Definition of pump is machine that is widely used to flow incompressible fluid from low place to higher place or low pressure to higher pressure. When viewed from pressure that generates fluid energy, pump can be classified into two types:
- Static Pressure Pump
- Dynamic Pressure Pump
Centrifugal pumps are included into the type of dynamic pressure pump. Centrifugal pumps have impeller that serves to lift fluid from low place to higher place or flow fluid from low pressure to higher pressure.
Power from outside is supplied into the shaft to rotate impeller in pump house, so fluid around impeller will also be spun as a result of encouragement impeller blades. Because of centrifugal force occurs, the fluid flows from center of impeller exit through channels between impeller blades. Fluid head will be greater because the fluid is accelerated. Fluid coming out of impeller will be accommodated by channel-shaped volute around impeller and fluid is channeled out by pump through nozzle, in the nozzle fluid flow velocity is converted into pressure head.
Characteristics of centrifugal pumps are determined by quantities such as capacity, high-pressure fluid, properties or state of suction side, power which is needed to rotate pump, rotary speed, and efficiency. The amount of power which is needed by centrifugal pumps is function of coupling that is given by motor that can be measured by several methods, such as by using brake dynamometer, weirmeter and Prony brake method.
In the process for setting the capacity of a pump installation or change the characteristics (setting by opening the valve) can be done, but this applies if the deviation required capacity of the nominal capacity is only valid within a short time, and when the engine power needed to pump drive capacity smaller become increasingly down (reduced and not increased up).
Setting capacity of pump installation or change characteristics of pump by setting opening valve can be done. However this can be performed when deviation of capacity which is required form nominal capacity is within short time and when the engine of power which is needed to pump is smaller and only need small capacity.