Comprehensive reading What is a Centrifugal Pump?

Centrifugal pumps are usually quick to install, require less maintenance than other alternatives, and the most standard centrifugal pumps are easy to repair. Centrifugal pumps are usually the best choice for lower viscosity (thin) liquids and high flow rates. Multi-stage centrifugal pumps have more than one impeller, and are used for applications that require higher pressure or head.

Piping connections on centrifugal pumps are available with standard pipe threads on smaller sizes, and flanges on larger sizes. The normal drivers supplied with centrifugal pumps are A.C. induction motors, but some pump manufacturers offer pumps with D.C. drives or adaptable to other power transmission devices such as engines and gear boxes.

How does a Centrifugal Pump work?

A centrifugal pump works by directing the liquid in the system into the suction port of the centrifugal pump and from there into the inlet of the impeller. The rotating impeller moves the liquid along the spinning vanes, which increases the velocity energy of the liquid. The liquid leaves the impeller vanes and then moves into the pump volute or diffuser casing, where the high velocity of the fluid is converted into high pressure through a diffusion process. The fluid is then guided into the discharge port of the centrifugal pump and from there out into the system, or on to the next stage in the case of a multi-stage centrifugal pump.

What is an axial flow pump?

An axial flow pump is a type of centrifugal pump that uses an impeller with vanes that direct the flow axially. In this way, they differ from most other centrifugal pumps, which direct the flow more radially. In general, axial flow pumps create less pressure (head) than radial flow centrifugal pumps, but they can produce much higher flow rates.

How do axial flow pumps work?

An axial flow pump usually consists of an impeller with a few number of vanes, typically only three or four vanes. The vanes are oriented in such a way that the pumped fluid exits axially (i.e., in the same direction as the shaft), rather than radially (90 degrees from the shaft). The impeller is normally driven by an electric motor. The axial orientation of the impeller vanes produces very low head as the liquid is pumped. 

An axial flow pump may generate only 10 to 20 feet of head, much lower than most other types of centrifugal pumps. Axial flow pumps are sometimes called propeller pumps, because the axial flow impeller looks similar to a boat propeller. Some types of axial flow pumps can have their flow and head adjusted by altering the pitch of the impeller vanes.

What is a gear pump?

Gear pumps are considered rotary positive displacement pumps. Gear pump are most common type of positive displacement pump.  Like all positive displacement pumps, gear pumps are fixed displacement pumps, meaning that an unchanging volume of liquid moves through at a constant rate provided the pump speed is constant.