How does a water pump work?
Date: 9 November 2022
Simple, yet effective
Water pumps function in a similar way to how you drink through a straw. When you suck, you create a partial vacuum in your mouth that causes the liquid to get pushed through thanks to the low pressure from the vacuum.
Pumps create this by displacing air with the moving part of the pump, in the case of centrifugal pumps, this is an impeller. This creates a partial vacuum that can be filled with more air, or in this case water.
Pumping Principles
At sea level, there is a constant 14.7PSI being applied to everything. If we placed one end of a tube into a body of water and applied a perfect vacuum to the other side then we could hold a column of water 33.9' vertically.
A perfect vacuum would be formed at 0PSI. Unfortunately, nothing is perfect and we can't create a perfect vacuum, the highest we can lift water is no more than 26' at sea level. This is reduced by 2' for every 1000' of altitude above sea level.
Centrifugal pumps
Centrifugal pumps use an impeller to create a partial vacuum by making the impeller spin in an anti-clockwise direction. This low pressure will draw in water from the inlet and the energy from the impeller will be transferred to it and using centrifugal force the water will be displaced through the outlet pipe.
Applications
| Type of Centrifugal pump | Application | Features |
|---|---|---|
| Canned Motor Pump | Hydrocarbons, chemicals where any leakage is not permitted | Sealless; impeller directly attached to the motor rotor; wetted parts contained in can |
| Magnetic Drive Pump | Sealless; impeller driven by close-coupled magnets | |
| Slurry Pump | Mineral processing, mining, industrial slurries | Designed to handle and withstand abrasive slurries |
| Trash Pump | Draining mines, construction sites, pits | Designed to pump water containing solid debris |
| Multistage Pump | High-pressure applications | Multiple impellers for increased discharge pressure |
| Circulator pump | Heating, air conditioning and ventilation | Inline compact design |
| Chopper/grinder pump | Wastewater in industrial, chemical and food processing/sewage | Impeller fitted with grinding teeth to chop solids |