WorldWide Drilling Resource

Basic Irrigation Terminology Part 8 Adapted from Information by Rain Bird Corporation and Washington State University T Transpiration - Water absorbed into a plant’s roots and transpired through its leaves. Traveler - A sprinkler unit which pro- pels itself using the water pressure operating the sprinkler. They are typi- cally manufactured to either operate via a pull wire or to follow the layout of the hose supplying the water. Most units have an automatic shut off at the end of the run. U Uniformity - Describes how evenly water is distributed over an irrigated area. V Valve - Simi lar to a faucet, valves respond to commands from the con- troller. When valves receive a signal to open, water flows to the sprinklers; and if they receive a signal to close, the flow of water stops. Velocity - The speed at which water travels. (In the United States, usually ex- pressed in feet per second. Its metric equivalent is meters per second. W Water Hammer - When water velocity in a pipeline changes abruptly, the pressure will spike so high it can cause entire pipelines to explode, implode, or break. Water doesn't compress, is heavy, and has a lot of momentum at high velocities. Pipes with water running at high veloc- ities are at much higher risk for bursting due to water hammer. The key to prevent- ing this is to open and close valves slowly and don't let water hit the end of a closed pipeline at high velocities. Water Holding Capacity - The difference between field capacity and wilting point. Water Horsepower - The energy or power added to water by the pump. Water Table - The upper surface of a sat- urated zone below the soil surface where the water is at atmospheric pressure. If you dig a hole deep enough, water will start filling the hole at the water table. Water Pressure - The force exerted by water. In the U.S., it is stated as PSI, or pounds per square inch. Water Use Efficiency - Percentage of the applied water which is beneficially used (consumptive use and/or satisfy- ing the leaching requirement). Winterization - The process of removing water from an irrigation system before freezing temperatures. Freezing water expands in the pipes causing damage to the sprinkler system. Wire Gauge - This is the standard unit of measurement for wire. The higher the gauge number, the smaller the wire. Working Pressure - The pressure of the irrigation system during operation, also called dynamic pressure. Z Zone - A section of a system served by a single control valve. Zones are comprised of similar sprinkler types and plant mate- rial types with similar water requirements and soil types. 51 WorldWide Drilling Resource ® DECEMBER 2015