GLOSSARY Much terminology is used in irrigation. The most commonly-used terms are defined here. Aquifer A water-bearing soil formation or group of formations having sufficient permeability to yield useable amounts of water to wells. Axial flow pump Pump design used for low-head, high flow conditions, also called a propeller pump. This design does not use centrifugal action (see Centrifugal Pump) to move water. Rather it uses the principle of a wedge. Water is physically forced through the pump by the rotating propeller. See page 61. Booster pump A pump used for providing a medium to high discharge pressure. Usually used for pumps supplying sprinkler or micro-irrigation systems. Bowl The bowl, also called the pump housing, is the stationary part of the pump and often contains guide vanes to convert the rotation energy into pressure. Bowl efficiency Efficiency of the pump by itself (as opposed to combination of the pump driver and transmission system). It is difficult to determine bowl efficiency in the field. An estimation can be made by subtracting out other losses associated with the pumping station such as the power plant and transmission efficiencies. Capacity The flow rate of a pump. It is generally used when referring to the normal (or required design) flow rate of the pumping station. towards the pump discharge. The increase in flow area converts the velocity achieved through centrifugal action into pressure. Check valve A valve installed in a pipeline that automatically closes and stops water from flowing backwards when a pump is shut off. This is also called a non return valve Chemigation The application of pesticides or system maintenance products through an irrigation system. Chlorination Periodic injection of chlorine compounds into wells to prevent the growth of bacteria and slimes. Also used when referring to injection into irrigation systems, most often micro-irrigation systems. Corrosion Deterioration and destruction of metal by chemical and/or galvanic reactions. Chemical corrosion dissolves the metal, which is then carried away by the water. Chemical corrosion can allow sand to enter the well. Galvanic corrosion is caused by electrolytic cells forming between dissimilar metals or surfaces. CO2 footprints A carbon footprint has historically been defined as the total set of greenhouse gas (GHG) emissions caused by an organisation, event, product or person. This is typically calculated as a carbon dioxide equivalent (CO2e), using the relevant 100-year global warming potential. For simplicity of reporting, it is often expressed in terms of the amount of carbon dioxide. Cavitation The rapid formation and collapse of air bubbles in water as it moves through a pump. This results from too high a vacuum in the pump itself due to insufficient “net positive suction head.” Cavitation causes pitting of the impeller and pump housing and can greatly degrade pump performance. See page 61. Centrifugal pump A pump in which water enters the center of a rotating impeller and is flung out radially, gaining energy in the process. This is also a term commonly used for a specific type of pump where the impeller is enclosed in a volute casing. A volute casing is a type of casing where the area of water flow increases uniformly Daily crop water use (evapotranspiration – ET) This is the net amount of water extracted from the soil daily by the crop and surface evaporation from the soil. Data bus This is also called a fieldbus and refers to the family of industrial computer network protocols used for real-time distributed control. An automated industrial system (e.g. a manufacturing assembly line) usually needs an organised hierarchy of controller systems to function. In this hierarchy there is usually a Human Machine Interface (HMI) at the top, where an operator can monitor or operate the system. This is typically linked to a middle layer of programmable logic controllers (PLC) via Ether-
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