MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

Chapter 4KineticMethods4.1 IntroductionThe kinetic class of waterlifters comprises a smaller variety of subclassesthan positive displacement devices, but is presently the most widelyused class (where available) for irrigation and drainage. This is primarilydue to its adaptability to most applications and prime movers. The termcentrifugal is commonly used, but erroneously, to denote this entire class--probably because centrifugal pumps were the first devices to develop inthis class (Chapter 1). As the term kinetic implies, this class of pumpsadds energy to the water by the motion of an impeller or, in the case ofjet pumps, the motion of another fluid mass.“Centrifugal” is also commonly used to classify the group of pumpswe have more appropriately labeled rotodynamic (Table 2.2), which includestrue centrifugal pumps as well as three other types. Peripheral pumps areoften given a distinctive subclass (as in the Hydraulic Institute Standards)since they, like propellers, are not true centrifugal devices. However,the use of this rotodynamic subclass (more commonly used in Europe) canbe used to classify all pumps which utilize a high speed rotary (as opposedto positive displacement rotary) motion. The terms velocity, impeller,and rotokinetic are also used occasionally instead of rotodynamic (Lazarkiewiczand Troskolanski, 1965, and Wagner and Lanoix, 1959).4.2 Rotodynamic PumpsAll rotodynamic devices consist of two primary parts; an impeller whichimparts energy by its rotary action, and a casing which guides the fluid to103