A pump is a device that is used to transfer fluids and gases using mechanical and physical actions. They have been in use for centuries, from the simple Egyptian ‘shadoof’, which was used in agriculture for irrigation, to the complex and technologically advanced pumps of today, which have their applications in diverse areas, from being used in submarines and even human implants.
Pumps are omnipresent, and are one of the most widely used machines in the world. Even the human heart is a kind of pump, pumping blood through blood vessels throughout the body. Several different types of pumps are used in various day-to-day and industrial activities, such as agriculture/irrigation, power plants, sewage and waste recycle plants, oil rigs, as well as cars, air-conditioning and refrigeration systems, etc. Because of such varied usage, they come in all shapes and sizes. They are capable of handling very high volume and can withstand very high pressure as well. It would be difficult to imagine life without pumps, they are the lifeline and backbone of the industrial world.
There are mainly three different kinds of pumps, the positive displacement pumps, gravity pumps, and direct lift pumps. Piston pumps and Diaphragm pumps use the Positive Displacement technique. They trap liquids and then force them into a pipe, which helps in transferring the liquids. Positive displacement pumps can be further divided into two classes:
- Reciprocating: These pumps have an expanding hollow chamber on one side from where the fluid is sucked in, and a collapsible chamber on the other end from where the fluid is discharged.
- Rotary: These pumps transfer fluids using the rotation principle. When the pump shaft inside rotates, it creates a vacuum which then draws in the fluid.
| Piston Pumps | Diaphragm Pumps |
| Definition | |
| The piston moves back and forth inside a cylinder, which pushes the liquid out of the cylinder. The soap dispenser so commonly used is an example of this kind of pump. | Use diaphragm and check valves to push a liquid out. Liquid can move only in one direction. Sewage handling pumps are an example of diaphragm pumps. |
| Characteristics | |
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| Types | |
Axial Piston Pumps Multiple cylinders are arranged within a cylindrical block, each in turn attached to a rotating shaft. These kinds of pumps are used in torpedoes and earth-moving machines. Radial Piston Pumps |
Hydraulic Diaphragm Pumps In these, the diaphragm acts as a divider between the fluid that needs to be pumped and the fluid that is pumped. The arrangement of pistons in such pumps makes them suitable for use in transferring highly inflammable or explosive liquids. Air-operated Diaphragm Pumps |
| Advantages | |
| Can be highly efficient and require low maintenance. | Can handle all kinds of liquids, ranging from the most viscous to the highly corrosive sorts. |
| Disadvantages | |
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Thus, depending upon the application involved, a piston pump or diaphragm pump can be used accordingly, keeping in mind the density of fluids and manufacturing costs involved.