ABSORPTION RATE - The rate at which a soil will accept water. Rate decreases as soil "capacity" is reached. (Also called percolation rate)

ACTUAL HEAD PRESSURE - Is defined as static pressure less all pressure losses.

ANTI-SIPHON DEVICE - Any device that introduces air into the system to prevent "back siphonage". See definitions for atmospheric vacuum breaker or pressure-type vacuum breaker below.

APPLICATION RATE Rate at which water is applied by sprinkler heads in a certain pattern. It is usually measured in inches per hour or gallons per hour/gallons per day.

ARC - The degrees of coverage of a sprinkler from one side of pattern to the other. A 90 degree arc would be a quarter circle sprinkler.

AS-BUILT-PLAN - A corrected or redrawn plan showing the ma!actual scaled location of all major components of the system and other information owner might require.

ATMOSPHERIC VACUUM BREAKER - A backflow prevention device which introduces air into piping system to prevent back siphonage. No back pressure can exist for proper operation. Cannot be under constant pressure for more than 12 hours. Must be installed 6" higher than highest sprinkler head.

AUTOMATIC CONTROL VALVE - An electric or hydraulic remote control valve in a sprinkler system which is activated by an automatic controller. Also called a section valve, zone valve, or remote control valve.

AUTOMATIC SYSTEM - An irrigation system which will automatically cycle (water) according to a preset program.

AWWA - Abbreviation for American Water Works Association.

BACK PRESSURE - Any condition that could create pressure in the non-potable piping system greater than in the potable water system. Pressure caused by gravity due to elevation differences is an example.

BACK SIPHONAGE - A form of backflow due to a negative or sub-atmospheric pressure within a potable water system.

BACKFLOW - Reverse flow of water in a piping system.

BACKFLOW PREVENTION DEVICE - Any approved device which prevents backflow or back siphonage by the introduction of air, use of check valves, or a combination of both principles.

BLOCK OF HEADS - A section of sprinklers controlled by one valve.

BODY OF HEAD - The exterior case or shell of the sprinkler.

BOOSTER PUMP - A pump which is installed in the water supply line and is designed to raise the pressure in the irrigation system.

BUSHING - The method of adapting a fitting to either a larger or smaller size.

BY-PASS - A relief valve designed to vent excess pressure or excess flow.

CHECK VALVE - A valve which permits water to flow in one direction only.

CLASS OF PIPE - A method by which PVC pipe is grouped according to the working pressure. Pressure rated with a wall thickness in direct ratio to the diameter. All sizes in that class have the same working pressure. (Class 160, Class 200, Class 315). See definition for S.D.R.

CONTROL WIRES - The wires which transmit the signals to open and close from the automatic controller to the automatic electric valves.

CONTROLLER - An automatic timing device, electro mechanical, digital or a combination of both, which signals the automatic valves to open or close according to a prescribed program.

COUPLER KEY - A bronze tube with a handle which insets into a quick coupling valve for supplemental water. May be fit with a hose swivel or faucet. See definition for "Quick Coupler Valve".

CYCLE - Refers to one complete operation of a controller through all pro- grammed stations.

DESIGN - The graphic or dimensional location of sprinkler heads, piping, valves, backflow prevention device, etc, used to show the assembly of component parts of an irrigation system.

DESIGN PRESSURE - The sum total of the desired head pressure added to the total of all pressure losses. A stated pressure indicating the minimum pressure required if the system is to operate properly.

DIAPHRAGM - That portion (flexible membrane) of an automatic valve which regulates the passage of water through the valve.

DIRECT BURIAL WIRE - Any wire approved by the National Electric Code for direct underground burial without conduit. UL approved requires a minimum insulator thickness of 4/64". UF 14 is the smallest UL approved wire at this time.

DISTRIBUTION CURVE (OF A SPRINKLER HEAD) - A curve showing the rate of water application by a sprinkler at various points along the radius in inches per hour.

DOUBLE CHECK VALVE ASSEMBLY - Backflow prevention device using two gate valves and two check valves assembled and pretested at the factory designed to physically block the backflow of water. Also called a double gate/double check assembly.

DRAIN VALVE - An automatic or manual valve used to drain water from a line.

DRIP IRRIGATION - The slow application of water to the specific root zone area of the plant material using very low pressure.

DRY LINE SHOCK - The shock which occurs when a section valve is opened and the water travels unrestricted in empty lateral piping. Air in piping is quickly voided through heads allowing velocities which would not normally occur. Damages heads and piping.

DUAL PROGRAMMING - The feature on some automatic controllers that allows two different watering schedules or programs.

ELEVATION GAIN - Pressure gained as water is used downhill from its source. It is figured at the pressure gain rate of .433 pounds per square inch for each foot of elevation-lost.

ELEVATION LOSS - Pressure lost as water is used uphill from its source. It is lost at the rate of .433 lbs. for each foot of elevation gained.

EMITTERS - A mechanical device to limit water flow to a drip or slow trickle. Discharge rate in gallons per hour rather than gallons per minute.

EVAPORATION - The natural process of changing water into vapor.

EVAPOTRANSPIRATION - The combination of evaporation and transpiration from plant material.

FIP - Abbreviation for "Female Iron Pipe".

FLOW - The movement of water in a piping system.

FLOW CONTROL VALVE - A valve that can be mechanically adjusted to restrict flow and thus discharge pressure.

FLOW RESTRICTIONS - Physical restrictions in a piping system that effect the flow of water causing a pressure loss.

FLUSH FLOW - The higher initial momentary flow through a drip or trickle system required to flush emitters before pressure compensation occurs.

FOOT-HEAD ("FEET OF HEAD") - A measure of pressure equivalent to .433 lbs. per square inch and equal to weight of I foot of water.

FRICTION LOSS - Pressure loss due to friction as water flows through the component parts of a system.

G.P.M. - Abbreviation for "gallons per minute".

GATE VALVE - Manual valve with straight through.flow using wedge type metal-to-metal or restricting partial seating surfaces. Not suitable for throttling section flow. Not suitable for section valves in an irrigation system.

GLOBE VALVE - A valve which uses a rubber or composition seat against the valve body used to restrict or stop the flow of water. Can be either straight through or angle configuration.

GAUGE (WIRE) - Standards used for wire sizing. The larger the gauge number, the smaller the wire.

HAZARD - Irrigation system with no back pressure on backflow device is rated as "low hazard". With fertilizer injector system is rated as a "high hazard" and Reduced Pressure Principle backflow device should be used.

HEAD TO HEAD SPACING - Spacing of heads is approximately equal to the published radius (plus or minus 5%). Spacing most frequently recommended by manufacturers of rotary heads for triangular spacing.

HYDRAULICALLY CONTROLLED - A system which uses water pressure through tubing to operate remote control valves.

INSERT FITTINGS - A fitting which fits into pipe. Usually used on poly- ethylene pipe and tubing.

IPS - Abbreviation for "Iron Pipe Size".

LATERAL PIPING - Piping after the remote control valve not subject to constant main line pressure.

LOOP MAIN LINE - A looped main line is a main line designed to provide water to any valve from two or more directions.

MAIN LINE - That portion of the piping under constant pressure located between the water source or remote control valves or quick coupler valves.

MANUAL SYSTEM - A system where control valves are operated manually and/or by hand.

MASTER VALVE - An automatic or manual valve installed at the supply point which controls water flow into the system mainline piping.

MIP - Abbreviation for "Male Iron Pipe".

NON-POTABLE WATER - Water not suitable for human consumption.

NORMALLY CLOSED VALVE - An automatic valve through which no water will flow unless external influences are applied to cause the valve to open. All electric valves are "normally closed type.

NORMALLY OPEN VALVES - An automatic valve through which water will flow unless external influences are applied to close the valve. All hydraulic valves are "normally open" type.

NOZZLE TREE - Refers to the interchangeable nozzle assortment, with different G.P.M. provided with many plastic gear driven heads.

P.O.C. - Abbreviation for "Point-of-Connection.

P.S.I. - Abbreviation for "Pounds-per-Square-Inch".

P.V.C. PIPE - Abbreviation for unplasticized PolyVinyl Chloride pipe.

POLYETHYLENE PIPE - Abbreviation for black, flexible plastic pipe which uses insert fittings for flexible connection between lateral pipe and head. Poly Nipple is semi-flexible threaded nipple used between lateral pipe and fittings.

POTABLE WATER - Treated water which is meant for human consumption. It can be used for irrigation systems as long as protection is provided to prevent contamination of the domestic supply.

PRESSURE COMPENSATING - A valve feature which maintains a constant discharge flow regardless of inlet pressure.

PRESSURE LOSS - The loss of pressure under flow conditions caused by friction or elevation.

PRESSURE RATING - A method of controlling the wall thickness of PVC pipe so all sizes of pipe in a "class" have the same pressure rating. See definition for S.D.R.

PRESSURE RELIEF VALVE - A valve which will open when the inlet pressure exceeds a preset pressure.

PRESSURE TO DESIGN TO - A general rule of thumb used in system design equal to the low static pressure less 10%-allowance for fluctuation.

PRESSURE VACUUM BREAKER - A backflow prevention device that introduces air into the system to prevent "back siphonage". Incorporates the use of a spring loaded seat for positive opening to atmosphere. Will operate under constant pressure. Commonly used for high hazard application with no back pressure.

PUMP CIRCUIT - The optional switch on some automatic controllers which energizes a pump starter when controller operation begins.

QUICK COUPLING VALVE - A constantly pressurized valve set vertically in the ground to provide supplemental water when a coupler key is inserted and turned one and a quarter revolutions.

R.P.P.,RPZ, OR R.P. - Reduced pressure principle backflow prevention device commonly used for high hazard applications. Uses a combination of check valves and an air chamber or zone which is open to-atmosphere.

RECORD DRAWING - A drawing of installed irrigation system showing the location of major components either scaled on the drawing or shown by dimension not to scale.

S.D.R. - Abbreviation for "standard dimension ratio". Relates to wall thickness of Class PVC pipe. S.D.R. 26 equals Class 160; S.D.R. 21 equals Class 200; S.D.R. 13.5 equals Class 315. No wall thickness can be less than .060 inches.

SADDLE - A type of fitting which attaches around the pipe. A hole is drilled through the pipe to furnish water to the outlet of the saddle which is usually threaded F.I.P.

SLEEVES - Piping or conduit under hardscape provided for irrigation system piping or wiring. Generally sized 2 sizes larger than irrigation piping required.

SCHEDULE PIPE - PVC pipe that has the same physical dimensions as iron pipe. Smaller sizes have higher working pressure than larger sizes. Example: Schedule 40 and Schedule 80.

SLIP FITTING - A smooth wall male or female fitting solvent welded to PVC pipe rather than screwed on a thread.

SOLVENT - A material which causes a partial dissolving of PVC pipe and fittings so that a chemical fusion occurs between the pipe and fitting.

SOLVENT WELDING - The act of chemically fusing pipe and fittings together using solvent and cement. Incorrectly called or referred to as glueing.

SPACING - The triangular or square distance between sprinkler heads.

STATIC PRESSURE - The pressure of water when it is not moving.

SURGE - An energy wave in pipe lines caused by sudden opening or closing of valves. See definition for "water hammer".

SWING JOINT - A series threaded nipple and elbow connections between the lateral 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 final grade. See definition for "Polyethylene Pipe".

THREADED FITTING - A fitting which has I.P.S. threads to receive the standard threaded pipe or fitting.

TRANSPIRATION - The process of plant material giving off water vapor from the leaves.

TUBING SPAGHETTI - Small tubing used in drip or trickle systems to carry water from emitter(s) to a specific plant.

UNIFORMITY OF APPLICATION - A general term designating how uniform the application of water is between heads.

VALVE IN HEAD - Indicates that the automatic control valve is part of the sprinkler.

VELOCITY OF WATER - The speed at which water travels.

WATER HAMMER - A shock wave created by a fast closing valve.

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