Pumps simplify the transportation of water and other fluids, making them very useful in all types of buildings - residential, commercial, and industrial. For example, fire pumps provide a pressurized water supply for firefighters and automatic sprinklers, water booster pumps deliver potable water to upper floors in tall buildings, and hydronic pumps are used in HVAC systems that use water to deliver space heating and cooling.
There are many pump designs, but most types can be classified into centrifugal and positive displacement pumps. This article will provide an overview of each pump type, comparing their performance features.
Centrifugal Pumps
A centrifugal pump uses an impeller, which has curved blades that accelerate the fluid outward when rotating. Impellers are normally driven by an electric motor or combustion engine, and their movement produces suction at the pump inlet, pulling water inside.
Based on the type of water flow they produce, centrifugal pumps can be classified into three sub-types. The flow pattern is determined by both the impeller shape and the pump’s construction.
Centrifugal pumps are the most common type since they are suitable for handling water and relatively easy to manufacture. These pumps also tend to have a lower price, since mass production has brought down their manufacturing cost.
Make sure the pumping systems in your building are professionally designed.
Positive Displacement Pumps
Positive displacement pumps move a fixed amount of fluid at regular intervals. They are built with internal cavities that fill up at the suction side, to be discharged with higher pressure at the outlet. Based on how fluid is displaced, positive displacement pumps can be reciprocating or rotary.
How Do Centrifugal and Positive Displacement Pumps Compare?
Both pump types move fluids in a specified direction, but accelerating a fluid continuously is not the same as displacing it in fixed amounts. As a result, there are important performance differences between both pump types.
When pumps are driven by an electric motor, a variable frequency (VFD) can achieve major energy savings, by reducing motor RPM when the full pump speed is not required. However, you must make sure to check compatibility: some pumps are incompatible with VFDs, while others allow speed control above a minimum RPM value.
VFDs and other pump controls can be combined with NEMA Premium Efficiency motors to achieve the lowest possible operating cost.
Conclusion
Pumps have multiple applications, and they are widely used in residential, commercial, and industrial buildings. As a result, a wide variety of pump designs has been developed. However, variety can also lead to confusion, and using the wrong pump for an application can cause energy waste or even equipment damage.
To ensure that all your building systems use the correct pump types, the best recommendation is to work with qualified MEP engineers. They can also help you integrate VFDs and other control features during the design phase, saving thousands of dollars in power bills over time.
Meet building codes and save on water bills with a professional plumbing design. has an 80% first-time design approval rate - write at info@ny-engineers.com or dial .
