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EP0541989A1 - Multi-stage vacuum pumping system - Google Patents

Multi-stage vacuum pumping system Download PDF

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Publication number
EP0541989A1
EP0541989A1 EP92117784A EP92117784A EP0541989A1 EP 0541989 A1 EP0541989 A1 EP 0541989A1 EP 92117784 A EP92117784 A EP 92117784A EP 92117784 A EP92117784 A EP 92117784A EP 0541989 A1 EP0541989 A1 EP 0541989A1
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EP
European Patent Office
Prior art keywords
stage
pump
vacuum
high vacuum
facing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP92117784A
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German (de)
French (fr)
Other versions
EP0541989B1 (en
Inventor
Gion Caduff
Roland Fischer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pfeiffer Vacuum GmbH
Original Assignee
Arthur Pfeiffer Vakuumtechnik Wetzlar GmbH
Balzers Pfeiffer GmbH
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Application filed by Arthur Pfeiffer Vakuumtechnik Wetzlar GmbH, Balzers Pfeiffer GmbH filed Critical Arthur Pfeiffer Vakuumtechnik Wetzlar GmbH
Publication of EP0541989A1 publication Critical patent/EP0541989A1/en
Application granted granted Critical
Publication of EP0541989B1 publication Critical patent/EP0541989B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
    • F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
    • F04B37/14—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use to obtain high vacuum

Definitions

  • the invention relates to a multi-stage vacuum pump system with intermediate suction between the individual stages.
  • Vacuum pumps which correspond to such pump systems, are used, for example, in gas analyzers, whose functional principle can only work under vacuum.
  • the vacuum system of such gas analyzers is to be illustrated using the example of a mass spectrometer which is equipped, inter alia, with a two-stage rotary vane pump.
  • a high vacuum system consisting of a two-stage rotary vane pump and a high vacuum pump, which can be, for example, a turbomolecular or diffusion pump, is used to maintain the vacuum in the analysis chamber.
  • Two-stage rotary vane pumps are useful here because they generate a final vacuum, which serves as an optimal forevacuum for the associated high vacuum pump.
  • the gas to be examined which is generally available under atmospheric pressure, must be fed to the gas analysis system under reduced pressure.
  • the pressure reduction stage is often formed by a further rotary vane pump in connection with a capillary stage at the gas inlet. Since the demands on the final vacuum are lower in this case than with the high vacuum pump, a single-stage rotary vane pump is sufficient.
  • a second rotary vane pump for the high vacuum system with an intermediate suction connection between the two stages is used.
  • the pressure reduction stage is evacuated via this intermediate suction connection using the second stage of the rotary vane pump.
  • the rotary vane pump thus serves simultaneously as a two-stage pump for generating the forevacuum for the high vacuum pump and as a one-stage pump for evacuating the pressure reduction stage.
  • the object of the invention is to develop a pump system which can be used universally for the abovementioned areas of application.
  • the aim is to ensure that the occurrence of larger or variable gas quantities at the intermediate suction connection of a multi-stage pump system, its mode of operation and the mode of operation of a subsequent high-vacuum pump are not impaired.
  • Claims 2 to 5 represent further design options of the invention.
  • the additional valve between the intermediate suction connection and the first pump stage facing the high vacuum side achieves a decisive improvement in the pump system. If there is little or no gas at the intermediate suction connection, the valve remains open, and in the example given here there is a two-stage rotary vane pump with its full function. When there is a large amount of gas, the valve closes, and the two pump stages work like two single-stage pumps, the second stage facing the higher pressure pumping off the large amount of gas against the atmosphere without the pressure in the first stage facing the high vacuum being increased significantly . This prevents the high vacuum pump from working.
  • the additional valve can be preloaded mechanically, for example by springs. This makes it possible to specify the time of closing and opening depending on the pressure.
  • the pump system consists of the pump stage 1, which faces the high vacuum pump 3 and the following pump stage 2, which is connected to the atmosphere via the valve 4.
  • the analysis chamber 5 is evacuated via the high vacuum pump 3.
  • the pump stage 2 and the capillary stage 7 together form the pressure reduction stage for the gas to be examined.
  • the two pump stages 1 and 2 are connected to one another via the bypass line 9.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Abstract

A multi-stage vacuum pumping system comprising intermediate exhaustion (6) between the individual pumping stages is fitted with one or more additional valves (8) between the intermediate exhaustion connection (6) and the pump stage (1) facing the high-vacuum side in each case. In order to maintain the vapour compatibility of the pump stage (1) facing the high-vacuum side, the pump stage is connected, in parallel to the additional valve (8), to the next pump stage (2) via a bypass line (9).

Description

Die Erfindung betrifft ein mehrstufiges Vakuum-Pumpsystem mit Zwischenabsaugung zwischen den einzelnen Stufen.The invention relates to a multi-stage vacuum pump system with intermediate suction between the individual stages.

Vakuumpumpen, die solchen Pumpsystemen entsprechen, werden zum Beispiel bei Gasanalysatoren, welche von ihrem Funktionsprinzip her nur unter Vakuum arbeiten können, eingesetzt. Das Vakuumsystem derartiger Gasanalysatoren soll am Beispiel eines Massenspektrometers, welches unter anderem mit einer zweistufigen Drehschieberpumpe ausgerüstet ist, dargestellt werden.Vacuum pumps, which correspond to such pump systems, are used, for example, in gas analyzers, whose functional principle can only work under vacuum. The vacuum system of such gas analyzers is to be illustrated using the example of a mass spectrometer which is equipped, inter alia, with a two-stage rotary vane pump.

Für die Aufrechterhaltung des Vakuums in der Analysenkammer wird ein Hochvakuumsystem, bestehend aus einer zweistufigen Drehschieberpumpe und einer Hochvakuumpumpe, die zum Beispiel eine Turbomolekular- oder Diffusionspumpe sein kann, verwendet.A high vacuum system consisting of a two-stage rotary vane pump and a high vacuum pump, which can be, for example, a turbomolecular or diffusion pump, is used to maintain the vacuum in the analysis chamber.

Zweistufige Drehschieberpumpen sind hier zweckmäßig, da sie ein Endvakuum erzeugen, welches als optimales Vorvakuum für die damit verbundene Hochvakuumpumpe dient.Two-stage rotary vane pumps are useful here because they generate a final vacuum, which serves as an optimal forevacuum for the associated high vacuum pump.

Das zu untersuchende Gas, welches in der Regel unter Atmosphärendruck zur Verfügung steht, muß unter reduziertem Druck dem Gasanalysensystem zugeführt werden. Die Druckreduktionsstufe wird hierbei vielfach durch eine weitere Drehschieberpumpe in Verbindung mit einer Kapillarstufe am Gaseinlaß gebildet. Da die Ansprüche an das Endvakuum in diesem Fall niedriger sind als bei der Hochvakuumpumpe, ist eine einstufige Drehschieberpumpe ausreichend.The gas to be examined, which is generally available under atmospheric pressure, must be fed to the gas analysis system under reduced pressure. The pressure reduction stage is often formed by a further rotary vane pump in connection with a capillary stage at the gas inlet. Since the demands on the final vacuum are lower in this case than with the high vacuum pump, a single-stage rotary vane pump is sufficient.

Somit wären zwei Drehschieberpumpen zum Betrieb des Gasanalysensystems notwendig.This would require two rotary vane pumps to operate the gas analysis system.

Man kann jedoch bei konstant anfallenden kleinen Gasmengen in der Druckreduktionsstufe den Einsatz einer zweiten Drehschieberpumpe vermeiden. Dazu wird als Drehschieberpumpe für das Hochvakuumsystem eine solche mit einem Zwischenabsauganschluß zwischen den beiden Stufen verwendet. Über diesen Zwischenabsauganschluß wird die Druckreduktionsstufe mit Hilfe der zweiten Stufe der Drehschieberpumpe evakuiert. Damit dient die Drehschieberpumpe gleichzeitig als zweistufige Pumpe zur Erzeugung des Vorvakuums für die Hochvakuumpumpe und als einstufige Pumpe zum Evakuieren der Druckreduktionsstufe.However, in the case of constant small amounts of gas in the pressure reduction stage, the use of a second rotary vane pump can be avoided. For this purpose, a rotary vane pump for the high vacuum system with an intermediate suction connection between the two stages is used. The pressure reduction stage is evacuated via this intermediate suction connection using the second stage of the rotary vane pump. The rotary vane pump thus serves simultaneously as a two-stage pump for generating the forevacuum for the high vacuum pump and as a one-stage pump for evacuating the pressure reduction stage.

Solche Pumpen sind bekannt, haben aber den Nachteil, daß der Enddruck der Drehschieberpumpe sehr stark vom Druck am Zwischenabsauganschluß abhängt. Dies kann akzeptiert werden, solange konstante Betriebsbedingungen an dieser Stelle herrschen und keine allzu großen Gasmengen gepumpt werden. Wenn jedoch unterschiedliche oder größere Gasmengen am Zwischenabsauganschluß anfallen, z.B. beim Austausch der Kapillarstufe oder beim Abpumpen von zusätzlichen Bauteilen, wird der Druckanstieg im Vorvakuum der Hochvakuumpumpe unzulässig hoch.Such pumps are known, but have the disadvantage that the final pressure of the rotary vane pump depends very much on the pressure at the intermediate suction connection. This can be accepted as long as there are constant operating conditions at this point and not too large amounts of gas are pumped. However, if there are different or larger amounts of gas at the intermediate suction connection, e.g. when replacing the capillary stage or when pumping out additional components, the pressure rise in the fore vacuum of the high vacuum pump becomes impermissibly high.

Dieses dem Stand der Technik entsprechende Vakuumsystem ist also, wie an diesem Beispiel gezeigt wurde, nur begrenzt einsetzbar.This vacuum system corresponding to the prior art can therefore only be used to a limited extent, as was shown in this example.

Der Erfindung liegt die Aufgabe zugrunde, ein Pumpsystem zu entwickeln, welches für die obengenannten Anwendungsgebiete universell einsetzbar ist. Insbesondere soll erreicht werden, daß beim Anfall von größeren oder variablen Gasmengen am Zwischenabsauganschluß eines mehrstufigen Pumpsystems, dessen Arbeitsweise und die Arbeitsweise einer sich anschließenden Hochvakuumpumpe nicht beeinträchtigt werden.The object of the invention is to develop a pump system which can be used universally for the abovementioned areas of application. In particular, the aim is to ensure that the occurrence of larger or variable gas quantities at the intermediate suction connection of a multi-stage pump system, its mode of operation and the mode of operation of a subsequent high-vacuum pump are not impaired.

Die Aufgabe wird durch den kennzeichnenden Teil des ersten Patentanspruches gelöst. Die Ansprüche 2 bis 5 stellen weitere Ausgestaltungsmöglichkeiten der Erfindung dar.The object is solved by the characterizing part of the first claim. Claims 2 to 5 represent further design options of the invention.

Durch das zusätzliche Ventil zwischen dem Zwischenabsauganschluß und der der Hochvakuumseite zugewandten ersten Pumpstufe wird eine entscheidende Verbesserung des Pumpsystems erreicht. Bei geringem oder keinem Gasanfall am Zwischenabsauganschluß bleibt das Ventil offen, und es ergibt sich bei dem hier angeführten Beispiel eine zweistufige Drehschieberpumpe mit ihrer vollen Funktion. Bei größerem Gasanfall schließt das Ventil, und die beiden Pumpstufen arbeiten wie zwei einstufige Pumpen, wobei die zweite, der Seite des höheren Druckes zugewandte Stufe den großen Gasanfall gegen Atmosphäre abpumpt, ohne daß der Druck in der ersten, der Hochvakuumseite zugewandten Stufe wesentlich erhöht wird. Dadurch wird eine Beeinträchtigung der Arbeitsweise der Hochvakuumpumpe vermieden.The additional valve between the intermediate suction connection and the first pump stage facing the high vacuum side achieves a decisive improvement in the pump system. If there is little or no gas at the intermediate suction connection, the valve remains open, and in the example given here there is a two-stage rotary vane pump with its full function. When there is a large amount of gas, the valve closes, and the two pump stages work like two single-stage pumps, the second stage facing the higher pressure pumping off the large amount of gas against the atmosphere without the pressure in the first stage facing the high vacuum being increased significantly . This prevents the high vacuum pump from working.

Die Vorbelastung des zusätzlichen Ventils kann mechanisch, zum Beispiel durch Federn, erfolgen. Dadurch wird es möglich, den Zeitpunkt des Schließens und Öffnens in Abhängigkeit vom Druck vorzugeben.The additional valve can be preloaded mechanically, for example by springs. This makes it possible to specify the time of closing and opening depending on the pressure.

Da der Druck am Ausgang der ersten Pumpstufe niedriger ist als am Ausgang der zweiten Pumpstufe, ist es sinnvoll, die Vorbelastung des zusätzlichen Ventils nicht größer zu machen als die des in der Regel vorhandenen Ausstoßventils der zweiten Pumpstufe.Since the pressure at the outlet of the first pump stage is lower than at the outlet of the second pump stage, it makes sense not to make the preload on the additional valve greater than that of the discharge valve of the second pump stage, which is usually present.

Bei dieser Konstruktion kann noch ein Nachteil auftreten welcher die Dampfverträglichkeit der ersten Pumpstufe betrifft. Bei geschlossenem Ventil zwischen den Pumpstufen steigt der Druck auf der Ausstoßseite der ersten Stufe an. Somit nimmt auch der Partialdruck der Dämpfe zu. Um diesen Anstieg in Grenzen zu halten und ein Kondensieren zu vermeiden, wird parallel zu dem Ventil eine Bypassleitung angebracht, welche die Ausstoßseite der ersten Stufe mit der Ansaugseite der zweiten Stufe verbindet. Der Querschnitt dieser Leitung muß so groß sein, daß beim Arbeitsdruck der Pumpe die dann noch anfallende Dampfmenge von der zweiten Stufe abgepumpt werden kann. Andererseits muß beachtet werden, daß die Rückströmung von der zweiten in die erste Stufe in solchen Grenzen gehalten wird, daß sie sich nicht störend auf das Hochvakuum auswirkt. Der optimale Querschnitt richtet sich nach den Druckverhältnissen und Saugvermögen in den beiden Pumpstufen. Zweckmäßigerweise wird die Bypassleitung so gestaltet, daß ihr Querschnitt durch an sich bekannte Mittel, wie z.B. Blenden, variiert werden kann.With this construction there can be a disadvantage which affects the steam compatibility of the first pump stage. When the valve between the pump stages is closed, the pressure on the discharge side of the first stage increases. This also increases the partial pressure of the vapors. In order to keep this increase within limits and to avoid condensation, a bypass line is connected in parallel to the valve, which connects the discharge side of the first stage to the suction side of the second stage. The cross-section of this line must be so large that the amount of steam then still available can be pumped out of the second stage at the working pressure of the pump. On the other hand, it must be ensured that the backflow from the second to the first stage is kept within such limits that it does not interfere with the high vacuum. The optimal cross-section depends on the pressure conditions and pumping speed in the two pump stages. The bypass line is expediently designed in such a way that its cross section by means known per se, such as e.g. Dazzle, can be varied.

Die der Erfindung zugrundeliegende Idee wurde hier am Beispiel einer zweistufigen Drehschieberpumpe erläutert. Die Anwendbarkeit der Erfindung ist jedoch nicht auf diese Pumpen beschränkt, sondern erstreckt sich allgemein auf mehrstufige Vakuumpumpen und -Pumpsysteme.The idea on which the invention is based was explained here using the example of a two-stage rotary vane pump. However, the applicability of the invention is not limited to these pumps, but extends generally to multi-stage vacuum pumps and pump systems.

Anhand der Abbildung soll die Erfindung näher erläutert werden.The invention will be explained in more detail with reference to the figure.

Das Pumpsystem besteht aus der Pumpstufe 1, welche der Hochvakuumpumpe 3 zugewandt ist und aus der folgenden Pumpstufe 2, welche über das Ventil 4 mit der Atmosphäre verbunden ist. Über die Hochvakuumpumpe 3 wird die Analysenkammer 5 evakuiert. Zwischen den beiden Pumpstufen 1 und 2 befindet sich der Zwischenabsauganschluß 6, welcher zum Beispiel mit der Kapillarstufe 7 verbunden ist. Die Pumpstufe 2 und die Kapillarstufe 7 bilden zusammen die Druckreduktionsstufe für das zu untersuchende Gas. Zwischen dem Zwischenabsauganschluß 6 und der der Hochvakuumseite zugewandten Pumpstufe 1 befindet sich ein zusätzliches Ventil 8, welches als vorbelastetes Druckventil ausgebildet sein kann. Darüberhinaus sind die beiden Pumpstufen 1 und 2 über die Bypassleitung 9 miteinander verbunden.The pump system consists of the pump stage 1, which faces the high vacuum pump 3 and the following pump stage 2, which is connected to the atmosphere via the valve 4. The analysis chamber 5 is evacuated via the high vacuum pump 3. Between the two pump stages 1 and 2 there is the intermediate suction connection 6, which is connected to the capillary stage 7, for example. The pump stage 2 and the capillary stage 7 together form the pressure reduction stage for the gas to be examined. Between the intermediate suction connection 6 and the pump stage 1 facing the high vacuum side there is an additional valve 8, which can be designed as a preloaded pressure valve. In addition, the two pump stages 1 and 2 are connected to one another via the bypass line 9.

Claims (5)

Mehrstufiges Vakuum-Pumpsystem mit Zwischenabsauganschlüssen (6) zwischen den einzelnen Pumpstufen, dadurch gekennzeichnet, daß zwischen einem Zwischenabsauganschluß (6) und der jeweils der Hochvakuumseite zugewandten Pumpstufe (1) ein zusätzliches Ventil (8) angebracht ist.Multi-stage vacuum pump system with intermediate suction connections (6) between the individual pump stages, characterized in that an additional valve (8) is attached between an intermediate suction connection (6) and the pump stage (1) facing the high vacuum side. Mehrstufiges Vakuum-Pumpsystem nach Anspruch 1, dadurch gekennzeichnet, daß das zusätzliche Ventii (8) ein Druckventil mit variabler Vorbelastung ist.Multi-stage vacuum pump system according to claim 1, characterized in that the additional valve (8) is a pressure valve with variable preload. Mehrstufiges Vakuum-Pumpsystem nach Anspruch 2, dadurch gekennzeichnet, daß die Vorbelastung des zusätzlichen Ventils (8) kleiner oder gleich der Vorbelastung des Ausstoßventils (4) ist.Multi-stage vacuum pump system according to claim 2, characterized in that the preload of the additional valve (8) is less than or equal to the preload of the exhaust valve (4). Mehrstufiges Vakuum-Pumpsystem nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Ausstoßseite der jeweils der Hochvakuumseite zugewandten Pumpstufe (1) mit der Ansaugseite der folgenden Pumpstufe (2) durch eine Bypassleitung (9) parallel zu dem zusätzlichen Ventil (8) verbunden ist, deren Querschnitt so bemessen ist, daß beim Arbeitsdruck der Pumpstufe (1) die dann noch anfallende Dampfmenge von der folgenden Pumpstufe (2) abgepumpt wird und daß der Gasanfall in dieser Pumpstufe nur in solch geringem Maße in die der Hochvakuumseite zugewandten Pumpstufe (1) zurückströmt, daß das Hochvakuum nicht wesentlich beeinträchtigt wird.Multi-stage vacuum pump system according to one of claims 1 to 3, characterized in that the discharge side of the pump stage (1) facing the high vacuum side with the suction side of the following pump stage (2) through a bypass line (9) parallel to the additional valve (8) is connected, the cross-section of which is dimensioned such that at the working pressure of the pump stage (1) the amount of steam still then produced is pumped out of the following pump stage (2) and that the gas accumulation in this pump stage only to such a small extent into the pump stage facing the high vacuum side ( 1) flows back that the high vacuum is not significantly affected. Mehrstufiges Vakuum-Pumpsystem nach Anspruch 4, dadurch gekennzeichnet, daß der Querschnitt der Bypassleitung (9) durch an sich bekannte Mittel variabel ausgeführt ist.Multi-stage vacuum pump system according to claim 4, characterized in that the cross section of the bypass line (9) is made variable by means known per se.
EP92117784A 1991-11-11 1992-10-17 Multi-stage vacuum pumping system Expired - Lifetime EP0541989B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4136950A DE4136950A1 (en) 1991-11-11 1991-11-11 MULTI-STAGE VACUUM PUMP SYSTEM
DE4136950 1991-11-11

Publications (2)

Publication Number Publication Date
EP0541989A1 true EP0541989A1 (en) 1993-05-19
EP0541989B1 EP0541989B1 (en) 1995-06-28

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EP92117784A Expired - Lifetime EP0541989B1 (en) 1991-11-11 1992-10-17 Multi-stage vacuum pumping system

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JP (1) JPH05248383A (en)
DE (2) DE4136950A1 (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4442174A1 (en) * 1994-11-26 1996-05-30 Leybold Ag Leak detector with vacuum pumps and operating procedures
EP0723080A1 (en) * 1995-01-13 1996-07-24 SGI-PROZESS-TECHNIK GmbH Vacuum pumping system
EP0730093A1 (en) 1995-02-28 1996-09-04 Iwata Air Compressor Mfg. Co.,Ltd. Control of a two-stage vacuum pump
EP0752531A1 (en) * 1995-07-06 1997-01-08 Leybold Aktiengesellschaft Apparatus for rapid evacuation of a vacuum chamber
DE19831123A1 (en) * 1998-07-11 2000-01-13 Pfeiffer Vacuum Gmbh Gas ballast device for multi-stage positive displacement pumps
DE19962445A1 (en) * 1999-12-22 2001-06-28 Leybold Vakuum Gmbh Dry compressing vacuum pump has gas ballast device with valve that only opens when difference between atmospheric pressure and pressure on pump side of valve exceeds set value
WO2020109790A1 (en) * 2018-11-28 2020-06-04 Edwards Limited Mutiple chamber vacuum exhaust system

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DE19630264A1 (en) * 1996-07-26 1998-01-29 Klein Schanzlin & Becker Ag Method for switching devices or machines in a flow system
DE202013000913U1 (en) * 2013-01-30 2014-05-05 Oerlikon Leybold Vacuum Gmbh Vacuum pump, in particular Roots pump

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US4505647A (en) * 1978-01-26 1985-03-19 Grumman Allied Industries, Inc. Vacuum pumping system
EP0343914A1 (en) * 1988-05-24 1989-11-29 The Boc Group, Inc. Evacuation apparatus and method

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US4361418A (en) * 1980-05-06 1982-11-30 Risdon Corporation High vacuum processing system having improved recycle draw-down capability under high humidity ambient atmospheric conditions
JP2607572B2 (en) * 1987-12-23 1997-05-07 株式会社日立製作所 Analysis device and method using charged particles

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US4505647A (en) * 1978-01-26 1985-03-19 Grumman Allied Industries, Inc. Vacuum pumping system
EP0343914A1 (en) * 1988-05-24 1989-11-29 The Boc Group, Inc. Evacuation apparatus and method

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4442174A1 (en) * 1994-11-26 1996-05-30 Leybold Ag Leak detector with vacuum pumps and operating procedures
US5595477A (en) * 1995-01-13 1997-01-21 Sgi-Prozesstechnik Gmbh Vacuum pumping stand
EP0723080A1 (en) * 1995-01-13 1996-07-24 SGI-PROZESS-TECHNIK GmbH Vacuum pumping system
EP0730093A1 (en) 1995-02-28 1996-09-04 Iwata Air Compressor Mfg. Co.,Ltd. Control of a two-stage vacuum pump
EP1101943A2 (en) 1995-02-28 2001-05-23 Anest Iwata Corporation Control of a two-stage vacuum pump
EP0752531A1 (en) * 1995-07-06 1997-01-08 Leybold Aktiengesellschaft Apparatus for rapid evacuation of a vacuum chamber
US6004109A (en) * 1995-07-06 1999-12-21 Balzers Und Leybold Deutschland Holding Ag Apparatus for the rapid evacuation of a vacuum chamber
DE19524609A1 (en) * 1995-07-06 1997-01-09 Leybold Ag Device for the rapid evacuation of a vacuum chamber
DE19831123A1 (en) * 1998-07-11 2000-01-13 Pfeiffer Vacuum Gmbh Gas ballast device for multi-stage positive displacement pumps
EP0972938A3 (en) * 1998-07-11 2000-06-28 Pfeiffer Vacuum GmbH Gas ballast device for a multistage positive displacement pump
DE19962445A1 (en) * 1999-12-22 2001-06-28 Leybold Vakuum Gmbh Dry compressing vacuum pump has gas ballast device with valve that only opens when difference between atmospheric pressure and pressure on pump side of valve exceeds set value
WO2020109790A1 (en) * 2018-11-28 2020-06-04 Edwards Limited Mutiple chamber vacuum exhaust system
US11933284B2 (en) 2018-11-28 2024-03-19 Edwards Limited Multiple chamber vacuum exhaust system

Also Published As

Publication number Publication date
DE59202713D1 (en) 1995-08-03
JPH05248383A (en) 1993-09-24
DE4136950A1 (en) 1993-05-13
EP0541989B1 (en) 1995-06-28

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