Select pump definitions are provided in this section. For complete pump design, installation, operation, maintenance, definitions, nomenclature and pump fundamentals for rotodynamic and positive displacement pumps refer to the complete suite of HI pump standards, guidelines and guidebooks at HI's e-store.
Pump is a general term used to describe a device that moves liquids by physical or mechanical action. There are many pump categories, variations and designs that are classified as pumps. Figure 9.0 shows a family tree of pumps covered by Hydraulic Institute pump standards, guidelines and guidebooks. Figure 9.0 Pump Family Tree Diagram
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A rotodynamic pump is a kinetic machine in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor. The most common types of rotodynamic pumps are axial flow, mixed flow, and centrifugal pumps (radial flow). Centrifugal pumps are the most common rotodynamic pump used today because they serve a wide range of applications and have a long history of safe and reliable operation.
Rotodynamic pumps have a variable head/flow profile. When the system head (system curve) is increased or decreased the delivered flow rate decrease and increase respectively as shown in the adjacent link. System Head Figure
A machine that pressurizes a fluid using a collapsing volume action. Examples include piston pumps, rotary pumps (screw, gear, lobe, etc.), and diaphragm pumps. This type of pump has a fixed displacement volume, consequently, the flow rates they deliver are directly proportional to their speed. Due to the fixed displacement volume characteristic, care must be taken to ensure the flow is not restricted. Restriction of the flow can result in pressures in excess of the pump or system design and/or power requirements in excess of the design.
Some applications where positive displacement pumps are most advantageous are:
- Highly viscous process fluid
- Flow rate must be constant or precisely metered
- High pressure low flow
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