Vocabulary Terms Flashcards
Irrigation Tech Terms
Air Gap
A complete physical separation between the free flowing discharge end of a potable water supply pipeline and an open or non-pressure receiving vessel.
Atmospheric Vacuum Breaker (AVB)
An assembly containing an air inlet valve, a check seat and an air inlet port. The flow of water into the body causes the air inlet valve to close the air inlet port. When the flow of water stops the air inlet valves falls and forms a check against back siphonage. At the same time it opens the air inlet port allowing air to enter and satisfy the vacuum. This device cannot be under constant pressure (more than 12 hours). It must be installed at least 6” higher than all downstream piping and the highest downstream outlet. No back pressure may exist. No shut off valves may be installed down-stream of the AVB.
Backflow Prevention
The mechanical prevention of reverse flow, or back siphonage, of non-potable water from an irrigation system into the potable water source.
Backpressure
any pressure, regardless of its source, against the outlet side of the backflow prevention device, which exceeds the supply pressure against the inlet side of the device. Examples: pressure caused by gravity due to elevation differences; a pump installed in the system; or steam and/or air pressure.
Backsiphonage
A form of backflow due to negative or sub-atmospheric pressure within a potable water system.
Cross-connections
an actual or potential connection between a potable water source and an irrigation system that may contain contaminates or pollutants, or any source of water that has been treated to a lesser degree in the treatment process.
Design Pressure
The pressure that is required for an emission device to operate properly. Design pressure is calculated by adding the operating pressure necessary at an emission device to the total of all pressure losses accumulated from an emission device to the water source.
Double Check Valve Backflow Prevention Assembly (DCVA)
Backflow Prevention assembly using two shut off valves and two check valves assembled and pre-tested at the factory, designed to physically prevent the backflow of water. May be used only in non-health hazard conditions.
Dynamic Pressure
The pressure of water as it is moving through the system. Also referred to as “working pressure”.
Emission Device
Any device that is contained within an irrigation system that is used to apply water. Common emission devices in an irrigation system include spray and rotary sprinkler heads, and drip irrigation emitters.
Head radius
Head spacing. Spacing of heads that is equal to the published radius.
Health hazard
a cross-connection or potential cross-connection with an irrigation systems that involves any substance that may, if introduced into the potable water supply, cause death or illness, spread disease, or have a high probability of causing such effects.
Irrigation Plan
A scaled drawing of a landscape irrigation system which lists required information, scope of the project and represents the changes made in the installation of the irrigation system.
Lateral Piping/ Lateral lines
The piping after the remote control valve that is not subject to constant main line pressure.
Main Line
The portion of piping, normally under constant pressure, located between the water source and remote control valves or quick coupler valves.
Maintenance Checklist
A document made available to the irrigation system’s owner or owner’s rep that contains info regarding the operation and maintenance of the irrigation system, including but not limited to: checking and repairing the system, setting the automatic controller, checking the rain or moisture sensor, cleaning filters, pruning grass and plants away from irrigation emitters, using and operating the irrigation system, the precipitation rates of each irrigation zone within the system, any water conservation measures currently in effect from the water purveyor, the name of the water purveyor, a suggested seasonal or monthly watering schedule based on current evapotranspiration data for the geographic region, and the minimum water requirements for the plant material in each zone based on the soil type and plant material where the system is installed.
Master Valve
An automatic or manual valve installed at the supply point, which controls water flow into the system main line piping. If a master valve is installed, it must be installed after the backflow prevention device.
Double Check Valve Backflow Prevention Assembly (DCVA)
Backflow Prevention assembly using two shut off valves and two check valves assembled and pre-tested at the factory, designed to physically prevent the backflow of water. May be used only in non-health hazard conditions. Do not confuse a DOUBLE check valve with a DUAL check valve. Although a dual check has two check valves like a double check, it is not an approved form of backflow prevention for irrigation systems.
Non-potable Water
Water not suitable for human consumption.
Precipitation Rate
also known as application rate. The rate at which water is applied by the irrigation system. It is usually measured in inches per hour. The following formula is used to figure precipitation rate. GPM( full circle head) x 96.3 divided by Head spacing x Row spacing OR total GPMx 96.3 divided by total area.
Pressure Compensating Spray Head
A spray head used in a method of maintaining a constant discharge pressure regardless of inlet pressure.
Pressure Differential Relief Valve
A valve that will open when the inlet pressure exceeds a pre-set pressure.
Flush Valve
Flush valves are used primarily in drip irrigation systems. The flow rates for drip systems are usually very low and, as a result, sediments can accumulate on the bottom of the drip tubing due to the slow velocities. A flush valve is a point on the drip line that can be opened to increase the flow of water and the velocity. A ball valve, gate valve or a capped off section of tubing can serve as the flush valve. The flush valve should be installed as far as from the water’s entry point as possible.
Head/Sprinkler Head
sprinkler heads can be broken down into three categories: spray, bubbler and rotary. Many people are familiar with these types of emission devices. When designed properly, a sprinkler system can be fairly efficient, however, high evaporation and run-off are always a problem with these systems due to the fact they project water through the air.
