US2939778A - Liquid explosive - Google Patents

Description

June 7, 1960 i c. MeKINLEY 2,939,778

LIQUID ExPLosIvE Filed June 21, 1956 5 Sheets-Sheet 1 llll :Iii

lllI

hill' ii" Mau/0012+611@ INVENTOR CL YDE @KM/LEY June 7, 1960 Filed June 2l. 1956 c. McKlNLEY 2,939,778

LIQUID EXPLOSIVE 5 Sheets-Sheet 3 SOLI D LIQUID EQUILIBRIA PROPANE' OXYGEN MOLE. PERCENT OXYGEN IN PROPANE-OXYGEN INVENTOR GLYDE M6 /NLEY ATTORNEY TEMPERATURE F June 7, 1960 c. MoKlNLEY f LIQUID EXPLOSIVE Filed June 21, 1956 OXYGEN METHANE SYSTEM \OLE. FRACTION OF METHANE 5 Sheets-Sheet 4 IN VENTOR GLYDE' Nek/NLE Y ATTORNEY 5 Sheets-Sheet 5 C. MC KIN LEY LIQUID EXPLOSIVE OXYGEN ETHANE SYSTEM MQLE. FRACTION OF ETHANE June 7, i960 Filed June 21, 195e -lao LIQUID EXPLOSIVE Clyde McKinley, Allentown, Pa., assigner to Air Products Incorporated, a corporation of Michigan Filed June 21, 1956, Ser. No. 592,800

29 Claims. (Cl. 52=1) This invention relates to explosives and more particularly to an explosive solution comprising fuel material dissolved in liquid oxygen. The invention further relates to the preparation, storage, and handling of such solutions, and to a method of producing Van explosion.

Users of oxygen and others familiar with the art have long looked upon fuel-oxygen mixtures as being extremely hazardous and to be avoided wherever possible. This teaching of the art is understandable in view of numerous violentexplosions experienced by those Working in the art over the years, and to minimize the danger of explosion in instances where intimate contact between oxygen and a readily oxidizable fuel material is likely, elaborate safety precautions have been practiced. However, such safety precautions, generally speaking, have been-limited to excluding oxygen from contact with a fuel material, or carefully controlling the oxygen concentration and the temperature of the fuel-oxygen mixture, or by limiting the quantity of fuel-oxygen mixture which is available at any given moment. For example, hydrocarbon lubricants are not employed as lubricants for compressors, valves, regulating` devices, etc. handling oxygen gas, and thus, by excluding such fuel material from intimate contact with the oxygen, explosions may be prevented. In chemical processes wherein oxygen is anoxidantand the nature of the material to be oxidized is such that there is likelihood of an explosion, the concentration-of oxygen and the temperature of the reactionl mixture is carefully maintained within narrow limits' in an effort to control the rate of reaction and thus prevent an explosion. Similarly, in certain other industrial applications,suchl as Oxy-acetylene welding, the oxyge'n and acetylene are stored in separate cylinders and each gas is fed from its storage cylinder throughasepar'ate line to the welding torch where the two gases are, mixed at the time of burning. The foregoing is illustrative of teachings presently .available in the art. .Itis apparent ithas always. been' assumed that the hazards linvolved when oxygen.' is brought into intimate contact with a fuel material are prohibitive, and n o teaching has been available here` tofore as to how such hazards could be overcome, especially with large quantities .of fuel-oxygen mixture and where the concentration of readily oxidizable fuel material in oxygenis relatively high. In fact, the art has never regarded the physical state of the fuel-oxygen mixture as 4important in reducing the hazard involved, 7or that fuel-oxygen mixtures could be prepared, stored and used in comparative safety.

VThe present invention resides in the. discovery that solutions of fuel in liquid oxygen constitute a new and improved form of explosive which can be prepared, storedand used in relative safety under certain controlled conditions. More specically, the present invention resides in the discovery that solutions of methane (or methane with small proportions of heavier normally gaseous hydrocarbons) in liquid oxygen constitute a new and improved form of explosive which can-be prepared,

. stored and used in relative safety under certain controlled conditions.

lt is a principal object of the present invention to pro-` vide a novel explosive comprising a solution of fuel material dissolved in liquid oxygen.v

lt is a further object of the present invention to provide a novel method for the preparation, handling and storage of solutions containing a fuel material dissolved in liquid oxygen.

It is still a further object of the present invention to provide an improved package containing a solution of fue material dissolved in liquid oxygen. f'

It is still a further object of the present invention to wherein an explosive chargecomprising a solution of fuel material dissolved in liquid oxygen is exploded.

Still other objects of the present invention and the advantages thereof will become apparent to those skilledin the art by reference to the following detailed description and the drawings, in which:

Fig. l is a diagrammatic sectional view taken through a package containing fuel material dissolved in liquid oxygen with means for refrigerating the solution;

Fig. 2 Iis a diagrammatic sectional view taken through a package comprising a receptacle provided with two compartments, wherein one compartment contains liquidoxygen and the other compartment contains fuel material; Fig. 3 diagrammatically illustrates one method of preparing, handling and storing a solution containing fuel material dissolved in liquid oxygen;

Figs. A, 5 and 6 are graphs illustrating solid-liqui equilibria for methane-oxygen, ethane-oxygen, and propane-oxygen systems, respectively; l.

Fig. 7 is a graph illustrating bubble point curves at' 14.7, 50, and 200 p.s.i.a. pressures for the oxygen- With partial pressure curves at 0.79, 2.7, 5.4 and 10.8 p.s.i. pressures for methane; and

Fig. 8 is a graph illustrating bubble point curves at 14.7, 50, 100 and 200 p.s.i.a. pressures for the oxygenethane system plotted against temperature, together with partial pressure curves at 0.60 and 2.05 p.s.i. pressures for ethane.

In accordance with one feature of the present invention, a new and improved explosive is provided bydssolving a suitable fuel material in liquid oxygen in'l quantities sutlicient to provide a solution which is -explosive but not in quantities sufficient to precipitate from the resultant solution a solid phase or second immiscible liquid phase comprising fuel material.

The term explosive is used herein in the generic sense, and is intended to include propellants and disrup-l tives. Explosives of the invention characterized by a higher and more violent release of energy may be obtained by exploding a body of the solution after adjusting the fuel content of the solution to about stoichiometric proportions, while explosives characterized by a lower and less violent release of energy may be obtained by exploding a body of the solution after adjusting either the fuel or oxygen to a proportion lower than that required for a stoichiometric solution. The release of energy-in the use of the explosive of the present invention can be controlled by a different method, covered by copending application Serial No. 592,748, having the same filing date as the present application.- Thus, the solutions .de-v

scribed herein are explosives which may have characteristics varying over a wide range depending upon the concentration of fuel in the solution and the method of use.

The chemical nature of suitable fuel materials useful for the purpose of the present invention may vary widely provided the particularV fuel material selected vis suf* Patented Junev 7, 19,60

ficiently `soluble in liquid oxygen under the controlled conditions to produce an explosive solution, and otherwise capable of being dissolved in liquid oxygen without appreciable hazard under the conditions taught herein. However, in accordance. with the present invention, methane is the preferred fuel material and as such stands in a class by itself because of a combination of factors:V

is about 75 mol percent, the. solubility o-fethane in iiquid oxygen is about mol percent and the solubility of propane .in .liquid oxygen (not shown) is about 5 mol percent. Thus While methane. is the preferred fuel ma-V terial, .it is apparent that a mixture of methane, ethane and propane maybe used. Natural gas, which is made up largely of methane together .with small percentages ofethane and inconsequential amounts of higher saturated open chain hydrocarbons is anY excellent fuel .material for purposes of this invention. v y Y Essentially pure liquid oxygen .may be advantageous in some applications where a solution providing a maximum amount'of available power per unit Weight is desired. However, small amounts of nitrogen and inert gases which may be .present in commercial liquid oxygen are not detrimental for the purposes of the present invention other than in possibly lowering the reaction rate slightly, or in necessarily requiring a greater weight of the impure liquid oxygen, and thus the resultant solution, to provide an equal'amount of explosive energy. f

- AThe present invention Vwill be described hereinafter it being understood, as mentioned above, that other suitmable when methane is present in concentrations varyis 4.1 mol percent, while the upper. limit is 50.5 mol pery cent.

With an increase in pressure, the lower inaminability limit in each instance is lowered only slightly, while the upper limit iny each instance is raised somewhat.

i By maintaining the composition of the methane-oxygen vapor' phase above the'solution at aconcentration of l methane which is noninflammable, the likelihood of exkplosion in the highly sensitive vapor phase `willbe greatly As pointed outV reduced or may even be eliminated. 1 above, an -nnobvious feature of thel present invention .is the lack of sensitivity of the solution of methane in. liquid oxygen.--Thus-uiider'pi'oper vapor phase conditions, or

no vapor phase, the .solution may be rendered safe.

In accordance with the present invention, the .concentration of methane in the `vapor phase may be controlledV by agnumber of ',rri'ethods.Y One such method comprises maintainingfthe concentration of methane `in liquid oxygen atsuch a level and the temperature of the resultant solution Ylow venough so as to prov-ide'a/noninammable iriixturev of vapor in equilibrium with the solution.Y For example, applicant has found that a solution containing stoichiometric quantities of methane,V iLe., about 33 mol percent methane, has noninflammable vapor in equilibrium with the soli'it-icinV at temperatures up to about 4291.5 'F., and byrefrigerating Ythe solution so :as tomaintai-n it Ybelow. this temperaturepthe vaporv phase may be rendered safe;V However, referring to Fig. 4 of the drawingsyitmay be seen that solid methane will begin to precipitate from Yavsolution containing 33 mol lpercent able fuels or mixtures of other suitable fuels with methane may be used.

, It is generally desirable from the standpoint of safety A to prepare solutions of methane in liquid oxygen in such v.afmanner that a solid phase or methane ice is not precipitated. ,Y Thus in preparing the solutions of the invention, the liquid oxygen and the methane preferably should bep-,brought together in such .proportions that a homogeneous liquid mixture or solution coiisisting'of a single liquid .phase is maintained at all times and without a solid precipitate and/or a second immiscible liquid phase com-` prising methane being present therein. Otherwise, the hazard involved .in preparing the solutions of the invention may be-increased appreciabl'y. However, it may `be stated that this is notralways essential and in s ome in- 1 'stances the solution may temporarily contain a precipitate and/or a second immiscible liquid phase during preparation which is later dissolved. Y

When the solution .is held at a temperature Vbelow its boiling point, the vapor pressure of the solution will be less than atmospheric pressure and for this reason it may Y tainer, as well as maintaining the vapor phase above the solution noninflammableli v Y .It is part of the present invention, from thestandpoint of reducing the hazardinvolved in preparing, handling and storing the solutions described herein, to maintain the 'composition of the vapor phase above'the solution i noninammable. Mixtures of methane and oxygen in thevapor phase and at atmospheric pressure 'are'inflammet'haneat about r348 lF.,.and it follows that .the temperature/of this solution should Apreferably be -main' tated` methane ice and with Ya noninammable vapor phase. inasmuch as the vapor pressures of both :oxygen and methane are well known at varying-temperatures, as Y well as the manner -of calculating the mol percent com position ofavapor phase in equilibrium with a solution of known mol percent composition, it follows that'one skilled 'in the art `may readily Vdetermine the upper -teni perature'limit which anyv given solution of -known com- -positionfmay not exceed in order :to 'provide a -noninammable fvapor'lphase in equilibrium with the solution.

Likewise, one skilledY in the art, by reference to Fig. 4, .may readily deterrninerthe llower temperature limit, ie',

provided the solution contains v11o-more than about .-70 Y m'ol percent methane, is liquid `nitrogen under atmosphericpressure'.. v

Another Amethod Yof'rendering the vapor phase lnoni'nflammab'l'e, even thoughV the `concentration `of `methane and the temperature of the solution is such'tha't normally the 'vapor phasev in equilibrium vwith thesolution would be inflammable, Vis by supplying :a gaseousY diluent Yto theno'rmally inflammable vapor phase. The gaseous diluent is suppliedY ltothe vvapor' phase inquantities s'uicient to provide arnoninammable vapor phase,l and preferably vin .such a rnanneras to''ow at least a portion of the diluent along .the surface. of the Vsolution'for the purpose .of preventing the temporary formation of 'a tained in a range above about -348 F. and below about Y '-291.5" F. `so as to provicle'aV solution freeV of precpiv localized inammable mixture of vapors near the surface of the solution. The term gaseous diluent as usedin the speciiication and claims is intended to include gaseous materials or mixtures, including oxygen, which are at least no more reactive with methane under the conditions employed herein than is oxygen. The particular gaseous diluent employed may be any suitable gaseous substance which will render the vapor mixture noninammable by reason of its inert properties under the conditions employed, such as nitrogen, or it may be a gas which simply dilutes the vapor mixture to such a level as to give a noninilammable mixture, such as where suiicient air or oxygen is supplied to yield a nonintlammable mixture. The source of gaseous diluent may be auxiliary in nature, that is supplied from a source outside the solution, or it may be supplied from the solution itself, as in instances where a relativelyrsmall mol fraction of methane is dissolved in a relatively large mol fraction of liquid oxygen with the resultant vapor composition being suiciently high in oxygen and low in methane as to be rendered noninammable. A third material such as nitrogen may be present in the solution for this purpose, as well as for the purpose of rendering the solution less sensitive.

Still another method of rendering the vapor phase noninilammable is by providing a iloating iilm or follower for the surface of the solution, thereby preventing or at least greatly reducing vaporization. This may be accomplished by a number of methods, such as by providing a thin plastic sheet in contact with the entire surface of the solution, or by covering the surface of the solution with a layer of minute plastic bubbles of a type commercially available for such purpose. Of course a rigid impervious structure, where practical will accomplish the desired result. The terms follower and oating follower where they appear in this specification and claims are intended to mean a thin plastic sheet, or a coating of minute plastic bubbles, rigid structure, or equivalent, as above described. The vapor pressure apparently exhibited by the solution may be lowered by the foregoing procedure and the term eiective vapor pressure of the solution where it appears in this specification and claims is intended to mean the vapor pressure of a solution after being lowered in this or similar manner, or the normal vapor pressure of a solution not provided with a follower or oating follower.

It is obvious that a combination of two-or more of the above described methods for rendering the vapor phase of the solution noninilammable may be of advantage in many instances. substituted along the lines of other well known methods.

'Ihe concentration of methane in liquid oxygen may vary over wide ranges. For example, the lower limit may be generally stated as that concentration of methane in liquid oxygen yielding a resultant solution which is explosive, while the upper limit is somewhat dependent upon the temperature of the solution and may be determined by reference to Fig. 4, but in any event the concentration is not sutliciently high as to cause a solid precipitate comprising methane to 'be formed therein. For example, at 320 F., the composition of the resultant solution may Vary between about 5 mol percent methane and about 75 percent methane. A solution containing about stoichiometric quantities of methane will provide an explosive having a maximum amount of energy available per unit weight of solution. 'Solutions containing a concentration of either oxygen or methane in excess of stoichiometric proportions will provide a solutionhaving less energy available per unit weight of solution. Thus the properties of the explosive may be varied somewhat by varying the concentration of methane, with the explosive being most violent at about stoichiometric proportions and decreasing in violence when either the methane or oxygen is present in excess of stoichiometric proportions. Generally, solutions con- Likewise, equivalents may he taining between 5 'mol percent methane and 50 mol 'per cent methane are desirable explosives. Solutions containing less than 5 mol percent methane do not usually have sufficient power, while there appears to be no economic advantage as an explosive in going above mol percent. For most applications, such as in mining operations, solutions containing between 25 and 50 mol percent methane give best results. In instances where` a maximum amount of power per unit weight of solution is desired, a solution containing about stoichiometric quantities of methane, i.e., about 33 mol percent, is preferred. Fig. 1 diagrammatically illustrates one suitable arrangement for storing or packaging the solutions of the present invention. The receptacle 1 is provided with an inlet 4 covered by a loosely tting cap 3 and contains a solution 2 of methane in liquid oxygen. The receptacle lis immersed in liquid nitrogen refrigerant 5, which lls insulated container 6 to a'desired level. While the refrigerant is speciiically shown as liquid nitrogen under atmospheric pressure, the liquid nitrogen may be evaporated under vacuum if additional cold is desired, or other suitable liqueed gas refrigerants may be used. Means for controlling the composition of the vapor phase above solution 2, such as the various means previously discussed herein or as diagrammatically illustrated in Fig. 3, may be included if desired.

Fig. 2 diagrammatically illustrates one suitable arrangement for packaging fuel and liquid oxygen wherebythe solutions described herein may be prepared, stored, and used in safety. The insulated receptacle 7 is provided with a frangible partition 8 dividing receptacle 7 into an upper compartment 9 and a lower compartment 10. Upper compartment 9 is provided with an inlet 11 for filling compartment 9 with the liquid oxygen 12.

' A rigid tube 14 extends into compartment 9 of receptacle 7 through a ilanged opening 15 which receivestube 14 in relatively movable relation. Tube 14 extends downwardly into compartment 10 through opening 16 in partition 8 thereby allowing compartment 10 to be filled with the liquid methane 17. Loosely iitting caps 18 and 19 cover inlet 11 and the outer end of tube/14, respectively. The frangible partition 8 is rigidly attached to tube 14. Tube 14 also extends upwardly and above inlet 11 a considerable distance soas to allow a falling weight or other force to drive tube 14 downwardly a sufficient distance to break frangible partition 8 without crushing receptacle 7.

When using receptacle 7, the lower compartment 10 is tilled with the desired quantity. of liquid methane 17 through tube 14 and cap 19 is snapped into place. Then compartment 9 is filled through inlet 11 with the desired quantity of liquid oxygen 12 and cap 18 snapped into place. The solution of methane in liquid oxygen 'may now be prepared safely by merely dropping a weight onto the upper end of tube 14, or otherwise applying suicient force thereto, to drive tube 14 downwardly a distance suicient to break frangible partition 8 without damaging receptacle 7. Compartment 9 is now in cornmunication with compartment 10 and the liquid oxygen 12, being of a much higher specific gravity than methane, is free to flow downwardly mixing with the liquid methane 17 and thereby forming a solution of methane in liquid oxygen.

Fig. 3 diagrammatically illustrates one very satisfactory arrangement for and method of preparing relatively large quantities of a solution containing methane dis'- solved in liquid oxygen. A first receptacle 20 containing liquid methane 2l is provided with an inlet 22 covered by a loosely fitting cap 23 and an outlet 24 leading into storage tank 25. A second receptacle 26 containing liquid oxygen 27 is provided with an inlet 28 covered by a loosely fitting cap 29 and an outlet 30 leading to storage tank 25. The receptacles 20 and 26 and storage tank 25 are preferably provided with a source of refrigeration (not shown) which may be arranged in the manner shown Vin Fig. 1. The storage tank 25 Vis also provided with an inlet 33 and outlet 34 for supplying g'aseous diluent to the vapor phase 31 above solution 32.

As mentioned above, it is generally desirable to provide refrigeration for receptacles 20 and 26 and storage tank 25. Preferably, liquid methane 21 should be cooled to a temperature only slightly above its freezing Apoint and liquid oxygen 27 to a temperature of about 320 F., or to a somewhat lower temperature if it is .desired to produce solution 32 'at a temperature ofV -320 F.

Liquid oxygen is a satisfactory refrigerant for liquid methane 21, while liquid nitrogen is the preferred'refrigerant for both liquid oxygen 27 and solution S2. The vsolution 32 is preferably Yprepared by adding desired quantities of subeooled liquid methane 21 and'liquid oxygen 27 to storage ltank 2S via outlets 24 and 30 whilesupplying a gaseous diluent, such as nitrogen, to the vapor phase 31 via Ainlet v33 and outlet 34 and kin quantities sufficient 'to' provide a noni'nflamrnable vapor phase.

The solutions described herein provide anrimproved method of producing an explosion. A number of different 'variations are possible in the foregoing method as specifically applied to mining oper-ations. For example,

referring to Fig. 1, -a blasting cap or the like may .be attached to receptacle 1 containing solution 2 and then receptacle 1 is lowered into a hole previouslyV drilled for this purpose. A'suitable packing may then bek applied above receptacle 1 and the. blasting cap is detonated, thereby exploding solution v2. Alternatively, referring now to Fig. 2 a blasting cap or the like may be attached t'o insulated receptacle 7 containing liquid oxygen .12 and liquid methane 17, and the package loweredinto'a hole previously drilled. A weight can be dropped onto tube 14 to break partition 8 thus allowing the contents-to mix 'and form a solution. The package is then ready to explode by means of the blasting cap.` It is also possible to vary the above byflling an insulated receptacle byimeans of a hose or the like with either liquid oxygen or liquid methane, or both, after lowering the vreceptacle provided with an attached blasting cap into the hole. vA

receptacle for the vsolution may not always be necessary. For example, Ain some instances where a dry hole or a dry natural crevice is available, a blasting cap may be lowered to the bottom of the hole or -crevice and 'the solution then added and exploded shortly thereafter.' In instances where it is desired to prepare `a fnumber of the above described explosive charges and over a relatively long .period of time, or under conditions -wherefotherlrefrigerant is not. practical or available, it .may be .desirable 'to use solutions containing as .little las about 5 mol ypercent methane. .Such solutions may be allowed to age for .three hours or more during which time the more -volatile -evaporating oxygen provides Vrefrigeration and the methane content gradually increases to about'l8 rmol'percent or higher. .After a desired period of time, the remainingsolution is exploded in the usual manner.

`Referring .now to Fig. 4 of the drawings which illustrates solid-,liquid equilibria for methane andoxygen mixltures, it may .be seen that a methane-oxygen mixture containing-l mol percent methane and maintained at a temperature below about -363 F. will 'consist oi' solid methane and solid oxygen. Upon warming to a temperature between about -363 F. and -344 F., this-mixture will compriseY solid `methane in equilibrium with liquid methane-oxygen solution, and. at temperatures Y Vabove about 344 F. .and belowits boiling point, the

imum temperature is preferably a temperature below the boiling point of the solution at'the pressure present and may be determined by refereneeto Fig. 7.

`Referring now to Fig, 7 of the drawings, the bubble Vpointeurs/ es 7A, 7B, 7C and 7D at 14.7, 5o, 10o and 200 p.s.i.a. pressures, respectively, for the oxygen-methane system are plotted'against temperature inthe graph. The bubble point curves represent the isobaric equilibrium composition of the liquid mixture and were'obtained by considering the oxygen-methane system an ideal solution. Thus, the bubble point curves representthe teme perature and pressure at which the rst bubble would form in a liquid mixtureof a particular indicated composition as .that mixture is gradually heated to a higher temperature. For example, a methane-0x1 -gen liquid mixture containing 0.40 mol fraction or 40 mol percent of methane and held at a total pressure of 14.7 p;s.i.a.'-would be entirely liquid at temperatures within the range appearing on the graph below about 290 F. and would have the first trace or bubble ofvapor form `at .that temperature. `1t willbe apparent tthat'if this particular Vsystem is held at 14.7 p.s.i.a. and warmed to its boiling point, further evaporation .takes place :in such away that the composition of the system movesfalong the bubble pointV curve 7A to higher 'temperatures and to higher compositions of methane. Since the lower limit of inflammability for'methane-oxygen :gaseous mixtures is 5.4 mol percent methane, the'rnaximum allowable partial pressure of methane for a :noninflamm-able mixture is less than 0.7.9., 2.7, .5.4 .and 1.0.8 psi. for gaseous oxygenmethane mixtures maintained under pressures of 14.7, 50, 1.00 vand .200 p.s.i.a., respectively. 'Thusg the partial pressure curves 7.(a'), Y7(11), 7(6) and 7(a) for'methane represent the lower limit of 'inammability for'the methane-oxygen system when maintained under pressures of 14.7, 50;, 10Q-.and 200 p.s.i.a'., respectively. For example, whenever the methane partial pressure fin the vapor phase yis under 0.79 p.s.i. vwith a total vpressure of l4i7 or above on'the system, 'the vapor phase mixture is below the lower inflammability limit. Similarly, any points under methanepartial pressures of 2.7, 5.4 and 10.8 p.s:i. and at or above total 'pressures of 50, 100 and 200'p.s.i.a.; respectively, are below lthe lower inammability limits. Thus, the.conditions required .for a noninliammable vapor in equilibrium with the' vliquid methane-oxygen .solution of'desired composition may berea'clily determined from the foregoing.

Referring Ynow vto Fig. 5 of 'the.drawings,. which illustrates solid-liquid equilibria for ethane and oxygen mixtures, it may lbesee'n that an ethane-.oxygen lmixture containing 40 ,mol 4percent ethane and maintainedlat a .temperature .below about --363 F.. will .consist of lsolid ethane and solid oxygen. Upon warming, this mixture will vcomprise solid 'ethaner in equilibrium with :liquid ethan'e-oxygen solution at temperatures between, `about --36? F. and -308 F.; liquid ethane rich ethane-oxygen solution in equilibrium withoxygen rich liquid ethaneoxygen `solution Sat ytemperatures between about 308 F. and -2985 F.; and a 'homogeneous Vliquid mixture .or solution of ethane inoxygen which is free of a second liquid phase or .solid precipitate comprising yethane at temperatures Labove about @298 F. and below the boiling' point vof the solution. Thus, Yit is, apparent that the minimum temperature at 'which an ethane-oxygen fs'olution of the vinvention v.having a desired .ethanecontent is ,maintained will be iin .the .area Vabove lineV `5A 'of the graph of `lrig. 5. The imaximunr temperature Vis'preferably a-temperature below the 4,boiling point of theisolution Y Iat the pressure employed andmay be determined by referencetoFig.

Referring now yto AFig. 8 of the-drawings, the bubble point curves-8A, 8B, 8C and 8D at 14.7, .50, l0() and .200 p.s.-i.a. pressures, respectively, yfor vthe -oxygen-ethane system are plotted against temperature in the graph. The bubble kpointeur-ves represent .the isobaric equilibrium composition of the liquid mixture and were obtained by considering the oxygen-ethane system an ideal solution. The bubble point curves thus represent the temperature and pressure at which the first bubble would form in a liquid mixture of a particular indicated composition as that mixture is gradually heated to a higher temperature'. For example, an ethane-oxygen liquid mixture containing 0.40 mol fraction or 40 rnol percent of ethane and held at a total pressure of 50 p.s.i.a would be entirely liquid at temperatures below about 260 F, and would have the first trace or bubble `of vapor form at that temperature. It will be apparent that if this particular system is `held at 50 p.s.i.a. and warmed to its boiling point, further evaporation` takes place in such a way that the composition of the system moves alongthe bubble point curve 8A to higher temperatures and to higher compositions of ethane. Since the lower limit of inflammability for ethane-oxygen gaseous mixtures is 4.1 mol percent ethane, the maximum allowable partial prsure of ethane for a nonina-mmable mixture is less than 0.60 and 2.05 p.s.i. for gaseous ethane-oxygen mixtures maintained under pressures of 14.7 and 50 p.s.i.a, respectively. Thus the partial pressure curves 8(0) and 8(b) for ethane represent the lower limit of inilammability for agaseous oxygen-ethane system when maintained at pressures of 14.7 and 50 p.s.i.a., respectively. It will be apparent that any point under an ethane partial pressure of 0.60 p.s.i. and at or above 14.7 p.s.i.a. total pressure on the system is below the lower inammability limit. Similarly, any point under an ethane partial pressure of 2;05 and at or above a total pressure of 50 p.s.i.a. is below the lower inammability limit. It follows that the conditions required for a noninamrnable vapor above the liquid ethane-oxygen may be readily determined from the foregoing.

' Fig. 6 illustrates solid-liquid equilibria for propane and oxygen mixtures. Applicant lacks data above 290 F. and the portions of curve 6A between 290 F. and 270 F. indicate reasonable extrapolation. Therel mainder of the loop of curve 6A above 270 F., constitutes a mere guess at the nature o'f this portion of the curve asit is based on the slopes of the portions below 270 F. Actually, it may not be possible to raise the temperature of the propane-oxygen system high enough to obtain a single liquid phase in the region of the curve 6A labove 270 F. It may be that the two phases will persist up to the critical temperature of the mixture, under which conditions a gaseous phase must necessarily exist.; It may be seen from Fig. 6 that a propane-oxygen mixture containing 40 mol percent propane and maintained at a temperature below about-363 F. will consist of solid propane and solid oxygen. Upon warming to temperatures between about 363 F. and about 270 F., this mixture will comprise solid propane in equilibrium with liquid propane-oxygen solution At higher temperatures, phase conditions are unknown but it seems reasonable to assume that a single phase solution cannot exist except at relatively high temperatures. Onthe other hand, a propane-oxygen mixture containing mol percent propane can be a single phase liquid solution at 300 F. f t

- Proper interpretation of Figs. '4 through 8 of the drawingsA will readily provide conditions necessary for the preparation, storage and use of preferred explosives of the nature described herein. For example, should it'be desirable to prepare amethane-oxygen solution containing 40 mol percent methane, the minimum temperature at which suc-h a solution exists free of a precipitate comprising methane may be determined from the graph of Fig. 4 to b e about 344 F. Then by referringto curve 7A of Fig. 7, the boiling point of a methane-oxygen solution containing 0.40 mol fraction or 40 mol percent of methane will be found to be about 290 F. at apressure of-l .4.7 p.s.i.a. Thus the solution may `be held at a temperaturen above 344F. but below 290 F.

10 and at a pressure of at least one atmosphere.A However, since a noninflammable vapor in equilibrium withv the solution isndesirable, it may be seen from the partial pressure curve Yfor methane 7(a) that the temperature of the solution should be below about 294 F. in order to not exceed the lower inammability limit and maintain a noninilammable v apor phase. In actual practice, a temperature about halfway between -the minimum temperature and the temperature at which the lower intlammability limit is exceeded for the particular composition is preferred. When the solution is held at a tempera-ture suliiciently `high to cause the lower iniiammability' limit to be exceeded, it is necessary to resort to a gaseous diluent or other means described herein to maintain the vapor phase noninliammable.

Similarly7 if an ethane-oxygen solution containing 40 mol percent ethane is desired, the minimum temperature at which such a l-iquid solution exists free of a second liquid phase or precipitate comprising ethane may be determined to be about 298 F. from the graph of Fig. 5. Then by referring to curves 8A and 8B of Fig. 8, the boiling point of an lethane-oxygen solution containing 0.40 mol fraction or 40 mol percent of ethane will be found to be about 288 F. and 260 F. at pressures of 14.7 and 50 p.s.i.a;, respectively. Since the minimum temperature is 298 F. and the boiling point of the solution at atmospheric pressure is 288 F., a pressure in excess of atmospheric must be resorted to in order to have a boiling point sufficiently higher than the minimum temperature of 298 F. to permit practical operation. Assuming the selection of a pressure of 50 p.s.i.a., the solution may be held at a temperature above the mum temperature of 298 F. and below its boiling point of 260 F. It may be seen from the partial pressure curve for ethane 8(b) that this temperature range is suficiently low so as not to exceed the lower inammability limit and tornaintain the vapor phase in equilibrium with the solution noninammable, even at its boiling point.

Inspection of Fig. 6 shows that propane as the sole fuel, i.e., in substantial proportions, can be maintained in single phase solution in oxygen, if at all, only at high temperatures and therefore high pressures. In small proportions, as in mixtures with methane and ethane, propane can be used at lower temperatures and pressures and in such case the inflammability of the vapor phase is not critically aifected by the propane.

A solution containing stoichiometric or higher proportions of a fuel material dissolved in liquid oxygen and which is free of asecond liquid phase or precipitate comprising fuel material may be prepared in many instances using fuels such 'as ethane or propanefwhich are not normally soluble in oxygen to the desired extent at the low temperatures necessary for handling the solution at atmospheric pressure. It is possible to provide a mixture including ethane, propane, or other suitable -fuel and liquid oxygen which normally exhibits at or near atrnospheric pressure a second liquid phase or precipitate cornprising fuel material and by increasing the temperature of the mixture while simultaneously increasing the pressure to at least lthe vapor pressure of the mixture at its particular temperature, it is possible to maintain the mixture as a solutionrfreeof a second liquid phase or precipitate comprising fuel material. This is of importance in applications where itis not necessary to control the temperature of the mixture in order to control the -hazard involved. In such instances, it may be possible to place the mixture in a closed vessel and allow the temperature to rise to a temperature under the critical temperature for the mixture, and thereby produce a solut-ionsuitable for the purposes of the invention. Where closed 'pressure vessels are desirable, the fuel material will be a compound or mixture of compounds which will dissolve in the desired proportions lin the liqueiied oxygen at the pressure and temperature employed.

Asolution of fuel in liquid oxygen has been found to Example I A standard blasting cap was fastened to the outer surface of a short section of bright .copper tubing and ythe copper tubing together with the blasting Gap imm-@fwd in liquid nitrogen. The blasting cap was then detonated and the copper tubing recovered J.for purposes `of'examination.

Upon examination ,o f the copper tubing, .only a very minor `surface area was found to be damaged V.or gliscolored. Y Y

Example Il A solution containing 33 mol percent methane in liquid oxygen was prepared by liquefying a mixture of gaseous methane and oxygen.

15 cc. of the above solution was placed -in a short `sec '4 tion of bright copper tubing which was closedoff at one end and provided with a standard commercial blasting cap fastened to the outer Vsurface of the tube. The copper tubing containing the solution together with the blasting cap was immersed in liquid nitrogen. The tubing, blasting cap, manner of fastening the blasting cap and immersion in 'liquid nitrogen was identical AWith that of Example I.

Upon detonation of the blasting cap, the 'solution exploded violently causing considerabledamage to the immediate surrounding area. Smallportions of copper tube found in the debris were brittle and exhibited numerous fissures. i

Example Alll A matchhead, whichris a term commonly Used-for a commercially available device Y.for initiating explosions and characterized by ,heat release only as compared-with the heat and detonating effect of a standard blasting cap, was fastened to the outer surfavceof la section of lbright copper tubing identical -with thatrof A'Example 15 cc. of the ysolution described 'in `l-lxarrip 1,e'II .Was placed in the copper tubing -and :the Isame inrmersed in liquid nitrogen fas inthe foregoing examples.

The matchhead was then tired, but 4the'srltltion failed to explode. The above `procedure wasfollowedesleveral times with -identical results. Y Y' The above procedure was modied by fastening the tureof the solution is maintained at er below the boiling point of liquid nitrogen, about .-320" F- In the instances where it may be desirable, the explosive lof the present invention may contain effective quantities of an additive such 4as an inhibitor Vor promoten for the. Pllrrpose of 'modifying the characteristics theIOf and thereby provide an explosive even more effective in a specific application. Additionally nitrogen, liquid air, etc. added to the solution as described above not only com trols the sensitivity of the vapor phase but is useful in controlling the sensitivity of the solution.

The foregoing detailed description and the specific ,eX- amples are for the purpose of illustration only, .and are not intended as limiting lto the scope or spirit of the ap.- pended claims.

What is claimed is: e

l. An explosive consisting essentially 'offat least one fuel material-'selected from the class consisting'of methane, ethane and lpropane dissolved in liquid oxygeninan amount -to produce an explosive and prevent the forma.-

v tion of a second nongaseous phase comprising fuel mate.-

rial and having a noniniiammaole vapor phase above theV resulting solution, the solution of fuel material in liquid oxygen containing up to about 75 mol `percent of methane, up to about 40 mol percent of ethane and up vto about 7 mol percent of propane and having a temperature below the critical temperature of the resultantisolution matchhead inside the tubing and within-,the solution.

The solution again failed to explode, although examina.- v

tion of the matchhead showed it lhad lfired. Y

It is apparent from this experiment thaty a stoichiometricsolution of ,methane in liquid oxygen is relatively safe provided the temperature of the solutionis -such as to provide a noninflammable vapor phase inequilibriurn withthesolution. Y

. Examplev `vIV Y A spark plug was arranged in a-.asks as tol-beslightly above the surfaceof solution .afteraddition `of'il-S cc. of solution. Then 15 cc. ,of the solution `described 'in Example ll was added to the gliask, land the lflask -im- Y mersed in a small quantity of liquid nitrogen.

longer covered ,the solution.

It is apparent .from the foregoing the waplor jphase zin Y equilibrium with aastoichiometrfilc solution o ffrnethane `in liquid oxygen is 4n0.:.niallaminable .nroitided .the temperaand above 363 Rand lthe nonintlamrnable vaporphase above the solution containing less than'5.4 mol percent-fof fuel material.

2. An explosive consisting essentially of methane dissolved in liquid oxygen in an amount Vto produce 'an explosive and prevent the lformation of a second nongaseo'us phase comprising methane and having -a noninflammable vapor phase above the resulting solution, the solution of methane dissolved in liquid oxygen containing 5-.-'75 mol percent of methane and having a temperature below .its critical temperature and above 3639 F.and the nonnflammable vapor phase above the vsolution containing less than 5.4 mol percent of methane.

3. An explosive in accordance ywith claim 2 Vwherein the'concentration of methane is'about 33 mol percent.

4. A package comprising a contained body lconsisting essentiallyof liquid oxygen having dissolved therein a fuel material selected from the class consisting of methane, ethaner and propane in an amount to produce "an explosive and prevent the formation 'of a second nongaseous phase comprising` fuel material, the body of-,fuel

material and 'liquid oxygen containing upto about 75 -mol percent methane, up to about 40 mol percent ethane 'and up toabout 7 mol percent propane, a contained body of liquefied gas refrigerant surrounding the first claimed` body, the refrigerant having a boiling point under the existing pressure not Agreater than the boiling point of the first claimed body, the pressure `on the surface of the body of oxygen and fuel material and the pressure on -the surface of the bodyof refrigerant being such ythat the body'of refrigerant has a temperatureflowerthan the boiling point of the body of oxygen and fuel and such as Ato maintain the composition of the vapor above the surface of the body of Yoxygen and fuel noninilammable, the-teniperatureV Iof lthe bodyv being maintained beloww-its critical temperature and above 363 iF. and the -va'por' containing less Ithan 5 .4 mol percent-of fuel material. Y Y

5. A package comprising a contained bodyconsisting essentially of liquid oxygen having" methane dissolved therein in eective amount to form an explosive but not in a concentration suiciently high to precipitate'a solid phase comprising methane, the body of methane tand liquid `oxygen containing 5-75` mol percent methane a contained body of liquefied gas refrigerant surrounding the first claimed Abody,rthe refrigerant having 'a boiling point ,under the vexisting pressure `not greater than the boiling point of oxygen, the pressure on the surface of the body of .oxygenfand methane and the pressureon'the surface of the body of refrigerant being such that the body of refrigerant has a temperature lower than the boiling point of the body of oxygen and methane and such as to maintain the composition of the vapor phase above the surface of the body of oxygen and methane noninilammable, the temperature of the body of liquid oxygen and methane being maintained below its critical temperature and above 363 F. and fthe vapor phase containing less than 5.4 mol percent of methane.

6. vThe package of claim wherein the refrigerant is nitrogen.

7.'The package of claim 5 wherein the concentration of methane in liquid oxygen is about 33 mol percent.

8. A package comprising a contained body consisting essentially of liquid oxygen having dissolved therein at least one fuel material selected from the class consisting of methane, ethane and propane, the fuel material being present in the liquid oxygen in effective amount to form an explosive but not in a concentration sufficiently high to precipitate a second nongaseous phase comprising fuel material, the body of fuel material and liquid oxygen containing up to about 75 mol percent' methane, up to about 40 mol percent ethane and up to about 7 mol percent propane, a contained body of liquefied gas refrigerant surrounding the first claimed body, the refrigerant having a boiling point under the existing pressure not greater than the boiling point of the rst claimed body, the pressure on the surface of the body of oxygen and fuel and the pressure on the surface of the body of refrigerant being such that the body of refrigerant has a temperature lower than the boiling point of the body of oxygen and fuel, and means for supplying a gaseous diluent above the surface of the body of oxygen and fuel at a rate sufficient to maintain the composition of the vapor phase above the body, of oxygen and fuel noninfiamrnable, the temperature of the body of liquid oxygen and fuel material being maintained below its critical temperature and above 363 F. and the concentration of the fuel in the vapor phase at less than 5.4 mol percent.

9. A package` comprising a contained body consisting essentially of liquid oxygen having methane dissolved therein in eiective amount to form an explosive but not in` a concentration sufficient-ly high to precipitate a solid phase comprising methane, the body of methane and liquid oxygen containing 5-75 mol percent methane a contained body of liquefied gas refrigerant surrounding the first claimed body, the refrigerant having a boiling point under -,the-existing pressure not greater Ithanfthe boiling point of oxygen, the pressure on the surface of the body of oxygen and methane and the pressure on the surface of the body of refrigerant being such that the body of refrigerant has a temperature lower than the boiling point of the body of oxygen and methane, and means for supplying a gaseous diluent above the surface of the body of oxygen and methane at a rate suflicient to maintain the composition of the vapor phase above the body of oxygen and methane noninlamrnable, the temperature of the body of methane and liquid oxygen being maintained below its critical temperature and above 363 F. and the concentration of methane in the vapor phase at less than 5.4 mol percent.

l0. The package of claim 9 wherein the refrigerant and the gaseous diluent comprise nitrogen.

1l. The package of claim 9 wherein the concentration of methane in the liquid oxygen is about 33 mol percent.

Al2. A package comprising a receptacle containing a body consisting essentially of liquid oxygen having at least one fuel material selected from the class consisting of methane, ethane and propane dissolved therein, the fuel material being present in the liquid oxygen in effective amount to form an explosive but not in a concentration sufficiently high to precipitate a second nongaseous phase comprising fuel material, the body of fuel material and liquid oxygen containing up to about 75 mol percent methane, up to about 40 mol percent ethane and up to about 7 mol percent propane, and means forsupplyinga gaseous diluentabove the surface of the body of liquid oxygen and fuel material at a rate suilicient to maintain the compositionof the vapor phase above the body of liquid oxygen and fuel. material noninflammable, the body of liquid oxygen and fuel material having a tem# perature below its critical temperature and above 363 F. and the vapor phase containing less than 5.4 mol'percent fuel material.

13. The package of claim 12 wherein the gaseous diluent comprises nitrogen. v 14. A package comprising a receptacle containing a body consisting essentially of liquod oxygen having methane dissolved therein in effective amount toform an ex'- plosive but not in a concentration suiciently high topre cipitate a solid phase comprising methane, the body of methane and oxygen containing 5-75 mol percent meth-A ane, and means for supplying a gaseous diluent above the body of lliquid oxygen and methane at a rate suflicient to maintain the composition of the vapor phase above the Ibody of liquid oxygen and methane noninammable, the body of liquid oxygen and methane hav.- ing a temperature below its critical temperature and above 363 F. and the vapor phase containing less than 5.4 mol percent methane.

15. The package of claim 14 wherein the gaseous diluent comprises nitrogen.

16. A package comprising a receptacle containinga body consisting essentially of liquid oxygen having at least one fuel material selected from the class consisting of methane, ethane and propane dissolved thereinin -effective amount to form an explosive but not -in a con centration sufliciently high to precipitate a second nongaseous phase comprising fuel material, the body of fuel material and liquid oxygen containing up to about 75 mol percent methane, up to about 40 mol percent ethane and up to about 7 mol percent propane, and the surface of the body of liquid oxygen and fuel material having a follower thereon selected from the class consisting of minute plastic-bubbles and thin plastic sheets to maintain the composition of the vapor phase above the body of liquid oxygen and fuel noninammable, the temperature of the body of liquid oxygen and fuel material being below its critical temperature and above 363 F. and the concentration of fuel material in the vapor phase being less than V 5.4 mol percent.

17. A package comprising a receptacle containing a body consisting essentiallyof liquid oxygen having methane dissolved therein in effective amount to form an explosive but not in a concentration suiiiciently high to precipitate a second nongaseous phase comprising methane, the body of liquid oxygen and methane containing 5-75 mol percent methane, and the surface of the body of liquid oxygen and methane having a follower thereon selected from the class consisting of minute plastic bubbles and thin plastic sheets to maintain the composition of the vapor phase above the body of liquid oxygen and methane noninllammable, the temperature of the body of liquid oxygen and methane being below its critical temperature and above 363 F. and the concentration of methane in the vapor phase fbeing less .than 5.4 mol percent. Y

18. The method of preparing a solution consisting essentially of at least one fuel material selected from the class consisting of methane, ethane and propane dissolved in liquid oxygen which comprises dissolving the fuel material in the liquid oxygen in an amount effective to produce an explosive and prevent formation of a second "mation of a second nongaseous phase-y resultant solutionibeiug .maintained below its oritiool temperature 4and, above :36.3 E. and the pressure being at least equal tothe eieotivo vopor pressure of the -re- Sultnt solution at its temperature,

119, The. l,rrlethorl of preparing@ Solution oorisistinges.- sentially of methane dissolved iu vliquid oxygen Wlu'oll comprises dissolving-the .methane ip liquid oxygen iu an amount effeetive'to produce an oxplosiveautl Aprevent :.foruprising fuel materiel while maintaining tlieooiuposi -offftlio vapor phase above the resultant solution pfe-ntetnan'e ,in liquid oxygen popiuilomoioble, the resultant .Solution oorltainr ing 5.-75 mol percent. methane arid theoopoeutrationoi metlieneip'the voporfph se being'less tirano-4 tirol. porS Cont, the 'resultant Sol oritiool temperature ami ove :T3639 F. euri tho :proof euroY being ot least equal: the eiieetivo vapor pressure ofthe resultontssolutiori et-itsfterpporature 2 9- The method of'ielaim i9 --whor 'utlie Gomposif tion offfthe vaporabove'theresultapt .ou is maiutoiped at o'-noniniiamrnttble-eorupositionV Aibi' Supplying 1o gaseousdiluentto thovapor phase.` .Y

.21- The method of claim' 19 'whereinthe composition of the Yoporphase above :the resultautsoiutionts mair1- tained at a noniniiammable composition by refrigeration of @the .resultant solution with :o lilueed-gasreniigerant. 22. The method of claim 19 wherein theQlIzlPosition of the Lvapor phase Aabove the solution. isimeinteined at Yo no tiiuflamrpable Composition by providing'a follower for-the Surface of the .resultant ,Solution seleeted from the o-,lass oonsistiug of .minute plastie :bubbles 'and ythin'plostio sheets,

t1 being maintained below `-.its

`23. .A :package .comprising a vfr ooptalcole,Y la partition e eiiootiveiy dividing the reoeptu'ole vinto two compartments? one of the compartments of the receptacle .containing liquid oxygen and the other oompartment of the recep- Vtaclwe containing Iat least one fuel material 'selected from $24. A package comprising' a receptacle, .a partition` efvectiyely dividing the receptacle into two compartments, one of the tzornpartments of the receptaclefcontaining liquid oxygen and the other compartment :of the -recepf 'i tacle ezgntai-ning methane, and means for removing at losst :a `portion of the partition thereby-allowing the conf tents of the two .compartments to miranti-term a-soiue tion .of methane in liquidioxtgen.

25. A method .of storing 'and hautliug'anexplosirs which consists essentially' o'f-at lejast one fuel material selected vfrom the .class .ooosisting of methane, '.e-thane and, propane 'dissolved fin liquid .oxygen comprising' .reducing the ,explosion hazard by maintaining 'the 'rcon'cenf tration of fuel material in the liquid oxygen in a range effective to produce an expiosivejand prevent the forma? tion of a Vseeond nongaseous phase comprising :fuel material, the resulting solution of fuel material dissolved in liquid oxygen being -at Va',tertperatnre below its'c'riti'cal temperature and agbove'fp E. and containingbas'ed upon the total molar amount of fuel Imaterial and liquid oxygen up to about 75V molgfpercent of methane, @up .t0 about 4Q molpercent .of Vethane and up toV .about i7 mol -peroentof propane.

2,6, methodof'glvaim 25 Where'intthe Yaporlphas above the vsolution -is noninammable, the -tconcentrat-ion of iuolit.r11a...riul in the sopor :phase being less .than-'5.5 ruolpercent.`

2 7, A Ymethodhof storing' and handling an bexplosiveV which V,consists essentially `of methane dissolved in liquid ogrygen comprising'reducing the Vexplosion hazard l.by maintaining the concentration of methane in tlgeliquid oxygen iu o roneeeteetive to' produce lau oxplosiyoud preventfthe formationof asecond-nongaseous phase com: prising methane, the resulting solution of.methane dis,- solved vn liquid loxygen being at a' `temperature fbeiow ernperatureV and movers-3,639 and con:

uiolar Vamount of methane aud liquid oxygen.l

A8N-'The methodiof vclaim 2'7 wherein the consent-ra.-v tion of methane is about 33 mol percent. 2 9, The lI netho'd of claim 27 wherein the vapor phase above thesolution is noninliammab'le, :the concentration of.rnethane in the -vapor phase'being less than 5.4 vlined poroout- Y vRefer-,ences Cited Vin thefle *of` this patent Uisrreo STATES ,PATENTS ornate REFERENCES. Aot-.ronaptios AuseSept. y1,932, 22. page 4- 'ng 5- v5v mol percent methane based upon the totalV

Claims (1)

1. AN EXPLOSIVE CONSISTING ESSENTIALLY OF AT LEAST ONE FUEL MATERIAL SELECTED FROM THE CLASS CONSISTING OF METHANE, ETHANE AND PROPANE DISSOLVED IN LIQUID OXYGEN IN AN AMOUNT TO PRODUCE AN EXPLOSIVE AND PREVENT THE FORMATION OF A SECOND NONGASEOUS PHASE COMPRISING FUEL MATERIAL AND HAVING A NONINFLAMMABLE VAPOR PHASE ABOVE THE RESULTING SOLUTION, THE SOLUTION OF FUEL MATERIAL IN LIQUID OXYGEN CONTAINING UP TO ABOUT 75 MOL PERCENT OF METHANE, UP TO ABOUT 40 MOL PERCENT OF ETHANE AND UP TO ABOUT 7 MOL PERCENT OF PROPANE AND HAVING A TEMPERATURE BELOW THE CRITICAL TEMPERATURE OF THE RESULTANT SOLUTION AND ABOVE -363*F. AND THE NONINFLAMMABLE VAPOR PHASE ABOVE THE SOLUTION CONTAINING LESS THAN 5.4 MOL PERCENT OF FUEL MATERIAL.

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