US 2483661 A
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Get. 4, W49. c. c. NEAS DISCHARGE DEVICE Filed Sept. 14, 1945 INVENTOR CHARLES C. W
BY WM LW ATTORNEY Patented Oct. 4, 1949 DIS CHARGE DEVICE" Charles G. Neas, Boston, Massi ais'signofi more United States of America as represented by the:
Secretary of theNavy Application September 14, 1'945, SerialNd; 616E387 3Glaims. 1
This invention relates to li'quified' gas containers and is illustratedhereinas embodied-in a dischargedevice-"for efiecting 'theadiabatic' removal of=the contents of a liquefiedgascontainer.
It is well known I that in any attempt to obtain nearly complete adiabatic discharge of cylinders of liquified gases such as N20 or G02; it-is necessary to remove'the cylinder contents as liquid. Otherwise; if a predominantly gaseousdischargeoccurs, theheat of vaporization given up by the remaining liquid will cool it" thus re ducing its vapor pressureand removing the driv ing pressure necessary to eject the gases.
In the ordinary use-of liquefied=gas, the container may'be-heldinan upright position, and-a discharge of the contents in a liquid state-is effected by a dip; pipe withopenings adjacent to the bottom of the'gas container. However; in several applications, suchas'life raft inflation and car'- bon dioxide fire'extinguishers', the positionof the cylinder during discharge-cannot be controlled or predicted so as to insure aliquiddischargeupon opening the release valve; If 'the'usual typeof container'is invertedthe" discharge will be" entirely gaseous with the undesirable" results noted above; and inithe inflation of a life raft aserious delay would ensue.
In the operation of aircraft overtcold' waters, itis necessary to have quick inflation of life rafts inorder to avoidfatal expjo'sure ofpersonnel to cold" water.
The airplane life raftsoflparti'cular interest in connection" with this invention are the larger ones of the automatic type. These rafts are stored in compartments in various positions in the fuselage and" maybe ejected in such a manner that a raft; with'its asso'ciatedgas container, turns end. over' end. whilebeing' elected and inflated. When on the surface ofthe Water the raft may float with either side up. Thus, the position of the liquefiedgas container is variable and unpredictable for any. stage, of the periodof. the discharge. I
At high altitudesvtemperatures as. low: as v-6 F. are encountered;and, duringa flight-of from 10 to12 hours at-those temperatures, a-liferaftand cylinder may be cooled to temperatures of -409 E; or lower, whereby: the vapor pressure imsidethe cylinder: reduced and: thetime' re quired to inflate: theiraft; completelyis increasedi Itxisdesirable to have :as? little? exposure of: personnelto the waterrasczpossible and evenito have therait fully inflatedin; thethirty secondsi'during whicli'za ditched airplane: may. sink tor permit oc 2: cupa-nts ofthe airplane to step directly from the planeto theraft without -beconring wet With ordinary co'ntia'iners; is not possible to get a satisfactorily complete and rapid discharge, particularly with a container at a lo-w temperature; toinflate a ratt beforethe planesinks for-, with-s: container in certain positions, an entirely gaseousdamaged-awnin s and the liquid remaining in-= the container" after partial discharge iscooled sufiicientiytc the-discharge Therefore, it-isa principalwki-iect of th'isinvention to provide for therapid and complete removal of liquified gases i-n-a precominantiy liquid state'- from a container in which they arest'ored; under liigh p ess re?- regardles'sof Y the position of the container;
To "this end; theinvcntion provides an improveddischarge" devicefor a; l-itlliified gas container which includesinsteachof the usual dip pipe referred to above; a tube which extends from one end of the" container longitudinally thereof substanti-ally tonsotiiei 'end, the tube having I openings adjaeent to" both of its ends-.- Accordingly, when thecontainers i1i -any-'other'-than-horizontal' position at" 1east onecpening in" the tube will be* immersed so 'long as the discharge 0f the container is not neariycompletem Iii-or der to irisiire thenompltedischarge of the container" wiien.it isdisposed: horizontally or in other tilted position's the iiiveiition further pro vides as another featiirethereof; a flexible ter: mina-l section on the time which is adapted to swing, under the infl'uencepfthefbrceof-gravity, close to or into engageinent witlsi' whatever part of the container wall is lowesti fineor more openings adjacent totheendof the flexible section are thus" disposed at nearly the lowest' point in the liquid when thecontainer is-horihontalor in any tilted position abtrvetrie horizontal position.
When-adiseharget dcdrfstfflctd in accord ance 1 with this i-iiv'erition is einployed to remove the contents of a container of liquified gas; at least some of theopeningsthere-hr are 'belowthe liquid surface regal-dress? of theposition of the container-'andat last'a part 'Ofthe contents are removed a's-liquid throughotit' tti'eentire period of 3 discharge tube being shown in section. The position of the tip of the tube when the cylinder is upright is shown in dotted lines.
As illustrated in the drawing, the liquified gas container includes a hollow body portion l of conventional design, the body portion being cylindrical and having a closed end 2 and an open mouth 3. A cap 4 closes the mouth 3. A T-shaped channel 5- in the cap 4 connects with the inside of the container. One free arm of the channel 5 is closed with a puncture disc 6 which may be attached to puncture mechanism associated with a life raft or other equipment (not shown). A safety disc 9 held in place by a cap 10, closes the other open arm of the channel 5.
A discharge tube II is located inside the container and is threaded to the cap 4. charge tube ll extends longitudinally through the container coaxially therewith. The tube has a plurality of openings lz adjacent to the mouth 3 and a further pluralityof openings l3, adjacent to the closed end 2 of the container through Which its contents are introduced into the discharge tube.
The greater portion of the tube II is constructed of rigidmaterial, but a tip portion [4 thereof is preferably made of flexible material. The flexible tip I4 is made sufficiently long that when the axis of the container is tilted away from the Vertical, the tip is pulled against the wall of the container by the force of gravity, as clearly shown in the drawing.
A cover in which the openings l3 are formed is attached to the end of the flexible tip and is so constructed as to prevent the openings from coming into direct contact with, and being closed by, the side walls of the container. The lower surface of the cover I5 is cone shaped as indicated at It; in the drawing; and as the container is tilted the flexible tip swings until the conical portion 16 of the cover rests against the lower portion of the side wall of the container as shown in the drawing. For best results, the flexible tip It! should be sufiiciently long that the cover I5 swing against the side wall of the container, the conical portion l6 resting against the wall, as shown in the drawing, when the container is tipped. Thus the openings l3 are kept away from the wall. However, the flexible tip should not be long enough to become kinked during rough handling of the container. Accordingly, the rigid portion of the tube should extend the greater part of the length of the container.
As shown in the drawing, the openings I3 are drilled in the cover a short distance above the conical portion 16. When the container is vertical, the openings l3 are adjacent to the closed end 2 of the container; and when the container is horizontal, the openings 13 are adjacent to the low side of the container wall. Dotted lines indicate the position of the flexible tip when the container is in an upright position.
For best operation, the combined areas of the openings I2 should be substantially smaller than the area of the bore of the tube in order that the flow of gas through the openings l2 will create a pressure drop slightly greater than the hydrostatic head of liquid when the cylinder is upright. In other words, in the upright position of the container, the flow of gas through the openings [2 at a particular temperature of the liquified gas within the container creates a pressure dif ferential or head between theoutside and the inside of tube ll of sufficient magnitude to force the liquid from the liquid level within the con- The dis 4 tainer to the free end of T-shaped channel 5 in which puncture disc 6 is located. That is, for a predetermined temperature of the liquid in the container, the flow of gas through the openings I2, which is formed above the liquid by evaporation of the liquid, is of such an amount that the pressure head between the outside and the inside of the tube overcomes the hydrostatic head of a column of liquid within the tube extending from the liquid level within the container to the outer extremity of the channel 5. The openings I3 in the. tip, on the other hand, are made large enough to permit a flow through them equal to that which the tubecan accommodate. It has been determined that best results are obtained when the ratio of the combined areas of the openings l2 and the area of the bore of the tube is substantially /2. For example, with a container charged with 3.25 pounds of liquid N20 and cooled to 40 F., a tube of 0.234 inch internal diameter having large openings in the tip and having two openings adjacent to the base each having a diameter of 0.116 inch, gave good results whether the container was upright or inverted. In 25 seconds, or more of the container contents were discharged in each container position.
When the openings are constructed as described, a discharge containing at least some liquid is provided in any position of the container. When the openings 13 in the tip are immersed and the openings [2 in the base of the tube are above the liquid surface, the pressure drop of gas flowing through the openings I 2 of the tube is sufficient to force liquid up the tube to be swept out of the cylinder in the gas stream. 0n the other hand, when the openings l2 of the tube are immersed, the hydrostatic head forces liquid into the tube 1 I through these openings in preference to gas through the openings 13 in the tip. The flexible portion M of the discharge tube 1 l is necessary to insure that openings are below the liquids surface when the axis of the container is horizontal regardless of the amount of liquid therein.
This invention thus insures, regardless of container position, a discharge in which liquid is always present. Although the gaseous phase may account for the major portion of the discharge on a volume basis, nevertheless, the discharge on a weight basis is predominantly liquid because of the higher density of the liquid.
, The device illustrated is particularly effective for discharge of containers of N20. How ver, it may be used satisfactorily with other gases liquified under pressure andthe scope of the invention is not to be limited to. use with N20.
Having described my invention what I claim as novel and desire to protect by Letters Patent of the United States is:
1. Apparatus for the adiabatic discharge of liquified gas under pressure from a container having a discharge cap, said apparatus comprising a tube secured to said cap and extending into said container, said tube having a rigid section and a flexible section, and a termina'l member securedto said flexible section and having an opening in the side thereof near its extremity, said rigid section of said tube having openings therein adjacent to said'discharge cap, the combined areas of said last-mentioned openings being of such size relative to the bore of said tube that the pressure drop of gas through said openings at the temperature of the liquified gas is greater than the hydrostatic head of a column of said liquid within said, tube extending from the liquid level within the container to said discharge cap.
2. In combination, a cylinder having a closed end and a discharge cap adapted to contain liquified gas under pressure, and a tube secured to said cap and extending into said cylinder substantially coaxial therewith, said tube being rigid for a substantial portion of its length and having a flexible section terminating adjacent to the closed end of said cylinder, said flexible section terminating in a cover having openings in the sides thereof, said rigid portion of said tube having a plurality of openings therein adjacent to said cap, the combined areas of said last-mentioned openings being of such size relative to the bore of said tube that the pressur drop of gas through said opening at the temperature of the liquified gas is greater than the hydrostatic head of a column of said liquid Within said tube extending from the liquid level within the cylinder to said discharge cap.
3. Apparatus for the adiabatic discharge of liquified gas under pressure from a closed container comprising, a tube attached to the outlet of said container and extending substantially to the bottom thereof, said tube having a first plu- REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,938,036 Martin et a1. Dec. 5, 1933 2,311,845 Lindsay Feb. 23; 19.43
FOREIGN PATENTS Number Country Date 628,195 Germany Mar. 30, 1 936