Irrigation systems are fairly straightforward but they rely on some common standards and terms, here is our guide to them.


Glossary of common terms

 

Adapter

A fitting that connects fittings and pipe of different sizes or thread types.

Air Gap

A backflow prevention system. An Air Gap prevents water from being sucked, or siphoned, back into the water supply. There is a physical space (vertically) between a discharge pipe and the flood-level rim of receiving vessel. The receiving vessel is open and not under pressure. The air gap must be at least double the diameter of the supply pipe measured vertically above the overflow rim of the receiving vessel. The Air Gap must be 3cm’s or greater. While not always practical, an Air Gap provides the maximum protection available against backflow (and potential contamination of water supply).

Anti-Siphon Valve

An economical irrigation control valve containing an atmospheric vacuum breaker (backflow preventer). This prevents a backflow (siphon) of irrigation water into the main household or commercial water supply. Usually made of brass or plastic, anti-siphon valves are primarily used in residential irrigation systems. They are installed at the beginning of the irrigation zone.

Arc

Portion of a full circle (360) covered by a sprinkler nozzle. Adjustable (variable) arc nozzles can be set from 0 - 360. Spray nozzles are most often designated as Quarter, Half, and Full circle.

Atmospheric Vacuum Breaker

An Atmospheric Vacuum Breaker is a backflow preventer that is installed above the highest point in an irrigation system. It contains a float (air inlet valve) which closes when water is moving in the normal direction, keeping air out of the system. If a siphon begins to form, the float drops to allow air into the system, breaking any potential backflow into the main water supply. Atmospheric Vacuum Breakers should be installed at a minimum of 6" above the highest pipe or outlet in the system.

Automatic Valve

A valve which can be remotely operated either electrically (the most common) or hydraulically. Automatic valves are commonly used as "control valves" for irrigation systems. See also valve and bleed valve.

AWG-UF

Designations for  direct-bury wire used in irrigation installations. The multi-strand wire is run from the irrigation controller to the automatic (electric) solenoid irrigation vales. AWG stands for American Wire Gauge, and it is a standard used for denoting wire conductor diameter. The lower the AWG, the thicker the conductor. UF cable is manufactured with insulated copper conductors in sizes ranging from AWG 14 through 4/0 AWG and with aluminum or copper-clad aluminum conductors in sizes 12 AWG through 4/0 AWG.  

Back Flow

An unintended reverse flow of water from an irrigation system into the main water supply. It is caused by backpressure or a back siphon. Irrigation systems come in contact with many potentially harmful materials including fertilizers, pesticides, bacteria, insects, and animal waste. These contaminates will pollute household water supplies if sucked back in via backflow. 

Backpressure can be created by a pump in the system or when pipe/sprinklers in the zone are at a higher elevation than the point of connection to the water source.   Back siphoning can occur if there is a break in the supply pipe and/or a drop in pressure of the supply line.

Backflow most commonly occurs when there is a temporary sudden loss of pressure from the main water supply.  A properly installed backflow preventer will prevent backpressure or back syphon from impacting the main water supply. 

Backflow Preventer

A device installed on an irrigation system to prevent water in the irrigation pipes from flowing back into the main (household) water supply. Irrigation systems come in contact with many potentially harmful materials including fertilizers, pesticides, bacteria, insects, and animal waste. These contaminates will pollute household water supplies if sucked back in via backflow.

Types of Backflow Preventers

Air Gap: An Air Gap is a backflow prevention system that prevents water from being sucked, or siphoned, back into the water supply. There is a physical space (vertically) between a discharge pipe and the flood-level rim of receiving vessel. The receiving vessel is open and not under pressure. The air gap must be at least double the diameter of the supply pipe measured vertically above the overflow rim of the receiving vessel. The Air Gap must be 3cms or greater. While not always practical, an Air Gap provides the maximum protection available against backflow (and potential contamination of water supply).

Atmospheric Vacuum Breaker (AVB): An Atmospheric Vacuum Breaker is a backflow preventer that is installed above the highest point in an irrigation system. It contains a float (air inlet valve) which closes when water is moving in the normal direction, keeping air out of the system. If a siphon begins to form, the float drops to allow air into the system, breaking any potential backflow into the main water supply. Atmospheric Vacuum Breakers should be installed at a minimum of 6" above the highest pipe or outlet in the system.

Double Check Valve Assembly (DC): A Double Check Valve (or double check assembly) is a backflow preventer containing two positive-seating check valves assembled in series.  A ball valve or gate valve is installed at each end for isolation and testing of each check valve. Small ball valves, called test cocks, provide locations for attachment of testing equipment. The benefit of the double check valve is that it does not need to be installed above the highest head or pipe in the irrigation system. It can be installed underground in a valve box.

Ball Valve

A simple control or shut-off valve containing a rotating ball, with a hole in the middle of it, that controls the flow of water . When the valve is open, the hole is aligned with the flow of water. When the valve is closed (or rotated toward the closed position), the hole is rotated out of open alignment and the water flow is restricted or completely shut off.

Barbed Fitting

A drip irrigation coupler, elbow, tee, or emitter with a barbed end. Barbs fit into holes punched in drip tubing. Barbs have ridges designed to hold the fitting in place.

Bleed Valve

Used to manually turn on an automatic valve. a bleed valve is located on or near the top of the valve. It can be a small screw, a lever, or built into the solenoid. When turned, the bleed valve allows water to flow out of the cavity over the internal diaphragm of the valve. This causes a pressure differential and opens the valve.  If the bleed valve is an external type, a small stream of water will flow from the bleed valve and outside of the valve while it is on. An internal bleed will keep the water inside the valve and empty it into the downstream side of the valve.

Booster Pump

A pump used to increase the water pressure for a household and/or irrigation system. Where water pressure is low or fluctuating, a booster pump is used to maintain strong, even water pressure.

Branch Line

In a drip irrigation system, a branch (or lateral) line attaches to the mainline tubing and carries water from the main line to the plant zone. It is usually 16mm or 4mm tubing.

Bubbler

Used for deep watering of trees and shrubs. Bubblers are generally installed on 4cm risers, on a per-plant basis, and bubble water only a short distance from the device. A "flood bubbler" is designed to flood irrigate. A "spider bubbler" or "stream bubbler" sprays "fingers" of water that can reach up to 50cm feet and is good for watering trees and shrubs.

Bushing

Usually a PVC fitting, a bushing connects pipes and fittings of different sizes. Also called a reducer bushing, it often has male and female ends. They can be found as slip, threaded, or slip x thread fittings.  

Check Valve

An in-line, one-way valve that allows water to flow in one direction only. The valve contains a spring that closes the valve until the water pressure increases to a level greater than the force of the spring. A check valve prevents water from flowing back toward the water source. They are used in sprinklers, irrigation systems and sump pump outflow pipes. 

Compression Fitting

Fittings used to connect lengths of 16mm and 20mm tubing. The tubing is simply inserted into the compression fitting.  

Controller

Also referred to as a timer, an irrigation controller is an electronic, programmable device that controls the timing of automatic electronic valves in an irrigation system. The valves control the flow of water to sprinklers and drip systems. The controller sends electricity (low voltage) to the valve on the day and time set in the controller schedule and for the duration programmed by the user.

Coupler

Also called a coupling, it joins fittings and pipe of like size together. Couplers may be threaded, barbed or compression. Connecting unlike items is called “adapting” and uses adapters.

Cross

A fitting that connects four sections of pipe at one point forming a cross.

Cubic Feet

A measurement of volume, depicted by a cube 1 foot high, 1 foot wide, and 1 foot deep. This measurement is commonly used to determine required materials for landscaping, gardening, and construction. (1 cubic foot is 1728 cubic inches). To determine cubic feet: • Measure the length and width of the space. • Measure the height or depth of the space. • Multiply length x width x height.  All of your measurements must be in the same units before multiplying. To convert cubic inches to cubic feet, divide cubic inches by 1728 (12 in x 12 in x 12 in). You can also convert inches to feet before you multiply by dividing each measurement by 12. (12 inches/foot). Cubic Meters A measurement of volume, depicted by a cube 1 meter high, 1 meter wide and 1 meter deep. To determine cubic meters: • Measure the length and width of the space. • Measure the height or depth of the space. • Multiply length x width x height.  All of your measurements must be in the same units before multiplying. 1 meter is 3.28 feet. To convert cubic meters to cubic feet, divide cubic meters by 35.23 (3.28 ft x 3.28 ft x 3.28 ft). You can also convert meters to feet before you multiply by dividing each measurement by 3.28.

Cut-Off Riser

Poly cut-off risers contain multiple sets of threads that can be cut-off to the desired height. Use a PVC pipe cutter, hacksaw, or utility knife to cut off a nipple section. Make your cut at the top of the thread section. Teflon tape is not required on poly cut-off risers.

Cycle

A complete run of all stations programed to operate on an irrigation controller.

Diameter

In irrigation, diameter is used to reference two things:

1. The measurement across the circular opening of a pipe. Note that both Inside Diameter and (ID) and Outside Diameter (OD) are often referenced. This is especially important when choosing drip tubing as there are at least five different sizes that could be called "1/2 inch drip tubing" on the market.

2.The Diameter of Throw for full-circle spray nozzles, rotors, drip emitters, and micro spray caps. Diameter of Throw The average diameter of the area covered by a full-circle sprinkler operating in a wind-free environment.

Diaphragm

The diaphragm is a flexible rubber membrane inside an automatic irrigation valve, between the upper chamber of the valve and the smaller valve inlet (water supply). When the valve is closed, both the upper chamber of the valve and the valve inlet are filled with water. Since the upper chamber is larger, a greater surface area of the diaphragm is covered with water than on the inlet side. This water pressure differential keeps the valve closed. When the solenoid is electronically activated, it releases water from the upper chamber above the diaphragm. This reduces the water pressure above the diaphragm and allows it to rise and open the valve. Water will now flow through the valve. A spring inside the valve pushes against the back of the diaphragm, but it does not exert much force on the diaphragm. It would stay closed without the spring.

Direct-Bury Wire

The most common direct bury wire for irrigation systems is multi-strand wire. Insulated, colored-coded wires are wrapped together in a black insulating jacket. Direct-bury wire is available in various wire thicknesses and number individual wires (called "conductors") bundled together. When wiring irrigation valves with direct-bury wire, each valve gets one wire and all valves share one common wire. For example, If you have three valves underground in a valve box, you will need to run 4-strand direct-bury wire from the irrigation controller to the valves in the valve box. If you anticipate adding more valves in the future, install direct-bury wire with more strands. Use waterproof connectors when connecting wire to irrigation valves. Distribution Tubing See micro tubing.

Double Check Valve Assembly

A Double Check Valve (or double check valve assembly) is a backflow preventer containing two positive-seating check valves assembled in series.  A ball valve or gate valve is installed at each end for isolation and testing of each check valve. Small ball valves, called test-cocks, provide locations for attachment of testing equipment. The benefit of the double check valve is that it does not need to be installed above the highest head or pipe in the irrigation system. It can be installed underground in a valve box.

Downstream

An irrigation term referring to pipe, fittings, sprinklers, etc. that are away from the water source in the direction of the water flow.

Drip Irrigation

Drip irrigation is a watering method that delivers water to plants slowly at the roots. It is also known as trickle or micro-irrigation. Where typical pop-up sprinklers spray water into the air and onto plants, drip irrigation systems combine flexible poly drip tubing and drip emitters (or drippers) to both conserve water and save money. Drip systems are not affected by wind and will greatly reduce evaporation and runoff common with traditional irrigation systems.

Drip irrigation is the perfect solution for raised beds, vegetable gardens, and potted plants. 

See also emitter, barbed fitting and poly pipe

Drip Tape

Commonly used by commercial growers, drip tape is a thin-walled dripline with inline emitters pre-installed at preset spacings. The tape is flat and expands when filled with water. It is a great product for row crops and vegetable gardens. 

Drip tape fittings use a twisting mechanism rather than compression or barbed fittings like conventional drip tubing.

Drip Tubing

Also called "Poly Tubing" or "Poly Pipe" it is a common term for Polyethylene pipe. a flexible, black tubing used for drip mainline and drip micro tubing. It is most commonly available in rolls of 25mtrs, 50mtrs or 100mtrs.

The inner diameter (ID) and outer diameter (OD) varies. We stock tubing with a 13mm inner and 16mm outer compatible with our barbed fittings.

Dripper

See emitter

Dynamic Water Pressure

Also known as working pressure or operating pressure, the Dynamic Water Pressure is the measure of water pressure with the irrigation system running. The dynamic water pressure will drop below the static water pressure when the system is turned on.

Elbow

An L-shaped fitting used in irrigation. to make a 90 or 45 degree turn in an irrigation or drainage line. Elbows (also called "Ells", "90s", or "45s") can be found in a variety of materials including PVC, polyethylene, galvanized steel, and copper. They may be threaded, slip, barbed or in combinations thereof.    

Elevation

It is important to consider changes in elevation when designing an irrigation system. If a particular zone has high and low spots, the water pressure will vary at those locations. This is of particular concern with drip systems, which operate at lower pressure than most sprinkler systems. Water pressure is represented in Bars or Pounds per Square Inch (PSI).  

Emitter

Also called a dripper, an emitter distributes water droplets at a specified flow rate when used as part of a drip irrigation system.

Drippers come in a variety sizes, styles, and flow rates. They have barbed or threaded bases. Barbed ends are either poked into 16mm tubing or inserted into the end of 4mm tube. Threaded bases are screwed into micro tubing stakes and risers. Drip Emitter Tubing comes with emitters pre-inserted in the tubing. It can be purchased in both 16mm sizes with drippers spaced at 33cm intervals.

Inline Emitters are use to create custom emitter tubing when used with 4mm solid drip tubing.

Pressure Compensating Emitters distribute a consistent flow rate regardless of fluctuations in pressure. Non-Pressure-Compensating Emitters will distribute varying flow rates as pressure fluctuates with elevation changes.

Staked Emitters sit on a spike and may distribute water in a spray or stream.

Multi-Outlet Emitters can be installed onto existing sprinkler rises as part of a sprinkler retrofit project. 4mm tubing is installed on the emitter outlets and run to individual plants.

Emitter Tubing

Also called dripperline, emitter tubing has emitters injected into the tubing as it is extruded. The tubing comes with emitters evenly spaced at 33cm center.

It is useful in row crops, vegetable gardens and evenly-spaced tree and shrub plantings. It is available in 16mm tube size.

Female Adapter

Adapters connect parts of unlike size, threads, or connection type. A female adapter has internal threads or slip fitting.

Fertigation

Applying fertilizer to plants through an irrigation system.

It is commonly used in drip systems with vegetable crops. Fertilizer is injected into the system so that the nutrients are mixed with water and delivered to all plants on that specific watering zone. Fertilizer is applied in small amounts early in the crop's season, as they begin to leaf out. The dosage is increased as the crop begins to produce fruit and nutrient requirements increase. 

The application of fertilizer is decreased as plants near the end of their growth cycle. Filter A filter contains a screen that is designed to remove particles from irrigation systems. Filters are critical components in a drip irrigation system.

Drip emitters may clog if proper filtration is not provided. Typical screen mesh is 120, 150, and 200 mesh. The greater the number, the smaller the openings in the screen. 200 mesh is recommended for foggers (misters).

Fittings

The common name for parts that connect irrigation parts and pipe. These include elbows, tees, couplers, crosses, male adapters, female adapters, swivel adapters, control valves, reducers, bushings, street elbows. They may be threaded, slip, barbed, compression, or a combination thereof.

Flow Control Valve

An in-line valve that allows a section of the watering zone to be turned off.

This is especially handy in drip systems when watering raised flower or vegetable garden beds. Install a control valve for each bed. If a particular bed does not get planted, simply shut off the control valve until it is planted and ready to be irrigation.  Install small 6mm flow control valves when adding drip irrigation to flower pots. The control valve allows you to adjust the flow to the pot or shut it off completely if the pot is empty.

Flow Rate

The movement of water through pipe, fittings, valves and generally measured in litres per hour. You will need to know the flow rate when planning an irrigation system. It is the key factor when determining the maximum number of zones or emitters per zone. Once you know your flow rate, you know the maximum amount of water available for your system. Keep that in mind when adding up the output (flow) of sprinklers or drip emitters that you are considering for your system.

Funny Pipe

See swing pipe.

Gate Valve

A manual on/off valve designed to be used in either the open or closed position and not meant to control or regulate flow in an irrigation system. It is best used as a back-up shut-off valve in case of line breaks. The internal mechanism, as the name implies, is a "gate" which slides up and down as the handle is turned and the valve is opened or closed.

Gear Drive Sprinkler

See sprinkler.

Goof Plug

Also called mistake plugs, goof plugs are used in drip irrigation to plug up small holes in mainline drip tubing. They are also used as end caps in 6mm drip micro tubing. It is always good to keep a handful of goof plugs on hand.

Gravity Drip Irrigation

A drip irrigation system that is that gravity fed. Water is placed into a raised container so that gravity will provide enough pressure to cause water to flow down to the drip emitters. Drip tape and non-pressure-compensating emitters are best used with a gravity fed system because both can operate at very low flow rates with low pressure.

Head Spacing

The space between sprinkler heads.  

Head-to-Head Coverage

The concept of spacing sprinklers so that each sprays water to the base of the nearest sprinkler (or sprinklers). Most sprinklers will perform best with head-to-head coverage. Designing for head-to-head coverage will ensure that you have no dry spots due to lack of water.

High Density Polyethylene (HDPE)

A black plastic used to make irrigation pipe, valves, and fittings. Hole Punch A device used to poke a hole into solid drip poly tubing for the insertion of drip emitters (drippers).

Hose Bibb / Hose Tap

A Hose Tap is a manual valve attached to the main water line and found at most homes and some commercial buildings. It has male hose threads and is designed to accommodate the connection of a garden hose. 

Hydro-Zone

The concept of planning your irrigation watering zones based on plant needs and micro climate (shade, sun, etc.). 

Hydro Zones include tree zone, shrub zone, sunny zone, shade-plant zone, succulent zone, etc. Degining an irrigation sytem with hydo zones allows you to modify the water distribution to plants of similar sizes, water needs, sun exposure etc.

ID

Abbreviation for Inside Diameter of pipe.

Impact Drive Sprinkler

See sprinkler.

In-Line-emitter

There are two types of inline emitter (or inline dripper):

1. Emitters that are inserted into drip tubing as it is extruded to make a drip irrigation product call emitter tubing or dripperline.

2. Emitter with barbed ends that can be used to make custom-sized emitter tubing

Injectors

Used to inject liquid fertiliser and other nutrients into a drip irrigation system. It actually a vacuum that sucks the fertiliser into the irrigation system. A pressure differential between the inlet and outlet of the injector creates a vacuum inside the fertigation device creating the suction.  Fertiliser is then "injected" into the drip system.  

Internal Bleed Valve

Used to manually turn on an automatic valve. a bleed valve is located on or near the top of the valve. It can be a small screw, a lever, or built into the solenoid. An internal bleed will keep the water inside the valve and empty it into the downstream side of the valve.

Irrigation Efficiency Irrigation Schedule

Refers to the programming of an irrigation controller. The irrigation schedule accommodates the needs of various plant types and locations on a property.

For example, large trees may require the slow, deep watering of a drip system for an hour or more. Trees may only need to be watered once per week (or less). At the same time, a lawn with a conventional sprinkler system, may need to be watered twice a day during the hot summer months. Start times are also important. If you can water during the early or late parts of the day, less water will be lost to evaporation. Clay soils are more compacted than loamy or sandy soils. Capillary action between clay particles bind the soil and may cause irrigation water to pool and run-off. In that case, you would schedule frequent waterings for short durations in areas where the soil is predominantly clay. All of these variations can be accommodated given a little thought and planning and the proper irrigation controller.

Lateral Line

Used to describe branch lines in an irrigation system, usually run from the main supply line in a particular zone. It is run from the main line to the drip emitters or sprinklers, and is not under constant pressure. Lateral lines are only under pressure when the zone is running. 

LCD

Liquid Crystal Display, often found in irrigation controllers. See also Controllers.

Litres Per Hour

A metric measurement of water flow, often found on flag emitters.

Litres per Minute

A metric measurement of water flow.

Looped Circuit

Generally used in mainline applications, a looped circuit is one that closes back onto itself and provides water to valves from more than one route.

Main Line

With standard irrigation systems using MDPE, the main line (or main) usually refers to the pressurized pipe that carries water from the water source (point of connection) to the irrigation control valves. With drip irrigation, the 16mm poly supply line is often referred to as the mainline or "drip main line".

Male Adapter

Adapters connect parts of unlike size, threads, or connection type. A male adapter has external threads on one end and a slip fitting on the other.

Manifold

A grouping of irrigation valves, often in a valve box, that send water to multiple watering zones. A street elbow made from high-density polyethylene (HDPE) and used to make swing joints and swing joint assemblies. See also swing joint

Master Valve

Master valves are electric valves used in irrigation systems to control main line water flow to a manifold (group of irrigation valves). The master valve is wired to the irrigation controller and is installed upstream from the manifold on the mainline. It is activated just before the irrigation zone valves. Since it is turned off when the system shuts down, it will reduce water loss if there is a leak in one of the zone valves. This is convenient if manifold valves need repair as the master valve shuts off water supply to the manifold.

Matched Precipitation Rate

When all the sprinkler heads in an irrigation zone have similar precipitation rates, that zone has matched precipitation rates. For example, when selecting nozzles for pop ups, the precipitation rate for the full circle (360°) nozzle should be roughly four times that or the same nozzle in a quarter spray (90°). The half circle (180°) should have a precipitation rate that is roughly double that of the quarter spray. To avoid areas of over or under watering within a zone, be sure to match the precipitation rates of the nozzles, rotors, impact heads, etc.

Meter Wrench

A T-handled tool for opening and closing residential water meters. The wrenches are long-handled since the meters are underground in valve boxes.

Micro Irrigation

See drip irrigation

Micro Spray

Micro spray covers a category of spray caps, bases, one-piece, and adjustable sprayers that are small and designed to operate with drip irrigation systems. They can be used in flower and vegetable gardens and landscapes when you need to water a large area. Caps and bases are combined for a variety of patterns, diameters, and flow rates. They are colour coded to indicate pattern and flow rate.

Micro Sprinkler Micro sprinklers (also called Rotary Micro Sprayers or Spinners) are a rotating mini sprinkler that is installed on drip tubing. They operate at low pressure (20 psi is ideal), and can cover an area up to 5mtrs in diameter.

Micro Tubing

Sometimes called "Spaghetti Tubing", 4mm ID / 6mm OD micro tubing can be used as main line for small deck/flower-pot installations, but is more often used as a lateral line coming off a 16mm poly supply line (main line).The micro tubing carries water to emitters (drippers), and micro sprays. Also referred to as "Distribution Tubing" it is available in polyethylene or, the more flexible, vinyl.  We caryy Rain Bird Micro tubing which is a blend of both poly and vinyl.

Mist Irrigation

Uses misters or foggers, installed on a drip irrigation system, to create a misty spray or fog. It is recommended that you used drip regulators of 45 psi or higher in order to generate finer water droplets.

Mulch

Mulch is a 2 - 6 inch layer of dried material that is spread onto the soil near plants. Common mulch materials include shredded bark and dried leaves. Used with drip irrigation systems, a layer of mulch will both extend the life of drip tubing and components and help retain water in the soil. 

Multiple Start Times

A common feature found in irrigation controllers that provides for a zone to be watered at multiple times on the same day. This is helpful when shallow rooted plants (like grass) are planted during hot summer months and require frequent waterings. Clay soil particles are tightly bound and can easily cause run-off.

Multiple start times allow you to prevent run-off by watering clay soils more often but for shorter durations, giving the water time to soak in before flowing away. Non-Potable Water Water that is not suitable for drinking.

Non-Pressure-Compensating

Non-Pressure-Compensating Emitters. The output will vary with changes in elevation and pressure. These non-pressure compensating drippers are best used where the watering zone is level. Some non-pressure-compensating drippers are used with gravity-fed drip systems. They operate best at lower pressures. Recommended Pressure for most non-p-c emitters: 15-20 psi.  

Nozzle

The orifice attached to the top of a sprinkler that determines the pattern and the distance of the spray that comes out of the sprinkler. Many nozzles require (or come with) a small filter that drops down into the sprinkler. The flow rate for the sprinkler is often determined by the nozzle size and pressure at the sprinkler head.

OD

Abbreviation for Outside Diameter of pipe. Orifice The opening in a valve, pipe, tubing, fitting, nozzle, spray nozzle, or micro spray fitting. It determines the flow rate through that part.   Percolation Rate The rate at which water moves through soil.

pH

A measure of acidity or alkalinity.

Pipe Dope

A chemical sealant (sometimes containing Teflon) that is used to seal pipe-threaded fittings. It has the consistency of a thick paste and is commonly white or yellow. It not only creates a water-tight seal, but it also helps the fittings thread together more easily. 

Poly Vinyl Chloride (PVC)

A type of plastic used to make pipe and fittings for irrigation. It is most often white but is also found in gray, brown, tan, and purple. These colours represent either the type of water being transported (e.g. purple represents reclaimed water) or pipe thickness (grey represents "Schedule 80" pipe thickness). It can become brittle with prolonged exposure to sunlight, so it is commonly buried.

Polyethylene (PE)

A very common plastic used for manufacturing irrigation tubing and fittings. High Density Polyethylene (HDPE) is the type of Polyethylene used to make pipes and fittings for water.

Pop-Up Sprinkler

See Sprinkler.

Potable Water

Water that is safe for drinking. 

Precipitation Rate

The rate at which a sprinkler head delivers water to an area, measured in inches per hour or millimeters per hour. It is important to ensure that water distribution is as even as possible in a given area.

Pressure

With respect to irrigation, pressure is a measurement of the force of water within an irrigation system or main line, usually expressed in bars or pounds per square inch (PSI). It is the force that moves (or has the potential to move) water through valves, pipes, fittings, sprinklers and emitters. 

Static Pressure is measured when the system is closed and no water is flowing through it.

Dynamic Pressure is measured when the system is open and water is flowing through. Flow and pressure affect each other.

Drip irrigation operates at pressure generally lower than most household water pressure.

Pressure Compensating

Pressure Compensating Emitters. The output will not vary with changes in elevation and pressure. Pressure compensating drippers deliver the stated l/hr even if pressures range from 10-50 psi. These pressure compensating drippers are best used with elevation changes. Pressure compensating drippers are self-flushing to reduce clogging.

Pressure Regulator

A device that lowers water pressure on the downstream side and maintains a constant operating pressure. Regulators are commonly used in drip irrigation applications as drip tubing and fittings are usually rated to operate at pressures lower than most household water systems. Always install a regulator after a valve and filter. They are not designed to be operated under constant pressure.

Pressure Vacuum Breaker

See backflow preventer.

Programmme

The process of entering watering information into a controller (or the information itself). The programmme will include the days to water, watering start times, and watering duration for each zone.

PSI

Pounds per Square Inch. A measurement of water pressure. One atmosphere is approximately 15 psi.

Pump

A mechanical device used to move water. A centrifugal pump is commonly used for irrigation systems.

Common Pumps Used in Irrigation and Drainage Applications:

Centrifugal Pump: Uses centrifugal force, has an internal impeller.Includes multi-flow, multi stage, radial flow, verticle turbine, and booster pumps.

Jockey pump: A small pump used in  multi-pump systems.

Submersible (sump) pump: Pump and motor are both submerged under water. Commonly used in drainage systems.

Pump Efficiency

The ratio of the water power produced by the pump to the power used by the pump to create that water power. It is expressed as a percentage or decimal.

Pump Start Circuit

A feature on many irrigation controllers that starts the pump which provides the water pressure to the irrigation system. It works in conjunction with a pump start relay.

Pump Start Relay

The pump start relay is an electronic device that uses a signal current from the irrigation controller to activate a pump to provide water to the irrigation system. It is only needed for irrigation systems using a pump to pressurise the irrigation system.

PVC Pipe

Irrigation pipe made from PVC (poly vinyl chloride).

Quick Coupling Valve

Often made of brass, it is an underground valve that is under constant pressure and designed to provide a quick water connection. A hollow, tubular coupler key is inserted in the quick coupler and turned to lock it into place. A garden hose is often connected to the key.

Radius of Throw

The distance from the sprinkler head to the farthest point of spray. Used in specifications for nozzles and spray heads with circular spray patterns.

Rain Delay

A feature on an irrigation controller which allows the user to delay watering for a period of time. The controller resumes its watering schedule once the delay period has ended.

Rain Gauge

A device used to measure rainfall. It can be as simple as a graduated cylinder on a stake or as sophisticated as a wireless, digital, self-emptying device with memory and temperature readings. Electronic sensors can be connected to irrigation controllers and suspend watering as needed.

Rain Sensor

A micro-switch weather-sensing device which measures rainfall. The sensor connects directly to the irrigation controller and stops the watering cycle when precipitation provides sufficient water for plant growth.

Rain Sensor Bypass

A feature on some irrigation controllers which allows the user to bypass a rain sensor (or soil moisture sensor) and use the controller. 

Reducer

Also called a "reducer bushing", this fitting is used to increase or decrease pipe/fitting size. They come in threaded, slip or a combination thereof. The bushing threads or slips into the larger fitting or pipe, allowing it to accommodate the smaller size.

Regulator

See pressure regulator.

Riser

Also called a nipple, a riser is a section of pipe which usually has male pipe threads on each end. It is often threaded into the bottom of a sprinkler and into a threaded fitting below ground. They are available in a variety of materials. Some have cut-off sections which allow you to fine tune the height of the sprinkler when installing.

Root Zone

Also called the "root depth" it is the area where most of a plant's rooting activity takes place. It is important to understand the pattern and depth of a plant's root zone when irrigating as water and nutrients must penetrate into this zone for the plant to obtain the greatest benefit. The maximum root zone can be affected by soil moisture, compaction, and profile.

Rotary Spray

A micro sprinkler that distributes large droplets of water and is best used for coverage of large areas (up to 5 mfrs).

Rotor Sprinkler

A gear-driven sprinkler head. See also sprinkler

Run Time

The length of time that a watering zone, or entire program, runs on an irrigation controller.

Runoff

Water that does not permeate the soil and instead flows away from the irrigated area. Runoff also occurs when sprinklers over spray planted areas an hit hard surfaces like concrete or pavement.

Shrub Adapter

An adapter fitting that attaches to a 1/2" riser and accepts a spray nozzle. The riser stands above ground and often extends above the shrub to provide for adequate spray coverage.   It is used in ground cover and shrub areas.

Shut-Off Valve

Generic name for a manual valve used to shut off the supply to an irrigation system. Usually a ball valve or gate valve, shut-off valves are installed on the main line near the main point of connection.

Solenoid

An electromagnet that is an integral part of an irrigation control valve. It is wired to an irrigation controller and facilitates the opening and closing of the valve. It operates at 24 Volts AC to pull a small plunger up from inside the valve. That action allows water to flow in over the internal diaphragm and open the valve.

Spider Bubbler

A stream bubbler that sprays individuals streams of water in full circle, half circle, and end strip patterns. It is screwed onto a half inch riser and is good for watering trees and shrubs..

Sprinkler

Also referred to as a "sprinkler head" or simply a head.

A sprinkler is a watering device that sprays water in fine or stream sprays when the irrigation system is under pressure. Sprinklers come in many sizes, shapes, and distribution types. Most sprinklers have removable or adjustable nozzles that control the pattern and distance of the spray that comes out of the sprinkler.

Some common sprinkler types:

Gear Drive Sprinkler (or Rotor): A gear box drives the smooth movement of this higher-end sprinkler.

Impact Drive Sprinkler: A spring-loaded arm is pushed by the stream of water exiting the sprinkler nozzle. This impact moves the adjustable sprinkler in a circular pattern.

Spray Head: A stationary spray head with a fixed nozzle attached to the top. Common in shrub applications.

Valve-in-Head:   Each sprinkler has a control valve integrated into the design. These large sprinklers are often used in golf course applications.

Pop-Up Sprinkler :  A below-ground sprinkler that pops up when pressurised. It has a fixed nozzle attached to the top. Common in turf (lawn) applications.

Static Water Pressure

Water pressure that is measured when the system is closed and no water is flowing through it, as opposed to Operating (or Dynamic) Water Pressure. Static Water Pressure is easily measured with a simple hose-thread pressure gauge found at DIY stores. Simply screw the gauge onto a hose tap and open the tap all the way. Read the pressure on the gauge.

Station

A station is a single circuit on an irrigation controller. It contains the watering schedule run-time information for an electric solenoid valve. The station corresponds to a watering zone, which may be a group of sprinklers or a drip irrigation system.

Subsurface Drip Irrigation

A method of placing drip emitter tubing (dripperline) underground and applying water directly to the root zone. Most emitter tubing is NOT designed to be buried under ground. Root intrusion can be a problem when burying drip tubing. Check with the manufacturer of the tubing before considering installing it under the soil.

Swing Assembly

Swing assemblies protect sprinklers from damage. They provide flexibility so that pipes or risers do not break when a sprinkler head is run over or stepped on. Pre-assembled swing assemblies make it easy to place sprinklers precisely where you want them.

Swing Joint

A flexible joint made from threaded Marlex elbows and threaded PVC fittings. The threaded elbows are designed to take the impact from foot traffic. If the sprinkler is accidentally kicked, the threads allow the head to move without breaking. Swing joints also allow for fine-tuning of the final placement of the sprinkler head, without the need to cut and glue PVC pipe.

Swing Pipe

Sometimes called "funny pipe", swing pipe is a flexible irrigation pipe that works at high pressure (up to 80 psi). It uses barbed fittings and requires no glue. Swing pipe is an ideal solution for high-traffic areas where vehicle or foot traffic may damage sprinkler heads.

Swivel

An irrigation adapter fitting with a female hose thread connection. A hose washer is required to make a water-tight seal.

Take-Off List

A list of materials needed for a project. It facilitates pricing and ordering parts. To create a take-off list write down the names of all the potential fittings and pipes that you may need for the project.   Walk around the location and mark down the number of fittings and pipe sections needed. Total the parts and pipes. You are now ready to price out and order your materials.

Tee

A T-shaped pipe fitting used to create a branch (or lateral) line from another. They come in a variety of materials and connection styles.

Transpiration

The loss of water by a plant through its leaves, flower parts, stems, etc. Transpiration makes up about 10 percent of the moisture found in the atmosphere.

Triangular Spacing

The method of staggering the spacing of sprinklers so that they form a triangle pattern. This creates a spray overlap that provides the most efficient coverage of the irrigation area.

Union

A three-piece pipe fitting, similar to a coupler. The difference is that a union can be taken apart again if needed. It consists of three parts: two threaded sections that are attached to two lengths of pipe, and a threaded ring that joins the two. 

VAC

Volts Alternating Current. Most irrigation controllers operate on 24 VAC and send 24VAC to the electric control valves in the field. 

Valve

A manual or electric irrigation device used to control the flow of water. These valves fall into two main categories:  

1. Shut-Off Valves.

Generally  installed on the main water supply to control the flow of water to the irrigation control valves and or to prevent the flow of water back into the main water supply. Gate Valve: A manual on/off valve that uses a "gate" mechanism to drop a metal plate into place when the wheel handle is turned. This should only be used for emergency shut off and not regular on/off usage. Ball Valve: A rotating ball opens and closes the valve. Water passes through a hole in the center of the ball. It and is a better choice for regular usage. In fact, hose end timers (for drip irrigation) use ball valves as the internal mechanism. Check Valve: Many Backflow Preventers are check valves. Quick Coupler Valve: Often made of brass, it is an underground valve that is under constant pressure and designed to provide a quick water connection.  

2. Irrigation Control Valve.

Also called remote control valves, they operate at 24VAC and are wired to an irrigation controller.  With the exception of anti-siphon valves, they are usually placed underground in valve boxes. Backflow Preventers are installed prior to the irrigation control vales to prevent back siphonage.  Globe Valve: Inlet water comes into the  from underneath and leaves the valve at a 90 degree angle. Angle Valve: Inlet water comes in from one side of the valve and leave the valves on the opposite side (in a straight line) Anti-Siphon Valve: An electric valve with a built-in atmospheric vacuum breaker. They must be placed 12: above the highest point in the irrigation system in order for the valve to successfully prevent backflow of water into the household water supply. Hydraulic Valve: Uses water pressure (modified via small flexible tubes) to operate the valve. Master Valve: Electric valve used in irrigation systems to control main line water flow to a manifold (group of irrigation valves).

Valve Box

A rigid plastic container which covers and protects underground irrigation valves. It has an access lid for valve maintenance.

Volume

The volume of water flowing through irrigation pipe.  It is often expressed as a flow rate [e.g. gallons per minute (gpm), gallons per hour (gph) cubic feet per second (ft3/s), cubic meters per hour (m3/h), liters per minute (l/m), or liters per second (l/s)]. 

Water Meter

A device used to measure the flow of water.

Water Table

Upper level of the sub-surface water zone (groundwater).

Winterization

The process of removing water from irrigation pipes fittings, sprinklers, and drip emitters to protect them from freezing water in winter. As water turns into ice and expands, it can crack pipe and fittings and damage other irrigation components.

Wire Irrigation

systems using electric valves and controllers will use low-voltage direct-bury wire or two-wire systems to power the valves.

Wire Gauge

A method/standard for denoting wire size. The larger the gauge number, the smaller the wire.

Xeriscaping

A landscape design technique that utilizes drought tolerant and native plants to create a finished product that requires no regular irrigation.  

Y Ball Valve

A 2-outlet ball valve that allows for connection of garden hose and drip system from the same hose tap.

Zone

Also called a watering zone, a "zone" is an individual watering area controlled by a single irrigation valve. It may be a group of sprinklers or a drip irrigation system. When designing an irrigation system, plan individual zones so that each contains plants with similar watering requirements. Watering zones should also consider micro climate factors like amount of sun exposure vs. shade, and design elements like sidewalks and driveways. With proper planning, you can create zones that allow flexible programming on your irrigation controller.