US3034700A - Method of producing high vacuum - Google Patents

Method of producing high vacuum Download PDF

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Publication number
US3034700A
US3034700A US14222A US1422260A US3034700A US 3034700 A US3034700 A US 3034700A US 14222 A US14222 A US 14222A US 1422260 A US1422260 A US 1422260A US 3034700 A US3034700 A US 3034700A
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pump
fluids
vapor
ring
polyphenyl
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US14222A
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English (en)
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Kenneth C D Hickman
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Rochester Institute of Technology
University of Rochester
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University of Rochester
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Priority to DENDAT1250049D priority Critical patent/DE1250049B/de
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Priority to US14222A priority patent/US3034700A/en
Priority to GB8747/61A priority patent/GB924784A/en
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/08—Materials not undergoing a change of physical state when used
    • C09K5/10—Liquid materials

Definitions

  • Vacuum Pumps and Pump Oils articles by applicant here, appearing in the Journal of The Franklin Institute, vol. 221, Nos. 2 and 3, February and March, 1936, discuss the operation of such working fluids in the production of high vacuums.
  • An object of this invention is to supply organic pumping fluids capable of producing vacuums which, without a cooled trap, are 100 times better than have been obtainable with previous fluids under the same operating conditions.
  • Another object of the invention is to provide fluids which can be heated to and used at higher boiler pressures and/or higher temperatures than hitherto known in the art, so that greater thermodynamic efliciency may be secured and pumps can be constructed which operate against unusually high fore pressures.
  • FIG. 1 is a vertical sectional view of a single stage vertical glass vapor-actuated pump in which the working fluids herein disclosed and claimed may be used for the production of high vacuums;
  • FIG. 2 is a vertical sectional view of a three-stage fractionating pump in which such working fluids may be used for the production of high vacuums.
  • the pumping fluids which I have discovered belong to the class of the polyphenyl ethers and the polyphenoxy benzenes, and for convenience they are referred to herein as polyphenyl ethers.
  • the materials are usually named either as benzene derivatives or as ethers, according as to whether they have odd or even numbers of benzene rings, and have the typical construction:
  • Such materials may be prepared according to any of the known methods or obtained from various commercial sources.
  • the first type of polyphenyl is the meta-, and the second paralinked.
  • the metas are generally to be preferred because of their exceptional thermal and oxidative stability at high temperatures.
  • Advantages of mixed isomers are lowered melting points and commercial availability.
  • Mixtures of the compounds themselves but of molecular weight other than the isomeric forms are also contemplated.
  • a useful working fluid would be a 4-ring phenyl ether or mixture thereof, plus a S-ring phenyl ether or mixture thereof in a fractionating pump.
  • the 4-ring compounds would gather at the fore pressure and the 5-ring compounds at the fine pressure end of the pump.
  • the invention contemplates a single vapor-actuated pump or a train of such pumps in which one or more of such ring compounds from 3 to 7 are employed.
  • the 4-ring compounds either singly or as a mixture of isomers, exert a true vapor pressure of less than 10* mm. at elevated room temperature F.) and provide highly robust fluids to create vacuums comparable to those obtainable with previous pump fluids.
  • the 5-ring meta-ether of the general formula C H O which exerts a true vapor pressure of less than 10 mm. Hg at summer room temperature.
  • Very many isomers are possible and a synthesized mixture may be a mixture of such isomers which remain liquid when the individually pure compounds might be solid.
  • I include, however, within my invention all polyphenyl ethers and phenoxy benzenes in the range of 3 to 7 phenyl groups linked by 2 to 6 oxygen atoms and of molecular weights between 264 and 641 and mixtures thereof which remain liquid under the operating conditions of a vapor vacuum pump. Particularly useful are mixtures which remain permanently fluid at room temperature.
  • polyphenyl ether compounds and their mixtures have surprising characteristics as condensation pump fluids vis-a-vis conventional working fluids. They have lower vapor pressures and higher boiling points than pump fluids heretofore employed, and a very much higher resistance to thermal decomposition and oxidization.
  • Table #1 A comparison of these properties of the poly phenyl ethers and prior art working fluids is shown in Table #1, as follows:
  • B-ring 400 excellent-- 155-175 1Xl0 -1 l0' 1 10-"-1 (l0- 4-ring 433 do K 210-250 5X10 7Xl0 1X10- 2X10- 5-1ing 460 do 11 260-300 1Xl0- 5X10- 6-ring 460 ..-do R 320-305 l l0- 5Xl0- 7-ring 450 do 300-400 1Xl0- 1X10- Monsanto data Preliminary Report on the Polyphcnyl Ethers, Bulletin No. A.V. 5, May 1959. b Vapor Pressure of Phlegmatic Liquids, II. High Molecular Weight Esters and Silicone Oils. E. S. Perry and W. N. Weber.
  • the polyphenyl ethers are often prepared by interlinking halogen derivatives with elimination of halogen, and an essential step in purification of the finished ether so prepared is removal of the last trace of halogen. This may be accomplished in any of the well-known ways, such as treatment with sodium exthoxide in ethanol with subsequent washing in water and drying. Another required step in purification is to remove light ends and thermally labile or oxidizable material, which can be done by prolonged moderate heating under vacuum or bubbling an inert gas or dry air at temperatures below 200 C. through the ethers, preferably under vacuum.
  • the material after preliminary chemical and physical clean-up, to a slow distillation under high vacuum, rejecting the first 1% to 5%, or even and the last 1% to 5% of the distillate.
  • the 5-ring compound is obtained as a mixture of isomers in the fraction distilling between 210 and 230 C. at mm. absolute.
  • the rejected fractions are also superior pump fluids, judged by previous standards, and may be employed for less critical use, for instance in a fore or booster pump.
  • Part of the purification procedure may include treatment with an absorption grade alumina or activated charcoal or clessicated silica gel, either before or after distillation.
  • I may omit one or more steps in the purification proceduresuch, for instance, as the chemical pretreatment or the highly critical vacuum distillation. Also in those pumps that are fitted with means for rejecting fore vacuum distillate, I may increase the quantity of the primary charge and reduce the volume to normal by distilling a substantial fraction directly out of the pump. Whether, therefore, the polyphenyl ether fluids are conditioned for high vacuum use during manufacture or separately thereafter or in the pump itself, I regard the operating fluid so produced as coming within the scope of my invention.
  • a polyphenyl ether or mixture as herein disclosed in any suitable vapor-actuated pump such as a single stage glass vertical pump, a three stage glass fractionating pump, or a Langmuir inverted type of metal pump, either single compartment or fractionating.
  • the heat requirements of the polyphenyl ethers may be as much as 25% to 50% greater than required for conventional working fluids, such as Octoil.
  • conventional working fluids such as Octoil.
  • I have found that by modifying the pump so as to cool the diffuser behind the jet to catch backstreaming molecules, but drastically cutting the cooling in front of the jet, I can maintain a long column of forwardly moving pump fluid vapor, and the longer this column the less chance the molecules have of diffusing backstream.
  • the chimney of the inverted type Langmuir pump can be lengthened so that a long hot diffuser region can be accommodated below the jet, thereby diminishing greatly the heat requirements. This expedient improves the ultimate vacuum and at the same time conserves so much heat that a pump thus modified may require no more, or even less, heat than an unmodified pump would using conventional working fluids.
  • a shallow alembic 6 is connected with manifold 5 and boiler 1 by branched tube 7.
  • a second alembic 8, a side tube 9, and a closure 10 complete the structural part of the pump.
  • a filling of polyphenyl ethers is placed in the boiler 1 to a depth shown at 12 permitting sufficicnt reserve so that the alembics and side tubes may be filled with liquid without the heater becoming bare.
  • Lagging 13 conveniently formed by a pad of glass wool batting, is applied around the upper portion of the diffuser and optionally a glass fibre fabric sleeve 14 is placed in the diffuser.
  • the pump boiler may be lagged as at 15, and a small air blast is conveniently directed at the region 16 while the pump is in operation.
  • Example 1 Using the pump of FIGURE 1, charged with a purified amount of the 5-ring meta polyphenyl ether and attached to an ionization gauge of the type known as VG-l-A, a reading indicating a vacuum of 5 1()* millimeters was obtained on blank-off at an ambient temperature of 80 F.
  • Example 2 150 grams of a purified sample of the 5-ring polyphenyl ether isomers were placed in a 3-stage glass fractionating pump of the type shown in FIGURE 2, except that the connecting tubes between the boilers were lengthened and provided with means such as loops to prevent 1 back diffusion of the pump fluids during their forward travel.
  • a Bayard-Alpert gauge 21, selected because of its ability to make the lowest known pressure measure- 7-ring meta- E-ring metam-B is (m-ph enoxyphenoxy) -benzeue Gring meta- Bis[m- (m-phenoxyphenoxy, phenyl] ether 5-ring meta-para m-Bls[m- (-phenoxyphenoxy) -phenoxy] benzene Q- -Q O- Q Q Q Q ments, was sealed by a wide bore bent glass tube 22 to the closed low pressure end of the pump.
  • the pump was heavily insulated with glass wool batting to conserve heat, and auxiliary heating coils 23 and 24 were placed around the necks of the middle and high vacuum jets further to minimize loss of heat.
  • the glass pump was evacuated by an oil sealed mechanical fore pump and heated by an electric current at 95 volts delivering 225 watts.
  • a system is evacuated by means of a vapor actuated pump, the step of entraining gas in a stream of vapors of a working fluid, comprising a polyphenyl ether having at least three phenyl groups and two oxygen linkages, and at most seven phenyl groups and six oxygen linkages.
  • said working fluid essentially consists of a polyphenyl ether or mixtures thereof which boil between C. and 300 C. at .1 millimeter.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Thermal Sciences (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Polyethers (AREA)
US14222A 1960-03-11 1960-03-11 Method of producing high vacuum Expired - Lifetime US3034700A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DENDAT1250049D DE1250049B (enrdf_load_stackoverflow) 1960-03-11
US14222A US3034700A (en) 1960-03-11 1960-03-11 Method of producing high vacuum
GB8747/61A GB924784A (en) 1960-03-11 1961-03-09 Improvements in or relating to method and apparatus for production of high vacua

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173873A (en) * 1962-01-23 1965-03-16 Monsanto Res Corp Functional fluid compositions
US3221058A (en) * 1965-11-30 Aromatic polyethers
US3228910A (en) * 1960-09-22 1966-01-11 Du Pont Process for preparing solid poly-1, 4-phenylene ethers
US3355094A (en) * 1963-07-02 1967-11-28 Ceskoslovenska Akademie Ved Diffusion vacuum pump
US3391195A (en) * 1963-12-04 1968-07-02 Monsanto Res Corp Fluorinated polyphenyl ethers
US3923424A (en) * 1974-11-11 1975-12-02 Alvin E Buggele Self-cleansing diffusion pump
US5059002A (en) * 1989-12-21 1991-10-22 Minnesota Mining And Manufacturing Company Second harmonic generation with achiral, straight-chain carbamic acid derivatives

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2951629A (en) * 1958-07-21 1960-09-06 Dow Corning Silicate diffusion pump fluids

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2951629A (en) * 1958-07-21 1960-09-06 Dow Corning Silicate diffusion pump fluids

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3221058A (en) * 1965-11-30 Aromatic polyethers
US3228910A (en) * 1960-09-22 1966-01-11 Du Pont Process for preparing solid poly-1, 4-phenylene ethers
US3173873A (en) * 1962-01-23 1965-03-16 Monsanto Res Corp Functional fluid compositions
US3355094A (en) * 1963-07-02 1967-11-28 Ceskoslovenska Akademie Ved Diffusion vacuum pump
US3391195A (en) * 1963-12-04 1968-07-02 Monsanto Res Corp Fluorinated polyphenyl ethers
US3923424A (en) * 1974-11-11 1975-12-02 Alvin E Buggele Self-cleansing diffusion pump
US5059002A (en) * 1989-12-21 1991-10-22 Minnesota Mining And Manufacturing Company Second harmonic generation with achiral, straight-chain carbamic acid derivatives

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GB924784A (en) 1963-05-01
DE1250049B (enrdf_load_stackoverflow) 1967-09-14

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