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

Dry vacuum pumps are now well established around the world as an efficient, reliable option for demanding chemical processing industry applications. Chemical processors are placing new demands on the market, driving an emerging trend for vacuum to be seen as a utility; highly reliable, flexible, and available on demand in a ′plug and pump′ system that requires minimum set up and maintenance. CXS dry vacuum pump systems from Edwards have been in operation worldwide for several years now, and are providing ′utilitarian′ high performing, highly controllable vacuum equipment allowing processors to minimise running costs and reduce environmental performance.     

Selbsttrocknende Membran‐ Vakuumpumpen für feuchte Gase

Diaphragm vacuum pumps have proved their superiority as dry‐running systems over other types of vacuum pumps in many applications, and in particular in the medical, analysis, and process engineering sectors, as well as in the chemical industry. These pumps deliver the media without any contamination of content, have a high gas tightness, and can be designed as chemically resistant with regard to those parts which come in contact with the media. Although they are in principle relatively insensitive towards condensates which may be formed or conveyed with the media, liquids in the vapor or gas flow may be the cause for the prolongation of a vacuum process, which can be considerable and is certainly undesirable. This applies in particular to applications involving multi‐user vacuum systems in chemical laboratories, which under certain circumstances may contain very substantial volumes of condensates, and to the use of pumps in steam sterilizers (autoclaves) and vacuum drying cabinets. These examples of applications will be considered in greater detail hereinafter. The condensates which occur in the pump head of a diaphragm vacuum pump cause interference in that — due to re‐evaporation during the suction cycle — they incur a substantial reduction in the usable suction capacity of the pump. This problem can be resolved by means of a drying system for diaphragm vac uum pump heads. The drying system makes use in this case of the pressure differential which pertains between the pump chamber and the atmosphere outside the pump. The function of the drying system can be described as follows: A solenoid valve vents the pump head in a cyclic manner, with the result that liquid in the pump head will be blown out, while the process vacuum in the process engineering system will continue to be maintained. Diaphragm vacuum pumps equipped with this drying system have provided excellent results, for example in the chem ical laboratory, both in individual diaphragm vacuum pumps as well as in multi‐user vacuum systems. Extremely good experience has also been gained in the evacuation of sterilizer autoclaves and vacuum drying cabinets with the use of diaphragm vacuum pumps fitted with the drying system. When using the drying system on steam sterilizer autoclaves, another favorable effect is also encountered: The vapor fraction in the pumping medium is cooled in the diaphragm pump head to below the evaporation or boiling temperature, with the result that the vapour condenses. This reduces its volume to a fraction of the initial value, which is the equivalent of an additional suction capacity, in the same manner as with a condenser. The condensate which occurs with this process is blown out of the pump heads by the drying system, and, as a result, can no longer cause interference due to re‐evaporation.     

Membranpumpen mit hoher Kompression durch tangentiale Membraneinspannung

Diaphragm pumps dominate the field of rough vacuum (down to 1 mbar) in modern industry and science. Their construction is quite simple and therefore warrants great reliability. Diaphragm pumps are oil‐free, maintenance free, have a low noise level and a long lifetime. Up to now, problems occurred in generating lower vacuum pressure. With a completely new tangential diaphragm insertion as well as with improvements of the gas flow, and the form and position of the valves, the of a Puchheim pump company now solved this problem: The tangential diaphragm pumps reach an ultimate pressure of 20 mbar (single‐stage) and less than 1 mbar (double‐stage). A pump head provides a pumping speed of 36 l/min at atmospheric pressure.     

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.     

Non-contact vacuum pumps

An overview of the main methods for mathematical modeling of the working process of non-contact vacuum pumps is given. The specifics and the main stages of mathematical model development for screw, scroll, claw and Roots vacuum pumps are considered. The results of mathematical modeling of pump characteristics are presented and compared with experimental data. The mathematical modeling technique presented here can be recommended for analyzing the influence of pump geometry and operating conditions on the pump characteristics of non-contact oil-free vacuum pumps.     

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.     

Kennfeldanalyse einer Schraubenvakuumpumpe

Operating Performance of Screw Vacuum Pumps This paper presents detailed analyses of the operating performance of a dry‐running screw vacuum pump. The characteristic parameters, suction speed and final attainable pressure ‐ which primarily define the operating performance of screw vacuum pumps ‐ are explored in experimental and theoretical investigations. Experiment and simulation in combination are used to show the correlation between the main physical and technical characteristics and the operating performance of screw vacuum pumps. This basic knowledge is essential for understanding the specific machine physics of positive displacement vacuum pumps, especially for screw vacuum pumps, and is useful in view of further design and optimization processes. The experiment covers measurements of the operating performance of the investigated isochoric screw vacuum pump working against ambient pressure. As operating parameters intake pressure (1000mbar to 10^‐3mbar) and rotor speed are varied over a wide range. The theoretical analysis of the operating performance contains simplifying models as well as simulations of the thermodynamic processing. The impact of external leakages, clearance vacuum flows and further losses on operating performance are described in detail.     

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.     

油气混和状态真空抽气系统试验初步研究

根据系统抽真空要求,完成管路设计选型与抽空能力计算.针对混和型介质及系统防火防爆的特点,优先选用干式真空泵.通过搭建真空管路系统,针对不同抽速真空泵、不同管路长度、不同抽空容器、不同混和介质开展多组试验.试验结果分析表明,干式真空泵能够满足抽空要求:管路中最小管径的管路长度对抽真空时间有较大影响;在本次试验条件下,环境温度变化对抽空时间有一定影响.     

Dry vacuum pumping technology outperforms oil-sealed pumps for investment casting

Investment casting is a demanding application for a vacuum pump. Indeed, many traditional oil-sealed pumps cannot maintain the required vacuum performance and have fallen by the wayside, due to the high wear on machinery inherent in this dusty environment. However, in a 20-month trial at an investment casting company in South-West England, a dry pumping system has shown greater reliability, improved vacuum performance and reduced maintenance downtime over the previous oil-sealed technology.     

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.     

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.     

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.     

EPX ‐ die Ein‐Pumpen‐Lösung

A single dry pump mechanism capable of reaching high vacuum and itself exhausting to atmospheric pressure is considered as a ’?vacuum technology panacea’. The development and deployment of a single‐shaft, high‐speed EPX dry pump has gone some considerable way to achieving this goal. This article describes the stages in its development history and applications.     

对《新的真空抽速特性系数及其应用》一文的讨论

指出新的抽速公式在扩散泵范畴内应用是正确的，在其他泵类应用时就不一定正确。     

液环真空泵转子力学性能的数值分析

液环真空泵是广泛应用于石油、化工、冶金、矿山、电力、轻工等行业的基础设备。其转子(叶轮和泵轴)是泵传递扭矩的关键零件之一,它的失效将直接导致整个机组停止工作。因此,对转子强度的计算和校核是进行液环泵设计的重要一环。传统的计算和校核方法计算繁琐,可靠性差;本文采用ANSYS软件给出一种新的计算转子强度的方法,它可以准确地获得应力和变形的大小及位置,从而进行精确的力学性能校核。计算结果表明:本文所采用的分析方法可以较好的计算和分析液环泵转子的力学性能,为实现产品的优化设计提供了可靠的理论依据。     

Völlig ölfreie neue Vorvakuumpumpe für saubere Anwendungen

Totally oil-free vacuum pumps have been gaining popularity for applications where clean forevacuum is needed, or clean gases are being pumped. The trend for these simple applications has been to substitute the complicated and expensive process pumps used in the production of semiconductors with simpler alternatives. In order to produce such a cost effective oil-free vacuum pump, the well known reliable and robust piston principle has been adapted as a vacuum pump. The resulting product is made up of four stages of compression arranged in series producing an ultimate pressure of 3 ? 4 × 10^?2 mbar. All compression spaces are totally dry as is the crank case. For additional cleanliness the grease lubricated bearings situated in the crank case are separately sealed. The special valve geometry, and the use of new low coefficient of friction sliding materials, combine to produce a very robust and low maintenance pump. The new pump is capable of surviving operational accidents such as the ingestion of broken wafers or liquid water. Applications for this new pump include load locks, analytical instruments, and research.     

一种新型嵌固叶片式真空泵的结构和原理

介绍一种新型嵌固叶片式旋片真空泵的结构和工作原理,该真空泵包含有一个旋转缸套和一个嵌固式的隔离叶片,它不仅继承了传统旋片式真空泵体积小、重量轻以及结构简单的优点,而且与之相比还具有较小的摩擦损耗和较少的泄漏损失。     

适用于化工工业的真空泵

真空泵在化工企业如水、电、压缩空气一样是不可缺少的公用设施。用于化工行业的真空泵必须结实、可靠,能处理大量蒸汽、腐蚀性气体和可燃性气体。本文介绍了各种真空泵的结构与性能,认为液环泵和螺杆真空泵最适合于化学工艺应用。     

Geräuscharme Flüssigkeitsring‐ Vakuumpumpen

Besides the requirements for processing, increasing investment charges and working expenses gain more and more importance during the past years as well as the noise level and noise development. Within this work new information's elaborated with regards to noise development were presented for liquid ring vacuum pumps. Based on these test and design data and its interpretation, a new pump type was designed. These studies resulted in a new type range, which corresponds to now‐a‐days standards with regards to increasing requirements on noise development. Combining new knowledge with the up‐to‐now experiences makes us considerably reduce the emissions at source. Latest technologies and production methods enabled us to create a robust construction at a favourable price.