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Home , Chlorotrifluorosilane, Cyanogen fluoride, Dielectric gas, Difluorosilane, Fluorine nitrate, Hypofluorous acid

US007807074 B2

(12) United States Patent (10) Patent No.: US 7,807,074 B2 Luly et al. (45) Date of Patent: Oct. 5, 2010

(54) GASEOUS WITH LOW Shiojiri, et al., Abstract of "Life cycle impact assessment of various GLOBAL WARMING POTENTIALS treatment scenarios for hexafluoride (SF6) used as an insulat ing ”. Environmental Progress, 2006. 25(3), 218-227. (75) Inventors: Matthew H. Luly, Hamburg, NY (US); Shiojiri, et al., Abstract of "A Life cycle impact assessment study. On Robert G. Richard, Hamburg, NY (US) (SF6) used as a gas ', 2004, American Institute of Chemical Engineers, 005E/1-005E/9. (73) Assignee: Honeywell International Inc., Goshima, et al., Abstract of “Estimation of cross-sectional size of gas-insulated apparatus using hybrid insulation system with SF6 Morristown, NJ (US) substitute'. Gaseous Dielectrics X, 2004, pp. 253-258. Telfer, et al., Abstract of "A novel approach to power (*) Notice: Subject to any disclaimer, the term of this design for replacement of SF6”. Centre for Intelligent Monitoring patent is extended or adjusted under 35 Systems, Dept. of Electrical Engineering and Electronics, 2004, U.S.C. 154(b) by 803 days. 44(2), pp. 72-76. Gustavino, et al., Abstract of "Performance of glass RPC operated in (21) Appl. No.: 11/637,657 streamer mode with four-fold gas mixtures containing SF6, Nuclear Instruments & Methods in Physics Research, Section A: Accelera (22) Filed: Dec. 12, 2006 tors, Spectrometers, Detectors, and Associated Equipment, 2004, 517(1-3), pp. 101-108. (65) Prior Publication Data Diaz, et al., Abstract of “Effect of the percentage of SF6 (100%-10%- US 2008/O135817 A1 Jun. 12, 2008 5%) On the decomposition of SF6-N2 mixtures under negative dc coronas in the presence of vapour or . Journal of Physics D: Applied Physics, 2003, 36(13), pp. 1558-1564. (51) Int. Cl. Yanabu, et al., Abstract of “New concept of for replacing HOIB 3/6 (2006.01) SF6 orgas mixture', Gaseous Dielectrics IX, 9', 2001, pp. 497-504. (52) U.S. Cl...... 252/571; 252/67; 252/68; Knobloch, et al., Abstract of “The comparison of arc-extinguishing 252/69 capability of sulfur hexafluoride (SF6) with alternative in (58) Field of Classification Search ...... 252/67, high-voltage circuit-breakers”. Gaseous Dielectrics VIII, 8", 1998, 252/68, 69,571 pp. 565-571. See application file for complete search history. Tioursi, et al., Abstract of “Conditioning phenomena in N2, SF6, and air”, IEE Conference, 467 ( Engineering, vol. 3), 1999, (56) References Cited pp. 3.212-3.215. U.S. PATENT DOCUMENTS Christophorou, et al., Abstract of "SF6/N2 mixtures. Basic and HV insulation properties”, IEEE Transactions on Dielectrics and Elec 2,786,804 A 3, 1957 Nelson ...... 2O3/50 trical Insulation, 1995, 205), pp. 952-1003. 4,257.905 A 3/1981 Christophorou et al. Pai, et al., Abstract of "Impulse breakdown of cis-octafluorobuiene/ 4,275,260 A 6, 1981 Wootton sulfur hexafluoride and cis-octafluorobuiene/sulfur hexaflouride/ni 4,288,651 A 9, 1981 Wootton trogen”, Gaseous Dielectr. Proc. Int. Sump. 2", 1980, pp. 190-199. 4,440,971 A 4, 1984 Harrold Devins, J.C., Abstract of "Replacement gases for sulfur 4,547.316 A 10, 1985 Yamauchi 4,816,624 A 3, 1989 Perrissin et al...... 200,148 B hexafluoride', IEEE Transactions on Electrical Insulation, 1980, 4,871,680 A * 10/1989 Barraud et al...... 436,103 EI-15-(2), pp. 81-86. 5,236,611 A 8, 1993 Shifett Devins, et al., Abstract of "Replacement gases for sulfur 5,918,140 A * 6/1999 Wickboldt et al...... 438,535 hexafluoride'. Annual Report—Conference on Electrical Insulation 6,886,573 B2 5/2005 Hobbs et al...... 134,22.1 and Phenomena, 1979, pp. 398-408. 6,897,396 B2 5/2005 Ito et al...... 218.120 Rhodes, et al., Abstract of "Assessment of the possible use of 2002/0135029 A1* 9/2002 Ping et al...... 257,401 polythene/gas dielectrics in high-voltage cables'. Proc. Inst. Elec. 2002/0137269 A1* 9/2002 Ping et al...... 438/197 Engrs., 1965, 112-*), pp. 1617-1624. 2003/0164513 A1* 9/2003 Ping et al...... 257/288 Howard, et al., Abstract of "Insulation properties of compressed 2005, 0181621 A1* 8, 2005 Borland et al. . ... 438,752 electronegative gases”. Proc. Inst. Elec. Engrs., 1957, 104(Pt. A), pp. 2006/0060818 A1* 3/2006 Tempel et al...... 252/1813 123-138. 2006/0133986 A1* 6/2006 Dukhedin-Lalla et al. ... 423,500 2009, 0211449 A1* 8, 2009 Olschimke et al...... 95/233 * cited by examiner Primary Examiner Douglas McGinty FOREIGN PATENT DOCUMENTS EP O129200 A 12, 1984 (57) ABSTRACT EP 1146522X 10, 2001 A dielectric gaseous compound which exhibits the following OTHER PUBLICATIONS properties: a boiling point in the range between about -20°C. CAS Reg. No. 7647-19-0, Nov. 16, 1984.* to about -273° C.; low depleting; a GWP less than Takuma, et al., “Gases as a Dielectric', pp. 195-2004, Gaseous about 22,200; chemical stability, as measured by a negative Dielectrics X. Springer, 2004. standard enthalpy of formation (dHf-0); a toxicity level such Lutz Niemeyer, “A Systematic Search for Insulation Gases and Their that when the dielectric gas leaks, the effective diluted con Environmental Evaluation': pp. 459-464, Gaseous Dielectrics VIII, 1998. centration does not exceed its PEL; and a Christophorou, et al., “Gases for Electrical Insulation and Arc Inter greater than air. ruption. Possible Present and Future Alternatives to Purse SF6”. NIST Technical Note 1425, Nov. 1997. 2 Claims, No Drawings US 7,807,074 B2 1. 2 GASEOUS DELECTRICS WITH LOW easily liquefied under pressure at room temperature allowing GLOBAL WARMING POTENTIALS for compact storage in gas cylinders. It presents no handling problems, is readily available, and reasonably inexpensive. FIELD SF replaced air as a dielectric in gas insulated equipment The present disclosure relates generally to a class of gas based on characteristics Such as insulation ability, boiling eous dielectric compounds having low global warming poten point, compressibility, chemical stability and non-toxicity. tials (GWP). In particular, such gaseous dielectric com They have found that pure SF, or SF- mixtures are pounds exhibits the following properties: a boiling point in the best gases to date. the range between about -20° C. to about -273° C.; low, 10 However, SF has some undesirable properties: it can form preferably non-ozone depleting; a GWP less than about highly toxic and corrosive compounds when Subjected to 22,200; chemical stability, as measured by a negative stan electrical discharges (e.g., SF, SOF); non-polar contami dard enthalpy of formation (dHf-0); a toxicity level such that nants (e.g., air, CF) are not easily removed from it; its break when the dielectric gas leaks, the effective diluted concentra down Voltage is sensitive to water vapor, conducting particles, tion does not exceed its PEL, e.g., a PEL greater than about 15 and conductor Surface roughness; and it exhibits non-ideal 0.3 ppm by Volume (i.e., an Occupational Exposure Limit gas behavior at the lowest temperatures that can be encoun (OEL or TLV) of greater than about 0.3 ppm); and a dielectric tered in the environment, i.e., in cold climatic conditions strength greater than air. These gaseous dielectric compounds (about -50° C.), SF becomes partially liquefied at normal are particularly useful as insulating-gases for use with elec operating pressures (400 kPa to 500 kPa). SF is also an trical equipment, such as gas-insulated circuit breakers and efficient infrared (IR) absorber and due to its chemical inert current-interruption equipment, gas-insulated transmission ness, is not rapidly removed from the earth's atmosphere. lines, gas-insulated , or gas-insulated Substa Both of these latter properties make SF a potent greenhouse tions. gas, although due to its chemical inertness (and the absence of and atoms in the SF molecule) it is benign BACKGROUND 25 with regard to stratospheric ozone depletion. That is, greenhouse gases are atmospheric gases which Sulfur hexafluoride (SF) has been used as a gaseous absorb a portion of the infrared radiation emitted by the earth dielectric (insulator) in high Voltage equipment since the and return it to earth by emitting it back. Potent greenhouse 1950s. It is now known that SF6 is a potent greenhouse gases have strong infrared absorption in the wavelength range warming gas with one of the highest global warming poten 30 from approximately 7um to 13um. They occur both naturally tials (GWP) known. Because of its high GWP, it is being in the environment (e.g., H2O, CO, CH, NO) and as man phased out of all frivolous applications. However, there is made gases that may be released (e.g., SF, perfluorinated currently no known Substitute for SF in high Voltage equip compound (PFC); combustion products such as CO, nitro ment. The electrical industry has taken steps to reduce the gen, and Sulfur oxides). The effective trapping of long-wave leak rates of equipment, monitor usage, increase recycling, 35 length infrared radiation from the earth by the naturally and reduce emissions to the atmosphere. However, it would occurring greenhouse gases, and its reradiation back to earth, still be advantageous to find a substitute for SF in electrical results in an increase of the average temperature of the earth's dielectric applications. Surface. Mans impact on climate change is an environmental The basic physical and chemical properties of SF, its issue that has prompted the implementation of the Kyoto behavior in various types of gas discharges, and its uses by the 40 electric power industry have been broadly investigated. Protocol regulating the emissions of man made greenhouse In its normal state, SF is chemically inert, non-toxic, non gases in a number of countries. flammable, non-explosive, and thermally stable (it does not SF is an efficient absorber of infrared radiation, particu decompose in the gas phase at temperatures less than 500 larly at wavelengths near 10.5 Lum. Additionally, unlike most C.). SF exhibits many properties that make it suitable for 45 other naturally occurring greenhouse gases (e.g., CO., CH). equipment utilized in the transmission and distribution of SF is only slowly decomposed; therefore its contribution to electric power. It is a strong electronegative (electron attach global warming is expected to be cumulative and long lasting. ing) gas both at room temperature and at temperatures well The strong infrared absorption of SF and its long lifetime in above ambient, which principally accounts for its high dielec the environment are the reasons for its extremely high global tric strength and good arc-interruption properties. The break 50 warming potential which for a 100-year time horizon is esti down voltage of SF is nearly three times higher than air at mated to be approximately 22,200 times greater (per unit atmospheric pressure. Furthermore, it has good heat transfer mass) than that of CO, the predominant contributor to the properties and it readily reforms itself when dissociated under greenhouse effect. The concern about the presence of SF in high gas-pressure conditions in an electrical discharge or an the environment derives exclusively from this very high value arc (i.e., it has a fast recovery and it is self-healing). Most of 55 of its potency as a greenhouse gas. its stable decomposition byproducts do not significantly Accordingly, many in the electrical equipment industry degrade its dielectric strength and are removable by filtering. have spent Substantial time and effort seeking Suitable It produces no polymerization, , or other conductive replacement gases to reduce the use of SF in high voltage deposits during arcing, and its is chemically compatible with electrical equipment. To date, the possible replacement gases most insulating and conducting materials used in elec 60 have been identified as (i) mixtures of SF and nitrogen for trical equipment attemperatures up to about 200° C. which a large amount of research results are available; (ii) Besides it good insulating and heat transfer properties, SF gases and mixtures (e.g., pure nitrogen, low concentrations of has a relatively high pressure when contained at room tem SF in N, and SF. He mixtures) for which a smaller yet perature. The pressure required to liquefy SF at 21°C. is significant amount of data is available; and (iii) potential about 2100 kPa; its boiling point is reasonably low, -63.8°C., 65 gases for which little experimental data is available. which allows pressures of 400 kPa to 600 kPa (4 to 6 atmo Some replacements which have been proposed have higher spheres) to be employed in SF-insulated equipment. It is GWPs than SF. For example, CFSFs falls into this category. US 7,807,074 B2 3 4 Because of fugitive emissions in the manufacture, transpor Hexafluorodimethyl sulfide tation, filling and use of Such chemicals, they should be 3-fluoro-3HH-diazirine-3-carbonitrile avoided. Ethyne However, the present inventors have determined that given 1.2.2-trifluoro-aziridine the environmental difficulty of SF, it is necessary to relax Ketene certain of the requirements traditionally held as important and (difluoro)vinylboran accept as an alternative gas, compromise candidates with a (Difluor)vinylboran (germ.) lower GWP. For example, gases which are non-toxic are often trifluoro-vinyl- inert with long atmospheric lifetimes which can yield high Ethinylsilan GWP. By accepting a somewhat more reactive gas than SF 10 ethyl-difluor-borane the GWP can be greatly reduced. It may also be necessary to Ethyl-difluor-boran (germ.) accept slightly more toxic materials in order to find the best methyl-methylen-amine alternative in these applications. Such an increase intoxicity Dimethyl ether can be offset by reducing equipment leak rates or installing vinyl-silane monitoring equipment. In some cases, the gases discovered 15 Dimethylsilane by the present inventors as suitable alternatives to SF are Chloroethyne show to be efficient at low levels and can be mixed with fluoroethyne/fluoro-acetylene nitrogen and/or another non-toxic gas to give dielectrics with Ethanedinitrile greatly reduced toxicity and acceptably low GWPs. tetrafluoropropyne/1,3,3,3-tetrafluoropropyne The unique gaseous compounds discovered by the present hexafluoro-oxetane inventors for use as substitutes for SF can be used in some Trifluoro(trifluoromethyl)oxirane existing electrical equipment, although they would preferably 1,1,1,3,3,3-Hexafluoropropanone be used in specific electrical equipment optimized for them. pentafluoro-propionyl /perfluoropropionyl fluoride The gaseous compounds of the present disclosure are prefer Trifluoromethyl trifluorovinyl ether ably used in pure form, but can also be used as part of an 25 1-Propyne azeotrope, or a mixture with an appropriate second gas, Such Cyclopropane as nitrogen, CO or NO. Propane Trimethylborane SUMMARY cyanoketene 30 butatriene A dielectric gaseous compound which exhibits the follow Cyano-bispentafluorethyl-phosphin ing properties: a boiling point in the range between about Trimethyl-1,1,2,2-tetrafluorethylsilan -20°C. to about -273°C.; low, preferably non-ozone deplet methyl diborane ing; a GWP less than about 22,200; chemical stability, as Methyldiboran (germ.) measured by a negative standard enthalpy of formation 35 carbonyl bromide fluoride (dHf-0); a toxicity level such that when the dielectric gas chloro-difluoro-nitroso-methane?/Chlor-difluor-nitroso leaks, the effective diluted concentration does not exceed its methan PEL (i.e., an Occupational Exposure Limit (OEL or TLV) of chloroperoxytrifluoromethane at least about 0.3 ppm); and a dielectric strength greater than carbonylchlorid-fluorid a1. 40 Carbonychloridifluorid (germ.) The dielectric gaseous compound is at least one compound 3,3-difluoro-3HH-diazirine selected from the group consisting of: difluoro diazomethane Difluordiazomethan (germ.) Carbonyl fluoride 45 Difluordioxiran Diborane difluoro-(3-fluoro-3#H!-diazirin-3-yl)-amine , 2-chloro-1,1,2,2-tetrafluoroethyl ester (9CI) trifluoromethylazide Perchloric acid, 1.2.2-trichloro-1,2-difluoroethyl ester Trifluormethylazid (germ.) Trifluoroacetyl chloride tetrafluoro-diaziridine trifluoromethylisocyanide (CF3-NC) 50 Fluorperoxytrifluorimethan trifluoromethyl isocyanide Bis(fluoroxy)difluorimethan trifluoro-nitroso-ethene?/Trifluor-nitroso-aethen Trifluormethyl-phosphonylfluorid Tetrafluoroethene fluoride 3,3,4,4-tetrafluoro-3,4-dihydro-1,2diazete Trifluorimethylphosphane (germ.) (Difluoramino)difluoracetonitril 55 Diazomethane Tetrafluorooxirane /Formalin Trifluoroacetyl fluoride (methyl)difluoroborane Perfluorimethylfluorformiat (Methyl)difluorboran (germ.) trifluoro-acetyl hypofluorite Chloromethane perfluoro-2-aza-1-propene 60 methylphosphonous acid difluoride/difluoro-methyl-phos Perfluor-2-aza-1-propen (germ.) phine N-Fluor-tetrafluor-1-aethanimin (germ.) trifluoro-methoxy-silane 3.3-difluoro-2-trifluoromethyl-oxaziridine Methylhypofluorid bis-trifluoromethyl-diazene/hexafluoro-icis-azomethane Methane Fluoroxypentafluoroethane 65 Methylsilane bis-trifluoromethyl peroxide #Sil-bromo-it-Sil. iSi!'-methanediyl-bis-silane 1,1-Bis(fluoroxy)tetrafluoroaethan #Si-iodo-it-Sili Si'-methanediyl-bis-silane US 7,807,074 B2

Difluormethylnitrit Fluoroethene trifluoromethanol 1,1,1-Trifluoroethane Formyl fluoride Ether, methyl trifluoromethyl Cyanic acid Ethene Chlorine 1,1-Difluoroethane Chlorine fluoride Fluoroethane Chlorine trioxide fluoride Ethane carbon oxide selenide/Kohlenoxidselenid fluoro-dimethyl-borane Disiloxane, 1,1,3,3-tetrafluoro-1,3-dimethyl-Trifluoroethene 10 trifluoroacetaldehyde?/Trifluor-acetaldehyd Fluorine oxide Pentafluoroethane fluorine peroxide Difluoromethyl trifluoromethyl ether Sulfuryl fluoride Tris(trifluoromethyl)bismuth sulphur difluoride tetrafluoropropadiene/tetrafluoro-allene?/1,1,3,3-tet trifluoride oxide 15 rafluoro-1,2-propadiene sulfide tetrafluorocyclopropene tetrafluorophosphorane Perfluoropropionyliodid pentafluoro-propionitrile?/pentafluoropropiononitrile hexafluoro-cyclopropane?/Hexafluor-cyclopropan//freon hexafluoro disiloxane HCl216 Hexafluordisiloxan (germ.) Hexafluoropropylene hexafluoro-1,3dioxolane Perfluormethylethylether Phosphorus trihydride 25 1,1-difluoro-propadiene/allenylidene difluoride? 1,1-dif Germanium hydride luoro-allene Silane 2,3,3,3-tetrafluoro-propene/HFO-1234yf Tin tetrahydride trans. HFO-1234ze Oxygen 3,3,3-Trifluoropropene OZone 30 cyclopropene Antimony monophosphide Allene Disilicon monophosphide 1,1-difluoro-propene/propenylidene Radon luor-propen methylketene Trifluoroborane 35 2-fluoropropene 1-Propene Bromopentafluoroethane DL-2-aminopropanoic acid Chlorotrifluoroethene 3,3,3-trifluoro-propyne/3,3,3-Trifluor-propin//trifluorom Trifluoroacetonitrile ethyl-ethyne/3,3,3-trifluoro-1-propyne trifluoromethyl isocyanate 40 1,1,3,3,3-pentafluoro-propene/1,1,3,3,3-Pentafluor-propen trifluoromethyl thiocarbonyl fluoride 1.2.3.3.3-pentafluoro-propene Trifluormethylthiocarbonylfluorid (germ.) 1.1.1.4.4.4-hexafluoro-2-butyne pentafluoro-nitroso-ethane/Pentafluor-nitroso-aethan 1,1,4,4-tetrafluoro-butane-2,3-dione (trifluoromethyl-carbonyl)-difluoro-amine Trifluormethylhypochlorit 45 Chlor-difluor-methyl-hypofluorit Bis-trifluorimethyl-nitroxid N-Chlor-N-fluor-trifluorimethylamin (germ.) bis-trifluoromethyl ether Chlordifluordifluoraminomethan bis(trifluoromethyl)tellurium thiocarbonyl difluoride bis(trifluoromethyl)ditelluride Thiocarbonyldifluorid (germ.) 50 selenocarbonyl difluoride N,N-Difluor-pentafluoraethylarnin (germ.) N-Fluor-bis(trifluorimethyl)-amin (germ.) N-Fluor-difluorimethanimin (germ.) N-Fluor-N-trifluorimethoxy-perfluormethylamin (germ.) trifluoro-nitroso-methane?/Trifluor-nitroso-methan fluoroformyl difluoro-carbamoyl fluoride 1-chloro-1-fluoro-ethene/71-Chlor-1-fluor-aethen//1-chloro 55 trifluoro-nitro-methane/Trifluor-nitro-methan//fluoropicrin 1-fluoroethylene Tetrafluoromethane 1,1-Difluoroethene Tetrafluorformamidin (germ.) itrans-1,2-difluoro-ethene//#trans-vinylene difluoride/ tetrafluorourea (E)-1,2-difluoroethylene/(E)-1,2-difluoro-ethene/ hypofluorous acid trifluoromethyl ester//Hypofluorigsaeure itrans-vinylene fluoride 60 trifluorimethylester//trifluoromethyl hypofluorite 1,2-difluoro-ethene/icis-vinylene difluoride/1.2-Difluor trifluoromethanesulfonyl fluoride aethen//vinylene fluoride N,N-Difluor-trifluorimethylamin (germ.) icis-1,2-difluoro-ethene//icis-Vinylene difluoride//(Z)-1, Trifluormethyloxydifluoramin 2-difluoroethylene/(Z)-1,2-difluoro-ethene/icis-vi (Difluoraminoxy)difluorimethylhypofluorit nylene fluoride 65 sulfurcyanide pentafluoride 1,1,1,2-Tetrafluoroethane Schwefelcyanid-pentafluorid (germ.) 1,1,2,2-Tetrafluoroethane difluoro-trifluoromethyl- US 7,807,074 B2 8 Hexafluormethandiamin (trifluoromethyl-carbonyl)-difluoro-amine perfluoro methylsilane Hexafluoroethane Perfluorimethylsilan (germ.) Bis-trifluorimethyl-nitroxid Trifluormethyl-tetrafluorphosphoran (germ.) bis-trifluoromethyl ether bis(trifluoromethyl)tellurium Fluoroiodomethane bis(trifluoromethyl)ditelluride //methyl fluoride/Fluor-methan//freon-41 N,N-Difluor-pentafluoraethylamin (germ.) trifluoromethyl-silane" CF3SiH3 N-Fluor-bis(trifluorimethyl)-amin (germ.) methyltrifluorosilane N-Fluor-N-trifluorimethoxy-perfluormethylamin (germ.) difluoro-methyl-silane 10 fluoroformyl cyanide fluoro-methyl-silane 1-chloro-1-fluoro-ethene/71-Chlor-1-fluor-aethen/71-chloro methylgermane 1-fluoroethylene 1,1-Difluoroethene Difluorformimin itrans-1,2-difluoro-ethene//#trans-vinylene difluoride/ Trifluoromethane (E)-1,2-difluoroethylene/(E)-1,2-difluoro-ethene/ trifluoromethane thiol 15 itrans-vinylene fluoride Trifluormethanthiol (germ.) 1,2-difluoro-ethene/icis-vinylene difluoride?/1,2-Difluor N.N.,1,1-Tetrafluorimethylamin aethen//vinylene fluoride difluoro icis-1,2-difluoro-ethene/icis-Vinylene difluoride//(Z)-1, Difluordichlorsilan (germ.) 2-difluoroethylene/(Z)-1,2-difluoro-ethene/icis-vi difluoro chlorosilane nylene fluoride Difluorchlorsilan (germ.) 1,1,1,2-Tetrafluoroethane Phosphorus chloride difluoride 1,1,2,2-Tetrafluoroethane Fluoroethene 1,1,1-Trifluoroethane Chlorosilane 25 Ether, methyl trifluoromethyl Ethene 1,1-Difluoroethane Carbonyl sulfide Fluoroethane Difluoramine Ethane trans-Difluorodiazine 30 fluoro-dimethyl-borane cis-Difluorodiazine Disiloxane, 1,1,3,3-tetrafluoro-1,3-dimethyl-Trifluoroethene trifluoroacetaldehyde?/Trifluor-acetaldehyd Trifluorosilane Pentafluoroethane Difluoromethyl trifluoromethyl ether Trifluoramine oxide 35 Tris(trifluoromethyl)bismuth thiazyl trifluoride tetrafluoropropadiene/tetrafluoro-allene?/1,1,3,3-tet Phosphorus trifluoride rafluoro-1,2-propadiene Germanium(IV) fluoride tetrafluorocyclopropene Tetrafluorosilane Perfluoropropionyliodid 40 pentafluoro-propionitrile?/pentafluoropropiononitrile hexafluoro-cyclopropane?/Hexafluor-cyclopropan//freon HCl216 fluorosilane Hexafluoropropylene hexafluoro-1,3dioxolane Fluorine 45 Octafluoropropane Perfluormethylethylether 1,1-difluoro-propadiene/allenylidene luoro-allene 2,3,3,3-tetrafluoro-propene/HFO-1234yf Krypton 50 trans. HFO-1234ze Nitrogen 3,3,3-Trifluoropropene dinitrogen oxide cyclopropene Allene Nitrogen oxide; and 1,1-difluoro-propene/propenylidene Xenon 55 luor-propen More preferably, the dielectric compounds can be selected methylketene from the group consisting of 2-fluoropropene Argon 1-Propene Trifluoroborane DL-2-aminopropanoic acid Hydrogen bromide 60 3,3,3-trifluoro-propyne/3,3,3-Trifluor-propin//trifluorom Bromopentafluoroethane ethyl-ethyne/3,3,3-trifluoro-1-propyne Chlorotrifluoroethene 1,1,3,3,3-pentafluoro-propene/1,1,3,3,3-Pentafluor-propen Trifluoroacetonitrile 1.2.3.3.3-pentafluoro-propene trifluoromethyl isocyanate 1.1.1.4.4.4-hexafluoro-2-butyne trifluoromethyl thiocarbonyl fluoride 65 1,1,4,4-tetrafluoro-butane-2,3-dione Trifluormethylthiocarbonylfluorid (germ.) Trifluormethylhypochlorit pentafluoro-nitroso-ethane/Pentafluor-nitroso-aethan Chlor-difluor-methyl-hypofluorit US 7,807,074 B2 10 N-Chlor-N-fluor-trifluorimethylamin (germ.) Hydrogen sulfide Chlordifluordifluoraminomethan Ammonia thiocarbonyl difluoride Helium Thiocarbonyldifluorid (germ.) Hydrogen iodide selenocarbonyl difluoride Krypton Trifluoroiodomethane Nitrogen N-Fluor-difluorimethanimin (germ.) trifluoro-nitroso-methane?/Trifluor-nitroso-methan Neon difluoro-carbamoyl fluoride Nitrogen oxide; and trifluoro-nitro-methane/Trifluor-nitro-methan//fluoropicrin 10 Xenon Tetrafluoromethane The dielectric gaseous compound is optionally formed as Tetrafluorformamidin (germ.) an azeotrope, which imparts many advantages in handling the tetrafluorourea mixture. Preferred mixtures for dielectric gaseous compound hypofluorous acid trifluoromethyl ester/Hypofluorigsaeure contain one additional gas selected from the group consisting trifluorimethylester//trifluoromethyl hypofluorite 15 of nitrogen, CO and N.O. trifluoromethanesulfonyl fluoride The present disclosure also includes an insulation-gas for N,N-Difluor-trifluorimethylamin (germ.) use in electrical equipment, wherein said insulation-gas is a Trifluormethyloxydifluoramin dielectric gaseous compound which exhibits the following (Difluoraminoxy)difluorimethylhypofluorit properties: a boiling point in the range between about -20°C. sulfurcyanide pentafluoride to about -273° C.; low, preferably non-ozone depleting; a Schwefelcyanid-pentafluorid (germ.) GWP less than about 22,200; chemical stability, as measured difluoro-trifluoromethyl-phosphine by a negative standard enthalpy of formation (dHf-0); a tox Hexafluormethandiamin icity level such that when the dielectric gas leaks, the effective perfluoro methylsilane diluted concentration does not exceed its PEL (i.e., Occupa Perfluorimethylsilan (germ.) 25 tional Exposure Limit (OEL or TLV) of at least about 0.3 Trifluormethyl-tetrafluorphosphoran (germ.) ppm); and a dielectric strength greater than air. Difluoromethane Preferably, the electrical equipment is at least one selected Fluoroiodomethane from the group consisting of gas-insulated circuit breakers fluoromethane//methyl fluoride/Fluor-methan//freon-41 and current-interruption equipment, gas-insulated transmis trifluoromethyl-silane" CF3SiH3 30 sion lines, gas-insulated transformers, and gas-insulated Sub methyltrifluorosilane stations. difluoro-methyl-silane fluoro-methyl-silane DETAILED DESCRIPTION OF THE PREFERRED methylgermane EMBODIMENT Difluorformimin 35 Trifluoromethane The compounds of the present disclosure are useful in trifluoromethane thiol gaseous phase for electrical insulation and for arc quenching Trifluormethanthiol (germ.) and current interruption equipment used in the transmission N.N.,1,1-Tetrafluorimethylamin and distribution of electrical energy. Generally, there are four difluoro dichlorosilane 40 major types of electrical equipment which the gases of the Difluordichlorsilan (germ.) present disclosure can be used for insulation and/or interrup difluoro chlorosilane tion purposes: (1) gas-insulated circuit breakers and current Difluorchlorsilan (germ.) interruption equipment, (2) gas-insulated transmission lines, Phosphorus chloride difluoride (3) gas-insulated transformers, and (4) gas-insulated Substa Chlorotrifluorosilane 45 tions. Such gas-insulated equipment is a major component of Hydrogen chloride power transmission and distribution systems all over the Chlorosilane world. It offers significant savings in land use, is aesthetically Carbon monoxide acceptable, has relatively low radio and audible noise emis Carbon dioxide sions, and enables Substations to be installed in populated Carbonyl sulfide 50 areas close to the loads. Difluoramine Depending on the particular function of the gas-insulated trans-Difluorodiazine equipment, the gas properties which are the most significant cis-Difluorodiazine vary. Thionyl fluoride For circuit breakers the excellent thermal conductivity and Trifluorosilane 55 high dielectric strength of Such gases, along with the fast Nitrogen trifluoride thermal and dielectric recovery (short time constant for Trifluoramine oxide increase in resistivity), are the main reasons for its high inter thiazyl trifluoride ruption capability. These properties enable the gas to make a Phosphorus trifluoride rapid transition between the conducting (arc ) and the Germanium(IV) fluoride 60 dielectric state of the arc, and to withstand the rise of the Tetrafluorosilane recovery Voltage. Phosphorus pentafluoride For gas-insulated transformers the cooling ability, compat Selenium hexafluoride ibility with Solid materials, and partial discharge characteris Tellurium hexafluoride tics, added to the dielectric characteristics, make them a desir fluorosilane 65 able medium for use in this type of electrical equipment. The Nitrosyl fluoride compounds have distinct advantages over oil insulation, including none of the fire safety problems or environmental US 7,807,074 B2 11 12 problems related to oil, high reliability, flexible layout, little influences, such as electrical breakdown and discharges. To maintenance, long service life, lower noise, better handling, be used in electrical applications, a dielectric gas should: and lighter equipment. (undergo no extensive decomposition; lead to no polymeriza For gas-insulated transmission lines the dielectric strength tion; form no carbon or other deposits; and be non-corrosive of the gaseous medium under industrial conditions is of para and non-reactive to , insulators, spacers, and seals. In mount importance, especially the behavior of the gaseous addition it should have: no byproduct with toxicity unaccept dielectric under metallic particle contamination, Switching able for industrial applications; removable byproducts; and a and lightning impulses, and fast transient electrical stresses. high recombination rate for reforming itself, especially for These gases also have a high efficiency for transfer of heat arc interruption. Finally, the gas must be environmentally from the conductor to the enclosure and are stable for long 10 periods of time (e.g., 40 years). These gas-insulated transmis friendly, e.g., it must not contribute to global warming, must sion lines offer distinct advantages: cost effectiveness, high not deplete stratospheric oZone, and must not persist in the carrying capacity, low losses, availability at all Voltage rat environment for long periods of time. ings, no fire risk, reliability, and a compact alternative to Specific properties of the gas under discharge and break overhead high Voltage transmission lines in congested areas 15 down conditions include: a high under that avoids public concerns with overhead transmission lines. uniform and non-uniform electric fields; insensitivity to Sur For gas-insulated Substations, the entire Substation (circuit face roughness or defects and freely moving conducting par breakers, disconnects, grounding Switches, busbar, trans ticles; good insulation properties under practical conditions; formers, etc., are interconnected) is insulated with the gas good insulator flashover characteristics; good heat transfer eous dielectric medium of the present disclosure, and, thus, characteristics; good recovery (rate of Voltage recovery) and all of the above-mentioned properties of the dielectric gas are self-healing; no adverse reactions with moisture and common significant. impurities; and no adverse effects on equipment, especially The properties of a dielectric gas that are necessary for its on spacers and electrode surfaces. use in high Voltage equipment are many and vary depending Specific properties of gaseous insulators for specific elec on the particular application of the gas and the equipment. 25 trical equipment is set forth below: Intrinsic properties are those properties of a gas which are Circuit breakers—The most significant required gas proper inherent in the physical atomic or molecular structure of the ties for arc interruption are: (i) high dielectric strength gas. These properties are independent of the application or the comparable to that of SF; (ii) high thermal conductivity; environment in which a gas is placed. One of the desirable (iii) fast gas recovery; and (iv) self-healing/dielectric integ properties of a gaseous dielectric is high dielectric strength 30 rity. (higher, for instance than air). The gas properties that are principally responsible for high dielectric strength are those Gas-insulated transmission lines—The required properties that reduce the number of electrons which are present in an include: (i) high dielectric strength; (ii) high vapor pressure electrically-stressed dielectric gas. To effect such a reduction at operating and ambient temperature; (iii) chemical inert in the electron number densities, as gas should: (i) be elec 35 ness; (iv) high thermal conductivity; (V) nothermal aging; tronegative (remove electrons by attachment over as wide an (vi) no deposits; (vii) easily removable, non-harmful energy range as possible); it should preferably exhibit byproducts; and (viii) no unacceptable level of hazards increased electron attachment with increasing electron (fire, explosion, toxicity, corrosion). energy and gas temperature since electrons have a broad Gas-insulated transformers—The properties of the gas range of energies and the gas temperature in many applica 40 required for this application include: (i) high dielectric tions is higher than ambient; (ii) have good electron slowing strength at reasonable pressures (e.g., 500 kPa); (ii) low down properties (slow electrons down so that they can be boiling point; (iii) acceptably low toxicity; (iv) chemical captured efficiently at lower energies and be prevented from inertness; (V) good thermal stability; (vi) non-flammable; generating more electrons by electron impactionization); and (vii) high cooling capability; (viii) good compatibility with (iii) have low ionization cross section and high ionization 45 Solid materials; (ix) good partial discharge characteristics; onset (prevent ionization by electron impact). Besides the (X) useable over a range oftemperatures; and (xi) safe, easy above properties, there are a number of other basic properties to handle, inexpensive and securely available. which are necessary for the complete characterization of the The present inventors have discovered a unique series of dielectric gas behavior and its performance in practice, e.g., dielectric gases for use in electric equipment applications, secondary processes such as electron emission from Surfaces 50 which exhibit many of the aforementioned properties, which by and photon impact; photoprocesses; absorption of avoiding the greenhouse problems associated with SF. Such photoionizing radiation (this is a controlling factor in dis dielectric compounds exhibit at least one of the following charge development in non-uniform fields); dissociation properties: under electron impact decomposition; ion-molecule reac Aboiling point in the range between about -20°C. to about tions; reactions with trace impurities; and reactions with Sur 55 -273° C. faces. Low, preferably, Non-oZone depleting The dielectric gas must also have the following chemical properties: high vapor pressure; high specific heat, high ther A GWP less than about 22,200 mal conductivity for gas cooling; thermal stability over long Chemical stability, as measured by a negative standard periods of time for temperatures greater than 400°K.: chemi 60 enthalpy of formation (dHf-0) cal stability and inertness with regard to conducting and insu A toxicity level Such that when the working gas leaks from lating materials; non-flammable; toxicity acceptable for equipment at the manufacturer's specified maximum industrial exposure; and non-explosive. When used in mix leak rate, the effective diluted concentration does not tures, it must have appropriate thermodynamic properties for exceeed its PEL, i.e., does not exceed the PEL of that mixture uniformity, composition, and separation. 65 specific compound. In general with minimal ventilation Extrinsic properties are those which describe how a gas PELs greater than about 0.3 ppm by volume are accept may interact with its Surroundings, or in response to external able (i.e., an Occupational Exposure Limit (OEL or

US 7,807,074 B2 15 16

TABLE 1-continued

Dielectric Compound Structure Name CAS MW pentafluoro-propionyl 422-61-7 166.O2 -27.0 fluoride?/perfluoropropionyl fluoride Trifluoromethyl 1187-93-5 166.O2 -26.0 trifluorovinyl ether 1-Propyne 74-99-7 40.06 -23.2 Cyclopropane 75-19-4 42.08 -32.8 Propane 74-98-6 44.10 -42.0 Trimethylborane 593-90-8 55.92 -20.2 cyanoketene 4452-08-8 67.05 -34.0 butatriene 2873-SO-9 S2.08 -78.0 Cyano-bispentafluorethyl 35.449-90-2 295.02 -78.0 phosphin Trimethyl-1,1,2,2- 41 68-08-5 174.21 -72.O tetrafluorethylsilan methyl diborane 23777-55-1 41.70 -350 Methyldiboran (germ.) carbonyl bromide fluoride 753-56-0 126.91 -20.6 chloro-difluoro-nitroso 421-13-6 115.47 -350 methane, Chlor-difluor nitroso-methan CF3- O O. Cl chloroperoxytrifluoromethane 327SS-26-3 136.46 -22.0 COCIF carbonylchlorid-fluorid 353-49-1 82.46 -46.0 Carbonychloridifluorid (germ.) 3,3-difluoro-3#H-diazirine 693-85-6 -91.3 ifluoro diazomethane 814-73-3 -91.3 Difluordiazomethan (germ.) Carbonyl fluoride 3S3-SO-4 66.01 -84.6 Difluordioxiran 96.740-99-7 82.01 -85.0 ifluoro-(3-fluoro-3#H- 4823-43-2 111.03 -36.0 iazirin-3-yl)-amine CF3- N N N trifluoromethylazide 3802-95-7 110.03 -285 Trifluormethylazid (germ.) etrafluoro-diaziridine 17224-09-8 116.02 -350 Fluorperoxytrifluorimethan 34511-13-2 120.00 -69.4 Bis(fluoroxy)difluormethan 16282-67-O 120.00 -64.0 Trifluormethyl 19162-94-8 153.98 -20.1 phosphonylfluorid 1495-SO-7 45.02 -46.2 rifluormethylphosphane 420-52-O 102.00 -26.5 (germ.) Diazomethane 334-88-3 42.04 -23.2 ormaldehyde?/Formalin SO-OO-O 30.03 -21.0 (methyl)difluoroborane 373-64-8 63.84 -62.3 (Methyl)difluorboran

74-87-3 SO.49 -24.2 methylphosphonous acid difluoridefidifluoro 84.01 -28.0 methyl-phosphine trifluoro-methoxy-silane 2S711-11-9 116.11 -78.0 Methylhypofluorid 36336-08-0 SO.O3 -33.0 Methane 74-82-8 16.04 -161.5 Methylsilane 992-94-9 46.14 -56.9 #Sil-bromo-#SilitSi!'- 56962-86-8 1SS.14 -64.0 methanediyl-bis-silane C 7 Si 2 #Si!-iodo-#SilitSi!'- 56962-87-9 2O2.14 -49.0 methanediyl-bis-silane F2CH O NO Difluorimethylnitrit 1493-06-7 97.02 -20.0 F3COH trifluoromethanol 1493-11-4 86.01 -20.0 HFCO Formyl fluoride 1493-02-3 48.02 -26.5 HOCN Cyanic acid 420-05-3 43.03 -64.2 C2 Chlorine 7782-50-5 70.91 -34.0 CIF Chlorine fluoride 7790-89-8 S4.45 -101.0 Chlorine trioxide fluoride 7616-94-6 102.45 -46.7 carbon oxide 1603-84-5 106.97 -21.7 selenide? Kohlenoxidselenid F2 Fluorine 77.82-41-4 38.00 -1882 SF2H2 Difluorosilane 13824-36-7 68.10 -77.8 OF2 Fluorine oxide 7783-41-7 S400 -144.7 FOOF fluorine peroxide 7783-44-0 70.00 -S7.0 SO2F2 Sulfuryl fluoride 2699-79-8 102.06 -SS3 SF2 sulphur difluoride 13814-25-0 70.06 -350 POF3 Phosphorus trifluoride 13478-20-1 103.97 -39.7 oxide US 7,807,074 B2 17 18

TABLE 1-continued

Dielectric Compound Structure Name CAS MW PSF3 Phosphorus trifluoride 120.03 -52.3 sulfide tetrafluorophosphorane 13659-66-0 107.98 -37.0 Tetrafluorohydrazine 10O36-47-2 104.01 -74.2 Sulfur tetrafluoride 7783-60-0 108.OS -40.5 hexafluoro disiloxane 1451S-39-0 186.16 -23.0 Hexafluordisiloxan (germ.) Nitryl fluoride 10O22-SO-1 6S.OO -72.3 Hydrogen 1333-74-0 2.02 -2529 Hydrogen selenide 7783-07-5 80.98 -41.3 Phosphorus trihydride 78O3-51-2 34.00 -87.8 Germanium hydride 7782-6S-2 76.62 -88.2 Silane 78O3-62-5 32.12 -112.2 Tin tetrahydride 24O6-52-2 122.72 -51.8 Oxygen 7782-44-7 32.00 -183.0 Ozone 10O28-15-6 48.00 -111.3 Antimony monophosphide l 152.72 -52.3 Disilicon monophosphide l 87.14 -52.3 Radon 10043-92-2 222.00 -61.7 Argon 7440-37-1 39.95 -1859 Trifluoroborane 7637-07-2 67.81 -101.2 Hydrogen bromide 10O3S-1O-6 80.91 -66.7 Bromopentafluoroethane 354-55-2 98.92 -21.0 Chlorotrifluoroethene 79-38-9 16.47 -28.4 Trifluoroacetonitrile 353-85-5 95.02 - 68.8 trifluoromethyl isocyanate 460-49-1 11.02 -36.0 trifluoromethylthiocarbonyl fluoride 32.08 -21.0 Trifluorimethylthiocarbonylfluorid (germ.) C pentafluoro-nitroso 49.02 -45.7 ethane, Pentafluor-nitroso aethan C (trifluoromethyl-carbonyl)- 32822-49-4 49.02 difluoro-amine Hexafluoroethane 76-16-4 38.01 -78.2 Bis-trifluorimethyl-nitroxid 2154-71-4 68.02 -20.0 bis-trifluoromethyl ether 1479–49-8 54.O1 -59.0 bis(trifluoromethyl)tellurium SS642-42-7 265.61 -98.0 bis(trifluoromethyl) 1718-20-3 393.21 -53.0 ditelluride N,N-Difluor 71.02 -38.0 pentafluoraethylamin (germ.) N-Fluor-bis(trifluorimethyl)- 359-62-6 71.02 -37.0 amin (germ.) CF3INFOCF3 N-Fluor-N-trifluormethoxy 4217-92-9 87.02 -25.0 perfluorimethylamin (germ.) fluoroformyl cyanide 683-55-6 73.03 -21.0 1-chloro-1-fluoro-ethene, 1 2317-91-1 80.49 -2S.S Chlor-1-fluor-aethen 1 chloro-1-fluoroethylene CF2-CH2 1,1-Difluoroethene 75-38-7 64.03 -85.7 CHF CHF #trans-1,2-difluoro 1630-78-0 64.03 -53.1 ethenefiti trans-vinylene difluoride? (E)-1,2- difluoroethylene? (E)-1,2- difluoro-ethenefiti trans vinylene fluoride FHC-CHF 1,2-difluoro-ethenefiticist 1691-13-O 64.03 -28.0 vinylene difluoride?/1,2- Difluor-aethen vinylene fluoride CHF CHF #cis-1,2-difluoro 1630-77-9 64.03 -26.0 ethenefiticist-vinylene difluoride? (Z)-1,2- difluoroethylene, f(Z)-1,2- difluoro-ethenefiticist vinylene fluoride 1,1,1,2-Tetrafluoroethane 811-97-2 102.03 -26.1 1,12,2-Tetrafluoroethane 359-35-3 102.03 -23.0 Fluoroethene 75-02-5 46.04 -72.2 1,1,1-Trifluoroethane 420-46-2 84.04 -47.3 Ether, methyl 421-14-7 100.04 -24.0 trifluoromethyl Ethene 74-85-1 28.05 -103.7 1,1-Difluoroethane 75-37-6 66.OS -24.0 Fluoroethane 3S3-36-6 48.06 -37.7 US 7,807,074 B2 19 20

TABLE 1-continued

Dielectric Compound Structure Name CAS MW

Ethane 74-84-O 30.07 -88.6 fluoro-dimethyl-borane 353-46-8 59.88 -44.0 Disiloxane, 1,1,3,3- 63O89-45-2 78.23 -39.0 etrafluoro-1,3-dimethyl Trifluoroethene 359-11-5 82O2 -510 trifluoroacetaldehyde?/Trifluor 75-90-1 98.02 -21.0 acetaldehy Pentafluoroethane 354-33-6 2O.O2 -48.1 Difluoromethyl 3822-68-2 36.02 -35.3 trifluoromethyl ether Tris(trifluoromethyl)bismuth S863-80-9 416.00 -SS.O etrafluoropropadienefitetrafluoro 461-68-7 12.03 -38.0 allene? (1,1,3,3- etrafluoro-1,2-propadiene etrafluorocyclopropene 19721-29-O 12.03 -20.0 Perfluoropropionyliodid 137741-03-8 273.93 -27.0 pentafluoropropionitrile?/ 422-04-8 45.03 -350 pentafluoropropiononitrile (X8OO 931-91-9 -33.0 cyclopropane? Hexafluor cyclopropan freon-#C216 Hexafluoropropylene 116-15-4 SO.O2 -29.6 hexafluoro-1,3dioxolane 21297-65-4 82O2 -22.1 Octafluoropropane 76-19-7 88.02 -36.7 Perfluormethylethylether 665-1 6-7 204.O2 -20.0 1-difluoro 430-64-8 76.05 -21.0 propadiene fallenylidene difluoride? 1,1-difluoro allene 2,3,3,3-tetrafluoro 754-12-1 114.04 -28.3 propene/HFO-1234yf EranSHFO-1234ze 114.04 -19.0 3,3,3-Trifluoropropene 677-21-4 96.OS -25.0 cyclopropene 2781-85-3 40.06 -36.0 Allene 463-49-O 40.06 -34.5 1-difluoro 430-63-7 78.06 -29.0 propenef propenylidene difluoride? 1,1-Difluor Oel methylketene 6004-44-0 56.06 -23.0 CH2CFCH3 2-fluoropropene 1184-60-7 60.07 -24.0 CH2CHCH3 -Propene 115-07-1 42.08 -47.7 DL-2-aminopropanoic acid 302-72-7 89.09 -50.2 3,3,3-trifluoro 661-54-1 94.04 -48.0 propyne? (3,3,3-Trifluor propini?trifluoromethyl ethyne? (3,3,3-trifluoro-1- propyne 1,1,3,3,3-pentafluoro 690-27-7 32.03 -21.0 propenef, 1,1,3,3,3- Pentafluor-propen ,2,3,3,3-pentafluoro 2252-83-7 32.03 -20.0 propene 1,144.4-hexafluoro-2- 692-50-2 62.03 -24.6 butyne 144-tetrafluoro-butane 58.05 -81.0 2,3-dione 14.10 -33.0 F3C O Cl Trifluormethylhypochlorit 22082-78-6 20.46 -47.0 CF2C OF Chlor-difluor-methyl 2O614-17-9 20.46 -25.0 hypofluorit N-Chlor-N-fluor 1388O-72-3 37.46 -32.8 trifluorimethylamin (germ.) Chlordifluordifluoraminomethan 13880-71-2 37.46 -28.0 thiocarbonyl difluoride 420-32-6 82.07 -46.0 Thiocarbonyldifluorid (germ.) selenocarbonyl difluoride S4393-39-4 28.97 -28.0 Trifluoroiodomethane 2314-97-8 95.91 -21.8 N-Fluor-difluorimethanimin 338-66-9 83.01 -101.0 (germ.) trifluoro-nitroso 334-99-6 99.01 -86.0 methane, Trifluor-nitroso methan US 7,807,074 B2 21 22

TABLE 1-continued

Dielectric Compound Structure Name CAS MW difluoro-carbamoyl fluoride 2368-32-3 99.01 -52.0 trifluoro-nitro 335-02-4 15.01 -33.6 methane, Trifluor-nitro methan fluoropicrin Tetrafluoromethane 75-73-0 88.00 -128.1 Tetrafluorformamidin 14362-70-0 16.O2 -3O.O (germ.) tetrafluorourea 10256-92-5 -20.0 hypofluorous acid trifluoromethylester?, -95.0 Hypofluorigsa.eure trifluorimethylesteri?trifluoromethyl hypofluorite C trifluoromethanesulfonyl 335-05-7 52.07 -21.7 fluoride C N,N-Difluor 335-01-3 21.01 -7S.O trifluorimethylamin (germ.) CFSNO Trifluormethyloxydifluoramin 4217-93-O 37.01 -59.8 CFSNO2 (Difluoraminoxy)difluorimethyl 36781-60-9 53.01 -29.0 hypofluorit CFSNS SFSCN Sulfurcyanide pentafluoride 1512-13-6 53.08 -25.0 Schwefelcyanid pentafluorid (germ.) CFSP C difluoro-trifluoromethyl 1112-04-5 37.98 -43.0 phosphine Hexafluorimethandiamin 4394-93-8 54.O1 -37.0 perfluoro methylsilane 335-06-8 54.09 -42.0 Perfluormethylsilan (germ.) C Trifluormethyl 1184-81-2 75.97 -350 etrafluorphosphoran (germ.) Difluoromethane 75-10-5 S2.O2 -51.7 Fluoroiodomethane 373-53-5 59.93 -53.8 fluoromethane?/methyl 593-53-3 34.03 -78.3 fluoride, Fluormethan reon-41 C C trifluoromethyl-silane" O112-11-5 OO.12 -383 CF3SH3 methyltrifluorosilane OO.12 -3O.O difluoro-methyl-silane 82.12 -35.6 fluoro-methyl-silane 64.13 -44.0 methylgermane 90.65 -23.0 Difluorformimin 6S.O2 -22.0 C Trifluoromethane 70.01 -82.1 C trifluoromethane thiol 493-15-8 102.08 -36.7 Trifluormethanthiol (germ.) C C N,N,1,1- 24708-53-0 103.02 -43.0 Tetrafluormethylamin C 2 F2 Si difluoro dichlorosilane 8356-71-3 136.99 -31.8 Difluordichlorsilan (germ.) C 2 H Si difluoro chlorosilane 102.56 -500 Difluorchlorsilan (germ.) Phosphorus chloride 4335-40-1 104.42 -47.3 difluoride SCF3 Chlorotrifluorosilane 4049-36-6 120.53 -70.2 HCI Hydrogen chloride 7647-01-0 36.46 -85.0 H3S SH3C Chlorosilane 3465-78-6 66.56 -303 CO CO Carbon monoxide 630-08-0 28.01 -1915 CO2 CO2 Carbon dioxide 24-38-9 44.01 -78.4 OCS Carbonyl sulfide 463-58-1 60.07 -50.3 NHF2 Difluoramine O405-27-3 53.01 -23.2 FNNF trans-Difluorodiazine 3776-62-O 66.01 -111.5 FNNF cis-Difluorodiazine 3812-43-6 66.01 -105.8 F2SO Thionyl fluoride 7783-42-8 86.06 -43.8 SHF3 Trifluorosilane 3465-71-9 86.09 -95.2 NF3 Nitrogen trifluoride 7783-54-2 71.OO -129.1 NOF3 Trifluoramine oxide 3847-6S-9 87.00 -87.5 NSF3 thiazyl trifluoride 5930-75-3 103.07 -27.1 PF3 Phosphorus trifluoride 7783-55-3 87.97 -101.5 GeF4 Germanium(IV) fluoride 7783-58-6 148.58 -36.5 SF4 Tetrafluorosilane 7783-61-1 104.08 -86.0 PF5 Phosphorus pentafluoride 7647-19-0 125.97 -84.5 SeF6 Selenium hexafluoride 7783-79-1 192.95 -46.5 TeF6 Tellurium hexafluoride 7783-80-4 241.59 -38.8 SH3F fluorosilane 13537-33-2 SO.11 -98.0 Nitrosyl fluoride 7789-25-5 49.00 -59.9 Fluorine nitrate 7789-26-6 81.00 -46.2

US 7,807,074 B2 25 26

TABLE 2-continued

Dielectric Compound Structure Name CAS MW F3COCH3 Ether, methyl 421-14-7 100.04 -24.0 trifluoromethyl Ethene 74-85-1 28.05 -103.7 ,1-Difluoroethane 75-37-6 66.OS -24.0 Fluoroethane 3S3-36-6 48.06 -37.7 Ethane 74-84-O 30.07 -88.6 fluoro-dimethyl-borane 353-46-8 59.88 -44.0 Disiloxane, 1,1,3,3- 63O89-45-2 178.23 -39.0 etrafluoro-1,3-dimethyl Trifluoroethene 359-11-5 82O2 -510 trifluoroacetaldehyde?/Trifluor 75-90-1 98.02 -21.0 acetaldehy HFS Pentafluoroethane 354-33-6 2O.O2 -48.1 HFSO Difluoromethyl 3822-68-2 36.02 -35.3 trifluoromethyl ether Tris(trifluoromethyl)bismuth S863-80-9 -SS.O etrafluoropropadienefitetrafluoro 461-68-7 -38.0 allene? (1,1,3,3- etrafluoro-1,2-propadiene etrafluorocyclopropene 19721-29-O -20.0 FSIO Perfluoropropionyliodid 137741-03-8 -27.0 FSN pentafluoropropionitrile?/ 422-04-8 -350 pentafluoropropiononitrile hexafluorocyclopropane?. 931-91-9 -33.0 Hexafluorcyclopropan. reon-iiCl216 Hexafluoropropylene 116-15-4 SO.O2 -29.6 hexafluoro-1,3dioxolane 21297-65-4 82O2 -22.1 Octafluoropropane 76-19-7 88.02 -36.7 Perfluormethylethylether 665-1 6-7 204.O2 -20.0 1-difluoro 430-64-8 76.05 -21.0 propadiene fallenylidene difluoride?/1,1-difluoro allene 2,3,3,3-tetrafluoro 754-12-1 114.04 -28.3 propene/HFO-1234yf EranSHFO-1234ze 114.04 -19.0 3,3,3-Trifluoropropene 677-21-4 96.OS -25.0 cyclopropene 2781-85-3 40.06 -36.0 Allene 463-49-O 40.06 -34.5 ,1-difluoropropenefit 430-63-7 78.06 -29.0 propenylidene difluoride?/1,1-Difluorpropen methylketene 6004-44-0 56.06 -23.0 CH2CFCH3 2-fluoropropene 1184-60-7 60.07 -24.0 CH2CHCH3 -Propene 115-07-1 42.08 -47.7 DL-2-aminopropanoic acid 302-72-7 89.09 -50.2 3,3,3-trifluoro 661-54-1 94.04 -48.0 propyne? (3,3,3-Trifluor propini?trifluoromethyl ethyne? (3,3,3-trifluoro-1- propyne 1,1,3,3,3-pentafluoro 690-27-7 32.03 -21.0 propenef, 1,1,3,3,3- Pentafluor-propen CF3 CF CFEH ,2,3,3,3-pentafluoro 2252-83-7 32.03 -20.0 propene 6 1,144.4-hexafluoro-2- 692-50-2 62.03 -24.6 butyne 144-tetrafluoro-butane 58.05 -81.0 2,3-dione 14.10 -33.0 F3C O Cl Trifluormethylhypochlorit 22082-78-6 20.46 -47.0 CF2C OF Chlor-difluor-methyl 2O614-17-9 20.46 -25.0 hypofluorit N-Chlor-N-fluor 1388O-72-3 37.46 -32.8 trifluorimethylamin (germ.) Chlordifluordifluoraminomethan 13880-71-2 37.46 -28.0 thiocarbonyl difluoride 420-32-6 82.07 -46.0 Thiocarbonyldifluorid (germ.) selenocarbonyl difluoride S4393-39-4 28.97 -28.0 Trifluoroiodomethane 2314-97-8 95.91 -21.8 N-Fluor-difluorimethanimin 338-66-9 83.01 -101.0 (germ.) US 7,807,074 B2 27 28

TABLE 2-continued

Dielectric Compound Structure Name CAS MW

C trifluoro-nitroso 334-99-6 99.01 -86.0 methane, Trifluor-nitroso methan difluoro-carbamoyl fluoride 2368-32-3 99.01 -52.0 trifluoro-nitro 335-02-4 15.01 -33.6 methane, Trifluor-nitro methan fluoropicrin Tetrafluoromethane 75-73-0 88.00 -128.1 Tetrafluorformamidin 14362-70-0 16.O2 -3O.O (germ.) etrafluorourea 10256-92-5 32.O2 -20.0 hypofluorous acid trifluoromethyl -95.0 ester? Hypofluorigsaeure trifluorimethylesteri?trifluoromethylhypofluorite C trifluoromethanesulfonyl 335-05-7 52.07 -21.7 fluoride FSN C N,N-Difluor 335-01-3 21.01 -7S.O trifluorimethylamin (germ.) FSNO Trifluormethyloxydifluoramin 4217-93-O 37.01 -59.8 FSNO2 (Difluoraminoxy)difluorimethyl 36781-60-9 53.01 -29.0 hypofluorit FSNS SFSCN Sulfurcyanide pentafluoride 1512-13-6 53.08 -25.0 Schwefelcyanid pentafluorid (germ.) C difluoro-trifluoromethyl 1112-04-5 37.98 -43.0 phosphine Hexafluorimethandiamin 4394-93-8 54.O1 -37.0 perfluoro methylsilane 335-06-8 54.09 -42.0 Perfluormethylsilan (germ.) C Trifluormethyl 1184-81-2 75.97 -350 etrafluorphosphoran (germ.) Difluoromethane 75-10-5 S2.O2 -51.7 Fluoroiodomethane 373-53-5 59.93 -53.8 fluoromethanet methyl 593-53-3 34.03 -78.3 fluoride, Fluormethan reon-41 C C trifluoromethyl-silane" 1O112-11-5 OO.12 -383 CF3SH3 methyltrifluorosilane 373-74-0 OO.12 -3O.O difluoro-methyl-silane 420-34-8 82.12 -35.6 fluoro-methyl-silane 753-44-6 64.13 -44.0 methylgermane 449-65-6 90.65 -23.0 Difluorformimin 6S.O2 -22.0 C Trifluoromethane 70.01 -82.1 C trifluoromethane thiol 493-15-8 102.08 -36.7 Trifluormethanthiol (germ.) C C N,N,1,1- 24708-53-0 103.02 -43.0 Tetrafluormethylamin difluoro dichlorosilane 8356-71-3 136.99 -31.8 Difluordichlorsilan (germ.) difluoro chlorosilane 102.56 -500 Difluorchlorsilan (germ.) Phosphorus chloride 4335-40-1 104.42 -47.3 difluoride SCF3 Chlorotrifluorosilane 4049-36-6 120.53 -70.2 HCI Hydrogen chloride 7647-01-0 36.46 -85.0 SH3C Chlorosilane 3465-78-6 66.56 -303 CO Carbon monoxide 630-08-0 28.01 -1915 CO2 Carbon dioxide 24-38-9 44.01 -78.4 OCS Carbonyl sulfide 463-58-1 60.07 -50.3 NHF2 Difluoramine O405-27-3 53.01 -23.2 FNNF trans-Difluorodiazine 3776-62-O 66.01 -111.5 FNNF cis-Difluorodiazine 3812-43-6 66.01 -105.8 F2SO Thionyl fluoride 7783-42-8 86.06 -43.8 SHF3 Trifluorosilane 3465-71-9 86.09 -95.2 NF3 Nitrogen trifluoride 7783-54-2 71.OO -129.1 NOF3 Trifluoramine oxide 3847-6S-9 87.00 -87.5 NSF3 thiazyl trifluoride 5930-75-3 103.07 -27.1 PF3 Phosphorus trifluoride 7783-55-3 87.97 -101.5 GeF4 Germanium(IV) fluoride 7783-58-6 148.58 -36.5 SF4 Tetrafluorosilane 7783-61-1 104.08 -86.0 PF5 Phosphorus pentafluoride 7647-19-0 125.97 -84.5 SeF6 Selenium hexafluoride 7783-79-1 192.95 -46.5 TeF6 Tellurium hexafluoride 7783-80-4 241.59 -38.8 SH3F fluorosilane 13537-33-2 SO.11 -98.0 US 7,807,074 B2 29 30

TABLE 2-continued

Dielectric MY Compound Structure Name CAS MW BP(° C.) FNO Nitrosyl fluoride 7789-25-5 49.00 -59.9 FNO3 Fluorine nitrate 7789-26-6 81.00 -46.2 H2S H2S Hydrogen sulfide 7783-06-4 34.08 -59.5 H3N NH3 Ammonia 7664-41-7 17.03 -33.3 He He Helium 7440-59-7 4.00 -268.9 HI HI Hydrogen iodide 10O34-85-2 127.91 -35.6 Kr Kr Krypton 7439-90-9 83.80 -1534 N2 N2 Nitrogen 7727-37-9 28.01 - 1958 N2O NON Nitrous oxide 10O24-97-2 44.01 -88.5 Ne Ne Neon 7440-01-9 20.18 -246.1 NO NO Nitrogen oxide 10102-43-9 3O.O1 -151.8 Xe Xe Xenon 7440-63-3 131.29 -108.1

The aforementioned dielectric compounds may be used in pure form, but can also be used as part of an azeotrope, or a mixture with an appropriate second gas, i.e., nitrogen, CO or NO. Breakdown voltage at Particularly preferred non-electrical properties for dielec Dielectric strength Pressure maximum pressure tric gases according to the present disclosure, include: Gas kVO.1 inch gap (psia) (kVO.1 inch gap) Non-liquefying, e.g., T. less than -20°C. Air 4.75 73.5 23.75 25 R143a 5.8 73.5 29 Chemically stable—decomposition temperature must be R152a. 5.9 73.5 29.5 higher than hot spot temperature in equipment, e.g., R12S 6.4 73.5 32 T 200° C., and gas should not decompose in partial R134a 6.6 73.5 33 discharge spark (approximately 1000 K) R22 7.2 73.5 39.9 R124 10.4 55.5 39.3 Low environmental impact, i.e., little to no destruction of SF6 14.O 73.5 70 ozone layer ODP-0; and low global warming impact 30 C318 16.O 45.3 49.3 GWP less than SF R115 16.O 73.6 8O Acceptably low toxicity of gas and discharge byproducts R114 17.0 31.1 36 Electrical equipment property requirements for dielectric gases according to the present disclosure, include: Insulation specific criteria include a critical field of E, and 35 EXAMPLE 2 no conducting decomposition products should be gen erated by discharge The dielectric strength of additional gases is measure at 1 Switching specific criteria include high critical field of E. atmosphere and at the maximum system pressure. Their arcing stability, i.e., a gas must recombine to original breakdown Voltages are found to be greater then air, which molecular structure after being decomposed in Switch 40 allows Smaller gaps and therefore Smaller equipment then ing arc (Gibbs free energy of reaction is<0) would be need if air was used. Here the measurements were Specific thermal interruption performance, i.e., must be performed on CTFE (Chlorotrifluoroethylene), HCl (hydro able to interrupt current flow at accurrent Zero gen chloride) and SiF4 ( tetrafluoride). Arc erosion product from equipment and gas must not form Having described the invention in detail by reference to the conduction deposits 45 preferred embodiments and specific examples thereof, it will Low velocity of sound be apparent that modifications and variations are possible without departing from the spirit and scope of the disclosure EXAMPLE1 and claims.

Measurements of the dielectric strength of potential alter 50 What is claimed is: natives were determined using ASTM D2477 or obtained 1. An insulation gas in electrical equipment, the insulation from literature. These measurements were performed at 1 gas consisting of phosphorous pentafluoride and at least one atmosphere pressure across a 0.1 inch gap and at ambient gas selected from the group consisting of nitrogen, CO, and temperature. NO. In the intended applications, the gas will not be at 1 atmo 55 2. The insulation-gas according to claim 1, wherein said sphere pressure but at a higher pressure. In this example 5 electrical equipment is selected from the group consisting of atmospheres pressure is used as a maximum pressure. If the current-interruption equipment, gas-insulated transmission gas liquefies at a lower pressure than that pressure was used. lines, gas-insulated transformers, and gas-insulated Substa These gases have higher dielectric strengths and break down tions. Voltages than air. Using 5 atmospheres (73.5 psia) pressure as 60 the upper pressure (rating of the equipment).