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US3198209A - Diffusion vacuum pump system apparatus - Google Patents

Diffusion vacuum pump system apparatus Download PDF

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Publication number
US3198209A
US3198209A US240874A US24087462A US3198209A US 3198209 A US3198209 A US 3198209A US 240874 A US240874 A US 240874A US 24087462 A US24087462 A US 24087462A US 3198209 A US3198209 A US 3198209A
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US
United States
Prior art keywords
vacuum
diffusion
sealed
pump
pumping fluid
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.)
Expired - Lifetime
Application number
US240874A
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English (en)
Inventor
Werner G Bachler
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.)
Leybold Holding AG
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Leybold Holding AG
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Filing date
Publication date
Application filed by Leybold Holding AG filed Critical Leybold Holding AG
Application granted granted Critical
Publication of US3198209A publication Critical patent/US3198209A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04FPUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F9/00Diffusion pumps
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S55/00Gas separation
    • Y10S55/15Cold traps
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/6851With casing, support, protector or static constructional installations
    • Y10T137/7036Jacketed
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/8593Systems
    • Y10T137/85978With pump
    • Y10T137/86083Vacuum pump

Definitions

  • This invention is related to diffusion pump vacuum systems and more particularly to a device for preventing the migration of the diffusion mememping fluid in such vacuum systems.
  • cooling traps positioned between the diffusion pump and the vacuum chamber being evacuated. These traps are expected to maintain on the high vacuum side of the system a diffusion pumping fluid vapor partial pressure corresponding to the pumping fluid vapor pressure at the temperature of the cooling traps cooled surfaces. Such partial pressures will in the case of a water cooled trap amount to only 10" Torr While for a condensed gas (for example, nitrogen) cooled trap the partial pressure will be completely negligible with respect to the total pressure produced by outgassing from the vacuum system walls as well as the back diffusion of hydrogen from the diffusion pump.
  • condensed gas for example, nitrogen
  • an operating diffusion pump vacuum system with a pre heat-ed high vacuum chamber will, after a short period of time, demonstrate a slow rise in pressure despite the fact that the cooling traps are functioning perfectly.
  • the rising pressure has been shown to result from an increasing partial pressure of the diffusion pump operating fluid and/or its decomposition products.
  • An exacting study of the construction materials used in such high vacuum system-s shows that the creepage of the pumping fluid in a thin film from the diffusion pump walls along the relatively warm internal walls of the cooling traps into the high vacuum chamber is the cause of the rise in pumping fluid partial pressure.
  • One feature of this invention is the provision in a diffusion vacuum pump system of a pumping fluid creepage barrier positioned so as to interrupt all wall surface paths between the diffusion pump and the high vacuum chamber wherein the pumping fluid creepage barrier is com- 3,1932% Patented Aug. 3, 1965 posed of a material which will not be wetted by the diffusion pumping fluid.
  • Another feature of this invention is the provision of a diffusion vacuum pump system of the above featured type wherein the pumping fluid creepage barrier is composed of a solid material having a surface energy less than that of the diffusion pumping fluid
  • Another feature of this invention is the provision of a diffusion vacuum pump system of the above featured type wherein the pumping fluid creepage barrier is composed of a solid material having a surface energy less than 25 dynes per centimeter.
  • Another feature of the present invention is the provision of a diffusion vacuum pump system of the above featured type wherein the pumping fluid creepage barrier is composed of a condensed fluorinated hydrocarbon material such as, for example, the materials known by the trade names Teflon, Chemelec-300, Fluoroflex-T, Fluoroplast, Gering TRW, Polypenco-T, and Kel-F.
  • a condensed fluorinated hydrocarbon material such as, for example, the materials known by the trade names Teflon, Chemelec-300, Fluoroflex-T, Fluoroplast, Gering TRW, Polypenco-T, and Kel-F.
  • FIG. 1 is a schematic sectional elevation view of a diffusion vacuum pump system according to this invention
  • FIG. 2 is a partial sectional plan view of the system shown in FIG. 1;
  • FIG. 3 is an enlarged partial sectional view of the pumping fluid creepage barrier shown in FIG. 1;
  • FIG. 4 is an enlarged partial sectional. view of another pumping fluid creepa-ge barrier embodiment of the subject invention. 1
  • FIGS. 1-3 thereis shown a diffusion vacuum pump system 11 having a diffusion pump 12 con nected to a vacuum sealed high vacuum chamber 13 to be evacuated.
  • the connections are made in a vacuum tight manner so that the inner walls 16 and 17 of the liqu-id nitrogen 14 and Water cooled trap 15, respectively, form a continuous vacuum wall 20 between the diffusion pump 12 and the high vacuum chamber 13.
  • annular gasket 21 Maintaining the annular gasket 21 in position is an annular retaining ring 22 which projects into the internal area joining the liquid nitrogen trap 14 and the water cooled trap 15. Attached to the lower projecting edge 23 of the retaining ring 22 by an annular space-r 24 and a plurality of bolts 25 is the annular pumping fluid creepage barrier 26.
  • annular creepage barrier 26 has a rectangular cross section with a width which is several times its height.
  • the outer edge of the cree-page barrier 26 is attached to the retaining ring 22 While the inner portion of the barrier extends into the internal area joining the liquid nitrogen trap 14 and the Water cooled trap 15.
  • the present invention utilizes for the creepage barrier 26 a material which will not be Wetted by the pumping fluid. In this way the migration or creepage of pumping fluid, along the vacuum systems internal wall can be effectively stopped.
  • FIGS. 13 The prefered embodiment of the invention shown in FIGS. 13 is particularly well suited for the function since since the internal projection of rectangular cross sectional creepage barrier 26 considerably lengthens the non- Wettable material path which must be traversed by the creeping pumping fluid. Also the extending spacer ring 24 may also be made of such a material to further extend the barrier length.
  • the positioning of the creepage barrier 26 between the condensed gas trap 14 and the water cooled trap is also of considerable advantage. Thi placement provides the barrier in an area where most of the potential barrier bypassing pumping fluid vapor has been obstructed by the water cooled trap 15 while still providing a long arduou path through condensed gas trap 14 for any vapor evaporating from the migrating surface film stopped by the creepage barrier 25.
  • FIG. 4 shows a partial view of another preferred embodiment of thi invention wherein components identical to those shown in FIG. 1 are given corresponding identical numbers.
  • the continuous annular creepage barrier 31 shown is of L shape with one arm 32 attached to retaining ring 22 and the other arm 33 extending above the retaining ring 22.
  • This embodiment has the advantage that projecting arm 33 together with cold surface 34 completely shields the relatively warm internal surface 16 of the condensed gas trap 14 from evaporated pumping fluid vapor.
  • Condensed fluorinated hydrocarbon materials have proven particularly effective as diffusion pump oil creepage barriers. These materials include, for example, the products sold under the trade name Teflon, Chemelec-300, Fluoro flex-T, Fluoroplast, Goring TRW, Polypenco-T and Kel-F.
  • thermoplastic Teflon which is a registered trade name of E. I. du Pont de Nemours & Co.
  • the chemical formula for this material is (-CF CF and it exhibits an extremely low surface energy against air of about 6 dynes per centimeter. This material also offers other good high vacuum properties such as a low vapor pressure and outgassing.
  • the creepage barrier 2-6 could be positioned in other parts of the system, the
  • barrier could be constructed of other materials and then coated with a non-wettable material, etc.
  • a vacuum system apparatus comprising a diffusion vacuum pump adapted to utilize a pumping fluid, a sealed vacuum chamber adapted to be evacuated by said diffusion vacuum pump, a vacuum sealed tubulation connected positioned so, as to interrupt all paths between said diffusion vacuum pump and said sealed vacuum chamber along the internal surface of said vacuum sealed tubulation and wherein said creepage barrier is composed of a solid material not wetted by the pumping fluid utilized in said diffusion pump thereby effectively preventing surface migration of the pumping fluid between said vacuum diffusion pump and said sealed vacuum chamber.
  • said creepage barrier is composed of a material having a surface energy in air less than that of the pumping fluid.
  • said creepage barrier is composed of a material which has a surface energy in air of less than 25 dynes per centimeter.
  • said creepage barrier is composed of the thermoplastic material sold under the trade name Teflon.
  • said vaccum sealed tubulation includes a trap adapted for use with compressed cooling gas positioned adjacent said sealed vacuum chamber and a trap adapted for use with cooling water positioned adjacent said vacuum diffusion pump, and said creepage barrier is an annular ring in contact with the internal surface of said vacuum sealed tubulation and positioned between said traps.
  • a vacuum system apparatus comprising a diffusion vacuum pump adapted to utilize a pumping fluid, a sealed vacuum chamber adapted to be evacuated by said diffusion vacuum pump, a vacuum sealed tubulation connected between said diffusion vacuum pump and said sealed vacuum chamber so as to provide for gas communication therebetween, a creepage barrier including a three dimensional portion which extends into the volume enclosed by said vacuum sealed tubulation and thereby serves to shield said vacuum chamber from the pumping fluid which evaporates in said diffusion pump, said creepage barrier positioned so as to interrupt all paths between said diffusion vacuum pump and said sealed vacuum chamber v along the internal surface of said vacuum sealed tubulation, and wherein said creepage barrier is composed of the thermoplastic material sold under the trade name Teflon thereby effectively preventing migration of the pumping fluid between said diffusion vacuum pump and said sealed vacuum chamber.
  • said vacuum sealed tubulation includes a trap adapted for use with compressed cooling gas positioned adjacent said sealed vacuum chamber and a trap adapted for use with cooling water positioned adjacent said vacuum diffusion pump, and said creepage barrier comprises an annular ring in contact with the internal surface of said vacuum sealed tubulation and positioned between said traps.
  • a vacuum system apparatus comprising a diffusion vacuum pump adapted to utilize a pumping fluid, a sealed vacuum chamber adapted to be evacuated by said diffusion vacuum pump, a vacuum sealed tubulation connected between said diffusion vacuum pump and said sealed vacuum chamber so as to provide for gas communication therebetween, a creepage barrier including a three dimensional portion which extends into the volume enclosed .by said vacuum sealed tubulation and thereby serves to shield said vacuumchamber from the pumping fluid which evaporates in said diffusion pump, said creepage barrier positioned so as to interrupt all paths between said diffusion vacuum pump and said sealed vacuum chamber along the internal surface of said vacuum sealed tubulation and wherein said creepage barrier is composed of a compressed fluoronated hydrocarbon material so as to effectively prevent migration of the pumping fluid between said vacuum diffusion pump and said sealed vacuum chamber.
  • said vacuum sealed tubulation includes a trap adapted for use with compressed cooling gas positioned adjacent said sealed vacuum chamber and a trap adapted for use with cooling water positioned adjacent said vacuum diffusion pump, and said creepage barrier comprises an annular ring in contact with the internal surface of said vacuum sealed tubulation and positioned between said traps.
  • a vacuum system apparatus comprising a diffusion vacuum pump adapted to utilize a pumping fluid, a sealed vacuum chamber adapted to be evacuated by said diffusion vacuum pump, a vacuum sealed tubulation connected between said diffusion vacuum pump and said sealed vacuum chamber so as to provide for gas communication therebetween, a creepage barrier including a three dimensional portion which extends into the volume enclosed by said vacuum sealed tubulation and thereby serves to shield said vacuum chamber from the pumping fluid which evaporates in said diffusion pump, said creepage barrier positioned so as to interrupt all paths between said diffusion vacuum pump and said sealed vacuum chamber along the internal surface of said vacuum sealed tubulation and wherein said creepage barrier is composed of a material having a surface energy of less than 25 dynes per centimeter so as to effectively prevent migration of the pumping fluid between said vacuum diffusion pump and said sealed vacuum chamber.
  • said vacuum sealed tubulation includes a trap adapted for use with compressed cooling gas positioned adjacent said sealed vacuum chamber and a trap adapted for use with cooling water positioned adjacent said vacuum diffusion pump, and said creepage barrier comprises an annular ring in contact with the internal surface of said vacuum sealed tubulation and positioned between said traps.
  • a vacuum system apparatus comprising a diffusion vacuum pump adapted to utilize a pumping fluid, a sealed vacuum chamber adapted to be evacuated by said diffusion vacuum pump, a vacuum sealed tubulation connected between said diffusion vacuum pump and said sealed vacuum chamber so as to provide for gas communication therebetween, a creepage barrier including a three dimensional portion which extends into the volume enclosed by said vacuum sealed tubulation and thereby serves to shield said vacuum chamber from the pumping fluid which evaporates in said diffusion pump, said creepage barrier positioned so as to interrupt all paths between said diffusion vacuum pump and said sealed vacuum chamber along the internal surface of said vacuum sealed tubulation, and wherein said creepage barrier is composed of a material having a surface energy in air less than that of the pumping fluid so as to effectively prevent migration of the pumping fluid between said diffusion vacuum pump and said sealed vacuum chamber.
  • said vacuum sealed tubulation includes a trap adapted for use with compressed cooling gas positioned adjacent said sealed vacuum chamber and a trap adapted for use with cooling water positioned adjacent said vacuum diffusion pump, and said creepage barrier comprises an annular ring in contact with the internal surface of said vacuum sealed tubulation and positioned between said traps.
  • a device for use in diffusion vacuum pump systems including a diffusion vacuum pump adapted for use with a pumping fluid, a vacuum chamber to be evacuated, and a vacuum sealed tubulation providing for gas communication therebetween, said device comprising a creepage barrier adapted for placement in the diffusion vacuum pump system in such a manner as to interrupt all paths between the diffusion vacuum pump and the vacuum chamber along the internal surface of the vacuum sealed tubulation, said creepage barrier comprising a three dimensional portion adapted to extend into the volume enclosed by the vacuum sealed tubulation and wherein said creepage barrier is composed of a material not wetted by the pumping fluid.
  • a device for use in diffusion vacuum pump systems including a diffusion vacuum pump adapted for use with a pumping fluid, a vacuum chamber to be evacuated, and a vacuum sealed tubulation providing for gas communication therebetween, said device comprising a creepage barrier adapted for placement in the diffusion vacuum pump system in such a manner as to interrupt all paths between the diffusion vacuum pump and the vacuum chamber along the internal surface of the vacuum sealed tubulation, said creepage barrier comprising a three d-imensional portion adapted to extend into the volume enclosed by the vacuum sealed tubulation and wherein said creepage barrier is composed of a material having a surface energy in air less than that of the pumping fluid.
  • a device for use in diffusion vacuum pump systems including a diffusion vacuum pump adapted for use with a pumping fluid, a vacuum chamber to be evacuated, and a vacuum sealed tubulation providing for gas communication therebetween, said device comprising a creepage barrier adapted for placement in the diffusion vacuum pump system in such a manner as to interrupt all paths between the diffusion vacuum pump and the vacuum chamber along the internal surfaceof the vacuum sealed tubulation, said creepage barrier comprising a three dimensional portion adapted to extend into the volume enclosed by the vacuum sealed tubulation and wherein said creepage barrier is composed of a material which has a surface energy in air of less than 25 dynes per centimeter.
  • a device for use in diffusion vacuum pump systems including a diffusion vacuum pump adapted for use with a pumping fluid, a vacuum chamber to be evacuated, and a Vacuum sealed tubulation providing for gas communication therebetween, said device comprising a creepage barrier adapted for placement in the diffusion vacuum pump system in such a manner as to interrupt all paths between the diffusion vacuum pump and the vacuum chamber along the internal surface of the vacuum sealed tubulation, said creepage barrier comprising a three dimensional portion adapted to extend int-o the volume enclosed by the vacuum sealed tubulation and wherein said creepage barrier is made of a compressed fluorinated hydrocarbon material.
  • a device for use in diffusion vacuum pump systems including a diffusion vacuum pump adapted for use with a pumping fluid, a vacuum chamber to be evacuated, and a vacuum sealed tubulation providing for gas communication therebetween, said device comprising a creepage barrier adapted for placement in the diffusion vacuum pump system in such a manner as to interrupt all paths between the diffusion vacuum pump and the vacuum chamber along the internal surface of the-vacuum sealed tubulation, said creepage barrier comprising a three dimensional portion adapted to extend into the volume enclosed by the vacuum sealed tubulation and wherein said creepage barrier is composed of the thermoplastic material sold under the trade name Teflon,
  • a vacuum system apparatus comprising a diffusion vacuum pump adapted to utilize a pumping fluid, a sealed vacuum chamber adapted to be evacuated by said diffusion vacuum pump, a vacuum sealed tubulation connected between said diffusion vacuum pump and said sealed vacuum chamber so as to provide for gas communication therebetween, a creepage barrier located entirely within said vacuum sealed tubulation so as to be isolated from the atmosphere during periods in which said tubulation is maintained at reduced pressure, said creepage barrier including a three dimensional portion which extends into the volume enclosed by said vacuum sealed tubulation and positioned so as to interrupt all paths between said diffusion vacuum p ump and said sealed vacuum chamber along the internal surface of said vacuum sealed tubulation, and wherein said creepage barrier is composed of the thermoplastic material sold under the trade name Teflon thereby preventing surface migration of the pumping fluid between said diffusion vacuum pump and said sealed vacuum chamber.
  • a creepage barrier located within said vacuum sea-led tubulation, said creepage barrier comprising a three dimensional portion positioned in the volume enclosed by said vacuum sealed tubulati-on thereby serving to shield said vacuum chamber from the pumping fluid which evaporates in said diffusion vacuum pump, and wherein said three dimensional portion is composed of a solid material not wetted by the pumping fluid utilized in said diflusion pump thereby effectively preventing surface migration of the pumping fluid in a direction towards said sealed vacuum chamber.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
US240874A 1961-11-29 1962-11-29 Diffusion vacuum pump system apparatus Expired - Lifetime US3198209A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEL40565A DE1266919B (de) 1961-11-29 1961-11-29 Kriechbarriere zum Verhindern des Eindringens von Treibmittel und Vakuumanlage unterVerwendung einer solchen Kriechbarriere

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US3198209A true US3198209A (en) 1965-08-03

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US (1) US3198209A (de)
CH (1) CH401341A (de)
DE (1) DE1266919B (de)
GB (1) GB996130A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3296810A (en) * 1964-08-24 1967-01-10 Nat Res Corp High conductance cold trap for vacuum systems
US3399691A (en) * 1966-08-15 1968-09-03 Gen Electric Liquid transfer system
US3478954A (en) * 1967-11-30 1969-11-18 Bendix Corp Vacuum pump

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1202397A (fr) * 1958-07-01 1960-01-11 Radiologie Cie Gle Perfectionnement aux pompes à jet de vapeur
FR1254532A (fr) * 1960-01-14 1961-02-24 Basses Pressions Lab Des Pompe à diffusion perfectionnée pour ultra-vide
US3077638A (en) * 1959-07-22 1963-02-19 Westinghouse Electric Corp Method for producing a sealing gasket

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE581133C (de) * 1930-01-06 1933-07-21 Ass Elect Ind Kondensations- oder Diffusionsvakuumpumpe mit ringfoermigem Strahl
DE1083480B (de) * 1953-05-26 1960-06-15 Sulzer Ag Kolbenkompressor
DE1028734B (de) * 1957-02-09 1958-04-24 Leybolds Nachfolger E Vorrichtung zum Verhindern des Einstroemens von Daempfen in Hochvakuumraeume

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1202397A (fr) * 1958-07-01 1960-01-11 Radiologie Cie Gle Perfectionnement aux pompes à jet de vapeur
US3077638A (en) * 1959-07-22 1963-02-19 Westinghouse Electric Corp Method for producing a sealing gasket
FR1254532A (fr) * 1960-01-14 1961-02-24 Basses Pressions Lab Des Pompe à diffusion perfectionnée pour ultra-vide

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3296810A (en) * 1964-08-24 1967-01-10 Nat Res Corp High conductance cold trap for vacuum systems
US3399691A (en) * 1966-08-15 1968-09-03 Gen Electric Liquid transfer system
US3478954A (en) * 1967-11-30 1969-11-18 Bendix Corp Vacuum pump

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Publication number Publication date
GB996130A (en) 1965-06-23
DE1266919B (de) 1968-04-25
CH401341A (de) 1965-10-31

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