INTAKE RATE OR INFILTRATION RATE – The measurement of the speed that water moves into the soil.

LATERAL LINE – Non-pressure pipe running from the valve to the sprinklers.

LOOPED CIRCUIT – A piping system, usually a main line, that closes back on itself in a loop, providing more than one path for the water to flow to the valve(s).

LOW HEAD DRAINAGE – Water left in the pipe after a valve is turned off that is gently flowing out of a low elevation sprinkler head.

MAINLINE – Pressurized pipe running from the point of connection to the zone control valves.

MANIFOLD – A group of valves.

MASTER VALVE – A normally closed valve installed at the supply point of the main that opens only when the automatic system is activated.

MATCHED PRECIPITATION RATE – A system or zone in which all the heads have similar precipitation rates is said to have matched precipitation rates.

NON-VOLATILE MEMORY – A feature in irrigation controllers that will retain the programmed information in electronic memory during a power failure, without the need for a battery.

NOZZLE – The final orifice through which water passes from the sprinkler or emitter to the atmosphere.

PIPE DOPE – Common name for commercial products used to apply to pipe fittings to assist in the appropriate fit of the threaded joints.

PITOT TUBE – A small ell shaped tube which can be attached to a pressure gauge or other measuring device to measure the velocity head of water discharging from a nozzle.

POINT OF CONNECTION (P.O.C.) – Location where irrigation system is connected to a (potable) water supply.

POLY PIPE – Polyethylene pipe is a black, flexible pipe popular for lateral line use in areas susceptible to long freezes in the winter. Soil moves as it freezes, and because poly pipe is flexible, it will hold up to this movement while the more rigid PVC pipe may break. An insert fitting with a hose clamp or a compression fitting is used with poly pipe.

POTABLE WATER – Water that is of known adequate quality to be used for human consumption. Domestic or drinkable water. It can be used as a source of irrigation water if protection is provided to prevent contamination to the domestic supply. Once water enters an irrigation system it is no longer considered potable.

PRECIPITATION RATE – The speed at which a sprinkler or an irrigation system applies water. The common units of measure for precipitation rates are inches per hour or millimeters per hour.

PRESSURE – Measured with a pressure gauge and expressed in pounds per square inch (PSI), bars or kPa. It is the amount of energy available to move water through pipe, valves, sprinklers or other components. Static pressure is the pressure measured when no water is flowing through a closed system. Dynamic pressure is the pressure measured when the system is open, or water is flowing through the system.

PRESSURE AT THE HEAD – When manufacturers discuss pressure for sprinkler use or nozzle performance, they are referring to the dynamic pressure as measured at the base of the sprinkler head.

PRESSURE RATING – The estimated maximum internal pressure that can be continuously exerted in a pipe or container with a high degree of certainty that it will not fail.

PRESSURE REGULATOR – A device that regulates the available pressure to a preset maximum.

PROGRAM – Information the user enters into the controller’s memory that determines when the system will water. A program contains three pieces of information: what days to water, what time to start watering, and how long each zone will water.

PSI – Abbreviation for pounds per square inch.

PUMP – A mechanical device that converts mechanical forms of energy into hydraulic energy.

PUMP START CIRCUIT – The feature on an irrigation controller that allows a connection to be made through a relay, with the pump starter, so the starter will be energized when a watering cycle begins.

PUMP START RELAY – An electronic device that uses a signal current from the irrigation controller to actuate a separate electrical circuit to energize the pump starter.

PVC PIPE – Generally white in color, PVC (poly vinyl chloride) pipe is more rigid than black poly pipe, and requires the use of PVC solvents (glue) for connections. The pipe manufacturers also recommend the use of primer just prior to the application of the solvent to ensure a strong, watertight connection. PVC pipe can be used both as a mainline or as a lateral line.