Vacuum engineering
Vacuum technology is concerned with devices and methods for generating, maintaining and measure a vacuum and technical application of the vacuum.
The research and the technical production of the vacuum began in the 17th century. Today, the vacuum technology is used in various fields of industry and research, such as in the production and manufacturing technology for the treatment of materials or handling in the food industry, in medicine, in physics and chemistry. Depending on the application, a certain vacuum region between the air pressure in the atmosphere of about 1000 hPa, and extreme ultra-high vacuum of 10-14 hPa is employed.
Vacuum generation
To generate a vacuum in a gas-filled volume before, the gas particles to be removed from the volume. This is done by using vacuum pumps, which can be divided into two groups according to their operating principle. Compression Pumps Remove gas particles from the volume by displacement or momentum transfer. Another way is to condense the gas particles to the wall of the volume pumped out or chemically bonding.
In vacuum technology, the following pressure ranges:
- Rough vacuum: 1013 hPa to 1 hPa,
- Fine vacuum: 1 hPa to 10-3 hPa,
- High vacuum: 10-3 to 10-7 hPa hPa,
- Ultra-high vacuum: below 10-7 hPa
The choice of the vacuum pump depends on the pressure to be achieved and the range of use. In a high vacuum multistage processes with pre-vacuum pump and a high vacuum to be applied.
Vacuum measurement and control
To measure the pressure used vacuum gauges, each with a characteristic measuring range which covers only a part of the total range because of the large pressure range in vacuum technology. The pressure measurement can be gas dependent.
Direct or absolute vacuum gauge to measure the pressure as the force acting on a surface. The direct pressure measurement is relatively accurate only in the rough vacuum range. In the indirect pressure measurement, the pressure is determined as a function of density and thus pressure dependent property. If the pressure with a low measurement uncertainty are obtained, a great effort is already in Feinvakuumbreich required.
In vacuum processes the pressure must be constantly monitored and controlled if necessary. The measured values are transmitted and registered to control and switch rooms. By this control and regulation of the pressure in the vacuum system is kept in a certain range.