EP0666309A1 - Cleaning solvent for aircraft hydraulic fluid - Google Patents
Cleaning solvent for aircraft hydraulic fluid Download PDFInfo
- Publication number
- EP0666309A1 EP0666309A1 EP94200278A EP94200278A EP0666309A1 EP 0666309 A1 EP0666309 A1 EP 0666309A1 EP 94200278 A EP94200278 A EP 94200278A EP 94200278 A EP94200278 A EP 94200278A EP 0666309 A1 EP0666309 A1 EP 0666309A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- volume percent
- solvent blend
- hydraulic fluid
- carbons
- alkyl chain
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/50—Solvents
- C11D7/5004—Organic solvents
- C11D7/5018—Halogenated solvents
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
- C23G5/02—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents
- C23G5/028—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents containing halogenated hydrocarbons
- C23G5/02809—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents containing halogenated hydrocarbons containing chlorine and fluorine
- C23G5/02812—Perhalogenated hydrocarbons
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/22—Organic compounds
- C11D7/24—Hydrocarbons
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/22—Organic compounds
- C11D7/28—Organic compounds containing halogen
Definitions
- This invention relates to an environmentally compliant solvent for cleaning unwanted aircraft hydraulic fluid.
- 1,1,2-Trichloro-1,2,2-trifluoroethane or CFC-113 marketed by E. I. du Pont Nemours & Co. under the tradename Freon TFTM, by Allied Signal as Genesolv DTM and by Imperial Chemical Industries as Arklone PTM, has traditionally been specified and used by commercial aircraft producers to remove unwanted Type IV commercial aircraft hydraulic fluids from assembled airplanes and aircraft parts.
- Freon TFTM by Allied Signal as Genesolv DTM and by Imperial Chemical Industries as Arklone PTM
- trichlorotrifluoroethane has been curtailed voluntarily and by law in an effort to reduce depletion of the earth's ozone layer. Production of trichlorotrifluoroethane will be eliminated by the year 1995. Accordingly, a new cleaning solvent for hydraulic fluids must be found.
- An environmentally compliant cleaning solvent for removing commercial aircraft hydraulic fluid comprises from about 25 to 35 volume percent perfluorocarbon with from about 4 to 8 carbons in the alkyl chain, from about 25 to 35 volume percent hydrochlorofluorocarbon with about 2 to 5 carbons in the alkyl chain; and the balance petroleum distillates with from about 5 to 9 carbons in the alkyl chain.
- Figure 1 is a ternary phase diagram for the subject solvent system at -20°F.
- an environmentally compliant solvent blend for cleaning aircraft hydraulic fluid comprises from about 25 to 35 volume percent of a perfluorocarbon having about 4 to 8 carbons in the alkyl chain.
- the most preferred perfluorocarbon is C6F14.
- C6F14 is marketed by the 3MTM Company of St. Paul Minnesota as PF-5060TM and FluorinertTM FC-72.
- the solvent blend also comprises from about 25 to 35 volume percent of a hydrochlorofluorocarbon having about 2 to 5 carbons in the alkyl chain.
- a hydrochlorofluorocarbon having about 2 to 5 carbons in the alkyl chain.
- the most preferred hydrochlorofluorocarbons are pentafluorodichloropropanes, particularly mixtures of 1,1,1,2,2-pentafluoro-3,3-dichloropropane and 1,1,2,2,3-pentafluoro-1,3-dichloropropane.
- One such mixture is marketed by Asahi Glass Co., Ltd. of Tokyo, Japan, under the tradename Asahiklin AK-225TM.
- the advantage of the perfluorocarbon over trichlorotrifluoroethane is it does not catalyze ozone depletion reactions in the upper atmosphere. It is also negligibly reactive in the lower atmosphere and consequently does not contribute to the formation of photochemical smog.
- the advantage of the hydrochlorofluorocarbon over fully halogenated trichlorotrifluoroethane is that it reduces the ozone depletion potential by more than 95 percent.
- the balance of the subject solvent blend comprises liquid hydrocarbons, preferably petroleum distillates with from about 5 to 9 carbons in the alkyl chain.
- a preferred distillate is normal heptane with naturally occurring amounts of byproducts such as 2- and 3-methylhexane; 2,3- and 3,3-dimethylpentane; 2,4- and 2,2-dimethylhexane; dimethylcyclopentane, methylcyclohexane, and ethylpentane.
- One such petroleum distillate is ExxsolTM Heptane marketed by the Exxon Chemical Company of Houston, Texas.
- Novel features of this solvent blend include the desired properties of cleaning capability, acceptable environmental properties regarding ozone depletion and volatile organic compound vapor pressure, rapid evaporation, and relatively low toxicity.
- a low dielectric constant allows use of the blend even when an airplane's electrical systems are operating.
- the blend is stable at practical operating temperatures between about 120° and -20° F and can be stored outdoors.
- the blend has no measurable flashpoint.
- Cleanup of Type IV hydraulic fluid by the subject solvent blend is also novel as compared to prior cleaning solutions.
- hydraulic fluid removal occurs by solvency and dilution.
- Removal occurs by displacement wetting, solvency, extraction and dilution.
- hydraulic fluid is dissolved in the chlorofluoroalkane and petroleum distillate, both of which become partially extracted. Concurrent with this process, is displacement wetting of the substrate by the perfluorocarbon constituent. I believe that this process depends on the low interfacial tension of the perfluorocarbon and chlorofluoroalkane and equilibrium phase partitioning among all the solvent constituents and the hydraulic fluid. The combination of these processes and favorable system kinetics result in rapid and effective removal of hydraulic fluid.
Abstract
An environmentally compliant cleaning solvent for removing commercial aircraft hydraulic fluid comprises from about 25 to 35 volume percent perfluorocarbon with from about 4 to 8 carbons in the alkyl chain, from about 25 to 35 volume percent hydrochlorofluorocarbon with about 2 to 5 carbons in the alkyl chain; and the balance petroleum distillates with from about 5 to 9 carbons in the alkyl chain.
Description
- This invention relates to an environmentally compliant solvent for cleaning unwanted aircraft hydraulic fluid.
- 1,1,2-Trichloro-1,2,2-trifluoroethane or CFC-113, marketed by E. I. du Pont Nemours & Co. under the tradename Freon TF™, by Allied Signal as Genesolv D™ and by Imperial Chemical Industries as Arklone P™, has traditionally been specified and used by commercial aircraft producers to remove unwanted Type IV commercial aircraft hydraulic fluids from assembled airplanes and aircraft parts. However, the production and use of trichlorotrifluoroethane has been curtailed voluntarily and by law in an effort to reduce depletion of the earth's ozone layer. Production of trichlorotrifluoroethane will be eliminated by the year 1995. Accordingly, a new cleaning solvent for hydraulic fluids must be found.
- Although I evaluated many commercially available single component solvents, solvent blends and cleaning mixtures, none complied with environmental regulations nor possessed all the requisite qualities of thorough, rapid and complete cleaning of hydraulic fluid; low toxicity; low flammability; high evaporation rate; wide operational temperature range; and compatibility with aircraft materials and systems. Accordingly, it was my object to invent a new solvent mixture with all these qualities.
- An environmentally compliant cleaning solvent for removing commercial aircraft hydraulic fluid comprises from about 25 to 35 volume percent perfluorocarbon with from about 4 to 8 carbons in the alkyl chain, from about 25 to 35 volume percent hydrochlorofluorocarbon with about 2 to 5 carbons in the alkyl chain; and the balance petroleum distillates with from about 5 to 9 carbons in the alkyl chain.
- My invention will be better understood in terms of the figures and detailed description which follows.
- Figure 1 is a ternary phase diagram for the subject solvent system at -20°F.
- Figure 2 in a ternary phase diagram for the subject solvent system at 32°F.
- In accordance with a preferred embodiment of the invention, an environmentally compliant solvent blend for cleaning aircraft hydraulic fluid comprises from about 25 to 35 volume percent of a perfluorocarbon having about 4 to 8 carbons in the alkyl chain. The most preferred perfluorocarbon is C₆F₁₄. C₆F₁₄ is marketed by the 3M™ Company of St. Paul Minnesota as PF-5060™ and Fluorinert™ FC-72.
- The solvent blend also comprises from about 25 to 35 volume percent of a hydrochlorofluorocarbon having about 2 to 5 carbons in the alkyl chain. The most preferred hydrochlorofluorocarbons are pentafluorodichloropropanes, particularly mixtures of 1,1,1,2,2-pentafluoro-3,3-dichloropropane and 1,1,2,2,3-pentafluoro-1,3-dichloropropane. One such mixture is marketed by Asahi Glass Co., Ltd. of Tokyo, Japan, under the tradename Asahiklin AK-225™.
- The advantage of the perfluorocarbon over trichlorotrifluoroethane is it does not catalyze ozone depletion reactions in the upper atmosphere. It is also negligibly reactive in the lower atmosphere and consequently does not contribute to the formation of photochemical smog. The advantage of the hydrochlorofluorocarbon over fully halogenated trichlorotrifluoroethane is that it reduces the ozone depletion potential by more than 95 percent.
- The balance of the subject solvent blend comprises liquid hydrocarbons, preferably petroleum distillates with from about 5 to 9 carbons in the alkyl chain. A preferred distillate is normal heptane with naturally occurring amounts of byproducts such as 2- and 3-methylhexane; 2,3- and 3,3-dimethylpentane; 2,4- and 2,2-dimethylhexane; dimethylcyclopentane, methylcyclohexane, and ethylpentane. One such petroleum distillate is Exxsol™ Heptane marketed by the Exxon Chemical Company of Houston, Texas.
- Novel features of this solvent blend include the desired properties of cleaning capability, acceptable environmental properties regarding ozone depletion and volatile organic compound vapor pressure, rapid evaporation, and relatively low toxicity. A low dielectric constant allows use of the blend even when an airplane's electrical systems are operating. The blend is stable at practical operating temperatures between about 120° and -20° F and can be stored outdoors. The blend has no measurable flashpoint.
- Cleanup of Type IV hydraulic fluid by the subject solvent blend is also novel as compared to prior cleaning solutions. When using trichlorotrifluoroethane, hydraulic fluid removal occurs by solvency and dilution. With the subject solvent blend,removal occurs by displacement wetting, solvency, extraction and dilution.
- In the subject invention, hydraulic fluid is dissolved in the chlorofluoroalkane and petroleum distillate, both of which become partially extracted. Concurrent with this process, is displacement wetting of the substrate by the perfluorocarbon constituent. I believe that this process depends on the low interfacial tension of the perfluorocarbon and chlorofluoroalkane and equilibrium phase partitioning among all the solvent constituents and the hydraulic fluid. The combination of these processes and favorable system kinetics result in rapid and effective removal of hydraulic fluid.
- Over 650 solvent and solvent mixtures were reviewed for compliance with the above mentioned criteria. The material groups examined included hydrocarbons derived from petroleum and agricultural feedstocks, alcohols, glycols, glycol ethers, esters, aldehydes, ketones, ethers, halogenated hydrocarbons, nitrogen compounds, sulfur compounds, silicone compounds and commercially available cleaning solutions. Of all the solvents tested, only those with the compositions set forth above were found to be acceptable regarding all criteria.
- Referring to figures 1 and 2, mixtures of C₆F₁₄, pentafluorodichloropropane and n-heptane were compounded in the proportion indicated by the filled
circles 2, open circles 4, and stars 6 on the ternary phase diagrams. The shaded-in regions 8 and 10 of figures 1 and 2, show the compositional ranges in which a phase separation occurred between the pentafluorodichloropropane and other constituents at temperatures of -20° F and 32° F, respectively. Such phase separations, at compositions 4, for example, are unacceptable for use of the solvent.Stars 6 indicate the composition best found to meet or surpass all the requirements set out in the table below.HYDRAULIC FLUID CLEANING SOLVENT BLEND PROPERTIES PROPERTY REQUIREMENT COMMENTS Cleaning Performance BAC 5750* Performance in factory conditions verified Materials Compatibility D6-17487* Sandwich corrosion Acrylic crazing Paint softening Hydrogen embrittlement Temperature Stability -20°F<T<120°F Flammability Flashpoint >200°F No flashpoint ASTM-D93 (Pensky-Martens Closed Tester) Dielectric Constant 2<x<7 Estimated Evaporation Rate 75-125% of Trichlorotrifluoroethane ODP <0.15 0.004-0.015 VOC Vapor Pressure <1.5 psia @ 70°F <1.5 psia @ 70°F *Boeing specification designation - In summary, I have invented an environmentally acceptable solvent blend for cleaning hydraulic fluid, the ozone depletion potential of which is more than 98 percent lower than that of the chlorofluorocarbon now used. While my invention has been described in terms of specific embodiments thereof, other forms may be readily adapted by one skilled in the art. Accordingly, the scope of my invention is to be limited only in accordance with the following claims.
Claims (8)
- A cleaning solvent blend for removing commercial aircraft hydraulic fluid consisting essentially of from about 25 to 35 volume percent perfluorocarbon with from about 4 to 8 carbons in the alkyl chain, from about 25 to 35 volume percent hydrochlorofluorocarbon with from about 2 to 5 carbons in the alkyl chain; and the balance petroleum distillates with from about 5 to 9 carbons in the alkyl chain.
- A cleaning solvent blend for removing commercial aircraft hydraulic fluid consisting essentially of from about 25 to 35 volume percent C₆F₁₄; from about 25 to 35 volume percent chlorofluoropropane; and the balance petroleum distillates with from about 5 to 9 carbons in the alkyl chain.
- A cleaning solvent blend for removing commercial aircraft hydraulic fluid consisting essentially of from about 25 to 35 volume percent C₆F₁₄; from about 25 to 35 volume percent chlorofluoropropane; and the balance normal heptane with naturally occurring fractions of other petroleum distillates.
- An environmentally compliant solvent blend for cleaning aircraft hydraulic fluid consisting essentially of from about 25 to 35 volume percent of C₆F₁₄; from about 25 to 35 volume percent pentafluorodichloropropane consisting essentially of one or more constituents selected from the group consisting of 1,1,1,2,2-pentafluoro-3,3-dichloropropane and 1,1,2,2,3-pentafluoro-1,3-dichloropropane; each said halogenated hydrocarbon substantially not catalyzing ozone depletion reactions in the upper atmosphere, and the balance normal heptane with naturally occurring amounts of one or more distillation byproducts selected from the group consisting of 2-methylhexane; 3-methylhexane; 2,3-dimethylpentane; 3,3-dimethylpentane; 2,4-dimethylhexane; 2,2-dimethylhexane; dimethylcyclopentane, methylcyclohexane, and ethylpentane.
- The solvent blend of claim 1, wherein no phase separation of the constituents occurs above about -20°F.
- The solvent blend of claim 2, wherein no phase separation of the constituents occurs above about -20°F.
- The solvent blend of claim 3, wherein no phase separation of the constituents occurs above about -20°F.
- The solvent blend of claim 4, wherein no phase separation of the constituents occurs above about -20°F.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP94200278A EP0666309A1 (en) | 1994-02-02 | 1994-02-02 | Cleaning solvent for aircraft hydraulic fluid |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP94200278A EP0666309A1 (en) | 1994-02-02 | 1994-02-02 | Cleaning solvent for aircraft hydraulic fluid |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0666309A1 true EP0666309A1 (en) | 1995-08-09 |
Family
ID=8216627
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94200278A Withdrawn EP0666309A1 (en) | 1994-02-02 | 1994-02-02 | Cleaning solvent for aircraft hydraulic fluid |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0666309A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0465037A1 (en) * | 1990-06-29 | 1992-01-08 | Minnesota Mining And Manufacturing Company | Solvent composition |
JPH05140591A (en) * | 1991-11-14 | 1993-06-08 | Sanken:Kk | Hydrocarbon composition |
WO1993023519A1 (en) * | 1992-05-13 | 1993-11-25 | Allied-Signal Inc. | Azeotrope-like compositions of 1,1-dichloro-1-fluoroethane, perfluorohexane, methanol or ethanol and optionally nitromethane |
-
1994
- 1994-02-02 EP EP94200278A patent/EP0666309A1/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0465037A1 (en) * | 1990-06-29 | 1992-01-08 | Minnesota Mining And Manufacturing Company | Solvent composition |
JPH05140591A (en) * | 1991-11-14 | 1993-06-08 | Sanken:Kk | Hydrocarbon composition |
WO1993023519A1 (en) * | 1992-05-13 | 1993-11-25 | Allied-Signal Inc. | Azeotrope-like compositions of 1,1-dichloro-1-fluoroethane, perfluorohexane, methanol or ethanol and optionally nitromethane |
Non-Patent Citations (1)
Title |
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DATABASE WPI Section Ch Week 9327, Derwent World Patents Index; Class E16, AN 93-217131 * |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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18D | Application deemed to be withdrawn |
Effective date: 19980901 |