Taken from this blog: http://blog.buildingautomationmonthly.com/pumping-systems-101/?subscribe=success#blog_subscription-2
How confusing could this be if unfamiliar with pumps?
Centrifugal Pumps
Centrifugal pumps are the big daddy of pumps (yes, that is a technical term). They have a capacity of more then 100k GPM and can be equipped with variable speed drives. If you need to move a lot of water in a medium pressure environment, a Centrifugal pump is the pump of choice. However you must be aware that a Centrifugal pump is limited in the pressures it supports and it significantly looses efficiency when you utilize it above 1000 psi.
A centrifugal pump utilizes an impeller to pull water into the suction side of the pump. The impeller spins and literally scoops the water up and pushes it out the pressure side of the pump. The action and angle of the impeller is typically engineered for the suction side to be horizontal and the pressure side of the pump to be vertical.
Reciprocating Pumps
While the Reciprocating pump does not have the high flow rate of the centrifugal pump, it makes up for its lower flow rate by having a significantly higher pressure capacity (100k PSIG+). When you need to move dense liquids or you need to pump against atmospheric pressure, you can utilize a reciprocating pump to overcome high pressure scenarios. A Reciprocating pump is great for pressures above 1000 psi that require a medium to low flow rate. Additionally, if you are going to be moving fluids such as oils or other viscous fluids, then you will want to utilize a reciprocating pump. Quite frankly, I can count on one hand the amount of reciprocating pumps I have seen in chiller plants.
A Reciprocating pump is mechanically quite simple. The pump utilizes a piston driven forward inside the cylinder by the motor the action of retracting the piston pulls liquid in the inlet and the contraction of the piston pushes the liquid out the outlet port. The lack of complex parts allows the reciprocating pump to be utilized for many corrosive liquids.
Rotary Pumps
The rotary pump has a low flow rate and does not have a high pressure rate. The rotary pump makes up for its lacking by being a highly efficient pump when it comes to viscous liquids. When you need to move viscous liquids, you can rely on a rotary pump to provide optimal performance. While not very common in central plants, you will see rotary pumps in process control and in some treatment facilities on processed water.
A rotary pump or a rotary vane pump is like most positive displacement pumps in that it positively displaces the water. Unlike a Reciprocating pump, which utilizes a piston, a rotary pump utilizes vanes that trap the water between the two vanes and move the water from the inlet side of the pump to the outlet side of the pump. These pumps are often utilized in situations that require a pump to handle highly viscous fluids that do not high pressure and flow requirements.
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