Vacuum technology
a) hemispheres filled with air
b) airless hemispheres
1. handle
2. airtight seal
3. Magdeburg hemisphere
4. air pressure
5. vacuum
The vacuum technique is concerned with devices and methods for generating, maintaining, and measurement of a vacuum as well as the technical applications.
The research and the technical production of the vacuum began in the 17th century. Today vacuum technology is used in numerous areas of industry and research, such as B. in production and manufacturing technology for the treatment of materials or for handling , in the food industry , in medical technology , in physics and chemistry . Depending on the application, a certain vacuum range is used between the air pressure of the atmosphere of around 1000 hPa and an extreme ultra-high vacuum of 10 −14 hPa.
Vacuum generation
In order to create a vacuum in a volume previously filled with gas, gas particles must be removed from the volume. This is done with the help of vacuum pumps , which can be divided into two groups according to their functional principle. Compression pumps remove gas particles from the volume by displacement or momentum transfer. Another possibility is to condense the gas particles on the wall of the volume to be pumped out or to bind them chemically .
The following pressure ranges are distinguished in vacuum technology:
- Rough vacuum: 1013 hPa to 1 hPa,
- Fine vacuum: 1 hPa to 10 −3 hPa,
- High vacuum: 10 −3 hPa to 10 −7 hPa,
- Ultra-high vacuum: below 10 −7 hPa.
The choice of vacuum pump depends on the pressure to be achieved and the area of application. In the case of a high vacuum, multi-stage processes with fore-vacuum and high-vacuum pumps are used.
Vacuum measurement and control
Vacuum gauges are used to measure the pressure , each of which has a characteristic measuring range which, due to the large pressure range in vacuum technology, only covers part of the total range. The pressure measurement can be gas-dependent.
Direct or absolute vacuum gauges measure pressure as a force that acts on a surface. Direct pressure measurement is only relatively accurate in the rough vacuum range. With indirect pressure measurement, the pressure is determined as a function of a density - and thus pressure-dependent property. If the pressure is to be determined with a low measurement uncertainty , a lot of effort is required even in the medium vacuum range.
In vacuum processes, the pressure must be continuously monitored and regulated if necessary. The measured values are transmitted to control and switch rooms and registered. This control and regulation keeps the pressure in the vacuum system in a certain range.
literature
- Walter Umrath among others: Basics of vacuum technology. 1997 ( PDF, 6 MB )
Web links
Individual evidence
- ↑ Duden: vacuum technology