motor. Pump Start Relay - Low amperage or electric switch designed for use with pump start circuits. Q Quick Coupling Valve - A permanently instal led valve which al lows direct access to the irrigation mainline. A quick coupling key is used to open the valve. R Rain Delay - Allows the irrigation system to be turned off for a specific number of days without having to remember to turn it back on. Rain Shut-Off Device - A device which prevents the controller from opening irri- gation valves when a specified amount of rain falls. Remote Control Valve - A valve which is activated by an automatic controller by electric or hydraulic means. Riser - A length of pipe which has male nominal pipe threads on each end. Usually affixed to a lateral or submain to support a sprinkler or antisiphon valve. May also be used underground to connect system components. Root Zone - Also referred to as root depth or effective rooting depth, this term refers to the depth or volume of soil plants can effectively extract water from. This is typ- ically defined as the depth of soil contain- ing 80% of plant roots. Runoff - Water not absorbed by soil which drains into streams and other sur- face locations. More Basic Irrigation Terminology next month! +3$ (1 -.2 )312 /0("$ !32 2'$ .4$0 ++ 1$04("$ -# $6/$0($-"$ .%%$0$# !7 '0../ ."* (2 .,/ -7 - $&(12$0$# 0& -(8 2(.- .6 9 .-* 5 6 , (+ 1 +$1 2'0../0."*!(2 "., 555 2'0../0."*!(2 "., 45 WorldWide Drilling Resource ® OCTOBER 2015