Carl Hoffmann (1844 – 1910), der Erfinder der Drehschieberpumpe

Among the numerous constructions and designs of mechanical (vacuum) pumps around the turn of the 19th/20th century Hoffmanns invention of the sliding vane rotary vacuum pump may be considered as the real breakthrough in this field. His pump, manufactured since 1905 excels by the introduction of the – by now standard – back pressure valve which has been retained as an essential component in all later constructions of similar pumps, in particular of Gaede's so called “box” pump. The articel describes Hoffmann's professional life in context with the state of vacuum technology at his time.     

Gaedes rotierende Quecksilberluftpumpe

The rotary mercury pump of Gaede Wolfgang Gaedes invention of a quickly acting high vacuum pump was induced by his studies about the Volta effect. The so far known pumps were not able to create sufficient low pressure to optain very clean surfaces. Alfred Schmidt, owner of the E. Leybold’s Nachfolger Company, Cologne, learned from the publication about the demonstration of the pump its importance. He made an agreement with Gaede to develop together the invention during 1906 and 1908 to a product for use in industrial application – first step into industrial high vacuum technology     

Wolfgang Gaede ‐ Wegbereiter der Vakuumtechnik

The inventions of Wolfgang Gaede were the beginning of the extensive industrial application of vacuum technology: the 1905 invented high vacuum mercury pump simplified the production of electric bulbs. From this time Gaede joined the company E. Leybold's Nachfolger research & development activities for 40years. Three of his inventions, the diffusion pump, the (turbo‐) molecular pump and the principle of “gas ballast” are worldwide in use even today. The most important stations of Gaede's biography are reported.     

Der Beginn einer Erfolgsgeschichte

The beginnings of a successful story The exciting invention of the molecular Pump by Wolfgang Gaede was followed by his new ‘Device of Producing High Vacua’ in 1913. It was announced in the second edition 1913 of E.Leybold's cataloge. Three years later Langmuir in the USA presented a similar pump called ‘condensationpump’, but with clearly better pumping speed. Another design of a pump with two stages was invented by Prof. Volmer in Berlin. Other European companies announced similar pumps. Because Gaede claimed the prinziple of evacuating gas by diffusion, he and Leybold succeeded in making all of them to ask for licences. Respective to Langmuir they exchanged licence to each other. By the time this ‘diffusion pump’ was produced from metal instead of glas, and used special mineral oil, not mercury. In the middle of the 20.century it became a most important tool for creating high vacuum, available with a few liters per second to some thousend liters of pumping speed.     

Geschichte der Gefriertrocknung bis 1910

History of freeze drying until 1910 Freeze drying or lyophilization is not an invention of the 20. or 19. century as many may believe. Central asian tribes probably knew the sublimation drying at atmospheric pressure before more than 10.000 years. The knowledge of the process migrated even through the american continent and is still in use for producing pemmikan or the south american “cuno” potatoes. Regarding the achievable vacuum below 1 hPa, it would have been possible, to realize modern vacuum freeze drying since 1782. With his cryophorus, Wollaston demonstrated the first sublimation of water vapour. The first lyophilisation of today’s definition was proceeded by Richarrd Altmann, professor for anatomy at the Leipzig university in 1890.     

Vakuumtechnologie für die chemische Verfahrenstechnik

Vacuum technology for the chemical industry process engineering – New developments – established principles Vacuum technology in chemical process engineering has evolved constantly over the past decades. In the beginning, liquid ring vacuum pumps were used in almost all chemical processes. But this all changed in the 1960s with the introduction of the once-through oil-lubricated rotary vane vacuum pump. The development of the dry screw vacuum pump in the 1990s represented another milestone. These are the three main types of technology available to chemical engineers today. They therefore have the choice between the traditional but proven technology of the liquid ring vacuum pump, the once-through oil-lubricated rotary vane vacuum pump and the modern screw vacuum pump that requires no operating fluids whatsoever. The decision as to which type is the right choice should be left to a proven vacuum specialist. Each and every critical parameter – from the process conditions, process gases and integration into process control right through to assessing the economic efficiency, safety and reliability of the future vacuum generation – must be taken into consideration.     

The naming of photography

Abstract

Photography now seems so natural a word for the process to which it refers that we tend to forget that the naming of this process was a matter of intense debate during the years leading up to 1839. Indeed photography's pioneers showed almost as much interest in the medium's nomenclature as in its invention, and almost all of them proposed one or more possible names. Given the importance attached to language at the time, it is reasonable to assume that the choice of name for their inventions was in each case indicative of their general thinking about photography and its character. In many cases the word actually came before the invention, or at least before the invention was fully operational. The choice of name therefore reflected not so much what photography was as what photography might be. It was a one-word summation of the idea of photography, and of the desires and aspirations that induced each of its various inventors to undertake their experiments. A history of photography's naming represents a useful insight into these desires, useful because it gives us one more glimpse into the manner of the medium's conception and early development.     

Der Gasballast

Wolfgang Gaedes last important invention: the Gasballast Gaedes invention of the rotating Mercury‐vacuumpump made highvacuum technology available for the industrial production. A second and third impact was given by gaedes molecular‐ and diffusionpump respectively, both depending on physikal effects firstly used for vacuum generation. Vacuum technology becomes increasing importance but the common oil sealed rotating pumps for fine vacuum suffer from contamination of the oil by vapor condensation. It was another invention from Gaede that eliminated this handycap in a very elegant way: the gasballast that is up to now a very important feature of this type of pumps.     

Die Geschichte der Vakuumtechnik

History of vacuum technology With the article “history of vacuum technology” the author presents insights from the philosophical picture of the world 2500 years ago and the thesis of the existence of vacuum through the for 1900 years believed antithesis by Aristoteles, that nature does not allow the existence of vacuum and finally the experimental proof by von Guericke, the founder of vacuum technology, that vacuum exists. The article also highlights some genius scientist's, engineer's and inventor's achievements and milestones. Their scientific models, equations of kinetic gas theories and dynamics as well as experimental results and inventions led to the well appreciated conveniences of mobility, communication, medicine and research of today.     

Geschichte der Vakuumtechnik. History of Vacuum Technology

The history of vacuum technology is more than 2000 years old. Over the past 400 years scientists, engineers and inventors such as Torricelli, Pascal, von Guericke and Gaede have been engaged in vacuum technology. Vacuum has become an essential instrument in science and technology and many processes could not exist without it. Furthermore vacuum technology has been developed as an individual industrially applied technology. The article describes the development of vacuum technology from ancient philosophical speculations about the mercurial glass pipe to the modern diffusion pump.     

冻干机用捕水器结霜特性研究中存在的问题

真空冷冻干燥过程中，从物料中升华出来的水分在真空泵的抽吸作用下，不断地在捕水器（也即冷阱）表面结霜，随着霜在捕水器表面不断凝结，致使其捕水效率不断降低，对真空系统形成不利的影响。但目前，对于低温、低压下的结霜机理研究极少，本文介绍了国内外有关低温冷壁面结霜的研究现状，并分析研究了真空冷冻干燥系统中冷壁面结霜过程中存在的问题。     

真空泵临界转速的快速计算

设计真空泵时,泵的临界转速的计算是不可缺少的一环,否则泵在运行时就有可能产生剧烈的振动,使泵无法正常工作.试图简要地叙述有关临界转速的几个基本概念及有关影响的因素.介绍了简单可行的快速计算真空泵临界转速的方法.     

Energieeffizienz in der Vakuumtechnik

Energy efficiency in vacuum technology Vacuum is used to produce a huge variety of products of our everyday life. To provide the vacuum environment, a lot of energy is usually used and therefore the vacuum pumps should run as efficient as possible. Actually, many various improvements can be made to gain energy savings on vacuum pumps. With those considered in this paper it's possible to save 928 GWh/a of energy in the EU and thereof 629 GWh/a or 64 % are economically realizable. Only specific improvements concerning the vacuum system are taken into account, basic technology options, like motors, controls, etc., are excluded. To show and discuss the results a conserved energy supply curve is used.     

Otto von Guericke und die Begründung der Lehre vom Luftdruck

The present paper is devoted to the quarter‐centenary celebration of Otto von Guericke, one of the prominent figures of the scientific revolution in the 17^th century. Guericke is well known for his invention of the air pump and his impressive demonstrations of the action of the atmospheric air pressure. Much less is known about Guerickes more theoretical achievements. In the present paper it is shown that Guericke also made, by some subtle vacuum experiments and their interpretation and the extension of the laws of hydrostatics of liquids to the air, important contributions to the basic principles of the physics of fluids.     

Vacuum metrology and its impact on research and industry

By accurate vacuum measurement, it is possible to control processes in industry, to ensure the necessary environmental conditions for many experiments in science and research and to support the commercial relationship between manufacturers and users of vacuum equipment. The main task of vacuum metrology, the science of vacuum measurement, is to provide traceability of vacuum measurements to the SI. In recent years, also the characterization of vacuum by partial pressure analysis and outgassing rate measurement, and the dynamics of vacuum measurement became an issue for vacuum metrology.     

Vacuum metrology and its impact on research and industry

To mark our anniversary, we are presenting articles that have been particularly appreciated by readers of our online edition once again in print. Here: By accurate vacuum measurement, it is possible to control processes in industry, to ensure the necessary environmental conditions for many experiments in science and research and to support the commercial relationship between manufacturers and users of vacuum equipment. The main task of vacuum metrology, the science of vacuum measurement, is to provide traceability of vacuum measurements to the SI. In recent years, also the characterization of vacuum by partial pressure analysis and outgassing rate measurement, and the dynamics of vacuum measurement became an issue for vacuum metrology.     

Kryopumpen im Vergleich zu anderen Hochvakuumpumpen

Within the last 10 years, the cryopump was added to the range of the pumps used in the high vacuum and ultra high vacuum fields. The choice of the right pump often turns out to be difficult. One of the reasons could surely be that the user is not often familiar with the properties of the cryopumps. The article is meant to make the reader aware of all possible criteria, which in turn will make it easier for him to make a decision concerning the pump required for the application. The refigerator cryopumps can be used in any application for which hydrocarbonfree vacuum is required as well as a high pumping speed for almost all gases.     

真空比对标准装置的研究

真空比对标准装置是由真空泵、校准室、真空管道、各种阀门及真空规组成的。根据实际使用情况,从四个方面对真空比对标准装置进行了详细的分析,包括:校准室的研究、微调阀性能的研究、标准规计量学特性的研究、比对校准技术的研究和应用。     

Die Membranpumpe - Entwicklung und technischer Stand

The modern diaphragm pump has become a proven device for generating coarse and fine vacuum. The article describes disigns and functions of various construction types as well as state-of-the art development and manufacturing. Physical and technical demands have resulted in diaphragm pumps with typical ultimate pressures of 70 to 0,1 mbar and a pumping speed of several m³/h. As an almost chemically resistant pump, the diaphragm pump is used in the chemical laboratory. Combining a diaphragm pump with an oil-free, not against atmosphere compressing pump, a contamination-free pump assembly for (ultra-)high vacuum is obtained which is well suited for coating technology, vacuum metallurgy and semiconductor industry due to its oilfree operation.     

Weitbereich-Turbomolekularpumpen und Membranvorvakuumpumpen als trockene HV- und UHV-Pumpsysteme

The development of new turbomolecular pumps with increased critical backing pressures up to 30 mbar made it possible to use oilfree diaphragm pumps as backing pumps. The combination of a wide-range turbomolecular pump with a diaphragm pump represents an inexpensive, compact and technical dry vacuum pumping system for high and ultrahigh vacuum applications. The interaction of wide-range turbomolecular pumps with diaphragm pumps is discussed in terms of gas throughput, compression ratio, ultimate pressure and power consumption of the turbomolecular pump and selection criteria for the diaphragm backing pump are shown.