Sprinkler System Terminology

100% Coverage: The design goal of all sprinkler system designers. Sometimes used (incorrectly) in place of the term "head to head coverage". 100% coverage is the objective of head-to-head coverage. But head-to-head coverage does not always result in 100% coverage.

Acre Foot (also acre feet): A measurement of water quantity most often used in agriculture. The amount of water needed to cover one acre of area with water one foot deep. Enough water to drown in, but not deep enough to swim in.

Acre Inch: See "acre foot" above and substitute "inch" for "foot

Angle Valve: A valve configured so its outlet is oriented 90 degrees away from its inlet. In irrigation, these valves are generally installed with the inlet at the bottom of the valve.

Anti-Siphon Device: A type of backflow preventer which seals off the atmospheric vent area when the system is pressurized. Should be installed downstream of a control valve in a location which is at least twelve inches higher than the highest point in the lateral which it serves. When system pressure drops to zero, the float and seal assembly drops, opening the vent to atmosphere and breaking any siphon effect. Consult local building codes or your Rain Bird distributor for laws applicable in your area. Synonymous with Atmospheric Vacuum Breaker.

Anti-Siphon Valve: 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: A measurement of the volume of water applied to landscape in a given time. (In the United States, usually expressed in inches per week. Its metric equivalent is centimeters per week.)

Arc: The area a part-circle sprinkler irrigates, expressed in degrees of a circle. For example, a 90 degree arc provides quarter-circle coverage, while an 180 degree arc provides half-circle coverage.

Atmospheric Vacuum Breaker (AVB): A type of backflow preventer. Synonymous with Anti-Siphon Valve

Audit or Irrigation Audit: A detailed review of an irrigation system, including tests to determine overall system efficiency, identify problems areas that need correction, and determine an ideal watering schedule.

Automatic Control Valve: A valve which is activated by an automatic controller using electric or hydraulic means. Synonymous with Remote Control Valve.

Automatic Valve: A valve which can be remotely operated. The remote operation method may be either electrical (the most common) or hydraulic. Automatic valves are commonly used as "control valves" for irrigation systems.

AWG-UF: The classification of the direct burial wire used for automatic sprinkler systems. Example: #14-1 AWG-UF means a 14 gauge wire, single wire cable, designed for direct burial (no conduit) in the ground. The wire should have this information stamped or printed directly on the wire's plastic insulation. The wire should be at least 18" deep for safety (in most areas this requirement is written into local law).

Backflow: The unwanted reverse flow of liquids in a piping system.

Backflow Preventer: A mechanical device which prevents backflow. In irrigation, it is used to protect the potable water supply from potentially contaminated irrigation water. There are several types of backflow preventers. The choice of backflow preventer used depends on the degree of hazard and the particular piping arrangement involved. Virtually all regulatory agencies in the United States require backflow prevention devices to protect the domestic water supply from contamination by the backflow of irrigation water. In areas where it is not required, it is highly recommended. Consult local building codes for laws applicable in your area.

Ball Valve: This type of valve controls the water by means of a rotating ball with a hole through the center of it. When the hole is aligned with the water flow the water flows freely through the valve with almost no friction loss. When the ball is rotated so that the hole is not aligned the flow is completely shut off. Ball valves are used primarily as isolation valves. They tend to be very reliable and trouble-free. Ball valves as a group tend to require more effort to turn on and off than other valves. For larger size pipes butterfly valves are usually used rather than ball valves

Bushing: A bushing is a small piece used to connect two pipes of different sizes together. A standard reducer bushing has one male end (for the larger pipe) and one female connection (for the smaller pipe).

Butterfly Valves: This type of valve uses a rotating disk to control the water flow. A true butterfly valve has two half-disks, hinged together in the center. When the disks, or "wings" are folded together the water flows freely past them. when folded out into the water stream the wings block the flow. Most "butterfly valves" are really "rotating disk" valves. They have a single, round disk that rotates on an axle. When fully open the disk is rotated so that it is aligned with the water flow. To close, the disk is rotated at a right angle so that it fully blocks the flow. Butterfly valves are used as both isolation and control valves. Butterfly valves tend to be very reliable and trouble free. They are mostly used on larger pipe sizes, seldom less than 3" in size. Ball valves are used on smaller size pipes.

Booster Pump: A device to increase the water pressure is a system where some pressure already exists. For example, if water comes from a water company at 40 PSI of pressure but you need 80 PSI of pressure for the irrigation system, you would use a booster pump to increase the pressure.

Calendar Days Off: A controller feature that allows you to suspend watering on a specific date.

Check Valve: A valve which allows water to flow in one direction only. Check valves are used to prevent low head drainage.

CL 125, 160, 200, 315: Pronounced "class-one-twenty-five", "class-one-sixty", "class-two-hundred" and "class-three-fifteen". Pipe classifications ( CL = class = classification). Based on standard dimension ratios. CL 125 pipe is rated for 125 PSI working pressure, CL 200 for 200 PSI, etc. Most industry professionals will tell you that it's not wise to use pipe rated at less than twice the actual maximum water pressure level. In other words, for a water pressure of 100 PSI use at least CL 200 pipe.

Coefficient of Uniformity: A numerical expression which serves as an index for the uniformity of water applied to a given area within a specific geometric arrangement of sprinklers (e.g., square or triangular).

Connecting Pipe or Main Line: The line from the service line to the valve manifold.

Controller or Timer or Clock: This is the brain of the sprinkler system. The controller automatically opens and closes valves according to a preset schedule. Controllers range from very simple to extremely sophisticated computer systems that utilize modems, cell-phones, or radios and allow 2-way communication between the controller and the units (valves, meters, weather stations, soil moisture sensors, etc.) being controlled. An automatic controller is usually more water-efficient that operating sprinklers manually.

Coupling: A fitting used to join two sections of pipe together.

Coverage: The area of landscape watered by a sprinkler or grouping of sprinklers.

Cross: A fitting that joins 4 sections of pipe at one point forming a "cross". Reducing crosses are available which have different size outlets. Unless you order a custom made cross the outlets opposite each other are always the same size.

Cubic Feet: A measurement of water quantity, often used by water companies in the United States of America to measure water use by customers. A cubic foot is one foot in length, one foot in width, and one foot deep

Cubic Meters: A metric measurement of water quantity, often used by water companies to measure water use by customers. A cubic meter is one meter in length, one meter in width, and one meter deep (right, like I really needed to tell you that!).

Cycle + Soak: Rain Bird 's exclusive feature which allows you to break the total irrigation run time into shorter cycles, segmented by breaks or soaks during which the landscape has time to absorb the water. Optimizes the watering of poor drainage sites, slopes, and heavy soil areas. Helps to prevent run-off.

Design Pressure: In the irrigation design tutorials the design pressure is the total pressure available to operate the irrigation system. Other uses of the term vary, but usually refer to the operating pressure at which a specific piece of irrigation equipment is designed to operate.

Diaphragm: Rubberized seal which keeps water from flowing through the valve.

Diaphragm Valve: A globe or angle pattern valve which uses a diaphragm to control the flow of water through the valve.

Distribution Uniformity (DU): A calculated value that shows how evenly water is distributed in a sprinkler system to avoid excessively wet or dry areas in the landscape. It 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: Potable or drinking water. It can be used as a source of irrigation water, but once water enters an irrigation system it is no longer considered domestic or potable.

Drain Valve: A valve used to empty water from a lateral or main line, usually for winterization purposes

Draw Down: The depth (from the top of the well) to the water in a well when the pump is operating. The water level typically drops when the pump is running. Artists who paint scenes with geese in them have been known to "draw down".

Drip Irrigation: Any type of irrigation system that applies water to the soil very slowly, thus the name "drip" irrigation. A low volume watering method that delivers water slowly and directly to the plant roots for maximum efficiency. Currently the most efficient irrigation technology in terms of both water and energy use

Drip System: An irrigation system that uses drip irrigation. See drip irrigation above.

Dynamic Pressure: The pressure of the irrigation system during operation. Synonymous with Working Pressure.

Elevation Head: A measurement of pressure.

Ell: A fitting used to change the direction of a pipe. For PVC and poly irrigation uses they are available in 90 degree and 45 degree bends. Some specialty ells are available in other angles but have limited availability. You can remember ells simply by their shape; they look like an "L". PVC ells are available with threads in both ends, threads in one end and a glued socket in the other, or with glue sockets in both ends. Insert ells come with male threads and barbs, female threads and barbs, glue sockets and barbs, glue spigots and barbs, or barbs and barbs.

Emitter: A term used with drip irrigation. The emitter, or dripper, is a small device that controls the flow going to the soil. A small watering device which delivers water at very low rate (measured in gallons per hour) and pressure at the outlet port. . Emitters come in many different flow rates and styles

Evapotranspiration (ET): The amount of water lost due to evaporation from the soil and transpiration from the plants. ET is used by Smart Controllers to help determine the amount of watering needed by a landscape

External Manual Bleed: A feature which allows an automatic valve to be opened manually (without controller) by releasing water from above the diaphragm to the outside of the valve. Useful during installation, system start-up and maintenance operations.

Female Adapter: A fitting used to adapt from solvent welded PVC to a threaded or barbed connection. Never, ever use a plastic female adapter on anything with metal threads. Never tighten a plastic female adapter with a wrench, hand tighten it only! The female adapter will split if you over tighten it. In plumbing, male parts always fit into female parts.

Fittings: The generic name for the various parts that attach the pipes together. Includes bushings, couplings, crosses, ells, female adapters, male adapters, reducers, and tees. Fittings may be threaded, barbed, soldered, or welded to the pipe. (The glue or cement used on plastic fittings is a solvent which results in a welded joint.) Plastic fittings with threads should never be tightened with wrenches. They should only be hand tighten.

Flow: The movement of water.

Flow Control: A valve which modulates in order to maintain a pre-determined flow rate without drastically altering the pressure.

Flow Sensor: A device which actively measures water flow through a piping system and reports its data to the computerized central control system.

FPT: Female nominal pipe thread.

Friction Loss: The amount of pressure lost as water flows through a system. Synonymous with Pressure Loss.

Gallons per Minute: A measurement of water flow primarily used only in the United States of America.

Gate Valve: Refers to the operating mechanism for the valve, which is a sliding gate which moves up or down to block the flow. Often used as isolation valves. Should never be used as control valves because the gate slides it is very subject to wear, and gate valves wear out fast when used often. Some gate valves use a wedge-shaped gate which holds up better. They are designed for emergency shut-off only.

Globe Valve: A valve 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: Abbreviation for "gallons per minute".

Gravity Flow: The term given a water system that relies on gravity to provide the pressure required to deliver the water. The water source is located at a higher elevation than the water delivery points.

Head: A toilet on a ship. In irrigation short for "sprinkler head”.

Head to Head: In irrigation "head to head" refers to the practice of placing sprinklers so that water from one sprinkler overlaps all the way to the next sprinkler head. This helps to increase overall system efficiency and prevents dry spots in the landscape.

Hydraulics: The science of fluids in motion. As it relates to irrigation there are two sub categories for hydraulics. They are open-channel hydraulics (canals, ditches, streams, rivers, etc.) and closed channel (or closed conduit) hydraulics (pipelines, tanks, etc.).

Hydro-Zone: An area of an irrigation system where all the factors that influence the watering schedule are similar. Typical factors to be considered would be the type of plants, the precipitation rate of sprinklers or emitters, solar radiation, wind, soil type, and slope. See the related term "valve zone".

Impact Drive: A sprinkler which rotates using a weighted or spring-loaded arm which is propelled by the water stream and hits the sprinkler body, causing movement around a circle.

Infiltration Rate: The rate at which water enters the soil, usually expressed in depth of water per hour. (In the United States, usually expressed in inches per hour. Its metric equivalent is centimeters per hour.) Infiltration rate is determined by the type of soil.

Irrigation Efficiency: The percentage of irrigation water which is actually stored in the soil and available for use by landscape as compared to the total amount of water provided to the landscape.

Irrigation System: 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 Requirements: The quantity of water needed by the landscape to satisfy the evaporation, transpiration and other uses of water in the soil. The Irrigation requirement is usually expressed in depth of water and equals the net irrigation requirement divided by the irrigation efficiency. (In the United States, usually expressed in inches per week. Its metric equivalent is centimeters per week.)

Isolation Valve: A valve used for isolating all or part of the irrigation system for repairs, maintenance, or winter shut-down (winterization). Common types of isolation valves are the ball valve, butterfly valve, and gate valve

Lateral: The name given to the pipes which go from the control valves to the sprinklers or drip emitter tubes. Liters per Minute A metric measurement of water flow used worldwide.

Low Head Drainage: Residual flow from low-elevation sprinkler heads in a system after the control valve has been closed.

Main (Mainline): A pipe under constant pressure which supplies water from the point of connection (water source) to the irrigation control valves.

Male Adapter: The fitting used to adapt from solvent weld PVC to a male threaded end. When connecting to metal threads male adapters should be used, so that the plastic male threads screw into the metal female threads. Plastic male adapters work better than plastic female adapters.

Manifold: A group of sprinkler valves that converts a single incoming water line into several outgoing line, each going to a separate zone. A sprinkler valve controls each outgoing line.

Mater Valve: A valve 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. For instance, a full-circle sprinkler discharges twice the flow of a half-circle sprinkler and a quarter-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 PR rate. Spray heads have fixed arcs and are matched by the manufacturer, while rotors offer a choice of nozzles to match the Designed arc pattern.

Microclimatic: The 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 monitors the amount of water present in the soil and modifies the watering schedule accordingly.

MPT: Male nominal pipe thread.

Nipple: The common plumbing term used in the irrigation trade for a short length of pipe, usually threaded on both ends.

Nozzle: It is the part of a sprinkler that the water comes out of. Usually it is a very carefully engineered part to assure a good spray pattern. In most cases the nozzle is removable so that it can be easily cleaned or replaced. With plastic nozzles replacement is generally preferred over cleaning as small scratches in the plastic can cause big problems with water distribution uniformity.

Operating Pressure: The pressure at which a device or irrigation system is designed to operate. The "operating pressure" is the pressure required for the sprinkler head or drip emitter to operate as desired.

Permanent Wilting Point: The point at which plants can no longer extract moisture from the soil and die. Point of Connection (POC) The place where the irrigation sub-main is joined to the water service line.

Potable Water: Domestic or drinking water. It can be used as a source of irrigation water, but once water enters an irrigation system it is no longer considered domestic or potable.

Polyethylene (PE): A plastic used for manufacturing irrigation tubing. "Poly" for short. Poly pipe is almost always black in color, sometimes with a strip of a different color for identification. It is very flexible, and is usually sold in coils of 100 feet or more of tube. Poly pipe is often used in areas where the ground freezes 12" deep or more, and also in mountainous areas that are extremely rocky. Poly pipe uses insert type fittings where a barbed shank is shoved into the end of the tubing. These fittings must be clamped; the barbs alone will not hole the tube on the fitting. Exception- special barbed fittings made for sprinkler risers do not need to be clamped. Also see "PVC" for the most commonly used pipe material.

Poly Vinyl Chloride: The real name for PVC.

Pop-Up Sprinkler Head: A sprinkler head that retracts below ground level when it is not operating

Precipitation Rate: A measurement of water application. The measurement is given in the depth of water applied to the soil. The depth that the water would be if it didn't run-off or soak into the soil. In the USA precipitation rate is measured in inches per hour. In metric countries it is measured in millimeters per hour.

Pressure: The force per unit area measured. (In the United States, usually expressed in pounds per square inch. Its metric equivalent is Bars.) Insufficient water pressure can result in poor sprinkler coverage, while excessively high water pressure may cause misting and fogging leading to water waste.

Pressure Gauge: A device used to measure water pressure. The best pressure gauges are "liquid filled", however most cheap gauges work well enough for irrigation use.

Pressure Head: Measurement of water pressure based on the water depth. Measurement is stated as "feet of head" or "meters of head". One foot of head is the pressure at the bottom of a 1 foot high column of water, which is also equal to 0.433 PSI. So it's really a measure of the weight of water of a given depth. It doesn't matter how much water is present, the pressure head is only determined by the depth of the water. The water pressure at the bottom of a 2" diameter, 20 foot tall water filled pipe is the same as the water pressure at the bottom of a 20 foot deep lake.

Pressure Vacuum Breaker (PVB): A type of backflow preventer.

Pressure Loss: The term given for the loss of energy, in the form of pressure, that occurs whenever water moves through a pipe or any other piece of irrigation equipment. Pressure loss also occurs when water moves uphill against the force of gravity. If the total pressure loss in a piping system exceeds the available static water pressure the water will not flow. In landscape irrigation systems no flow means no grow.

Pressure Regulator: A device which maintains constant downstream operating pressure which is lower than the upstream operating pressure.

Program: The watering plan or schedule that tells the controller exactly when and how long to run each set of sprinklers. Many controllers offer multiple programs which can be useful on sites where different plant groups have different irrigation needs.

PSI: It is the abbreviation for "pounds per square inch".

Puddling: When water gathers in one location, such as at the base of a sprinkler or at a low spot on the site. Can be caused by low-head drainage, over-irrigation, or slow soil infiltration.

Pump: A device which increases the water pressure or moves water. Technically most pumps don't move the water, they increase the water pressure, and the water pressure moves the water. Some pumps, for example a water wheel, actually move the water one bucket full at a time.

Pump Start Circuit: The feature on automatic controllers which supplies 24 VAC, which can be used to activate a pump through an external pump start relay.

Pump Start Relay: Low-amperage or electric switch designed for use with pump start circuits. PVC It is the abbreviation for poly-vinyl-chloride. A type of plastic used to make water pipe. Usually white in color.

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.

Radius: The distance that a sprinkler will throw water. Dependent on pressure and GPM.

Rain Shut-off Device or Rain Sensor: A device which prevents the controller from activating the valves when a preset amount of rainfall is detected.

Rain Delay: Lets you turn the irrigation system off for a specific number of days without having to remember to turn it back on.

Reducer: A fitting used to change from one size pipe to another. Two types are generally available. The first, and most common is the reducer bushing (abbreviated "red. bush." or RB). The reducer bushing fits inside a coupling or other fitting on the large end. The pipe fits into the red. bush. on the small end. The other common reducer is a "bell reducer". The pipe fits inside the reducer on both ends of the bell reducer.

Remote Control Valve: A valve which is actuated by an automatic controller by electric or hydraulic means. Synonymous with Automatic Control Valve.

Retraction: When the pop-up riser of a sprinkler such as a spray head or rotor returns to the case in the ground. Also called Pop-down.

Riser: A length of pipe which has male nominal pipe threads on each end. Usually affixed to a lateral or sub-main to support a sprinkler or anti-siphon valve. May also be used underground to connect system components.

Run-off: Water which is not absorbed by the soil and drains to another location. Run-off occurs when water is applied in excessive amounts or too quickly for the soil to absorb

SCH 40, SCH 80: Means "schedule 40, 80". Sometimes abbreviated "SCHED". A set of standards for pipe diameter and wall thickness used for both plastic and steel pipe. SCH 40 pipe is the standard type used for water pipes sized 1 1/2 and smaller. SCH 80 is a similar standard having thicker walls than SCH 40. Also see "CL 125, 160, 200, 315" for related standards.

Scheduling Coefficient: A numerical expression which serves as an index of the uniformity of water application to a given area within a specific geometric arrangement of sprinklers (e.g., triangular or square). Used to measure the uniformity of landscape irrigation systems.

Service line: The line that supplies water to the home. It will also be the source of water of the sprinkler system.

Shrub Sprinkler Head: A sprinkler head mounted above ground level on a pipe, usually used for watering shrubs.

Shut-off valve: They are used to shut off the water supply to the sprinkler and are installed between the service line and the valve manifold. Gate valve or ball valves are two types of shut-off valves.

Slip Configuration (Slip: A threadless connection which is solvent-welded.

Smart Controller: An irrigation control system that uses weather-based calculations and environmental conditions to determine how much water to apply to a landscape based on the plant water needs.

Socket: A socket is a female connection on a fitting. It can be threaded, or glued, but most of the time the term is used for glued fittings.

Spigot: A spigot is a male connection on a fitting. A spigot fits inside a socket. It can be threaded, or glued, but most of the time the term is used for glued fittings.

Spray Head: A type of fixed spray sprinkler that pops up from underground and waters a set pattern, usually from 4 to 15 feet in range. Used for lawns and shrubbery areas.

Soil Type: The texture and structure of the soil particles which affects its ability to take in and store water for use by plants. Soils range from clay to loam to sand. Clay soils take in water more slowly than loam or sandy soils (lower infiltration rate).

Solenoid: An electromagnet which is connected to a controller and causes the opening and closing of automatic control valves.

Spring: It is A place where the water flows from the ground. In most cases springs are the points at which the underground water table intercepts the earth’s surface, and thus, water flows from the ground. Some springs are the outlets of underground streams or rivers that flow through channels in the ground 2. The coiled metal device that retracts a sprinkler head or helps a hydraulic valve close.

Sprinkler: A hydraulically operated mechanical device which discharges water through a nozzle or nozzles.

Sprinkler heads are devices which distribute water over a given area for irrigation (or to put out fires

Sprinkler Square Spacing The term given to a sprinkler head layout pattern where the sprinklers, when viewed from above, appear as more or less a square with one sprinkler in each corner. See also the more efficient "triangle spacing".

Sprinkler valves: Automatic or manual valves that turn the water on and off to different zones in a system. Automatic valves are the most common type used today and are controlled by a timer. Used in underground sprinkler systems.

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 Water Pressure: The water pressure as measured when the water is not moving. The "not moving" part is critical, if the water is moving it isn't "static".. When measuring static water pressure all the water outlets on the pipe must be closed. So if you're measuring the static pressure at a house you connect the pressure gauge, then take the reading while all the faucets, the ice maker, etc., are turned off. Static water pressure is a measure of the water's energy potential.

Station: A circuit on the controller which activates a single control valve in the irrigation system to control watering for a particular zone.

Stop-A-Matic Valve (SAM): A spring-loaded check valve used beneath a sprinkler to prevent low-head drainage. The check valve feature may also be built into the sprinkler.

Swing Assembly: An assembly of flexible swing pipe and fittings that are used to connect a sprinkler to the lateral pipe. It allows you to easily adjust the sprinklers to grade level and also helps to prevent breakage due to force on the sprinkler.

Swing Joint: A threaded connection of pipe and fittings between the pipe and sprinkler which allows movement to be taken up in the threads rather than as a sheer force on the pipe. Also used to raise or lower sprinklers to a final grade without plumbing changes.

Take-Off: The building industry term for an itemized list of materials used to build something such as a home, deck, or, even an irrigation system! Derived from "taking the list off the plan".

Tee: A tee is a fitting used to branch a side pipe off of a pipeline. A related fitting is the "Y" which is used primarily for sewer pipelines not sprinklers.

Total Pressure Head: The sum of all the factors which increase or decrease the available water pressure.

Transpiration: The process where a plant's moisture is lost to the atmosphere through its leaves.

Triangle Spacing: The term given to a sprinkler head layout pattern where the sprinklers, when viewed from above, appear as a more or less equilateral triangle with one sprinkler in each corner. Triangular spacing results in the most uniform and efficient water application using sprinklers.

Trickle Irrigation: Another name for drip irrigation. Probably a more accurate name since for most drip irrigation systems the water flow is more of a trickle than a drip.

Uniformity: How evenly water is distributed over an irrigated area.

VAC: Volts Alternating Current. Most electric control valves operate on 24 VAC. That's "alternating current", like household electricity, not "direct current" like batteries!

Valve: A device used to control the flow of water. Isolation valves are used to shut-off water for repairs.

Control valves turn on and off the water to the individual circuits of sprinklers or drip emitters. Check valves allow the water to flow in only one direction. Master valves are located at the water source and turn on and off the water for the entire irrigation system when not in use.

Valve Zone It’s an area where the irrigation is all controlled by a single control valve. Each valve zone must be within only one hydrozone.

Velocity: The speed at which water travels. (In the United States, usually expressed in feet per second, Its metric equivalent is meters per second)

Water: An odor-less, tasteless liquid necessary for keeping your garden alive.

Water Budget: A feature of Rain Bird controllers that let you easily change the run times of your sprinklers without having to reprogram the controller. Use water budget to increase or decrease watering in response to changing seasonal needs throughout the year.

Water Company: A private or public entity which provides water, in most cases to properties by means of pipe lines. Some water companies sell water in containers of various sizes

Water Hammer: A damaging shock wave created when the flow of water in a pipe system suddenly stops. Usually the result of a fast-closing valve.

Water Meter: A device used to measure the quantity of water that flows through a pipe.

Water Pressure: The force which is exerted by water. (In the United States, usually expressed in pounds per square inch. Its metric equivalent is Bars.)

Water Table: The top of an underground aquifer or the "groundwater" level. Below the water table the ground is saturated with water.

Water Window: The time of day available when watering can take place on a site.

Watering Days: The specific days of the week on which watering will take place. For example, every Monday, Wednesday and Friday, or every third day.

Well: A ground-water source, usually a whole dug in the ground down to the water table. Some "wells" such as artesian wells are probably better classified as "springs".

Winterization: The process of removing water from an irrigation system before the onset of freezing temperatures. Necessary to prevent damage to the sprinkler system that can be caused by expansion due to freezing water in the pipes.

Wire Gauge: Standard unit of measure for wire size. The larger the gauge number, the smaller the wire.

Working Pressure: The pressure of the irrigation system during operation. Synonymous with Dynamic Pressure.

Zone: A section of an irrigation system served by a single control valve. Zones are comprised of similar sprinkler types and plant material types with similar water requirements and soil types.

Zone circuit: A zone is an area to be watered by the sprinklers connected to one valve.






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