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Vacuum
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A vacuum is a place where there is no matter. Sound cannot move in a vacuum. Outer space is not a perfect vacuum, because there is a very small number of particles there.
Industrial vacuums
Vacuum is needed for some kinds of industrial production. Vacuum pumps are used to pump air out of the vacuum chamber. In the real world it is not possible to create 100% vacuum, but some vacuum pumps are able to create 99.9999% vacuum. This is called "hard vacuum". Most industrial purposes do not need hard vacuum; 0.001% is good enough.
Industrial vacuums are mainly used in:
- Food industry
- Electronics industry
- Packaging
- Manipulation
- Coating and degasing
Vacuum chambers are also used in many experiments in laboratories. Some experiments in physics and chemistry need hard vacuum.
