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     

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.     

Thermodynamische Belastung von Seitenkanalverdichtern im Vakuumbetrieb

Like all turbo machines and rotating displacement machines side channel compressors are able to work in the pressure region and in the vacuum region. At present side channel compressors are used in vacuum operation only for the low vakuum region with an absolute suction pressure down to p_s = 10 kPa. The benefits of side channel compressors with the expansion flow in the breaker clearly grow contrasting the pressure operation mode and contrasting other compressor constructions with decreasing suction pressure. Therefore it is appropriate to make the working range of side channel compressors accessible also for the operation in the higher vacuum region down to the fine vacuum region because in this way side channel pumps open the possibility to cover the whole vacuum region from fine vacuum up to atmospheric pressure. This offers the advantage of using only high-speed turbo compressors in the vacuum region which have small construction dimensions, are simple designed and work lubrication free. These advantages also meet the desire of the vacuum technology for oil free delivery of gases and drawing off fumes.     

Entwicklungstendenzen von Vakuumpumpen für die Grob‐ und Feinvakuumtechnik. Developing trends of vacuum pumps for the roughly and fine vacuum technology

Presently coarse vacuum and fine vacuum is generated in engineering arrangements mainly with rotating displacement compressor pumps and some special current machines as well as by means of combinations of these pumps. Besides, took place in last decades a noteworthy change of the used styles of vacuum pumps and her parameters which is not concluded up to the today's day. She will also continue in future with the advancement of vacuum pumps and with the new development of machines and investment‐engineering requirements. In the following contribution some promising developing trends are outlined, outgoing by the today's developing state of the mostly used vacuum pumps, for the closer future. This is sensible because in last decades important ranges of application as for example the food industry or the microelectronic one and the pharmaceutical industry came.     

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.     

真空镀铝技术在反光布上的应用

介绍反光布的结构及反光原理,对其中形成反射层的真空镀铝技术做综述探讨。介绍了真空镀铝机的原理,主要包括真空系统和真空室。真空系统工作时,按照滑阀泵、罗茨泵、油增压泵、油扩散泵的顺序依次运行。真空室内卷绕室与镀膜室并联,其中卷绕室容积与镀膜室之比为3：1,工作时卷绕室的压力为镀膜室压力的10倍以上。其次,通过分析铝层结合力、温度湿度来阐述其对真空镀铝性能的影响。一般而言,玻璃微珠型的反光材料的镀铝层厚度控制在150～400A之间。为了保证该结合力,蒸发舟间隙为100～150mm,其与冷却辊的距离控制在160—240mm。当空气湿度大于85％时,考虑到被镀材料的放气,选择油性胶植珠的薄膜,否则真空度达不到要求。     

Non‐contact vacuum pumps

Non‐contact oil‐free vacuum pumps are widely used in different technological processes such as nanomaterials industry, pharmaceuticals industry, food industry, medicine, etc., thanks to absence of oil seal, high discharge, long operating life, yet low energy consumption. Scroll pumps are of particular interest as they make it possible to isolate bearing assemblies with grease from the working volume of the pump with the help of bellows. Pumping characteristics of non‐contact vacuum pumps are greatly influenced by backward leakage through slot channels of the rotor mechanism. The conductance is the main value characterizing backward leakage. In this paper an efficient method for prompt conductance calculation of slot channels with any geometry with the minimal clearance at a certain point along gas flow direction is presented. The calculation error of the presented method does not exceed 6%. The presented method was used in mathematical models for the pumping process of scroll pumps, claw pumps and Roots pumps. This method is recommended for pumping characteristics calculation of different non‐contact pumps and gas flow rates in vacuum systems channels.     

Sind Trockenläufer wirklich die Lösung aller Probleme?

With this article the author intents to generate the awareness, that dry pumps due to its pump principle, performance characteristic and physical limitations not always to be seen as the solution to all challenges in vacuum technology out there. Monitoring and protective measures are resulting in more sensitivity to failures and operational errors, higher operating and maintenance cost as well as a certain knowledge about safe operation of dry pumps for system manufacturers and users is required in comparison to the classical rotary vane pumps. The requirement for oil free process chambers and apparatus were the major push to develop and improve dry pump technology but despite this trend the rotary vane pumps is for certain applications the pump of choice will be still around for quite some time.     

Flüssigkeitsring-Vakuumpumpen

Liquid ring vacuum pumps – Oldtimers of vacuum technology and yet highly up-to-date Liquid ring vacuum pumps were developed over a hundred years ago. In the meantime, vacuum technology has evolved considerably and offers optimum economic and technical solutions for a wide variety of applications. However, liquid ring vacuum technology still has its reason for existence and is the most suitable principle for vacuum generation in some applications. Thanks to its functionality it is perfectly suited for the extraction of humid gases or vapours. Due to the use of process-compatible operating fluid and the possibility of different construction materials, it can be perfectly matched to different operating fluids and process conditions. In addition, it is available in many sizes on the market and can therefore extract very small and very high quantities of gas and vapour.     

Wasserstoff in Hochvakuumsystemen mit Turbomolekularpumpen bei verschiedenen Vorpumpen

The combination of diaphragm pumps with wide‐range turbomolecular pumps constitutes a small but powerful oil‐free high vacuum pumping system. Turbomolecular pumps show gas dependent compression ratios, the lowest for hydrogen. Thus, the high vacuum can be governed by the hydrogen partial pressure. In the present investigation the residual gas composition of a turbomolecular pump and different backing pumps shows no improvement if diaphragm pumps with low ultimate pressure are replaced by rotary vane or Roots pumps. In this case the ultimate pressure in the high vacuum chamber is basically determined by the ratio of outgassing to pumping speed and not by the product of compression ratio and backing pressure. However, the hydrogen partial pressure increased if the ultimate pressure of the diaphragm pump was raised. At a backing pressure of 0.5 mbar the high vacuum reached a stable value not improvable by reduction in backing pressure.     

Correction: Sind Trockenläufer wirklich die Lösung aller Probleme?

With this article the author intents to generate the awareness, that dry pumps due to its pump principle, performance characteristic and physical limitations not always to be seen as the solution to all challenges in vacuum technology out there. Monitoring and protective measures are resulting in more sensitivity to failures and operational errors, higher operating and maintenance cost as well as a certain knowledge about safe operation of dry pumps for system manufacturers and users is required in comparison to the classical rotary vane pumps. The requirement for oil free process chambers and apparatus were the major push to develop and improve dry pump technology but despite this trend the rotary vane pumps is for certain applications the pump of choice will be still around for quite some time.     

Surface Migration of Oil in Vacuum Systems

A comprehensive investigation of the phenomenon of surface migration of oil in vacuum systems with oil diffusion pumps was made. The migration is caused by the temperature gradient along the wall. Theoretical calculations were performed which are based on the film flow approximation taking the conditions at the moving contact line into account. In order to prove the theoretical results, experiments with different vacuum working fluids on metallic surfaces, often used in vacuum technology, were carried out. The results obtained provide a better understanding of the surface migration process and allow to control oil film displacement.     

如何选择和使用涡轮分子泵

本文首先介绍了涡轮分子泵的工作原理,结构型式及其优缺点。为了利用涡轮分子泵,获得清洁真空,国外多利用干式机械泵作其前级泵,构成无油的真空系统。然而,目前国内涡轮分子泵多以油封机械泵为其前级泵,构成了有油真空系统,如果操作不当,很难避免油蒸汽返流,对真空系统的污染。利用有油系统获得清洁真空,国内外都有一些有效防止返流的措施和成功的操作经验。这些对用户正确选择和使用涡轮分子泵有油系统获得清洁真空,有一定的参考价值。     

Überlastgrenzen bei Hochvakuumpumpen

High-vacuum pumps have a limited inlet pressure above which they cannot function. Recognizing and dealing with the approaching overload conditions is an important aspect of vacuum system operation. This paper outlines the basic considerations for selecting the pressure at which the high vacuum pumps are started, emphasizing the importance of mass flow (throughput) limits rather than the pressure as such. Some basic parameters, such as the ratio of pumping speeds of the roughing pump and the high vacuum pump are associated with the choice of the cross-over pressure. Practical engineering recommendations are offered for system design and operation. Adverse system effects (e.g., backstreaming and oil loss) resulting from pump overload are noted for momentum transfer pumps (diffusion pumps and turbomolecular pumps) and capture pumps (sputter-ion pumps and cryogenic pumps). To prevent any adverse effect, normally, the transient pressure rise during switching should not be longer than a few seconds.     

Aufbau und Eigenschaften verschiedener ölfreier Vakuumpumpen für den Grob- und Feinvakuumbereich

The development of high vacuum pumps and systems during the last 35 years can be characterized by a trend of gradual elimination of liquids exposed to vacuum environment. The need for high purity vacuum process equipment precipitated the development of new pumping techniques: iongettering pumps, turbomolecular pumps and cryopumps. During the last 5 years, a number of dry coarse-vacuum pumps have been developed. Some are entirely oilfree, some still use lubricants at the seals separating the driving mechanism from the vacuum side. This review contains general design and performance characteristics of four classes of equipment: hermetically sealed pumps using bellows to isolate the driving mechanism, a variety of multistaged positive displacement blowers, pumping trains based on turbo-drag pumps, and multistaged reciprocal piston pumps. It is entirely practical to achieve pressure of 10⁵ to 10⁶ while discharging to atmosphere. Despite a complete absence of conventional lubrication in some of these pumps, periods exceeding 10000 hours without maintenance are obtained, providing a viable technology for clean vacuum systems.     

65 Years of Turbopumps

Vacuum technology is not necessarily one of the sciences mentioned in connection with groundbreaking inventions. Nevertheless, it is a basic prerequisite for many developments and products that are taken for granted today. The influence of vacuum technology on our lives today can be traced back to the invention of the turbopump 65 years ago. Until then, the diffusion pump was considered the most widely used high and ultra-high vacuum pump, but with the help of Dr. Willi Becker's invention, it became possible to create hydrocarbon-free vacuum. It was only through a ‚clean' vacuum that many analyses and manufacturing processes became possible.     

Das Vakuumsystem der TOSKA-Spulentestanlage

Plasma confinement in fusion reactors requires large magnetic fields which are generated by superconducting solenoids. The coils of the future reactor ITER have a size of some 18 m × 10 m. Their construction is a technical challenge: the body of the coil suffers from large mechanical forces, originating from the magnetic field, as well as substantial thermal stress resulting from the cooling to 4.2 K. Nevertheless, the coils are required to be absolutely vacuum tight since no loss of the refrigerant helium is permissible. In the Research Center Karlsruhe (FZK) prototype coils are tested in operation under high vacuum conditions. The test chamber has a volume of 170 m³. It is pumped by an oil diffusion pump with a nominal pumping speed of 16 000 l/s. As fore and roughing pumps, a combination of Roots and rotating vane pump are employed. The available effective pumping speed of the oil diffusion pump has been measured by two different procedures: via the resulting equilibrium pressure in case of an injected stationary gas flow, and via the time-dependent decrease of pressure during pump-down. The measurements give an effective pumping speed of some 2 000 l/s. The main reason for the small pumping speed (as compared to the nominal value) is the small conductances of the inserted vacuum components and baffles. When the heating power of the oil diffusion pump is reduced to one half, the pumping speed decreases only slightly, whereas the maximum throughput decreases to one third.     

CXS chemical dry vacuum pump brings smart vacuum to the process industry

The chemical sector as a whole has been quick to recognise the clear advantages of dry vacuum pumps over traditional wet technologies, and dry vacuum pumps are now well established around the world as an efficient, reliable option. A new trend is now emerging: for vacuum to be seen as a ‘utility’. In response, dry vacuum technology is being developed by manufacturers to be available on demand in a ‘plug and pump’ system that requires minimum set‐up and maintenance. The most advanced chemical dry vacuum pumps, such as the new CXS pump from Edwards, deliver exceptional energy efficiency and performance, are cost‐effective to run, and are environmentally sound.     

Verhinderung von Ölrückströmungen in Wälzkolbenpumpen

Prevention of oil backflow in Roots pumps - Residual gas analysis by quadrupole mass spectrometry In industrial vacuum applications too, there is a growing trend towards dry, oil-free, pump systems. But what does oil-free mean? All bearings and gearboxes used in roots and screw pumps require lubrication with oil or grease. While constructive measures are implemented to avoid contamination of the process gas by back-flowing lubricants from the pumps, no tests have yet been carried out on complete pumping stations to confirm their effectiveness. With the help of this report it is possible for the first time to make qualitative statements about the oil-free nature of dry pumping stations.     

Ventillose Flüssigkeitsring‐Vakuumpumpen

Valveless liquidring‐vacuumpumps Besides the procedural requirements in recent years, investment‐ and operation costs become more and more important. In the context of this essay concerning the simplification of the construction and reduction of the costs of wear the latest technical expertises to the processes in liquid ring vacuum pumps have been presented. The analysis of present single stage liquid ring vacuum pumps with valve technology over the whole pressure range was source for a new development. Result of the examinations is now a product range, which sets new standards concerning the more and more important cost consciousness. The combination of latest perceptions with existing experiences lead to a considerable simplification of the construction and an improvement of the operating behaviour. Latest technologies and possibilities of production made possible a robust and low‐cost construction.