# Patent

## Title
Gaseous dielectrics with low global warming potentials

## Abstract

A dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about −20° C. to about −273° C.; low ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf<0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL; and a dielectric strength greater than air.

## Background
FIELD
The present disclosure relates generally to a class of gaseous dielectric compounds having low global warming potentials (GWP). In particular, such gaseous dielectric compounds exhibits the following properties: a boiling point in the range between about −20° C. to about −273° C.; low, preferably non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf<0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL, e.g., a PEL greater than about 0.3 ppm by volume (i.e., an Occupational Exposure Limit (OEL or TLV) of greater than about 0.3 ppm); and a dielectric strength greater than air. These gaseous dielectric compounds are particularly useful as insulating-gases for use with electrical equipment, such as gas-insulated circuit breakers and current-interruption equipment, gas-insulated transmission lines, gas-insulated transformers, or gas-insulated substations.
BACKGROUND
Sulfur hexafluoride (SF6) has been used as a gaseous dielectric (insulator) in high voltage equipment since the 1950s. It is now known that SF6 is a potent greenhouse warming gas with one of the highest global warming potentials (GWP) known. Because of its high GWP, it is being phased out of all frivolous applications. However, there is currently no known substitute for SF6 in high voltage equipment. The electrical industry has taken steps to reduce the leak rates of equipment, monitor usage, increase recycling, and reduce emissions to the atmosphere. However, it would still be advantageous to find a substitute for SF6 in electrical dielectric applications.
The basic physical and chemical properties of SF6, its behavior in various types of gas discharges, and its uses by the electric power industry have been broadly investigated.
In its normal state, SF6 is chemically inert, non-toxic, non-flammable, non-explosive, and thermally stable (it does not decompose in the gas phase at temperatures less than 500° C.). SF6 exhibits many properties that make it suitable for equipment utilized in the transmission and distribution of electric power. It is a strong electronegative (electron attaching) gas both at room temperature and at temperatures well above ambient, which principally accounts for its high dielectric strength and good arc-interruption properties. The breakdown voltage of SF6 is nearly three times higher than air at atmospheric pressure. Furthermore, it has good heat transfer properties and it readily reforms itself when dissociated under high gas-pressure conditions in an electrical discharge or an arc (i.e., it has a fast recovery and it is self-healing). Most of its stable decomposition byproducts do not significantly degrade its dielectric strength and are removable by filtering. It produces no polymerization, carbon, or other conductive deposits during arcing, and its is chemically compatible with most solid insulating and conducting materials used in electrical equipment at temperatures up to about 200° C.
Besides it good insulating and heat transfer properties, SF6 has a relatively high pressure when contained at room temperature. The pressure required to liquefy SF6 at 21° C. is about 2100 kPa; its boiling point is reasonably low, −63.8° C., which allows pressures of 400 kPa to 600 kPa (4 to 6 atmospheres) to be employed in SF6-insulated equipment. It is easily liquefied under pressure at room temperature allowing for compact storage in gas cylinders. It presents no handling problems, is readily available, and reasonably inexpensive.
SF6 replaced air as a dielectric in gas insulated equipment based on characteristics such as insulation ability, boiling point, compressibility, chemical stability and non-toxicity. They have found that pure SF6, or SF6-nitrogen mixtures are the best gases to date.
However, SF6 has some undesirable properties: it can form highly toxic and corrosive compounds when subjected to electrical discharges (e.g., S2F10, SOF2); non-polar contaminants (e.g., air, CF4) are not easily removed from it; its breakdown voltage is sensitive to water vapor, conducting particles, and conductor surface roughness; and it exhibits non-ideal gas behavior at the lowest temperatures that can be encountered in the environment, i.e., in cold climatic conditions (about −50° C.), SF6 becomes partially liquefied at normal operating pressures (400 kPa to 500 kPa). SF6 is also an efficient infrared (IR) absorber and due to its chemical inertness, is not rapidly removed from the earth's atmosphere. Both of these latter properties make SF6 a potent greenhouse gas, although due to its chemical inertness (and the absence of chlorine and bromine atoms in the SF6 molecule) it is benign with regard to stratospheric ozone depletion.
That is, greenhouse gases are atmospheric gases which absorb a portion of the infrared radiation emitted by the earth and return it to earth by emitting it back. Potent greenhouse gases have strong infrared absorption in the wavelength range from approximately 7 μm to 13 μm. They occur both naturally in the environment (e.g., H2O, CO2, CH4, N2O) and as man-made gases that may be released (e.g., SF6; perfluorinated compound (PFC); combustion products such as CO2, nitrogen, and sulfur oxides). The effective trapping of long-wavelength infrared radiation from the earth by the naturally occurring greenhouse gases, and its reradiation back to earth, results in an increase of the average temperature of the earth's surface. Mans impact on climate change is an environmental issue that has prompted the implementation of the Kyoto Protocol regulating the emissions of man made greenhouse gases in a number of countries.
SF6 is an efficient absorber of infrared radiation, particularly at wavelengths near 10.5 μm. Additionally, unlike most other naturally occurring green house gases (e.g., CO2, CH4), SF6 is only slowly decomposed; therefore its contribution to global warming is expected to be cumulative and long lasting. The strong infrared absorption of SF6 and its long lifetime in the environment are the reasons for its extremely high global warming potential which for a 100-year time horizon is estimated to be approximately 22,200 times greater (per unit mass) than that of CO2, the predominant contributor to the greenhouse effect. The concern about the presence of SF6 in the environment derives exclusively from this very high value of its potency as a greenhouse gas.
Accordingly, many in the electrical equipment industry have spent substantial time and effort seeking suitable replacement gases to reduce the use of SF6 in high voltage electrical equipment. To date, the possible replacement gases have been identified as (i) mixtures of SF6 and nitrogen for which a large amount of research results are available; (ii) gases and mixtures (e.g., pure nitrogen, low concentrations of SF6 in N2, and SF6—He mixtures) for which a smaller yet significant amount of data is available; and (iii) potential gases for which little experimental data is available.
Some replacements which have been proposed have higher GWPs than SF6. For example, CF3SF5 falls into this category. Because of fugitive emissions in the manufacture, transportation, filling and use of such chemicals, they should be avoided.
However, the present inventors have determined that given the environmental difficulty of SF6, it is necessary to relax certain of the requirements traditionally held as important and accept as an alternative gas, compromise candidates with a lower GWP. For example, gases which are non-toxic are often inert with long atmospheric lifetimes which can yield high GWP. By accepting a somewhat more reactive gas than SF6, the GWP can be greatly reduced. It may also be necessary to accept slightly more toxic materials in order to find the best alternative in these applications. Such an increase in toxicity can be offset by reducing equipment leak rates or installing monitoring equipment. In some cases, the gases discovered by the present inventors as suitable alternatives to SF6 are show to be efficient at low levels and can be mixed with nitrogen and/or another non-toxic gas to give dielectrics with greatly reduced toxicity and acceptably low GWPs.
The unique gaseous compounds discovered by the present inventors for use as substitutes for SF6 can be used in some existing electrical equipment, although they would preferably be used in specific electrical equipment optimized for them. The gaseous compounds of the present disclosure are preferably used in pure form, but can also be used as part of an azeotrope, or a mixture with an appropriate second gas, such as nitrogen, CO2 or N2O.
SUMMARY
A dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about −20° C. to about −273° C.; low, preferably non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf<0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL (i.e., an Occupational Exposure Limit (OEL or TLV) of at least about 0.3 ppm); and a dielectric strength greater than air.
The dielectric gaseous compound is at least one compound selected from the group consisting of:

    Arsenic pentafluoride
    Arsine
    Diboron tetrafluoride
    Diborane
    Perchloric acid, 2-chloro-1,1,2,2-tetrafluoroethyl ester (9CI)
    Perchloric acid, 1,2,2-trichloro-1,2-difluoroethyl ester
    Trifluoroacetyl chloride
    trifluoromethylisocyanide (CF3-NC)
    trifluoromethyl isocyanide
    trifluoro-nitroso-ethene//Trifluor-nitroso-aethen
    Tetrafluoroethene
    3,3,4,4-tetrafluoro-3,4-dihydro-[1,2]diazete
    (Difluoramino)difluoracetonitril
    Tetrafluorooxirane
    Trifluoroacetyl fluoride
    Perfluormethylfluorformiat
    trifluoro-acetyl hypofluorite
    perfluoro-2-aza-1-propene
    Perfluor-2-aza-1-propen (germ.)
    N-Fluor-tetrafluor-1-aethanimin (germ.)
    3,3-difluoro-2-trifluoromethyl-oxaziridine
    bis-trifluoromethyl-diazene//hexafluoro-#cis!-azomethane
    Fluoroxypentafluoroethane
    bis-trifluoromethyl peroxide
    1,1-Bis(fluoroxy)tetrafluoroaethan
    Hexafluorodimethyl sulfide
    3-fluoro-3#H!-diazirine-3-carbonitrile
    Ethyne
    1,2,2-trifluoro-aziridine
    Ketene
    (difluoro)vinylboran
    (Difluor)vinylboran (germ.)
    trifluoro-vinyl-silane
    Ethinylsilan
    ethyl-difluor-borane
    Ethyl-difluor-boran (germ.)
    methyl-methylen-amine
    Dimethyl ether
    vinyl-silane
    Dimethylsilane
    Chloroethyne
    fluoroethyne//fluoro-acetylene
    Ethanedinitrile
    tetrafluoropropyne//1,3,3,3-tetrafluoropropyne
    hexafluoro-oxetane
    Trifluoro(trifluoromethyl)oxirane
    1,1,1,3,3,3-Hexafluoropropanone
    pentafluoro-propionyl fluoride//perfluoropropionyl fluoride
    Trifluoromethyl trifluorovinyl ether
    1-Propyne
    Cyclopropane
    Propane
    Trimethylborane
    cyanoketene
    butatriene
    Cyano-bispentafluorethyl-phosphin
    Trimethyl-1,1,2,2-tetrafluorethylsilan
    methyl diborane
    Methyldiboran (germ.)
    carbonyl bromide fluoride
    chloro-difluoro-nitroso-methane//Chlor-difluor-nitroso-methan
    chloroperoxytrifluoromethane
    carbonylchlorid-fluorid
    Carbonychloridfluorid (germ.)
    3,3-difluoro-3#H!-diazirine
    difluoro diazomethane
    Difluordiazomethan (germ.)
    Carbonyl fluoride
    Difluordioxiran
    difluoro-(3-fluoro-3#H!-diazirin-3-yl)-amine
    trifluoromethylazide
    Trifluormethylazid (germ.)
    tetrafluoro-diaziridine
    Fluorperoxytrifluormethan
    Bis(fluoroxy)difluormethan
    Trifluormethyl-phosphonylfluorid
    Cyanogen fluoride
    Trifluormethylphosphane (germ.)
    Diazomethane
    formaldehyde//Formalin
    (methyl)difluoroborane
    (Methyl)difluorboran (germ.)
    Chloromethane
    methylphosphonous acid difluoride//difluoro-methyl-phosphine
    trifluoro-methoxy-silane
    Methylhypofluorid
    Methane
    Methylsilane
    #Si!-bromo-#Si!,#Si!′-methanediyl-bis-silane
    #Si!-iodo-#Si!,#Si!′-methanediyl-bis-silane
    Difluormethylnitrit
    trifluoromethanol
    Formyl fluoride
    Cyanic acid
    Chlorine
    Chlorine fluoride
    Chlorine trioxide fluoride
    carbon oxide selenide//Kohlenoxidselenid
    Fluorine
    Difluorosilane
    Fluorine oxide
    fluorine peroxide
    Sulfuryl fluoride
    sulphur difluoride
    Phosphorus trifluoride oxide
    Phosphorus trifluoride sulfide
    tetrafluorophosphorane
    Tetrafluorohydrazine
    Sulfur tetrafluoride
    hexafluoro disiloxane
    Hexafluordisiloxan (germ.)
    Nitryl fluoride
    Hydrogen
    Hydrogen selenide
    Phosphorus trihydride
    Germanium hydride
    Silane
    Tin tetrahydride
    Oxygen
    Ozone
    Antimony monophosphide
    Disilicon monophosphide
    Radon
    Argon
    Trifluoroborane
    Hydrogen bromide
    Bromopentafluoroethane
    Chlorotrifluoroethene
    Trifluoroacetonitrile
    trifluoromethyl isocyanate
    trifluoromethyl thiocarbonyl fluoride
    Trifluormethylthiocarbonylfluorid (germ.)
    pentafluoro-nitroso-ethane//Pentafluor-nitroso-aethan
    (trifluoromethyl-carbonyl)-difluoro-amine
    Hexafluoroethane
    Bis-trifluormethyl-nitroxid
    bis-trifluoromethyl ether
    bis(trifluoromethyl)tellurium
    bis(trifluoromethyl)ditelluride
    N,N-Difluor-pentafluoraethylarnin (germ.)
    N-Fluor-bis(trifluormethyl)-amin (germ.)
    N-Fluor-N-trifluormethoxy-perfluormethylamin (germ.)
    fluoroformyl cyanide
    1-chloro-1-fluoro-ethene//1-Chlor-1-fluor-aethen//1-chloro-1-fluoroethylene
    1,1-Difluoroethene
    #trans!-1,2-difluoro-ethene//#trans!-vinylene difluoride//(E)-1,2-difluoroethylene//(E)-1,2-difluoro-ethene//#trans!-vinylene fluoride
    1,2-difluoro-ethene//#cis!-vinylene difluoride//1,2-Difluor-aethen//vinylene fluoride
    #cis!-1,2-difluoro-ethene//#cis!-vinylene difluoride//(Z)-1,2-difluoroethylene//(Z)-1,2-difluoro-ethene//#cis!-vinylene fluoride
    1,1,1,2-Tetrafluoroethane
    1,1,2,2-Tetrafluoroethane
    Fluoroethene
    1,1,1-Trifluoroethane
    Ether, methyl trifluoromethyl
    Ethene
    1,1-Difluoroethane
    Fluoroethane
    Ethane
    fluoro-dimethyl-borane
    Disiloxane, 1,1,3,3-tetrafluoro-1,3-dimethyl-Trifluoroethene
    trifluoroacetaldehyde//Trifluor-acetaldehyd
    Pentafluoroethane
    Difluoromethyl trifluoromethyl ether
    Tris(trifluoromethyl)bismuth
    tetrafluoropropadiene//tetrafluoro-allene//1,1,3,3-tetrafluoro-1,2-propadiene
    tetrafluorocyclopropene
    Perfluoropropionyliodid
    pentafluoro-propionitrile//pentafluoropropiononitrile
    hexafluoro-cyclopropane//Hexafluor-cyclopropan//freon-#C!216
    Hexafluoropropylene
    hexafluoro-[1,3]dioxolane
    Octafluoropropane
    Perfluormethylethylether
    1,1-difluoro-propadiene//allenylidene difluoride/1,1-difluoro-allene
    2,3,3,3-tetrafluoro-propene//HFO-1234yf
    trans HFO-1234ze
    3,3,3-Trifluoropropene
    cyclopropene
    Allene
    1,1-difluoro-propene//propenylidene difluoride//1,1-Difluor-propen
    methylketene
    2-fluoropropene
    1-Propene
    DL-2-aminopropanoic acid
    3,3,3-trifluoro-propyne//3,3,3-Trifluor-propin//trifluoromethyl-ethyne//3,3,3-trifluoro-1-propyne
    1,1,3,3,3-pentafluoro-propene//1,1,3,3,3-Pentafluor-propen
    1,2,3,3,3-pentafluoro-propene
    1,1,1,4,4,4-hexafluoro-2-butyne
    1,1,4,4-tetrafluoro-butane-2,3-dione
    Trifluormethylhypochlorit
    Chlor-difluor-methyl-hypofluorit
    N-Chlor-N-fluor-trifluormethylamin (germ.)
    Chlordifluordifluoraminomethan
    thiocarbonyl difluoride
    Thiocarbonyldifluorid (germ.)
    selenocarbonyl difluoride
    Trifluoroiodomethane
    N-Fluor-difluormethanimin (germ.)
    trifluoro-nitroso-methane//Trifluor-nitroso-methan
    difluoro-carbamoyl fluoride
    trifluoro-nitro-methane//Trifluor-nitro-methan//fluoropicrin
    Tetrafluoromethane
    Tetrafluorformamidin (germ.)
    tetrafluorourea
    hypofluorous acid trifluoromethyl ester//Hypofluorigsaeure-trifluormethylester//trifluoromethyl hypofluorite
    trifluoromethanesulfonyl fluoride
    N,N-Difluor-trifluormethylamin (germ.)
    Trifluormethyloxydifluoramin
    (Difluoraminoxy)difluormethylhypofluorit
    sulfurcyanide pentafluoride
    Schwefelcyanid-pentafluorid (germ.)
    difluoro-trifluoromethyl-phosphine
    Hexafluormethandiamin
    perfluoro methyl silane
    Perfluormethylsilan (germ.)
    Trifluormethyl-tetrafluorphosphoran (germ.)
    Difluoromethane
    Fluoroiodomethane
    fluoromethane//methyl fluoride//Fluor-methan//freon-41
    trifluoromethyl-silane′′ CF3SiH3
    methyltrifluorosilane
    difluoro-methyl-silane
    fluoro-methyl-silane
    methylgermane
    Difluorformimin
    Trifluoromethane
    trifluoromethane thiol
    Trifluormethanthiol (germ.)
    N,N,1,1-Tetrafluormethylamin
    difluoro dichlorosilane
    Difluordichlorsilan (germ.)
    difluoro chlorosilane
    Difluorchlorsilan (germ.)
    Phosphorus chloride difluoride
    Chlorotrifluorosilane
    Hydrogen chloride
    Chlorosilane
    Carbon monoxide
    Carbon dioxide
    Carbonyl sulfide
    Difluoramine
    trans-Difluorodiazine
    cis-Difluorodiazine
    Thionyl fluoride
    Trifluorosilane
    Nitrogen trifluoride
    Trifluoramine oxide
    thiazyl trifluoride
    Phosphorus trifluoride
    Germanium(IV) fluoride
    Tetrafuorosilane
    Phosphorus pentafluoride
    Selenium hexafluoride
    Tellurium hexafluoride
    fluorosilane
    Nitrosyl fluoride
    Fluorine nitrate
    Hydrogen sulfide
    Ammonia
    Helium
    Hydrogen iodide
    Krypton
    Nitrogen
    dinitrogen oxide
    Neon
    Nitrogen oxide; and
    Xenon


More preferably, the dielectric compounds can be selected from the group consisting of:

    Argon
    Trifluoroborane
    Hydrogen bromide
    Bromopentafluoroethane
    Chlorotrifluoroethene
    Trifluoroacetonitrile
    trifluoromethyl isocyanate
    trifluoromethyl thiocarbonyl fluoride
    Trifluormethylthiocarbonylfluorid (germ.)
    pentafluoro-nitroso-ethane//Pentafluor-nitroso-aethan
    (trifluoromethyl-carbonyl)-difluoro-amine
    Hexafluoroethane
    Bis-trifluormethyl-nitroxid
    bis-trifluoromethyl ether
    bis(trifluoromethyl)tellurium
    bis(trifluoromethyl)ditelluride
    N,N-Difluor-pentafluoraethylamin (germ.)
    N-Fluor-bis(trifluormethyl)-amin (germ.)
    N-Fluor-N-trifluormethoxy-perfluormethylamin (germ.)
    fluoroformyl cyanide
    1-chloro-1-fluoro-ethene//1-Chlor-1-fluor-aethen//1-chloro-1-fluoroethylene 1,1-Difluoroethene
    #trans!-1,2-difluoro-ethene//#trans!-vinylene difluoride//(E)-1,2-difluoroethylene//(E)-1,2-difluoro-ethene//#trans!-vinylene fluoride
    1,2-difluoro-ethene//#cis!-vinylene difluoride//1,2-Difluor-aethen//vinylene fluoride
    #cis!-1,2-difluoro-ethene//#cis!-vinylene difluoride//(Z)-1,2-difluoroethylene//(Z)-1,2-difluoro-ethene//#cis!-vinylene fluoride
    1,1,1,2-Tetrafluoroethane
    1,1,2,2-Tetrafluoroethane
    Fluoroethene
    1,1,1-Trifluoroethane
    Ether, methyl trifluoromethyl
    Ethene
    1,1-Difluoroethane
    Fluoroethane
    Ethane
    fluoro-dimethyl-borane
    Disiloxane, 1,1,3,3-tetrafluoro-1,3-dimethyl-Trifluoroethene
    trifluoroacetaldehyde//Trifluor-acetaldehyd
    Pentafluoroethane
    Difluoromethyl trifluoromethyl ether
    Tris(trifluoromethyl)bismuth
    tetrafluoropropadiene//tetrafluoro-allene//1,1,3,3-tetrafluoro-1,2-propadiene
    tetrafluorocyclopropene
    Perfluoropropionyliodid
    pentafluoro-propionitrile//pentafluoropropiononitrile
    hexafluoro-cyclopropane//Hexafluor-cyclopropan//freon-#C!216
    Hexafluoropropylene
    hexafluoro-[1,3]dioxolane
    Octafluoropropane
    Perfluormethylethylether
    1,1-difluoro-propadiene//allenylidene difluoride//1,1-difluoro-allene
    2,3,3,3-tetrafluoro-propene//HFO-1234yf
    trans HFO-1234ze
    3,3,3-Trifluoropropene
    cyclopropene
    Allene
    1,1-difluoro-propene//propenylidene difluoride//1,1-Difluor-propen
    methylketene
    2-fluoropropene
    1-Propene
    DL-2-aminopropanoic acid
    3,3,3-trifluoro-propyne//3,3,3-Trifluor-propin//trifluoromethyl-ethyne//3,3,3-trifluoro-1-propyne
    1,1,3,3,3-pentafluoro-propene//1,1,3,3,3-Pentafluor-propen
    1,2,3,3,3-pentafluoro-propene
    1,1,1,4,4,4-hexafluoro-2-butyne
    1,1,4,4-tetrafluoro-butane-2,3-dione
    Trifluormethylhypochlorit
    Chlor-difluor-methyl-hypofluorit
    N-Chlor-N-fluor-trifluormethylamin (germ.)
    Chlordifluordifluoraminomethan
    thiocarbonyl difluoride
    Thiocarbonyldifluorid (germ.)
    selenocarbonyl difluoride
    Trifluoroiodomethane
    N-Fluor-difluormethanimin (germ.)
    trifluoro-nitroso-methane//Trifluor-nitroso-methan
    difluoro-carbamoyl fluoride
    trifluoro-nitro-methane//Trifluor-nitro-methan//fluoropicrin
    Tetrafluoromethane
    Tetrafluorformamidin (germ.)
    tetrafluorourea
    hypofluorous acid trifluoromethyl ester//Hypofluorigsaeure-trifluormethylester//trifluoromethyl hypofluorite
    trifluoromethanesulfonyl fluoride
    N,N-Difluor-trifluormethylamin (germ.)
    Trifluormethyloxydifluoramin
    (Difluoraminoxy)difluormethylhypofluorit
    sulfurcyanide pentafluoride
    Schwefelcyanid-pentafluorid (germ.)
    difluoro-trifluoromethyl-phosphine
    Hexafluormethandiamin
    perfluoro methyl silane
    Perfluormethylsilan (germ.)
    Trifluormethyl-tetrafluorphosphoran (germ.)
    Difluoromethane
    Fluoroiodomethane
    fluoromethane//methyl fluoride//Fluor-methan//freon-41
    trifluoromethyl-silane′′ CF3SiH3
    methyltrifluorosilane
    difluoro-methyl-silane
    fluoro-methyl-silane
    methylgermane
    Difluorformimin
    Trifluoromethane
    trifluoromethane thiol
    Trifluormethanthiol (germ.)
    N,N,1,1-Tetrafluormethylamin
    difluoro dichlorosilane
    Difluordichlorsilan (germ.)
    difluoro chlorosilane
    Difluorchlorsilan (germ.)
    Phosphorus chloride difluoride
    Chlorotrifluorosilane
    Hydrogen chloride
    Chlorosilane
    Carbon monoxide
    Carbon dioxide
    Carbonyl sulfide
    Difluoramine
    trans-Difluorodiazine
    cis-Difluorodiazine
    Thionyl fluoride
    Trifluorosilane
    Nitrogen trifluoride
    Trifluoramine oxide
    thiazyl trifluoride
    Phosphorus trifluoride
    Germanium(IV) fluoride
    Tetrafuorosilane
    Phosphorus pentafluoride
    Selenium hexafluoride
    Tellurium hexafluoride
    fluorosilane
    Nitrosyl fluoride
    Fluorine nitrate
    Hydrogen sulfide
    Ammonia
    Helium
    Hydrogen iodide
    Krypton
    Nitrogen
    Nitrous oxide
    Neon
    Nitrogen oxide; and
    Xenon


The dielectric gaseous compound is optionally formed as an azeotrope, which imparts many advantages in handling the mixture. Preferred mixtures for dielectric gaseous compound contain one additional gas selected from the group consisting of: nitrogen, CO2 and N2O.
The present disclosure also includes an insulation-gas for use in electrical equipment, wherein said insulation-gas is a dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about −20° C. to about −273° C.; low, preferably non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf<0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL (i.e., Occupational Exposure Limit (OEL or TLV) of at least about 0.3 ppm); and a dielectric strength greater than air.
Preferably, the electrical equipment is at least one selected from the group consisting of: gas-insulated circuit breakers and current-interruption equipment, gas-insulated transmission lines, gas-insulated transformers, and gas-insulated substations.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The compounds of the present disclosure are useful in gaseous phase for electrical insulation and for arc quenching and current interruption equipment used in the transmission and distribution of electrical energy. Generally, there are four major types of electrical equipment which the gases of the present disclosure can be used for insulation and/or interruption purposes: (1) gas-insulated circuit breakers and current-interruption equipment, (2) gas-insulated transmission lines, (3) gas-insulated transformers, and (4) gas-insulated substations. Such gas-insulated equipment is a major component of power transmission and distribution systems all over the world. It offers significant savings in land use, is aesthetically acceptable, has relatively low radio and audible noise emissions, and enables substations to be installed in populated areas close to the loads.
Depending on the particular function of the gas-insulated equipment, the gas properties which are the most significant vary.
For circuit breakers the excellent thermal conductivity and high dielectric strength of such gases, along with the fast thermal and dielectric recovery (short time constant for increase in resistivity), are the main reasons for its high interruption capability. These properties enable the gas to make a rapid transition between the conducting (arc plasma) and the dielectric state of the arc, and to withstand the rise of the recovery voltage.
For gas-insulated transformers the cooling ability, compatibility with solid materials, and partial discharge characteristics, added to the dielectric characteristics, make them a desirable medium for use in this type of electrical equipment. The compounds have distinct advantages over oil insulation, including none of the fire safety problems or environmental problems related to oil, high reliability, flexible layout, little maintenance, long service life, lower noise, better handling, and lighter equipment.
For gas-insulated transmission lines the dielectric strength of the gaseous medium under industrial conditions is of paramount importance, especially the behavior of the gaseous dielectric under metallic particle contamination, switching and lightning impulses, and fast transient electrical stresses. These gases also have a high efficiency for transfer of heat from the conductor to the enclosure and are stable for long periods of time (e.g., 40 years). These gas-insulated transmission lines offer distinct advantages: cost effectiveness, high-carrying capacity, low losses, availability at all voltage ratings, no fire risk, reliability, and a compact alternative to overhead high voltage transmission lines in congested areas that avoids public concerns with overhead transmission lines.
For gas-insulated substations, the entire substation (circuit breakers, disconnects, grounding switches, busbar, transformers, etc., are interconnected) is insulated with the gaseous dielectric medium of the present disclosure, and, thus, all of the above-mentioned properties of the dielectric gas are significant.
The properties of a dielectric gas that are necessary for its use in high voltage equipment are many and vary depending on the particular application of the gas and the equipment.
Intrinsic properties are those properties of a gas which are inherent in the physical atomic or molecular structure of the gas. These properties are independent of the application or the environment in which a gas is placed. One of the desirable properties of a gaseous dielectric is high dielectric strength (higher, for instance than air). The gas properties that are principally responsible for high dielectric strength are those that reduce the number of electrons which are present in an electrically-stressed dielectric gas. To effect such a reduction in the electron number densities, as gas should: (i) be electronegative (remove electrons by attachment over as wide an energy range as possible); it should preferably exhibit increased electron attachment with increasing electron energy and gas temperature since electrons have a broad range of energies and the gas temperature in many applications is higher than ambient; (ii) have good electron slowing-down properties (slow electrons down so that they can be captured efficiently at lower energies and be prevented from generating more electrons by electron impact ionization); and (iii) have low ionization cross section and high ionization onset (prevent ionization by electron impact). Besides the above properties, there are a number of other basic properties which are necessary for the complete characterization of the dielectric gas behavior and its performance in practice, e.g., secondary processes such as electron emission from surfaces by ion and photon impact; photoprocesses; absorption of photoionizing radiation (this is a controlling factor in discharge development in non-uniform fields); dissociation under electron impact decomposition; ion-molecule reactions; reactions with trace impurities; and reactions with surfaces.
The dielectric gas must also have the following chemical properties: high vapor pressure; high specific heat, high thermal conductivity for gas cooling; thermal stability over long periods of time for temperatures greater than 400° K.; chemical stability and inertness with regard to conducting and insulating materials; non-flammable; toxicity acceptable for industrial exposure; and non-explosive. When used in mixtures, it must have appropriate thermodynamic properties for mixture uniformity, composition, and separation.
Extrinsic properties are those which describe how a gas may interact with its surroundings, or in response to external influences, such as electrical breakdown and discharges. To be used in electrical applications, a dielectric gas should: (undergo no extensive decomposition; lead to no polymerization; form no carbon or other deposits; and be non-corrosive and non-reactive to metals, insulators, spacers, and seals. In addition it should have: no byproduct with toxicity unacceptable for industrial applications; removable byproducts; and a high recombination rate for reforming itself, especially for arc interruption. Finally, the gas must be environmentally friendly, e.g., it must not contribute to global warming, must not deplete stratospheric ozone, and must not persist in the environment for long periods of time.
Specific properties of the gas under discharge and breakdown conditions include: a high breakdown voltage under uniform and non-uniform electric fields; insensitivity to surface roughness or defects and freely moving conducting particles; good insulation properties under practical conditions; good insulator flashover characteristics; good heat transfer characteristics; good recovery (rate of voltage recovery) and self-healing; no adverse reactions with moisture and common impurities; and no adverse effects on equipment, especially on spacers and electrode surfaces.
Specific properties of gaseous insulators for specific electrical equipment is set forth below:

    Circuit breakers—The most significant required gas properties for arc interruption are: (i) high dielectric strength comparable to that of SF6; (ii) high thermal conductivity; (iii) fast gas recovery; and (iv) self-healing/dielectric integrity.
    Gas-insulated transmission lines—The required properties include: (i) high dielectric strength; (ii) high vapor pressure at operating and ambient temperature; (iii) chemical inertness; (iv) high thermal conductivity; (v) no thermal aging; (vi) no deposits; (vii) easily removable, non-harmful byproducts; and (viii) no unacceptable level of hazards (fire, explosion, toxicity, corrosion).
    Gas-insulated transformers—The properties of the gas required for this application include: (i) high dielectric strength at reasonable pressures (e.g., 500 kPa); (ii) low boiling point; (iii) acceptably low toxicity; (iv) chemical inertness; (v) good thermal stability; (vi) non-flammable; (vii) high cooling capability; (viii) good compatibility with solid materials; (ix) good partial discharge characteristics; (x) useable over a range of temperatures; and (xi) safe, easy to handle, inexpensive and securely available.


The present inventors have discovered a unique series of dielectric gases for use in electric equipment applications, which exhibit many of the aforementioned properties, which avoiding the greenhouse problems associated with SF6. Such dielectric compounds exhibit at least one of the following properties:

    
    
        A boiling point in the range between about −20° C. to about −273° C.
        Low, preferably, Non-ozone depleting
        A GWP less than about 22,200
        Chemical stability, as measured by a negative standard enthalpy of formation (dHf<0)
        A toxicity level such that when the working gas leaks from equipment at the manufacturer's specified maximum leak rate, the effective diluted concentration does not exceeed its PEL, i.e., does not exceed the PEL of that specific compound. In general with minimal ventilation PELs greater than about 0.3 ppm by volume are acceptable (i.e., an Occupational Exposure Limit (OEL or TLV) of at least about 0.3 ppm). OSHA sets enforceable permissible exposure limits (PELs) to protect workers against the health effects of exposure to hazardous substances. OSHA PELs are based on an 8-hour time weighted average (TWA) exposure. Approximately 500 PELs have been established. Existing PELs are contained in 29 CFR 1910.1000, the air contaminants standard. Most PELs are listed in 29 CFR 1910.1000, Table Z-1, and 29 CFR 1910.1000, Table Z-2.
        A dielectric strength greater than air.
    
    


These unique dielectric gases are at least one gas selected from the group consisting of those set forth in Table 1 below:












TABLE 1





Dielectric




MY


Compound
Structure
Name
CAS
MW
BP(° C.)




















AsF5
AsF5
Arsenic pentafluoride
7784-36-3
169.91
−52.8


AsH3
AsH3
Arsine
7784-42-1
77.95
−62.2


B2F4
B2F4
Diboron tetrafluoride
13965-73-6
97.61
−34.2


B2H6
H2B(H2)BH2
Diborane
19287-45-7
27.67
−92.3


C2Cl2F4O4
O3ClOCF2CF2Cl
Perchloric acid, 2-chloro-
38126-28-2
234.92
−95.0




1,1,2,2-tetrafluoroethyl




ester (9CI)


C2Cl4F2O4
O3ClOCFClCFCl2
Perchloric acid, 1,2,2-
38126-29-3
267.83
−35.0




trichloro-1,2-difluoroethyl




ester


C2ClF3O
CF3CCl(O)
Trifluoroacetyl chloride
354-32-5
132.47
−27.0


C2F3N
(CF3)—NC
trifluoromethylisocyanide
19480-01-4
95.02
−84.0




(CF3—NC)


C2F3N
CF3—NC
trifluoromethyl isocyanide
19480-01-4
95.02
−35.0


C2F3NO
CF2═CF—NO
trifluoro-nitroso-
2713-04-4
111.02
−23.7




ethene//Trifluor-nitroso-




aethen


C2F4
C2F4
Tetrafluoroethene
116-14-3
100.02
−75.6


C2F4N2
cyclo —CF2—N═N—CF2—′
3,3,4,4-tetrafluoro-3,4-
694-60-0
128.03
−36.0




dihydro-[1,2]diazete


C2F4N2
NF2—CF2—CN
(Difluoramino)difluoracetonitril
5131-88-4
128.03
−32.0


C2F4O
O(CF2CF2)
Tetrafluorooxirane
694-17-7
116.01
−63.5


C2F4O
CF3CF(O)
Trifluoroacetyl fluoride
354-34-7
116.01
−59.0


C2F4O2
FC(O)OCF3
Perfluormethylfluorformiat
3299-24-9
132.01
−33.0


C2F4O2
CF3C(O)OF
trifluoro-acetyl hypofluorite
359-46-6
132.01
−25.0











C2F5N
CF3N═CF2
perfluoro-2-aza-1-propene
133.02
−34.0




Perfluor-2-aza-1-propen (germ.)












C2F5N
CF3CFNF
N-Fluor-tetrafluor-1-
758-35-0
133.02
−32.0




aethanimin (germ.)


C2F5NO
cyclo(—CF2—N(CF3)—O—)
3,3-difluoro-2-
60247-20-3
149.02
−34.8




trifluoromethyl-oxaziridine


C2F6N2
(CF3)N═N(CF3)
bis-trifluoromethyl-
372-63-4
166.03
−20.0




diazene//hexafluoro-#cis!-




azomethane


C2F6O
C2F5OF
Fluoroxypentafluoroethane
3848-94-0
154.01
−50.0


C2F6O2
CF3—O—O—CF3
bis-trifluoromethyl peroxide
927-84-4
170.01
−40.0


C2F6O2
CF3C(OF)2F
1,1-
16329-92-3
170.01
−35.0




Bis(fluoroxy)tetrafluoroaethan


C2F6S
(CF3)2S
Hexafluorodimethyl sulfide
371-78-8
170.08
−22.2


C2FN3
(—N═N—)
3-fluoro-3#H!-diazirine-3-
4849-85-8
85.04
−30.0



CF(CN)
carbonitrile


C2H2
HCCH
Ethyne
74-86-2
26.04
−84.7


C2H2F3N
—CF2—NF—CH2—
1,2,2-trifluoro-aziridine
1514-44-9
97.04
−24.0


C2H2O
CH2CO
Ketene
463-51-4
42.04
−49.8


C2H3BF2
F2BCHCH2
(difluoro)vinylboran
358-95-2
75.85
−38.8




(Difluor)vinylboran (germ.)


C2H3F3Si
F3Si—CH═CH2
trifluoro-vinyl-silane
421-24-9
112.13
−25.0


C2H4Si
HCCSiH3
Ethinylsilan
1066-27-9
56.14
−22.4


C2H5BF2
(C2H5)F2B
ethyl-difluor-borane
430-41-1
77.87
−25.0




Ethyl-difluor-boran (germ.)


C2H5N
CH2═NCH3
methyl-methylen-amine
1761-67-7
43.07
−35.0


C2H6O
CH3OCH3
Dimethyl ether
115-10-6
46.07
−24.8


C2H6Si
H2CCHSiH3
vinyl-silane
7291-09-0
58.15
−22.8


C2H8Si
(CH3)2SiH2
Dimethylsilane
1111-74-6
60.17
−20.2


C2HCl
ClCCH
Chloroethyne
593-63-5
60.48
−30.2


C2HF

fluoroethyne//fluoro-
2713-09-9
44.03
−105.0




acetylene


C2N2
NCCN
Ethanedinitrile
460-19-5
52.03
−21.2


C3F4
FCCCF3
tetrafluoropropyne//1,3,3,3-
20174-11-2
112.03
−50.0




tetrafluoropropyne


C3F6O
cyclo-CF2—CF2—O—CF2—
hexafluoro-oxetane
425-82-1
166.02
−38.0


C3F6O
cyclo(—CF2—O—CF(CF3)—)
Trifluoro(trifluoromethyl)oxirane
428-59-1
166.02
−27.4


C3F6O
(CF3)2CO
1,1,1,3,3,3-
684-16-2
166.02
−27.3




Hexafluoropropanone


C3F6O
CF3CF2C(O)F
pentafluoro-propionyl
422-61-7
166.02
−27.0




fluoride//perfluoropropionyl




fluoride


C3F6O
CF3OCFCF2
Trifluoromethyl
1187-93-5
166.02
−26.0




trifluorovinyl ether


C3H4
CH3CCH
1-Propyne
74-99-7
40.06
−23.2


C3H6
—CH2CH2CH2—
Cyclopropane
75-19-4
42.08
−32.8


C3H8
CH3CH2CH3
Propane
74-98-6
44.10
−42.0


C3H9B
B(CH3)3
Trimethylborane
593-90-8
55.92
−20.2


C3HNO
OCCHCN
cyanoketene
4452-08-8
67.05
−34.0


C4H4
CH2═C═C═CH2
butatriene
2873-50-9
52.08
−78.0


C5F10NP
(C2F5)2PCN
Cyano-bispentafluorethyl-
35449-90-2
295.02
−78.0




phosphin


C5H10F4Si
CHF2CF2Si(CH3)3
Trimethyl-1,1,2,2-
4168-08-5
174.21
−72.0




tetrafluorethylsilan


CB2H8
CH3B2H5
methyl diborane
23777-55-1
41.70
−35.0




Methyldiboran (germ.)


CBrFO
COBrF
carbonyl bromide fluoride
753-56-0
126.91
−20.6


CClF2NO
(F2Cl)CN═O
chloro-difluoro-nitroso-
421-13-6
115.47
−35.0




methane//Chlor-difluor-




nitroso-methan


CClF3O2
CF3—O—O—Cl
chloroperoxytrifluoromethane
32755-26-3
136.46
−22.0


CClFO
COClF
carbonylchlorid-fluorid
353-49-1
82.46
−46.0




Carbonychloridfluorid




(germ.)


CF2N2
F2C(—N═N—)
3,3-difluoro-3#H!-diazirine
693-85-6
78.02
−91.3


CF2N2
F2C═N═N
difluoro diazomethane
814-73-3
78.02
−91.3




Difluordiazomethan




(germ.)


CF2O
F2CO
Carbonyl fluoride
353-50-4
66.01
−84.6


CF2O2
F2C(OO)
Difluordioxiran
96740-99-7
82.01
−85.0


CF3N3
(NF2)(F)C(—N═N—)
difluoro-(3-fluoro-3#H!-
4823-43-2
111.03
−36.0




diazirin-3-yl)-amine


CF3N3
CF3—N—N—N
trifluoromethylazide
3802-95-7
110.03
−28.5




Trifluormethylazid (germ.)


CF4N2
cyclo-(—NF—NF—CF2—)
tetrafluoro-diaziridine
17224-09-8
116.02
−35.0


CF4O2
CF3—O—O—F
Fluorperoxytrifluormethan
34511-13-2
120.00
−69.4


CF4O2
F2C(OF)2
Bis(fluoroxy)difluormethan
16282-67-0
120.00
−64.0


CF5OP
OPF2CF3
Trifluormethyl-
19162-94-8
153.98
−20.1




phosphonylfluorid


CFN

Cyanogen fluoride
1495-50-7
45.02
−46.2


CH2F3P
CF3PH2
Trifluormethylphosphane
420-52-0
102.00
−26.5




(germ.)


CH2N2
H2CNN
Diazomethane
334-88-3
42.04
−23.2


CH2O

formaldehyde//Formalin
50-00-0
30.03
−21.0


CH3BF2
CH3BF2
(methyl)difluoroborane
373-64-8
63.84
−62.3




(Methyl)difluorboran




(germ.)


CH3Cl
CH3Cl
Chloromethane
74-87-3
50.49
−24.2











CH3F2P
F2PCH3
methylphosphonous acid difluoride//difluoro-
84.01
−28.0




methyl-phosphine












CH3F3OSi
F3Si—O—CH3
trifluoro-methoxy-silane
25711-11-9
116.11
−78.0


CH3FO
CH3—O—F
Methylhypofluorid
36336-08-0
50.03
−33.0


CH4
CH4
Methane
74-82-8
16.04
−161.5


CH6Si
CH3SiH3
Methylsilane
992-94-9
46.14
−56.9


CH7BrSi2
H3Si—CH2—SiH2Br
#Si!-bromo-#Si!,#Si!′-
56962-86-8
155.14
−64.0




methanediyl-bis-silane


CH7ISi2
H3Si—CH2—SiH2I
#Si!-iodo-#Si!,#Si!′-
56962-87-9
202.14
−49.0




methanediyl-bis-silane


CHF2NO2
F2CH—O—NO
Difluormethylnitrit
1493-06-7
97.02
−20.0


CHF3O
F3COH
trifluoromethanol
1493-11-4
86.01
−20.0


CHFO
HFCO
Formyl fluoride
1493-02-3
48.02
−26.5


CHNO
HOCN
Cyanic acid
420-05-3
43.03
−64.2


Cl2
Cl2
Chlorine
7782-50-5
70.91
−34.0


ClF
ClF
Chlorine fluoride
7790-89-8
54.45
−101.0


ClFO3

Chlorine trioxide fluoride
7616-94-6
102.45
−46.7


COSe
Se═C═O
carbon oxide
1603-84-5
106.97
−21.7




selenide//Kohlenoxidselenid


F2
F2
Fluorine
7782-41-4
38.00
−188.2


F2H2Si
SiF2H2
Difluorosilane
13824-36-7
68.10
−77.8


F2O
OF2
Fluorine oxide
7783-41-7
54.00
−144.7


F2O2
FOOF
fluorine peroxide
7783-44-0
70.00
−57.0


F2O2S
SO2F2
Sulfuryl fluoride
2699-79-8
102.06
−55.3


F2S
SF2
sulphur difluoride
13814-25-0
70.06
−35.0


F3OP
POF3
Phosphorus trifluoride
13478-20-1
103.97
−39.7




oxide


F3PS
PSF3
Phosphorus trifluoride
2404-52-6
120.03
−52.3




sulfide


F4HP
PHF4
tetrafluorophosphorane
13659-66-0
107.98
−37.0


F4N2
F2NNF2
Tetrafluorohydrazine
10036-47-2
104.01
−74.2


F4S
SF4
Sulfur tetrafluoride
7783-60-0
108.05
−40.5


F6OSi2
SiF3OSiF3
hexafluoro disiloxane
14515-39-0
186.16
−23.0




Hexafluordisiloxan (germ.)


FNO2
O2NF
Nitryl fluoride
10022-50-1
65.00
−72.3


H2
H2
Hydrogen
1333-74-0
2.02
−252.9


H2Se
H2Se
Hydrogen selenide
7783-07-5
80.98
−41.3


H3P
PH3
Phosphorus trihydride
7803-51-2
34.00
−87.8


H4Ge
GeH4
Germanium hydride
7782-65-2
76.62
−88.2


H4Si
SiH4
Silane
7803-62-5
32.12
−112.2


H4Sn
SnH4
Tin tetrahydride
2406-52-2
122.72
−51.8


O2
O2
Oxygen
7782-44-7
32.00
−183.0


O3
O3
Ozone
10028-15-6
48.00
−111.3


PSb
SbP
Antimony monophosphide
na
152.72
−52.3


PSi2
Si2P
Disilicon monophosphide
na
87.14
−52.3


Rn
Rn
Radon
10043-92-2
222.00
−61.7


Ar
Ar
Argon
7440-37-1
39.95
−185.9


BF3
BF3
Trifluoroborane
7637-07-2
67.81
−101.2


BrH
HBr
Hydrogen bromide
10035-10-6
80.91
−66.7


C2BrF5
CF3CF2Br
Bromopentafluoroethane
354-55-2
198.92
−21.0


C2ClF3
CFCl═CF2
Chlorotrifluoroethene
79-38-9
116.47
−28.4


C2F3N
CF3CN
Trifluoroacetonitrile
353-85-5
95.02
−68.8


C2F3NO
(CF3)NCO
trifluoromethyl isocyanate
460-49-1
111.02
−36.0











C2F4S
CF3C(S)F
trifluoromethyl thiocarbonyl fluoride
132.08
−21.0




Trifluormethylthiocarbonylfluorid (germ.)












C2F5NO
CF3CF2NO
pentafluoro-nitroso-
354-72-3
149.02
−45.7




ethane//Pentafluor-nitroso-




aethan


C2F5NO
CF3C(O)NF2
(trifluoromethyl-carbonyl)-
32822-49-4
149.02
−21.1




difluoro-amine


C2F6
CF3CF3
Hexafluoroethane
76-16-4
138.01
−78.2


C2F6NO
CF3N(O)CF3
Bis-trifluormethyl-nitroxid
2154-71-4
168.02
−20.0


C2F6O
CF3OCF3
bis-trifluoromethyl ether
1479-49-8
154.01
−59.0


C2F6Te
(CF3)2Te
bis(trifluoromethyl)tellurium
55642-42-7
265.61
−98.0


C2F6Te2
CF3TeTeCF3
bis(trifluoromethyl)
1718-20-3
393.21
−53.0




ditelluride


C2F7N
CF3CF2NF2
N,N-Difluor-
354-80-3
171.02
−38.0




pentafluoraethylamin




(germ.)


C2F7N
(CF3)2NF
N-Fluor-bis(trifluormethyl)-
359-62-6
171.02
−37.0




amin (germ.)


C2F7NO
CF3NFOCF3
N-Fluor-N-trifluormethoxy-
4217-92-9
187.02
−25.0




perfluormethylamin (germ.)


C2FNO
FC(O)CN
fluoroformyl cyanide
683-55-6
73.03
−21.0


C2H2ClF
CH2CFCl
1-chloro-1-fluoro-ethene//1-
2317-91-1
80.49
−25.5




Chlor-1-fluor-aethen//1-




chloro-1-fluoroethylene


C2H2F2
CF2═CH2
1,1-Difluoroethene
75-38-7
64.03
−85.7


C2H2F2
CHF═CHF
#trans!-1,2-difluoro-
1630-78-0
64.03
−53.1




ethene//#trans!-vinylene




difluoride//(E)-1,2-




difluoroethylene//(E)-1,2-




difluoro-ethene//#trans!-




vinylene fluoride


C2H2F2
FHC═CHF
1,2-difluoro-ethene//#cis!-
1691-13-0
64.03
−28.0




vinylene difluoride//1,2-




Difluor-aethen//vinylene




fluoride


C2H2F2
CHF═CHF
#cis!-1,2-difluoro-
1630-77-9
64.03
−26.0




ethene//#cis!-vinylene




difluoride//(Z)-1,2-




difluoroethylene//(Z)-1,2-




difluoro-ethene//#cis!-




vinylene fluoride


C2H2F4
CF3CH2F
1,1,1,2-Tetrafluoroethane
811-97-2
102.03
−26.1


C2H2F4
CF2HCF2H
1,1,2,2-Tetrafluoroethane
359-35-3
102.03
−23.0


C2H3F
CH2═CHF
Fluoroethene
75-02-5
46.04
−72.2


C2H3F3
CF3CH3
1,1,1-Trifluoroethane
420-46-2
84.04
−47.3


C2H3F3O
F3COCH3
Ether, methyl
421-14-7
100.04
−24.0




trifluoromethyl


C2H4
H2CCH2
Ethene
74-85-1
28.05
−103.7


C2H4F2
CHF2CH3
1,1-Difluoroethane
75-37-6
66.05
−24.0


C2H5F
CH3CH2F
Fluoroethane
353-36-6
48.06
−37.7


C2H6
CH3CH3
Ethane
74-84-0
30.07
−88.6


C2H6BF
(CH3)2BF
fluoro-dimethyl-borane
353-46-8
59.88
−44.0


C2H6F4OSi2
CH3SiF2OSiF2CH3
Disiloxane, 1,1,3,3-
63089-45-2
178.23
−39.0




tetrafluoro-1,3-dimethyl-


C2HF3
CF2═CFH
Trifluoroethene
359-11-5
82.02
−51.0


C2HF3O
CF3C(O)H
trifluoroacetaldehyde//Trifluor-
75-90-1
98.02
−21.0




acetaldehyd


C2HF5
CF3CF2H
Pentafluoroethane
354-33-6
120.02
−48.1


C2HF5O
CF3OCHF2
Difluoromethyl
3822-68-2
136.02
−35.3




trifluoromethyl ether


C3BiF9
Bi(CF3)3
Tris(trifluoromethyl)bismuth
5863-80-9
416.00
−55.0


C3F4
F2C═C═CF2
tetrafluoropropadiene//tetrafluoro-
461-68-7
112.03
−38.0




allene//1,1,3,3-




tetrafluoro-1,2-propadiene


C3F4
═CFCF2CF═
tetrafluorocyclopropene
19721-29-0
112.03
−20.0


C3F5IO
CF3CF2C(O)I
Perfluoropropionyliodid
137741-03-8
273.93
−27.0


C3F5N
C2F5CN
pentafluoropropionitrile//
422-04-8
145.03
−35.0




pentafluoropropiononitrile


C3F6
cyclo
hexafluoro-
931-91-9
150.02
−33.0



—CF2CF2CF2—
cyclopropane//Hexafluor-




cyclopropan//freon-#C!216


C3F6
CF3CF═CF2
Hexafluoropropylene
116-15-4
150.02
−29.6


C3F6O2
cyclo-CF2—O—CF2—CF2—O—
hexafluoro-[1,3]dioxolane
21297-65-4
182.02
−22.1


C3F8
CF3CF2CF3
Octafluoropropane
76-19-7
188.02
−36.7


C3F8O
CF3CF2OCF3
Perfluormethylethylether
665-16-7
204.02
−20.0


C3H2F2
F2CCCH2
1,1-difluoro-
430-64-8
76.05
−21.0




propadiene//allenylidene




difluoride//1,1-difluoro-




allene


C3H2F4
H2CCFCF3
2,3,3,3-tetrafluoro-
754-12-1
114.04
−28.3




propene//HFO-1234yf


C3H2F4
CHF═CHCF3
trans HFO-1234ze

114.04
−19.0


C3H3F3
CH2═CHCF3
3,3,3-Trifluoropropene
677-21-4
96.05
−25.0


C3H4
c-(CH═CH—CH2)
cyclopropene
2781-85-3
40.06
−36.0


C3H4
H2CCCH2
Allene
463-49-0
40.06
−34.5


C3H4F2
CH3CH═CF2
1,1-difluoro-
430-63-7
78.06
−29.0




propene//propenylidene




difluoride//1,1-Difluor-




propen


C3H4O

methylketene
6004-44-0
56.06
−23.0


C3H5F
CH2CFCH3
2-fluoropropene
1184-60-7
60.07
−24.0


C3H6
CH2CHCH3
1-Propene
115-07-1
42.08
−47.7


C3H7NO2

DL-2-aminopropanoic acid
302-72-7
89.09
−50.2


C3HF3
F3CCCH
3,3,3-trifluoro-
661-54-1
94.04
−48.0




propyne//3,3,3-Trifluor-




propin//trifluoromethyl-




ethyne//3,3,3-trifluoro-1-




propyne


C3HF5
CF3CH═CF2
1,1,3,3,3-pentafluoro-
690-27-7
132.03
−21.0




propene//1,1,3,3,3-




Pentafluor-propen


C3HF5
CF3—CF—CFH
1,2,3,3,3-pentafluoro-
2252-83-7
132.03
−20.0




propene


C4F6
CF3CCCF3
1,1,1,4,4,4-hexafluoro-2-
692-50-2
162.03
−24.6




butyne


C4H2F4O2
CF2HC(O)C
1,1,4,4-tetrafluoro-butane-

158.05
−81.0



(O)CF2H
2,3-dione


C4H6N2O2



114.10
−33.0


CClF3O
F3C—O—Cl
Trifluormethylhypochlorit
22082-78-6
120.46
−47.0


CClF3O
ClF2C—OF
Chlor-difluor-methyl-
20614-17-9
120.46
−25.0




hypofluorit


CClF4N
CF3NFCl
N-Chlor-N-fluor-
13880-72-3
137.46
−32.8




trifluormethylamin (germ.)


CClF4N
ClCF2—NF2
Chlordifluordifluoraminomethan
13880-71-2
137.46
−28.0


CF2S
F2C═S
thiocarbonyl difluoride
420-32-6
82.07
−46.0




Thiocarbonyldifluorid




(germ.)


CF2Se
F2C═Se
selenocarbonyl difluoride
54393-39-4
128.97
−28.0


CF3I
CF3I
Trifluoroiodomethane
2314-97-8
195.91
−21.8


CF3N
CF2—N—F
N-Fluor-difluormethanimin
338-66-9
83.01
−101.0




(germ.)


CF3NO
CF3N═O
trifluoro-nitroso-
334-99-6
99.01
−86.0




methane//Trifluor-nitroso-




methan


CF3NO
FC(O)NF2
difluoro-carbamoyl fluoride
2368-32-3
99.01
−52.0


CF3NO2
CF3NO2
trifluoro-nitro-
335-02-4
115.01
−33.6




methane//Trifluor-nitro-




methan//fluoropicrin


CF4
CF4
Tetrafluoromethane
75-73-0
88.00
−128.1


CF4N2
NF2CF═NF
Tetrafluorformamidin
14362-70-0
116.02
−30.0




(germ.)


CF4N2O
(NF2)2CO
tetrafluorourea
10256-92-5
132.02
−20.0










CF4O
hypofluorous acid trifluoromethylester//
104.00
−95.0



Hypofluorigsaeure-



trifluormethylester//trifluoromethyl



hypofluorite












CF4O2S
CF3SO2F
trifluoromethanesulfonyl
335-05-7
152.07
−21.7




fluoride


CF5N
CF3NF2
N,N-Difluor-
335-01-3
121.01
−75.0




trifluormethylamin (germ.)


CF5NO
CF3ONF2
Trifluormethyloxydifluoramin
4217-93-0
137.01
−59.8


CF5NO2
F2NOCF2OF
(Difluoraminoxy)difluormethyl-
36781-60-9
153.01
−29.0




hypofluorit


CF5NS
SF5CN
sulfurcyanide pentafluoride
1512-13-6
153.08
−25.0




Schwefelcyanid-




pentafluorid (germ.)


CF5P
CF3PF2
difluoro-trifluoromethyl-
1112-04-5
137.98
−43.0




phosphine


CF6N2
F2NCF2NF2
Hexafluormethandiamin
4394-93-8
154.01
−37.0


CF6Si
CF3SiF3
perfluoro methyl silane
335-06-8
154.09
−42.0




Perfluormethylsilan (germ.)


CF7P
CF3PF4
Trifluormethyl-
1184-81-2
175.97
−35.0




tetrafluorphosphoran




(germ.)


CH2F2
CH2F2
Difluoromethane
75-10-5
52.02
−51.7


CH2FI
CH2FI
Fluoroiodomethane
373-53-5
159.93
−53.8


CH3F

fluoromethane//methyl
593-53-3
34.03
−78.3




fluoride//Fluormethan//




freon-41


CH3F3Si
CF3SiH3
trifluoromethyl-silane′′
10112-11-5
100.12
−38.3




CF3SiH3


CH3F3Si
CH3SiF3
methyltrifluorosilane
373-74-0
100.12
−30.0


CH4F2Si
F2HSiCH3
difluoro-methyl-silane
420-34-8
82.12
−35.6


CH5FSi
CH3SiH2F
fluoro-methyl-silane
753-44-6
64.13
−44.0


CH6Ge
H3GeCH3
methylgermane
1449-65-6
90.65
−23.0


CHF2N
F2C═NH
Difluorformimin
2712-98-3
65.02
−22.0


CHF3
CHF3
Trifluoromethane
75-46-7
70.01
−82.1


CHF3S
CF3SH
trifluoromethane thiol
1493-15-8
102.08
−36.7




Trifluormethanthiol (germ.)


CHF4N
CF2H—NF2
N,N,1,1-
24708-53-0
103.02
−43.0




Tetrafluormethylamin


Cl2F2Si
SiF2Cl2
difluoro dichlorosilane
18356-71-3
136.99
−31.8




Difluordichlorsilan (germ.)


ClF2HSi
SiF2HCl
difluoro chlorosilane
80003-43-6
102.56
−50.0




Difluorchlorsilan (germ.)


ClF2P
PF2Cl
Phosphorus chloride
14335-40-1
104.42
−47.3




difluoride


ClF3Si
SiClF3
Chlorotrifluorosilane
14049-36-6
120.53
−70.2


ClH
HCl
Hydrogen chloride
7647-01-0
36.46
−85.0


ClH3Si
SiH3Cl
Chlorosilane
13465-78-6
66.56
−30.3


CO
CO
Carbon monoxide
630-08-0
28.01
−191.5


CO2
CO2
Carbon dioxide
124-38-9
44.01
−78.4


COS
OCS
Carbonyl sulfide
463-58-1
60.07
−50.3


F2HN
NHF2
Difluoramine
10405-27-3
53.01
−23.2


F2N2
FNNF
trans-Difluorodiazine
13776-62-0
66.01
−111.5


F2N2
FNNF
cis-Difluorodiazine
13812-43-6
66.01
−105.8


F2OS
F2SO
Thionyl fluoride
7783-42-8
86.06
−43.8


F3HSi
SiHF3
Trifluorosilane
13465-71-9
86.09
−95.2


F3N
NF3
Nitrogen trifluoride
7783-54-2
71.00
−129.1


F3NO
NOF3
Trifluoramine oxide
13847-65-9
87.00
−87.5


F3NS
NSF3
thiazyl trifluoride
15930-75-3
103.07
−27.1


F3P
PF3
Phosphorus trifluoride
7783-55-3
87.97
−101.5


F4Ge
GeF4
Germanium(IV) fluoride
7783-58-6
148.58
−36.5


F4Si
SiF4
Tetrafuorosilane
7783-61-1
104.08
−86.0


F5P
PF5
Phosphorus pentafluoride
7647-19-0
125.97
−84.5


F6Se
SeF6
Selenium hexafluoride
7783-79-1
192.95
−46.5


F6Te
TeF6
Tellurium hexafluoride
7783-80-4
241.59
−38.8


FH3Si
SiH3F
fluorosilane
13537-33-2
50.11
−98.0


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
10034-85-2
127.91
−35.6


Kr
Kr
Krypton
7439-90-9
83.80
−153.4


N2
N2
Nitrogen
7727-37-9
28.01
−195.8


N2O
NNO
dinitrogen oxide
10024-97-2
44.01
−88.5


Ne
Ne
Neon
7440-01-9
20.18
−246.1


NO
NO
Nitrogen oxide
10102-43-9
30.01
−151.8


Xe
Xe
Xenon
7440-63-3
131.29
−108.1









The preferred dielectric compounds are selected from the group consisting of those set forth in Table 2 below:












TABLE 2





Dielectric




MY


Compound
Structure
Name
CAS
MW
BP(° C.)




















Ar
Ar
Argon
7440-37-1
39.95
−185.9


BF3
BF3
Trifluoroborane
7637-07-2
67.81
−101.2


BrH
HBr
Hydrogen bromide
10035-10-6
80.91
−66.7


C2BrF5
CF3CF2Br
Bromopentafluoroethane
354-55-2
198.92
−21.0


C2ClF3
CFCl═CF2
Chlorotrifluoroethene
79-38-9
116.47
−28.4


C2F3N
CF3CN
Trifluoroacetonitrile
353-85-5
95.02
−68.8


C2F3NO
(CF3)NCO
trifluoromethyl isocyanate
460-49-1
111.02
−36.0











C2F4S
CF3C(S)F
trifluoromethyl thiocarbonyl fluoride
132.08
−21.0




Trifluormethylthiocarbonylfluorid (germ.)












C2F5NO
CF3CF2NO
pentafluoro-nitroso-
354-72-3
149.02
−45.7




ethane//Pentafluor-nitroso-




aethan


C2F5NO
CF3C(O)NF2
(trifluoromethyl-carbonyl)-
32822-49-4
149.02
−21.1




difluoro-amine


C2F6
CF3CF3
Hexafluoroethane
76-16-4
138.01
−78.2


C2F6NO
CF3N(O)CF3
Bis-trifluormethyl-nitroxid
2154-71-4
168.02
−20.0


C2F6O
CF3OCF3
bis-trifluoromethyl ether
1479-49-8
154.01
−59.0


C2F6Te
(CF3)2Te
bis(trifluoromethyl)tellurium
55642-42-7
265.61
−98.0


C2F6Te2
CF3TeTeCF3
bis(trifluoromethyl)
1718-20-3
393.21
−53.0




ditelluride


C2F7N
CF3CF2NF2
N,N-Difluor-
354-80-3
171.02
−38.0




pentafluoraethylamin




(germ.)


C2F7N
(CF3)2NF
N-Fluor-bis(trifluormethyl)-
359-62-6
171.02
−37.0




amin (germ.)


C2F7NO
CF3NFOCF3
N-Fluor-N-trifluormethoxy-
4217-92-9
187.02
−25.0




perfluormethylamin (germ.)


C2FNO
FC(O)CN
fluoroformyl cyanide
683-55-6
73.03
−21.0


C2H2ClF
CH2CFCl
1-chloro-1-fluoro-ethene//1-
2317-91-1
80.49
−25.5




Chlor-1-fluor-aethen//1-




chloro-1-fluoroethylene


C2H2F2
CF2═CH2
1,1-Difluoroethene
75-38-7
64.03
−85.7


C2H2F2
CHF═CHF
#trans!-1,2-difluoro-
1630-78-0
64.03
−53.1




ethene//#trans!-vinylene




difluoride//(E)-1,2-




difluoroethylene//(E)-1,2-




difluoro-ethene//#trans!-




vinylene fluoride


C2H2F2
FHC═CHF
1,2-difluoro-ethene//#cis!-
1691-13-0
64.03
−28.0




vinylene difluoride//1,2-




Difluor-aethen//vinylene




fluoride


C2H2F2
CHF═CHF
#cis!-1,2-difluoro-
1630-77-9
64.03
−26.0




ethene//#cis!-vinylene




difluoride//(Z)-1,2-




difluoroethylene//(Z)-1,2-




difluoro-ethene//#cis!-




vinylene fluoride


C2H2F4
CF3CH2F
1,1,1,2-Tetrafluoroethane
811-97-2
102.03
−26.1


C2H2F4
CF2HCF2H
1,1,2,2-Tetrafluoroethane
359-35-3
102.03
−23.0


C2H3F
CH2═CHF
Fluoroethene
75-02-5
46.04
−72.2


C2H3F3
CF3CH3
1,1,1-Trifluoroethane
420-46-2
84.04
−47.3


C2H3F3O
F3COCH3
Ether, methyl
421-14-7
100.04
−24.0




trifluoromethyl


C2H4
H2CCH2
Ethene
74-85-1
28.05
−103.7


C2H4F2
CHF2CH3
1,1-Difluoroethane
75-37-6
66.05
−24.0


C2H5F
CH3CH2F
Fluoroethane
353-36-6
48.06
−37.7


C2H6
CH3CH3
Ethane
74-84-0
30.07
−88.6


C2H6BF
(CH3)2BF
fluoro-dimethyl-borane
353-46-8
59.88
−44.0


C2H6F4OSi2
CH3SiF2OSiF2CH3
Disiloxane, 1,1,3,3-
63089-45-2
178.23
−39.0




tetrafluoro-1,3-dimethyl-


C2HF3
CF2═CFH
Trifluoroethene
359-11-5
82.02
−51.0


C2HF3O
CF3C(O)H
trifluoroacetaldehyde//Trifluor-
75-90-1
98.02
−21.0




acetaldehyd


C2HF5
CF3CF2H
Pentafluoroethane
354-33-6
120.02
−48.1


C2HF5O
CF3OCHF2
Difluoromethyl
3822-68-2
136.02
−35.3




trifluoromethyl ether


C3BiF9
Bi(CF3)3
Tris(trifluoromethyl)bismuth
5863-80-9
416.00
−55.0


C3F4
F2C═C═CF2
tetrafluoropropadiene//tetrafluoro-
461-68-7
112.03
−38.0




allene//1,1,3,3-




tetrafluoro-1,2-propadiene


C3F4
═CFCF2CF═
tetrafluorocyclopropene
19721-29-0
112.03
−20.0


C3F5IO
CF3CF2C(O)I
Perfluoropropionyliodid
137741-03-8
273.93
−27.0


C3F5N
C2F5CN
pentafluoropropionitrile//
422-04-8
145.03
−35.0




pentafluoropropiononitrile


C3F6
cyclo
hexafluorocyclopropane//
931-91-9
150.02
−33.0



—CF2CF2CF2—
Hexafluorcyclopropan//




freon-#C!216


C3F6
CF3CF═CF2
Hexafluoropropylene
116-15-4
150.02
−29.6


C3F6O2
cyclo-CF2—O—CF2—CF2—O—
hexafluoro-[1,3]dioxolane
21297-65-4
182.02
−22.1


C3F8
CF3CF2CF3
Octafluoropropane
76-19-7
188.02
−36.7


C3F8O
CF3CF2OCF3
Perfluormethylethylether
665-16-7
204.02
−20.0


C3H2F2
F2CCCH2
1,1-difluoro-
430-64-8
76.05
−21.0




propadiene//allenylidene




difluoride//1,1-difluoro-




allene


C3H2F4
H2CCFCF3
2,3,3,3-tetrafluoro-
754-12-1
114.04
−28.3




propene//HFO-1234yf


C3H2F4
CHF═CHCF3
trans HFO-1234ze

114.04
−19.0


C3H3F3
CH2═CHCF3
3,3,3-Trifluoropropene
677-21-4
96.05
−25.0


C3H4
c-(CH═CH—CH2)
cyclopropene
2781-85-3
40.06
−36.0


C3H4
H2CCCH2
Allene
463-49-0
40.06
−34.5


C3H4F2
CH3CH═CF2
1,1-difluoropropene//
430-63-7
78.06
−29.0




propenylidene




difluoride//1,1-Difluorpropen


C3H4O

methylketene
6004-44-0
56.06
−23.0


C3H5F
CH2CFCH3
2-fluoropropene
1184-60-7
60.07
−24.0


C3H6
CH2CHCH3
1-Propene
115-07-1
42.08
−47.7


C3H7NO2

DL-2-aminopropanoic acid
302-72-7
89.09
−50.2


C3HF3
F3CCCH
3,3,3-trifluoro-
661-54-1
94.04
−48.0




propyne//3,3,3-Trifluor-




propin//trifluoromethyl-




ethyne//3,3,3-trifluoro-1-




propyne


C3HF5
CF3CH═CF2
1,1,3,3,3-pentafluoro-
690-27-7
132.03
−21.0




propene//1,1,3,3,3-




Pentafluor-propen


C3HF5
CF3—CF—CFH
1,2,3,3,3-pentafluoro-
2252-83-7
132.03
−20.0




propene


C4F6
CF3CCCF3
1,1,1,4,4,4-hexafluoro-2-
692-50-2
162.03
−24.6




butyne


C4H2F4O2
CF2HC(O)C
1,1,4,4-tetrafluoro-butane-

158.05
−81.0



(O)CF2H
2,3-dione


C4H6N2O2



114.10
−33.0


CClF3O
F3C—O—Cl
Trifluormethylhypochlorit
22082-78-6
120.46
−47.0


CClF3O
ClF2C—OF
Chlor-difluor-methyl-
20614-17-9
120.46
−25.0




hypofluorit


CClF4N
CF3NFCl
N-Chlor-N-fluor-
13880-72-3
137.46
−32.8




trifluormethylamin (germ.)


CClF4N
ClCF2—NF2
Chlordifluordifluoraminomethan
13880-71-2
137.46
−28.0


CF2S
F2C═S
thiocarbonyl difluoride
420-32-6
82.07
−46.0




Thiocarbonyldifluorid




(germ.)


CF2Se
F2C═Se
selenocarbonyl difluoride
54393-39-4
128.97
−28.0


CF3I
CF3I
Trifluoroiodomethane
2314-97-8
195.91
−21.8


CF3N
CF2—N—F
N-Fluor-difluormethanimin
338-66-9
83.01
−101.0




(germ.)


CF3NO
CF3N═O
trifluoro-nitroso-
334-99-6
99.01
−86.0




methane//Trifluor-nitroso-




methan


CF3NO
FC(O)NF2
difluoro-carbamoyl fluoride
2368-32-3
99.01
−52.0


CF3NO2
CF3NO2
trifluoro-nitro-
335-02-4
115.01
−33.6




methane//Trifluor-nitro-




methan//fluoropicrin


CF4
CF4
Tetrafluoromethane
75-73-0
88.00
−128.1


CF4N2
NF2CF═NF
Tetrafluorformamidin
14362-70-0
116.02
−30.0




(germ.)


CF4N2O
(NF2)2CO
tetrafluorourea
10256-92-5
132.02
−20.0










CF4O
hypofluorous acid trifluoromethyl
104.00
−95.0



ester//Hypofluorigsaeure-



trifluormethylester//trifluoromethylhypofluorite












CF4O2S
CF3SO2F
trifluoromethanesulfonyl
335-05-7
152.07
−21.7




fluoride


CF5N
CF3NF2
N,N-Difluor-
335-01-3
121.01
−75.0




trifluormethylamin (germ.)


CF5NO
CF3ONF2
Trifluormethyloxydifluoramin
4217-93-0
137.01
−59.8


CF5NO2
F2NOCF2OF
(Difluoraminoxy)difluormethyl-
36781-60-9
153.01
−29.0




hypofluorit


CF5NS
SF5CN
sulfurcyanide pentafluoride
1512-13-6
153.08
−25.0




Schwefelcyanid-




pentafluorid (germ.)


CF5P
CF3PF2
difluoro-trifluoromethyl-
1112-04-5
137.98
−43.0




phosphine


CF6N2
F2NCF2NF2
Hexafluormethandiamin
4394-93-8
154.01
−37.0


CF6Si
CF3SiF3
perfluoro methyl silane
335-06-8
154.09
−42.0




Perfluormethylsilan (germ.)


CF7P
CF3PF4
Trifluormethyl-
1184-81-2
175.97
−35.0




tetrafluorphosphoran




(germ.)


CH2F2
CH2F2
Difluoromethane
75-10-5
52.02
−51.7


CH2FI
CH2FI
Fluoroiodomethane
373-53-5
159.93
−53.8


CH3F

fluoromethane//methyl
593-53-3
34.03
−78.3




fluoride//Fluormethan//




freon-41


CH3F3Si
CF3SiH3
trifluoromethyl-silane′′
10112-11-5
100.12
−38.3




CF3SiH3


CH3F3Si
CH3SiF3
methyltrifluorosilane
373-74-0
100.12
−30.0


CH4F2Si
F2HSiCH3
difluoro-methyl-silane
420-34-8
82.12
−35.6


CH5FSi
CH3SiH2F
fluoro-methyl-silane
753-44-6
64.13
−44.0


CH6Ge
H3GeCH3
methylgermane
1449-65-6
90.65
−23.0


CHF2N
F2C═NH
Difluorformimin
2712-98-3
65.02
−22.0


CHF3
CHF3
Trifluoromethane
75-46-7
70.01
−82.1


CHF3S
CF3SH
trifluoromethane thiol
1493-15-8
102.08
−36.7




Trifluormethanthiol (germ.)


CHF4N
CF2H—NF2
N,N,1,1-
24708-53-0
103.02
−43.0




Tetrafluormethylamin


Cl2F2Si
SiF2Cl2
difluoro dichlorosilane
18356-71-3
136.99
−31.8




Difluordichlorsilan (germ.)


ClF2HSi
SiF2HCl
difluoro chlorosilane
80003-43-6
102.56
−50.0




Difluorchlorsilan (germ.)


ClF2P
PF2Cl
Phosphorus chloride
14335-40-1
104.42
−47.3




difluoride


ClF3Si
SiClF3
Chlorotrifluorosilane
14049-36-6
120.53
−70.2


ClH
HCl
Hydrogen chloride
7647-01-0
36.46
−85.0


ClH3Si
SiH3Cl
Chlorosilane
13465-78-6
66.56
−30.3


CO
CO
Carbon monoxide
630-08-0
28.01
−191.5


CO2
CO2
Carbon dioxide
124-38-9
44.01
−78.4


COS
OCS
Carbonyl sulfide
463-58-1
60.07
−50.3


F2HN
NHF2
Difluoramine
10405-27-3
53.01
−23.2


F2N2
FNNF
trans-Difluorodiazine
13776-62-0
66.01
−111.5


F2N2
FNNF
cis-Difluorodiazine
13812-43-6
66.01
−105.8


F2OS
F2SO
Thionyl fluoride
7783-42-8
86.06
−43.8


F3HSi
SiHF3
Trifluorosilane
13465-71-9
86.09
−95.2


F3N
NF3
Nitrogen trifluoride
7783-54-2
71.00
−129.1


F3NO
NOF3
Trifluoramine oxide
13847-65-9
87.00
−87.5


F3NS
NSF3
thiazyl trifluoride
15930-75-3
103.07
−27.1


F3P
PF3
Phosphorus trifluoride
7783-55-3
87.97
−101.5


F4Ge
GeF4
Germanium(IV) fluoride
7783-58-6
148.58
−36.5


F4Si
SiF4
Tetrafuorosilane
7783-61-1
104.08
−86.0


F5P
PF5
Phosphorus pentafluoride
7647-19-0
125.97
−84.5


F6Se
SeF6
Selenium hexafluoride
7783-79-1
192.95
−46.5


F6Te
TeF6
Tellurium hexafluoride
7783-80-4
241.59
−38.8


FH3Si
SiH3F
fluorosilane
13537-33-2
50.11
−98.0


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
10034-85-2
127.91
−35.6


Kr
Kr
Krypton
7439-90-9
83.80
−153.4


N2
N2
Nitrogen
7727-37-9
28.01
−195.8


N2O
NON
Nitrous oxide
10024-97-2
44.01
−88.5


Ne
Ne
Neon
7440-01-9
20.18
−246.1


NO
NO
Nitrogen oxide
10102-43-9
30.01
−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, CO2 or N2O.
Particularly preferred non-electrical properties for dielectric gases according to the present disclosure, include:

    
    
        Non-liquefying, e.g., Tboil less than −20° C.
        Chemically stable—decomposition temperature must be higher than hot spot temperature in equipment, e.g., Tdec=200° C., and gas should not decompose in partial discharge spark (approximately 1000° K)
        Low environmental impact, i.e., little to no destruction of ozone layer ODP=0; and low global warming impact GWP less than SF6 
        Acceptably low toxicity of gas and discharge byproducts
    
    


Electrical equipment property requirements for dielectric gases according to the present disclosure, include:

    
    
        Insulation specific criteria include a critical field of Ecr, and no conducting decomposition products should be generated by discharge
        Switching specific criteria include high critical field of Ecr, arcing stability, i.e., a gas must recombine to original molecular structure after being decomposed in switching arc (Gibbs free energy of reaction is<0)
        Specific thermal interruption performance, i.e., must be able to interrupt current flow at ac current zero
        Arc erosion product from equipment and gas must not form conduction deposits
        Low velocity of sound
    
    


EXAMPLE 1
Measurements of the dielectric strength of potential alternatives were determined using ASTM D2477 or obtained from literature. These measurements were performed at 1 atmosphere pressure across a 0.1 inch gap and at ambient temperature.
In the intended applications, the gas will not be at 1 atmosphere pressure but at a higher pressure. In this example 5 atmospheres pressure is used as a maximum pressure. If the gas liquefies at a lower pressure than that pressure was used. These gases have higher dielectric strengths and break down voltages than air. Using 5 atmospheres (73.5 psia) pressure as the upper pressure (rating of the equipment).
















Breakdown voltage at



Dielectric strength
Pressure
maximum pressure


Gas
kV/0.1 inch gap
(psia)
(kV/0.1 inch gap)


















Air
4.75
73.5
23.75


R143a
5.8
73.5
29


R152a
5.9
73.5
29.5


R125
6.4
73.5
32


R134a
6.6
73.5
33


R22
7.2
73.5
39.9


R124
10.4
55.5
39.3


SF6
14.0
73.5
70


C318
16.0
45.3
49.3


R115
16.0
73.6
80


R114
17.0
31.1
36









EXAMPLE 2
The dielectric strength of additional gases is measure at 1 atmosphere and at the maximum system pressure. Their breakdown voltages are found to be greater then air, which allows smaller gaps and therefore smaller equipment then would be need if air was used. Here the measurements were performed on CTFE (Chlorotrifluoroethylene), HCl (hydrogen chloride) and SiF4 (silicon tetrafluoride).
Having described the invention in detail by reference to the preferred embodiments and specific examples thereof, it will be apparent that modifications and variations are possible without departing from the spirit and scope of the disclosure and claims.

## Claims

1. An insulation gas in electrical equipment, the insulation gas consisting of phosphorous pentafluoride and at least one gas selected from the group consisting of nitrogen, CO2, and N2O.

2. The insulation-gas according to claim 1, wherein said electrical equipment is selected from the group consisting of current-interruption equipment, gas-insulated transmission lines, gas-insulated transformers, and gas-insulated substations.