Centrifugal pumps velocity head

A centrifugal pump operates in this particular system with a total head against mean velocity curve represented by the equation... 

The centrifugal pump operates over a very wide range of flows and pressures. For low heads but high flows the axial pump is best suited. Both the centrifugal and axial flow pumps impart energy to the fluid Iw the rotational speed of the impeller and the velocity it imparts to the fluid. 

Centrifugal pumps are dynamic machines, which means that they convert velocity into feet of head. 

The impeller is the working part of a centrifugal pump. The function of the impeller is to increase the velocity or kinetic energy of the liquid. The liquid flows into the impeller, and leaves the impeller, at the same pressure. The black dot shown at the top of the impeller in Fig. 23.6 is called the vane tip. The pressure at the vane tip is the same as the pump s suction pressure. However, as the high-velocity liquid escapes from the impeller and flows into the volute, its velocity decreases. The volute (which is also called the diffuser) is shaped like a cone. It widens out in the manner illustrated in Fig. 23.7. As the liquid flows into the wider section of the volute, its velocity is reduced, and the lost velocity is converted—well, not into pressure, but into feet of head. 

A centrifugal pump is defined in the glossary at the end of this chapter as a machine in which a rotor in a casing acts on a liquid to give it a high velocity head that is in turn converted to pressure head by the time the liquid leaves the pump. Other common nomenclature relating to the construction and performance of centrifugal and related kinds of pumps also is in that table. 

Centrifugal pump consists of a rotor (impeller) in a casing in which a liquid is given a high velocity head that is largely converted to pressure head by the time the liquid reaches the outlet. 

A centrifugal pump consists of a casing in which revolves an impeller, that is a wheel carrying a number of suitably shaped vanes. The centrifugal force sets up a static head in the casing and a certain velocity is imparted to the liquid. With the discharge valve closed only the static head is noticeable and can be... 

PUMP PRIMING. Equation (8.21) shows that the theoretical head developed by a centrifugal pump depends on the impeller speed, the radius of the impeller, and the velocity of the fluid leaving the impeller. If these factors are constant, the developed head is the same for fluids of all densities and is the same for liquids and gases. The increase in pressure, however, is the product of the developed head and the fluid density. If a pump develops, say, a head of 100 ft and is full of water, the increase in pressure is 100 x 62.3/144 = 43 (2.9 atm). If the pump is... 

CENTRIFUGAL PUMP - Pump which produces fluid velocity and converts it to pressure head. 

---