In this world where we all strive to save energy and develop products that will do just that we also have to be aware of the trade offs that can come with it. In the pump world it means making pumps that can achieve the highest efficiency and use less power to drive them. An example would be a water pump running 24 hours a day in a cooling system at a plant. The difference in the cost of electric power consumed by a pump that is 50% efficient versus one that is 75% efficient could be huge and over time the more efficient pump pays for itself in the energy saved. This would be great if we only pumped clear water all the time.
In the real world we are confronted with many pumping challenges. The liquids may contain solids, which can be heavy or viscous, stringy, abrasive and may even need to be chopped or agitated in order to flow properly. What good is a high efficiency water pump when it becomes clogged with solids and stops pumping?
This is why there are so many different types of pumps designed for specific tasks. While pump manufacturers always want to build pumps that are efficient, making sure the pump does the job is the first priority. When that tank full of waste material has to be moved or that lake needs to be dredged or that sewer needs to be by-passed while repairs take place, using pumps that are practical for the job become more important than the efficiency of the pump.