Glossary of Terms
In order to fully understand your sprinkler system you must also understand the sprinkler and irrigation terminology.
Below we have compiled a glossary of terms so that you will understand their meanings.
Angle Valve - An angle valve is configured so its outlet is oriented 90 degrees away from its inlet. In irrigation, these valves are installed with the inlet at the bottom of the valve.
Anti-Siphon Device - An anti-siphon device is a type of backflow preventer that which seals off the atmospheric vent area when the system is pressurized. An anti-siphon device should be installed downstream of the control valve in a location which is at least twelve inches higher than the highest point in the lateral that it serves. When system pressure drops to zero, the float and seal assembly drops. This opens the vent to atmosphere and breaks any siphon effect.
Anti- Siphon Valve - The anti-siphon valve is the combination of an angle valve and anti-siphon device in one unit. The anti-siphon device is located downstream of the angle valve.
Application Rate - The application rate is a measurement of the volume of water applied to landscape in a given time. In the United States, this is usually expressed in inches per week.
ARC - The arc is the area a part-circle sprinkler irrigates that is expressed in degrees of a circle. For example, a 90 degree arc provides quarter-circle coverage, while a 180 degree arc provides half-circle coverage.
Audit/Irrigation Audit - An audit or irrigation audit is a detailed review of an irrigation system that includes tests to determine overall system efficiency and to identify problem areas that need correction, and also determine an ideal watering schedule.
Automatic Control Valve - An automatic control valve is a valve which is activated by an automatic controller by using electricity or hydraulics.
Backflow - Backflow is the unwanted reverse flow of liquids in a piping system.
Backflow Preventer - A backflow preventer is a device which prevents backflow. In irrigation, it is used to protect water supply from potentially contaminated irrigation water.
Calendar Days Off - A calendar days off is a controller feature that allows you to suspend watering on a specific date.
Check Valve - A check valve is a valve which allows water to flow in one direction only. Check valves are used to prevent low head drainage.
Coefficient of Uniformity (CU) - A coefficient of uniformity is a numerical expression that serves as an index for the uniformity of water applied to a given area within a specific geometric arrangement of sprinklers.
Controller/Timer/Clock - The controller, timer or clock are is the brain of the sprinkler system. The controller automatically opens and closes valves according to a preset schedule. An automatic controller is usually more water-efficient than operating sprinklers manually.
Coverage - Coverage is the area of landscape watered by a sprinkler or grouping of sprinklers.
Diaphragm - A Diaphragm is a rubberized seal that keeps water from flowing through the valve.
Diaphragm Valve - A diaphragm valve is a globe or angle pattern valve which uses a diaphragm to control the flow of water through the valve.
Distribution Uniformity (DU) - Distribution Uniformity is a calculated value that shows how evenly water is distributed in a sprinkler system to avoid excessively wet or dry areas in the landscape. Distribution Uniformity depends on the spacing of sprinklers, type of sprinkler used, wind and water pressure among other factors. High distribution uniformity is obtained when an equal amount of water is placed on all areas of the landscape.
Domestic Water - Domestic water or drinking water can be used as a source of irrigation water, but once water enters an irrigation system it is no longer considered domestic.
Drain Valve - A drain valve is used to empty water from a lateral or main line and is usually for winterization purposes.
Drip Irrigation - Drip Irrigation is a method of irrigation that uses a low volume watering method to delivers water slowly and directly to the plant roots for maximum efficiency.
Dynamic Pressure - Dynamic Pressure- is the pressure of the irrigation system during operation.
Emitter - An emitter is a small watering device which delivers water at very low rate.
ET/ Evapotranspiration - Evapotranspiration or ET is the amount of water lost due to evaporation from the soil and transpiration from the plants.
External Manual Bleed - External Manual bleed is a feature which allows an automatic valve to be opened manually by releasing water from above the diaphragm to the outside of the valve.
Flow - Flow is simply the movement of water.
Flow Control - A flow control is a valve which modulates in order to maintain a pre-determined flow rate without altering the pressure.
Flow Sensor - A flow sensor is a device which actively measures water flow through a piping system and reports its data to the computerized central control system.
FPT - FPT is the female nominal pipe thread.
Friction Loss - Friction Loss is the amount of pressure lost as water flows through a system.
Globe Valve - A globe valve is configured with its outlet oriented 180 degrees from its inlet. In irrigation, these valves are generally installed so that the inlet and outlet are parallel to the ground.
GPM - GPM is an acronym for gallons per minute.
Head To Head Coverage - Head To Head Coverage is the practice of placing sprinklers so that water from one sprinkler overlaps all the way to the next sprinkler head. Head To Head Coverage helps to increase overall system efficiency and prevent dry spots in the landscape.
Impact Drive - Impact drive is a sprinkler which rotates using a weighted or spring-loaded arm that is propelled by the water stream and hits the sprinkler body which causes movement around a circle.
Infiltration Rate - Infiltration Rate is the rate at which water enters the soil, usually expressed in depth of water per hour. Infiltration rate is determined by the type of soil.
Irrigation Efficiency - Irrigation efficiency is the percentage of irrigation water that is stored in the soil and available for use by landscape as compared to the total amount of water provided to the landscape.
Irrigation System - An irrigation system or sprinkler system is a set of components which includes the water source (e.g., domestic service or pump), water distribution network (e.g., pipe), control components (e.g., valves and controllers), emission devices (e.g., sprinklers and emitters) and possibly other general irrigation equipment (e.g. quick coupler and backflow preventer).
Irrigation Requirement - Irrigation requirement is the quantity of water needed by the landscape to satisfy the evaporation, transpiration and other uses of water in the soil.
Lateral - The lateral pipe is the pipe that is installed downstream from the control valve from which the sprinklers are located.
Low Head Drainage - Low head drainage is the residual flow from low-elevation sprinkler heads in a system after the control valve has been closed.
Main (MAINLINE) - The Main is the pipe that is under constant pressure that supplies water from the point of connection to the control valves.
Master Valve - A master valve is a valve that is used to protect the landscape from flooding in case of a ruptured main or malfunctioning downstream valve. The master valve is installed on the mainline after the backflow preventer and the control valves.
Matched Precipitation Rate (MPR) - Matched precipitation rate (MPR) refers to sprinklers that apply water at the same rate per hour no matter the arc of coverage or part of a circle they cover.
Microclimate - Microclimate is the unique environmental conditions in a particular area of the landscape. Factors of the microclimate include amount of sunlight or shade, soil type, slope and wind.
Moisture Sensor - A moisture sensor is a device that monitors the amount of water present in the soil and modifies the watering schedule.
MPT - The MPT is the male nominal pipe thread.
Nozzle - The nozzle is the final orifice through which water passes from the sprinkler or emitter.
Operating Pressure - Operating pressure is the pressure that a system of sprinklers operates.
Permanent Wilting Point - Permanent wilting point is the point at which plants can no longer extract moisture from the soil.
Polyvinyl Chloride Pipe (PVC Pipe) - PVC pipe is a semi-rigid plastic material that is used in irrigation systems.
Polyethylene Pipe(PE Pipe) - PE pipe is a flexible black pipe that is used in irrigation systems.
Potable Water - Potable water is domestic or drinking water. Potable Water can be used as irrigation water, but once the water enters an irrigation system it is no longer considered domestic or potable.
Precipitation Rate(PR) - Precipitation rate is the rate that a sprinkler system applies water to the landscape.
Pressure - Pressure is the force per unit area measured. Insufficient water pressure can result in poor sprinkler coverage, while excessively high water pressure may cause misting and fogging leading to water waste.
Pressure Loss - Pressure loss is the amount of pressure lost as water flows through a system.
Pressure Regulator - A pressure regulator is a device that maintains constant downstream operating pressure.
Program - The program is the watering plan or schedule that tells the controller exactly when and how long to run each set of sprinklers.
PSI - PSI is an acronym for pounds per square inch.
Puddling - Puddling occurs when water gathers in one location, such as at the base of a sprinkler or at a low spot on the site. Puddling can be caused by low-head drainage, over-irrigation, or slow soil infiltration.
Pump Start Circuit - The Pump Start Circuit is the feature on automatic controllers which supplies 24 VAC, that can be used to activate a pump through an external pump start relay.
Pump Start Relay - Pump Start relay is the electric switch that is designed for use with pump start circuits.
Quick Coupling Valve - A permanently installed valve which allows direct access to the irrigation mainline. A quick coupling key is used to open the valve.
Rain Shut-Off Device/Rain Sensor - A rain sensor is a device which prevents the controller from activating the valves when rainfall is detected.
Rain Delay - The rain delay allows you to turn the irrigation system off for a specific number of days without having to remember to turn it back on.
Remote Control Valve - The remote control valve is a valve that is activated by an automatic controller.
Retraction - Retraction or pop-down occurs when the pop-up riser of a sprinkler returns to the case in the ground.
Riser - The riser is the length of a pipe that has male nominal pipe threads on each end. The riser is usually attached to a submain to support a sprinkler or anti-siphon valve. The riser may also be used underground to connect system components.
Run-Off - Run-Off is water that is not absorbed by the soil and drains to another location.
Scheduling Coefficient - A scheduling coefficient is a numerical expression that serves as an index of the uniformity of water application.
Slip Configuration - A slip configuration is a threadless connection that is solvent-welded.
Smart Controller - A smart controller is an irrigation control system that uses weather-based calculations and environmental conditions to determine how much water is needed.
Spray Head - A spray head is a type of fixed spray sprinkler that pops up from underground and waters a set pattern, usually from 4 to 15 feet in range.
Soil Type - The soil type is the texture and structure of the soil particles which affects its ability to take in and store water for use by plants.
Solenoid - A solenoid is an electromagnet which is connected to a controller and causes the opening and closing of automatic control valves.
Sprinkler - A sprinkler is a hydraulically operated device that discharges water through a nozzle.
Start Times - When you program a controller, you schedule the precise time you want to begin watering on water days. The start time is the time the first station in a program begins to water. All other stations in the program follow in sequence. Remember, start times usually apply to the entire program, not to the individual stations.
Static Pressure - Static Pressure is the pressure in a closed system.
Station - A station is a circuit on the controller that activates a single control valve in the irrigation system to control watering for a particular zone.
Swing Assembly - A swing assembly is an assembly of flexible swing pipe and fittings that are used to connect a sprinkler to the lateral pipe. The swing assembly allows you to easily adjust the sprinklers to grade level and also helps to prevent breakage due to force on the sprinkler.
Swing Joint - The swing joint is a threaded connection of pipe and fittings between the pipe and sprinkler that allows movement to be taken up in the threads rather than as a sheer force on the pipe.
Transpiration - Transpiration is the process where a plant's moisture is lost to the atmosphere through its leaves.
Uniformity - Uniformity is how evenly water is distributed over an irrigated area.
Valve - A valve is like a faucet. Valves respond to commands from the controller. When valves receive a signal to open, water flows to the sprinklers. when they receive another signal to close, the flow of water stops.
Velocity - Velocity is the speed at which water travels.
Water Hammer - A water hammer is a damaging shock wave created when the flow of water in a pipe system suddenly stops.
Water Pressure - Water Pressure is the force that is exerted by water.
Water Window - Water window is the time of day available when watering can take place.
Watering Days - Watering Days are the specific days of the week that watering will take place.
Winterization - Winterization is the process of removing water from an irrigation system before the onset of freezing temperatures.
Wire Gauge - Wire Gauge is a standard unit of measure for wire size. The larger the gauge number, the smaller the wire.
Working Pressure - Working Pressure is the pressure of the irrigation system during operation.
Zone - A zone is a section of an irrigation system served by a single control valve.