Vacuum Pumps are those devices which remove gas molecules from a sealed environment or chamber. This creates a partial vacuum in that environment.
History of the Vacuum Pump
The vacuum pump was first invented by Otto von Guericke in 1650. The apparatus was then built by Nikola Tesla. This apparatus used a Sprengel pump to create a high amount of exhaustion, which helped create a high degree of vacuum.
The vacuum pumps which were built before 1980 often contained a mixture of many dangerous PCBs or Polychlorinated Biphenyls. It was discovered that these PCBs are very toxic and are also carcinogenic (can cause cancer). They were also found to be organic pollutants.
Types of Vacuum Pumps
There are broadly 3 types of vacuum pumps. They are:
Positive Displacement Pumps - These pumps expand a cavity and allow the gases to flow out of the sealed environment or chamber. Then they seal the cavity and cause it to exhaust it to the atmosphere. These pumps are most useful for creating low vacuums. Examples are: Diaphragm Pump, Piston Pump, and Scroll Pump.
Momentum Transfer Pumps or Molecular Pumps - These pumps use high speed dense fluids or high speed rotating blades to remove gas molecules from the sealed environment or chamber. These pumps are often used along with Positive Displacement Pumps to create high vacuum chambers. Examples are: Turbomolecular Pump and Diffusion Pump.
Entrapment Pumps - These pumps catch gases in either a solid or in an absorbed state. These pumps are used along with Positive Displacement Pumps and Molecular Pumps to create ultra high vacuum chambers. Examples are: Ion Pumps and Cyropumps.
Industrial Vacuum Pump Uses
Due to their specific functions, different types of vacuum pumps find their uses and applications in a variety of industrial environment. These are:
The production of electric lamps and vacuum tubes where the device is left evacuated and is then re-filled with a specific gas or a mixture of gases.
Medical processes needing suction.
Semiconductor processing such as ion implantation, dry etching, and in the deposition of PVD, ALD, CVD and PECVD.
Analytical instrumentation to analyze solid, liquid, gas, surface and bio materials.
Vacuum coating for decoration, energy saving and durability.
Mass spectrometers to create ultra high vacuum levels between the ion source and the detector.
Medical Applications such as Radiotherapy, Radiopharmacy and Radiosurgery.
Normally two or more different types of vacuum pumps are used either in parallel or in series to create a high level of vacuum. It is quite difficult to achieve a high level of vacuum because the materials used must be capable of withstanding the high amount of heat and pressure generated during the process of vacuum generation.
Therefore, materials such as greases, oils, plastic and rubber gaskets which are used to seal the chambers where vacuum is to be created must be such that they will not boil away or produce any gases while the process occurs. To do that, many times the surfaces of the chamber which are to be exposed to vacuum creation are heated at high temperatures so that all the absorbed gases are removed.
Alternatively, some vacuum creation systems use liquid nitrogen to cool the chambers to temperatures below room temperature so that the residual out gassing is shut down while running the Cyropump system at the same time.
Vacuum pumps have also found their uses in power mechanical devices. In a diesel engine automobile, such a vacuum pump is usually fitted on the engine, on the camshaft. In gasoline engine automobiles, the effect similar to a vacuum pump is generated due to the operation of the engine and the flow restriction created by the throttle plate. The vacuum thus generated is used to power many applications such as the booster for the power brakes etc.
In aircraft, the vacuum generated is used to power the gyroscopes in several flight instruments.
Thus vacuum pumps have become an integral part of our modern lives.
Read more at Buzzle: http://www.buzzle.com/articles/vacuum-pump-basics-and-uses-of-industrial-vacuum-pump.html