Velocis Solutions
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info@velocis-solutions.com
CHAPTER 7
PUMPS
CHAPTER 6
VELOCIS SOLUTIONS @2018
1
PUMPS
PUMPS GENERAL CHARACTERIZATION
Pumps are rotating equipment to increase liquid pressure for transporting from one place to
another. There are two categories of pumps: dynamic(kinetic) and positive displacement.
Table 7.1: Pumps classification
Pump selection is made on the flow rate and head required, together with other process
considerations, such as liquid density, viscosity and corrosivity; the presence of solids or entrained
gases in the fluid.
Viscosity have significant effect on performance of centrifugal pumps. For highly viscous fluids
positive displacement pumps are the best choice.
Solid-liquid slurries cause particular problems for all rotating pumps. A special slurry pump with
low speed is supposed to be used.
If the liquid contains small amount of gases, positive displacement pumps are more appropriate.
Since erosion is natural companion of corrosion, lower velocity is essential for highly corrosive
liquids.
The selection of the pump cannot be separated from the design of the complete piping system.
The total head required will be the sum of the dynamic head due to friction losses in the piping,
fittings, valves and process equipment, and any static head due to differences in elevation.
The pressure drop required across a control valve will be a function of the valve design. Sufficient
pressure drop must be allowed for when sizing the pump to ensure that the control valve operates
satisfactorily over the full range of flow required. If possible, the control valve and pump should be
sized together, as a unit, to ensure that the optimum size is selected for both.