Vacuum technology

In the middle and late 19th century, the success of the British industrial revolution promoted the development of productivity and scientific experiments, and also promoted the development of vacuum technology. In 1850 and 1865, a mercury column vacuum pump and a mercury drop vacuum pump were invented.
A technique that makes the gas pressure lower than the atmospheric pressure on the ground.

Vacuum refers to a thin gas space where the pressure is much less than 101.325 kilopascals (kPa) (i.e., 1 atmosphere). In the vacuum technology, in addition to the pressure unit Pa of the International System of Units, Torr is often used as a unit of vacuum. 1 Torr is equal to the pressure generated by a 1 mm high mercury column, ie 1 Torr = 133.3224 Pa. According to the difference of gas pressure, the vacuum range is usually divided into: low vacuum 1×105~1×102Pa, medium vacuum 1×102~1×10-1Pa, high vacuum 1×10-1~1×10-5Pa, Ultra-high vacuum 1×10-5~1×10-9 Pa, extremely high vacuum 1×10-9Pa or less. Vacuum technology includes the acquisition, measurement and application of vacuum. The piston pump, the rotary vane pump, etc. change the volume of the pump body through the continuous movement of the piston or the rotary vane, and discharge the gas to obtain a vacuum. The diffusion pump uses a high-speed moving air stream to carry away the gas molecules that have diffused into the pump body. In addition, there are cryogenic pumps that use low temperature surfaces to condense or freeze gases, such as liquid helium condensate pumps; adsorption pumps that utilize getter materials such as activated carbon, etc. Measuring the degree of vacuum, that is, measuring the pressure of a thin gas, is called a vacuum gauge or a vacuum gauge. Can be divided into absolute vacuum gauge and relative vacuum gauge two categories. The former directly determines the magnitude of the air pressure by its measured physical quantity, such as U-tube, film meter, McLaugh vacuum gauge (using Boyle's law), thermocouple vacuum gauge, etc.; the latter must be corrected by absolute vacuum gauge. The air pressure is measured, such as an ionization vacuum gauge, a Pirani vacuum gauge, a damping vacuum gauge, and the like.

The pressure difference between the vacuum and the ground atmosphere can be used to transport fluids, vacuum, and the like. Various electric vacuum devices such as electric light sources, electron tubes, and the like can be manufactured by utilizing the characteristics of low gas molecular density in a vacuum. The vacuum environment is conducive to the welding and smelting of certain metals, the fractionation and purification of certain low-melting metals such as Mg, Li, Zn, etc., and the reduction of oxides of certain active metals such as Ca, Li, Cs, etc., vacuum environment (1 Low temperature dehydration at ~10-1 Pa), vacuum drying has been successfully used to concentrate food, milk powder, and plasma. Isotope separation, processing of large-scale integrated circuits, coating, etc. are also required to be carried out under vacuum. In scientific research, such as surface physics experiments, various accelerators, fusion reactions, and space environment simulations are all inseparable from vacuum.
History As far back as 1643, the Italian physicist Tori Split found that atmospheric and atmospheric pressures exist in vacuum and natural spaces. He filled a long glass tube closed at one end with mercury and when standing upside down in the mercury bath, he found that the mercury surface in the tube dropped until it was 76 cm away from the mercury surface outside the tube. Tori Split believes that the space on the mercury side of the glass tube is vacuum, and the 76 cm high mercury column is due to atmospheric pressure. In 1650, Germany's Galik made a piston vacuum pump. In 1654, he performed the famous Martborough hemisphere test in Fort Maddenburg: using a vacuum pump to vacuum two together 14-inch (35.5 cm) diameter copper hemispheres, and then using two sets of eight The horse pulled the copper ball in the opposite direction and never separated the two hemispheres. This famous experiment proves once again that there is an atmosphere in space and there is tremendous pressure on the atmosphere. In order to commemorate the great discovery and contribution of Tori's science in science, the vacuum pressure unit used in the past is named after him.

In the middle and late 19th century, the success of the British industrial revolution promoted the development of productivity and scientific experiments, and also promoted the development of vacuum technology. In 1850 and 1865, a mercury column vacuum pump and a mercury drop vacuum pump were invented, resulting in the development of an incandescent bulb (1879), a cathode ray tube (1879), a dewar (1893), and a compression gauge (1874). For the first time, the application of compression gauges makes low pressure measurements possible. At the beginning of the 20th century, vacuum tubes appeared, prompting the development of vacuum technology to high vacuum. In 1935~1937, gas-fired vacuum pumps, oil diffusion pumps and cold cathode ionization meters were invented. These results and the Pirani vacuum gauges made in 1906 are still commonly used in most vacuum systems. After 1940, vacuum applications expanded to nuclear research (cyclotron and isotope separation, etc.), vacuum metallurgy, vacuum coating and freeze drying, and vacuum technology began to become an independent discipline. During the Second World War, the need for atomic physics experiments and the need for high-quality electrical vacuum devices for communications further contributed to the development of vacuum technology.
Vacuum technical standard - basic standard GB 4982~4983-85 Vacuum quick release flange GB 4982-85 Clamping vacuum quick release flange GB 4983-85 Tightening vacuum quick release flange GB 6071.1~6071.3-85 Ultra high vacuum Flange GB 6071.1-85 Ultra-high vacuum flange structure type GB 6071.2-85 Ultra-high vacuum flange size GB 6071.3-85 Ultra-high vacuum flange copper gasket GB/T 3163-93 Vacuum technical term GB/T 3164- 93 Vacuum technology system with graphic symbol GB/T 6070-1995 Vacuum flange GB/T 16709-1996 Vacuum technology pipe fittings assembly size JB 1090~1092-91 Vacuum dynamic seal type and size JB 1090-91 J type vacuum rubber Seal type and size JB 1091-91 JO type skeleton type rubber seal type and size JB 1092-91 O type vacuum rubber seal type and size JB 5278.1~5278.3-91 Copper wire sealable vacuum flange JB 5278.1-91 Copper wire sealable vacuum flange connection type JB 5278.2-91 Copper wire sealable vacuum flange flange structure size JB 5278.3-91 Copper wire sealable vacuum flange copper wire seal structure Size JB/T 7673-95 Vacuum equipment model preparation method JB/T 8105 .1~8105.2-1999 Vacuum gauge pipe joint JB/T 8105.1-1999 Rubber seal vacuum gauge pipe joint JB/T 8105.2-1999 Metal seal vacuum gauge pipe joint vacuum life application Vacuum packaging of puffed food, can prevent food deterioration, prolong Food storage time; vacuum bulb to prevent oxidation of the filament and prolong its service life.
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