WorldWide Drilling Resource

25 WorldWide Drilling Resource ® SEPTEMBER 2015 Basic Irrigation Terminology Part 5 Adapted from Information by Rain Bird Corporation and Washington State University M Matched Precipitation Rate - Also known by the acronym MPR, this term refers to sprinklers capable of applying water at the same rate per hour regard- less of the arc of coverage. For example, a full-circle sprinkler discharges twice the flow of a half-circle sprinkler and a quar- ter-circle sprinkler discharges half of what the half-circle unit does. MPR allows the same type of sprinklers, no matter what their arc, to be circuited on the same valve and to deliver the same precipita- tion rate. Matric Potential - The force the soil exerts on water, measured in units of negative pressure. Microclimate - Unique environmental conditions in a particular area of the landscape. Factors include amount of sunlight or shade, soil type, slope, and wind. Moisture Sensor - A device which moni- tors the amount of water in soil and mod- ifies the watering schedule accordingly. MPT - An acronym for male nominal pipe thread. N Nonpoint Source Pollution - Small amounts of pollution from large areas without a well-defined source. Nozzle - The final orifice the water pass- es through from the sprinkler or emitter to the atmosphere. Nozzle shape, size, and placement has a direct effect on the distance, watering pattern, and distribu- tion efficiency. O Operating Pressure - The average pressure at the sprinkler head. Equivalent to the static pressure less pressure loss- es. Usually as measured at the base or nozzle of a sprinkler. Osmotic Potential - The equivalent force that a salinity differential can cause across a semipermeable membrane. P Permanent Wilting Point - The point when plants can no longer extract mois- ture from the soil. Plant Available Water - The total amount of water held in the plant root zone. It is calculated as the root zone depth mul- tiplied by the available water capacity. Point of Connection - The place where the irrigation submain is joined to the water service line. Polyvinyl Chloride Pipe - Commonly known as PVC pipe. Polyvinyl chloride is a plastic material frequently used for pipes and fittings. The material is light- weight, inexpensive, easy to assemble, and can have a long useful life. Polyethylene (PE) Pipe - A flexible black pipe used in irrigation systems. Pore Space - Empty space between soil particles which is normally filled with either air and/or water. Potable Water - Domestic or drinking water. 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 ".,