DE2510739A1 - METHOD AND DEVICE FOR DISPENSING GAS - Google Patents

Description

March 10, 1975 Gzs / goe

UNION CARBIDE CORPORATION

Method and device for dispensing gas.

The invention relates to a method and a device for dispensing from gas, e.g. from gaseous oxygen for inhalation a source that contains the gas in a liquefied state * oxygen for breathing, produced by the vaporization of liquefied gas is provided, is used in the context of medical therapy for lung and heart problems to a large extent at home or in Used in hospitals. For the sake of convenience, and the easier portability, it is advantageous to dispense the vaporized liquid from a relatively small storage container, the is refilled from time to time with liquid from a large storage container. In the applicant's German patent 1,491,847 describes a device for providing oxygen .zum breathing, in which the oxygen in a compressed state is kept in a relatively small dispensing container, which can be supplied with liquid oxygen from a larger storage container if required can be replenished. To do this, the dispensing container is turned upside down over the storage container.

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ORIGINAL INSPECTED

brought a fixed line, which protrudes from the liquid space of the storage container, connected to a fixed line, which leads from the interior of the dispensing container. The connecting devices, in which the corresponding lines are normally closed, form, after connection, a transition through which the liquid flows into the dispensing container under the action of a suitable vapor pressure in the storage container arranged below. Has been after the dispensing container suspended and placed in upright position _s, the liquid in an evaporator device occur, which is fixedly connected to the dispensing container, whereby oxygen gas may be delivered as required.

However, it is not, for example, in such a device possible to completely close the upturned oxygen-releasing container from the larger storage container for liquid oxygen fill, -which is arranged below the dispensing container and connected to the first-mentioned smaller vessel. The reason for this is that the gas discharge line from the smaller container both in the inverted position when filling liquid as well as in the upright position for dispensing liquid for dispensing of gas is effective »In other words, the gas discharge line ends approximately in the middle of the smaller container so that it leads to the Oxygen delivery during the introduction of liquid can be used as long as the container is in an upside-down position.

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tion is located. Accordingly, the container can only be filled halfway, because otherwise the gas discharge line is submerged would. Of course, this means that the storage volume for liquid is only half used, which is a considerable disadvantage represents, if you consider that the dispensing container for the frozen liquid must be small enough to allow a manual Operation by one person is possible, in particular the change between upright and inverted position.

These disadvantages have been addressed by a method and an apparatus eliminated for releasing gas, which is described in the earlier patent application P 23 58 956 · 2 of the applicant. An important feature this improved system is the dual function of certain elements. For example, the pipe that is used for venting the highest zone of the dispensing container (top of the container facing up) during the gas dispensing operation to avoid Positive pressure is used to fill the line when the container is inverted to the position with the bottom facing up. Liquefied Gas is poured from the storage container through this same line into the lowest zone of the inverted dispensing container, with the top of the container facing down. Similarly, the one used to draw fluid from the bottom Zone (bottom down) of the dispensing container during the gas dispensing operation to the vent line, if the Container is upside down. The evaporator that is used for gasification

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-ileus liquids dispensed into the dispensing container during the Gas delivery operation is used to heat the cold venting gas during the filling operation, whereby the delivery of cold Gas in the vicinity of the user is avoided. This interchangeability of functions facilitates the construction of an extremely, light one and compact system that is well suited to providing respiratory oxygen to patients who need to move while they carry the dispensing container. It enables-also the full Filling the dispensing container with liquefied gas.

Despite the advantages of this gas delivery system, hereinafter referred to as the "reversible, dual gas delivery system", there are a very specific disadvantage * If the container is accidentally placed in a non-vertical position (e.g. tilted or horizontal), and when the container is almost or completely filled with liquefied gas, the inner ends of both the line for gas venting or liquid filling (which normally leaves the container at the upper end) as well as the Line for the liquid discharge or gas venting (which normally leaves the container at the lower end) in liquid be immersed. Such immersion drastically diminishes

the ability of the vent circuits to depressurize, and dangerous overpressures can occur. In addition, cold, liquefied gas could be released to the outside, resulting in a Hazard to the user and high loss of stored fluid at the same time.

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In known systems for supplying ventilation oxygen with the aid of liquefied oxygen, these dangers did not exist, because the gas vent line was always in the inner vapor space, regardless of the position of the liquefied gas containing it Container. This prevented liquid from leaking out through the gas discharge line. The meaning of this The feature becomes clear by briefly considering the practical use of such oxygen delivery devices. The reversible liquefied oxygen dispensing container is intended to be carried by a moving patient and must therefore be carried should be relatively small, e.g. * should only contain about 730 g of liquid oxygen. When you consider the smallness of this container taken into account, it becomes clear that any loss of fluid is to be avoided because it is a significant loss of respiratory oxygen capacity. More importantly, such venting is dangerous for the user, because there is a possibility of severe burns on the skin that comes in contact with liquefied oxygen. Even The release of liquid when it evaporates leads to locally high concentrations of oxygen, which increases the risk of inflammation in the vicinity of combustible materials.

It might seem that the problem is the delivery of cold liquid such horizontally arranged reversible gas delivery systems would be eliminated simply by having an automatic

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Closing device attached to both gas vent lines and these closing devices are actuated when the container is brought out of the vertical. Because of the dual punctures of these lines, that is, v / eil both lines be used when the container is brought into the filling position with the bottom up, this is not a practical solution of the problem. If, in addition, both lines are closed, there is no device for reducing an overpressure, which occurs due to the evaporation of the enclosed liquid.

Another attempted solution to the vent problem could be can be seen in this, simply the gas delivery capacity of the overpressure safety device, aie on the line for gas venting or liquid filling is to be increased and the liquid released in this way through an evaporation and superhit ζligation apparatus through the outside of the container is arranged. The capacity of the overpressure protection and the associated Evaporator could be made large enough to adequately limit overpressure even when the inner end of the gas vent or liquid fill conduit is inadvertently submerged. However would be the size and weight of such an evaporator and superheater impracticably large. The size of the increase in capacity the overpressure protection that would be necessary to be sufficient

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functioning with the inlet end submerged can be more easily judged from the following comparison. Assume that a unit volume of liquefied gas is withdrawn from the container at an excess pressure of -3.5 kg / cm and heated at this pressure to a temperature of 21 ° C to be released as a gas. If the unit of volume was withdrawn as liquid, the volume present at 3> 5 kg / cm increases after heating to a volume that is fifty times greater than the volume that would have resulted if the unit volume had been withdrawn as vapor. In addition, a unit volume of liquid requires approximately one hundred times the amount of heat to warm to 21 ° C compared to a unit volume of steam. Thus, the attempt to solve the ventilation problem in this way would be to df; m not, transportable breathing oxygen apparatus Add accessories of excessive weight and high bulkiness "The size of a practically usable ventilator 5% this would necessarily increase by an estimated 30 to J> will.

The object of the invention is to provide a reversible dual gas delivery system to create the gas only vented if it is accidentally / oine non-vertical position is brought, with no increase in the device dimensions are required.

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The task is solved as follows: The gas delivery container, the consists of a thermally insulated, liquefied oxygen-containing container with an upper and a lower end, and brought into a dispensing position with the top side up and in a filling position with the bottom side up can, has a line for gas venting and filling with liquid, one end of which is inside the container at his upper end opens, while the other end opens outside the container in your upper end. There is also a line to Liquid extraction and gas venting available, one end of which opens inside the container at the bottom of the container, while the other end opens outside the container at its upper end. Furthermore, it is a reversible liquid vaporizer and fiber ventilation control circuit outside the container arranged and with a first inlet end at the second end of the line for liquid extraction or gas venting connected. This circuit includes a first vaporizer, gas flow control means between the first vaporizer and the other end of the circuit dispensing gas.

The device according to the invention comprises one which is effective in all positions Pressure reducing system, for the container, consisting of (a) a first high pressure reducing device between the first Evaporator and said gas flow control device,

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(b) a branch pipe, one end of which is in flow communication the second end of the line stands for gas venting and liquid filling,

(c) second flow and pressure reducing devices in the branch line,

(d) which is designed to deliver gas at a lower absolute pressure than the first pressure reducing device and operating at a maximum flow rate which is between three to twenty-five times the normal rate of evaporation of the container, and

(e) a second evaporator in flow communication at its inlet end stands at one end of the branch line and at its output end in flow communication with the second flow reducing and pressure reducing device. The second evaporator is designed with a heat transfer capacity no greater than one Third of the heat transfer capacity of the first evaporator, and which is also sufficient to carry liquefied gas that © in Entering inlet end to vaporize and to discharge vaporized gas at its discharge end, the discharge rate being the i 1.30 times the maximum rate.

The object is also achieved by a method in which gas is released is made up of a thermally insulated container for liquefied gas, the container having an upper and a lower end

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has and between a dispensing position with the upper end upwards and a filling position with the bottom end upwards is reversible, and wherein liquefied during the gas delivery operation Gas is pushed upwards from the lowest zone of the container by the vapor pressure generated above the liquid level is discharged at the top of the container and is evaporated by ambient heat to form the gas source su. That The method according to the invention is further improved by the fact that in the position for the gas discharge, the upper end upwards shows that the following occurs:

(a) If gas is not supplied, the vapor is vented through a passage from the highest zone of the container and which allows a flow limited maximum rate that is between di'el to twenty-five times normal Evaporation rate inside the container is heated by the ambient heat, releasing the gas is when the container pressure is above a first lower, above atmospheric pressure relief pressure limit lies.

(b) When gas is to be supplied, liquefied gas, driven by the vapor pressure above the liquid, flows up from the lowest zone of the container and is discharged from the top of the container. The liquid thus discharged is evaporated through the atmospheric heat, warmed and taken off as a gas source, gas is vented at the same time in accordance with step (a).

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If the container is in a non-vertical position, so that liquid pours through the opening of step (a), and when the gas pressure within the container is above the first, lower limit pressure lying above atmospheric pressure increases, liquid is initially drawn from the normally overhead end of the container with a first, lower flow rate limited speed issued, evaporated and durci the ambient temperature is warmed up and then released at a pressure, the pressure limit above the first, lower, above atmospheric pressure. The tank pressure rises to a second higher, above atmospheric, relief pressure that is 1.08 and 1.73 times the first, above atmospheric, relief pressure is on an absolute basis, the second being fluid is dispensed simultaneously from the normally at the bottom end of the container at a second higher rate, then evaporated and warmed by ambient temperature and finally released at a pressure that is above the second, is above atmospheric pressure limit pressure.

As used herein, the term "evaporator" means a heat exchanger with a closed bushing for receiving liquefied gas and for delivering gas and for delivery of latent heat of vaporization to the liquefied gas exclusively from the ambient atmosphere, so that the heat from

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a second liquid is taken, which would circulate in a second closed passage * "Heat transfer capacity" from the first or »second evaporator refers to their external surfaces, since the latter is the determining contact resistance form for heat transfer. If one or both evaporators with external secondary heat transfer surfaces are provided, such as fins, then the term "heat transfer capacity" refers to the equivalent primary Surface of the evaporator. That is, such a secondary surface is converted to an equivalent primary Surface by applying lamellar effectiveness factors in a known manner.

The term "normal rate of evaporation" means the LurcIioChnitts · Evaporation rate at which stored, liquefied oxygen

is evaporated

inside the insulated container / as well as the corresponding gas release, which only comes about due to the penetration of heat from the environment and compensates for this. The determination of the normal evaporation rate is made by keeping a container is used, which has a thermal insulation of normal effectiveness, that then the container to normal full level is filled that the container is placed in the normal orientation with the top up, whereupon the container and the contents in a thermal equilibrium state

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can arrive at an internal pressure which is essentially equal to the minimum desired operating pressure for the delivery of liquefied oxygen, which measures the rate at which gas is being released. The state of thermal equilibrium is considered to be given when the initial high venting rate drops to a uniform rate after filling is. After equilibrium has been reached, the venting rate can be measured directly by taking the current Rate of gas flow is measured, but advantageously several such measurements at certain time intervals made and averaged. Alternatively, the container with contents weighed at the beginning and at the end of a period of uniform venting and the change in weight can be proportioned an average venting rate in the past time obtain. The average rate of deflation that so determines is then converted to normal temperature and normal pressure, i.e. to a pressure of 1 kg / cm at 21 ° C, around the normal Obtain evaporation rate of the container.

The invention is explained in more detail with reference to drawings.

It shows

Fig. 1 is a schematic drawing of one shown in section Dispensing container for liquefied gas as well as a control circuit for liquid evaporation and gas discharge

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be, shown in the upright position, and with the inventive gas vent circuit for all positions;

FIG. 2 is a schematic view of the container of FIG. 1 in cross section, of the gas exhaust circuit for the liquid evaporation and gas release in the reverse Position, bottom up, and connected to a liquefied storage tank Gas during filling operation j

3 shows a schematic cross-sectional illustration of a preferred Embodiment of the control circuit for the Liquid evaporation and gas venting in the upright position, with the upper part upwards, with differences in the design compared to FIG. 1 are because a pneumatic control and a four-way valve are provided for venting to atmosphere is;

Figure 4 is a graph of oxygen gas pressure and the weight over time for the arrangement of FIGS. 5 and 7, the container for the liquid oxygen is arranged horizontally;

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Pig. Figure 5 is a side assembly view of a portable dispensing container for liquid oxygen and a control circuit for gas delivery for ventilation, with one Embodiment of the gas venting circuit according to the invention was used as it is shown schematically in Pig. 3 is shown;

FIG. 6 A view of the arrangement according to FIG. 5 in the direction 6 ~ 6j

Figure 7 is a sectional view of the article of Figure 5 along central axis C-C.

1 shows a vertical dispensing container 10 for liquefied gas and the gas venting circuit according to the invention for all positions during the gas dispensing operation. The container 10 comprises an outer housing 11 and an inner vessel 12 to contain the liquefied gas with an evacuated space between them, which is preferably filled with thermally insulating material 13, e.g. with alternating layers of aluminum foil and fiberglass mats, such as is described in U.S. Patent 3,007,596. The container 10 has an upper end I ¹ J and a lower end 15 and can be brought into a position with the top up and in a position with the bottom up. The container is preferably sufficient

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small to be carried by hand and turned over. A line 16 for gas venting and liquid filling has a first end 17 which extends through the normally above end ik of the container 10 and ends there, and a second end l8 which is outside and above this normally overhead end of the container. A second coupling device 19 is connected to and above the second end 18 when the container 10 is in the upright position.

A line 21 for liquid extraction and gas venting also extends through the upper end Ik of the container, the first end 22 of this line opening into the normally lower end 15 above the inner vessel base. The second end 23 of the line 21 for liquid extraction and gas venting is outside and above the normally overhead end Ik of the container 10. A reversible liquid vaporizing and gas venting control circuit 2k includes liquid sensing devices 25 which are connected to the second end 23 of the device for the Fluid withdrawal

and gas vent are connected, a first evaporator 26 connected at one end to the liquid sensing device 25 is connected, while the other end of the evaporator with a valve device 27 for gas venting to the atmosphere connected is.

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Furthermore, a signal transmission device is provided to automatically close the valve device 27 when of liquid is detected by the liquid sensing device. Such a device may, for example, consist of a thermistor 25a exist and an electrical signal receiving wire 28, a controller 29 and a wire 30 for transmitting an electrical Signal exist which is in communication with a vent valve 27 actuated by a magnet. More precisely, it contains the regulator 29 is a relay and a low level current flows from the coil of the relay through the wire 28 and the thermistor 25a. If there is only gas around the thermistor 25a, its resistance is 100 to 300 ohms, but if it is due to, is wet from liquefied gas, its resistance increases to 6,000 to 10,000 ohms. This increased resistance actuates the regulator relay 29, so that its contacts in the circuit consisting of the wire 30 open to the vent valve 27 and the valve is closed with it «·

During the gas delivery operation, the user can gas (e.g. oxygen) Adjust delivery rates manually by turning the gas flow regulator operated, such as Z..B. the supply valve 31, which is between the other end of the first evaporator opposite the liquid sensing device 25 and the gas vent valve 27 is arranged. When the valve 31 is open, the vapor pressure above the liquid pushes the

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liquid gas from the lowermost zone or the lowermost end 15 of the container upwards through the line 21 for the liquid extraction and gas venting, past the liquid sensing device 25 and through the first evaporator 26 where the liquid is evaporated.

The gas venting circuit for all .Stellungen comprises a first pressure reducing valve 32 in the branch line 33 downstream of the first evaporator k6 »In other words, the first pressure reducing valve 32 is in connection with the line system between the" other "end of the evaporator 26, the atmospheric vent valve 27 and the Cas supply valve 31, and is designed to deliver gas at a pressure higher than atmospheric pressure.

The main vent circuit also includes a branch line 3 ^ i which is in flow communication with the at its inlet Line 16 for gas venting and liquid filling, it also has second flow-limiting and pressure-reducing devices 36, which are constructed in such a way that gas is emitted at a pressure which is above atmospheric pressure, but below the pressure supplied by the first pressure reducing valve 32, as well as with a maximum predetermined one Flow rate that is three to twenty-five times normal Evaporation rate for the container is. 'A second

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Evaporator 35 is located in the branch line 3 ¹ J, with its inlet end is in flow communication with the inlet end of the branch line, while its output end being in flow communication with said second flow Display Constraint and pressure reducing means 36 · The second evaporator 35 is provided with a Wärmeübertragungskapazitä't -equipped sufficient to vaporize liquid entering at the inlet of the vaporizer and to discharge the heated gas at its exit end at a flow rate that is 1.04 to 1.30 times the maximum flow rate through the second Flow restriction and pressure reducing device 36 is.

Although this valve 36, shown in Figure 1, is the main flow restrictor and pressure reducing device, other structural components in addition to this may be used to perform some of this function. For example, a special flow restriction element 36a, such as a nozzle or a porous member, may be used at the outlet end of the line J> k, downstream of the valve 36. If the flow rate of the line 34 and the evaporator 35 is relatively large, e.g. "the same diameter as the branch line 33", a separate flow restriction element is necessary to keep the flow within the limits of three to twenty-five times the normal evaporation rate, and to keep the required length of the evaporator 35 small, in over-

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agreement with the overall small size of the device. the As an alternative, the flow limiter 36a can also be arranged upstream instead of downstream from the pressure reducing valve 36 and will then provide the same overall system performance, but the downstream arrangement is preferable because it is in this way prevents atmospheric contaminants such as dust from entering through the discharge end of the conduit 3 ^ will.

It is particularly advantageous if a fixed flow-limiting element 36a is arranged in series with the vent valve 36, because this provides greater security that the heat transfer capacity of the second evaporator is not exceeded. In many vent valves, the size df ^{1 increases} : · Flow passage through the valve increases when the pressure is above its set point, thus reducing its effectiveness as a flow restrictor. With a fixed restriction in the circuit, as the valve opening increases, a greater part of the total flow resistance is transferred to the fixed restriction, thereby changing an overload condition in the venting circuit.

It is also advantageous to use the second evaporator 35 to reduce to equip space and weight with a heat transfer capacity, which is no greater than about a third and preferential

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wise no greater than a fifth of the capacity of the first evaporator. With such a restriction, the overall size of the portable unit is not greatly increased, however gas venting can be ensured if the unit is inadvertently placed horizontally. To ensure, that the capacity of the second evaporator is not exceeded, the second flow restriction and venting device 36 designed so that the maximum flow rate is limited to a value which is below the value of the evaporator capacity would exceed, because that would be exposed to the ambient air Side of this evaporator the flow (heat transfer) capacity determine, the outer surface for this Ve! 'can be used immediately.

It will also be understood that, for safety reasons, a high pressure breakthrough disk 38 can be placed in line ~ $ k between the second evaporator 35 and the second flow restriction and pressure reducing valve 36. Alternatively, the breakthrough disk can be arranged in the gas discharge line 33 directly upstream of the gas discharge valve 31, but the first-mentioned point is preferable. The reasons for this are as follows:

(1) The breakthrough disk is in direct contact with the gas phase when the container _{9 is in an upright position}

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(2) the length of the gas discharge pipe 33 is reduced and

(3) the breakthrough disk is at ambient temperature during operation held so that their accuracy is not decreased.

It has already been indicated that, with d ^u rn inventive device, the second flow limiting and pressure relief valve J> 6 is constructed such that it releases gas at a lower pressure than the first Druckmindereinrichtu-ig 32, as well as with a maximum flow rate which the three to twenty-five times the normal evaporation rate (NER) of the container is preferably at a flow rate of five to twenty times the NER. Similarly, in the method described, in the upright gas delivery position, steam is vented through f ^ ne passage from the highest zone of the container at a flow rate which is limited to a maximum rate which is between three and twenty-five times NER, preferably five. 'up to twenty times NER.

The part having the gas venting circuit for all positions, the lower pressure should preferably serve dasu to prevent an overpressure _s when the container 10 is in the normal upright liquid dispensing position _f, and if a sufficient thermal insulation 1? is present and if there is a low absolute pressure in the evacuable space, in the order of magnitude of 10 · * mm Hg ₅ under these circumstances

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only needs about three times the maximum gas venting rate of NER in order to have a protection against the possibility that the insulating vacuum is partially lost due to leaks goes, so that the evaporation rate increases significantly above NER. Of course, the first venting device 32 acts as a support for the second pressure venting device for higher pressures Flow reducing device 36 for lower pressure, yes the operation of the latter device is to be avoided, except in cases when unexpectedly high vent loads for liquefied gas occur, for example when the container IO

unintentionally brought into a non-vertical position "is This is because such an operation pretty f! chr ₅ all virtually releases the entire contents of the container, resulting in an approach of frost (and thus loss of effectiveness) on the outer surface of the first evaporator 26 leads and can even lead to the fact that the venting device 32 freezes solid.

The maximum gas venting rate of the second flow restrictor and Pressure relief device 36 does not exceed twenty-five times the container NER, thus eliminating the need for an inconveniently large and heavy second evaporator 35 that would be unsustainable. The maximum gas vent rate lies in the range from 5 to 20 and represents a preferred compromise of the previous considerations.

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Another requirement for the apparatus in question is that the second evaporator must be provided with a heat transfer capacity which is not greater than one third, and which is preferably not greater than one fifth of the heat capacity of the first evaporator. The capacity of the latter is determined by the need to heat the vapor emitted from container 10 in the inverted liquid fill position, thereby avoiding pressure build-up and discharge of cold vapor during rapid liquid fill, ie less than ¹ minute. The first evaporator 26 must be relatively large, ⁽¹ I 1 / inch), for example tubes of a total length of 5.20 m and 6.3 rom diameter without cooling ribs, and takes the most space available within the container 10 surrounding the housing a. Under these circumstances, the second evaporator 35 can only be a fraction of the size of the first evaporator, because otherwise the overall arrangement would be too large and heavy for transport.

n.

It has been said that in the method of the present invention, when the container is in a non-vertical position, a second liquid is dispensed from the normally lower end ^ at the same time as the first liquid is dispensed from the normally upper end of the container as the container pressure increases to a second higher above Relief pressure lying at atmospheric pressure increases, which is between 1.08 and 1.75 times the first

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atmospheric relief pressure, measured on an absolute basis, is, but preferably between 1.15 and 1.4 times Value of the first relief pressure. The mentioned lower limit of 1.08 and preferably the limit of 1.15 is necessary to ensure that the first relief valve 32 with the higher pressure is only effective when the pressure relief capability the second relief device 36 for the lower pressure is exceeded. This lower limit represents manufacturing and grading tolerances for the commercially available ones Pressure relief devices are »

The above-mentioned upper limit of 1.75 and preferably 1.4 is due to the increased mass flow through the branch line 3 ^ and due to the relief circuit for lower pressure when the tank pressure rises to a second, higher, above atmospheric pressure relief pressure »When the If the pressure difference between the settings of the two relief valves 32 and 36 becomes too great and the first end 17 of the line 16 for gas venting and liquid filling is immersed in liquefied gas, the heat transfer capacity of the second evaporator 35 would be exceeded. This is due to the increased flow that causes cold gas to reach the second relief valve 36 and possibly freeze »

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It should also be recalled that in the apparatus discussed here, the second evaporator is equipped with a heat transfer capacity sufficient to evaporate the liquefied gas entering its inlet end and to discharge the gas at a rate equal to the 1st , 0 ^ to 1.30 times the maximum venting rate of the second flow restriction and pressure relief valve J>& , but preferably the values should be 1.08 to 1.2 times the maximum venting rate. The increase in pressure between the adjustment of the two vent means also generates an increase in the Durchfluförate through the ventilation circuit of lower pressure, such as in de _t n previous section was carried out. This increase in flow rate is most likely to occur when the. The container is in a non-vertical position and the first end 17 is immersed in liquid. The lower limit of the flow rate ratio reflects the need for a sufficient difference between the relief pressures of the two devices, as discussed above. The upper limit of the flow rate ratio serves to avoid exceeding the heat transfer capacity of the second evaporator 35 due to the increased liquid flow.

Fig «-2 explains the filling of the dispensing container 10 with liquefied Gas from a storage container 40. The storage container 40 has a similar basic construction as the container 10,

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but is usually larger and comprises an outer housing 41 and an inner vessel 42 to contain the liquefied gas with an evacuable space therebetween which is preferably filled with thermal insulation 43. Liquefied gas can be introduced into the storage container 40 through a supply valve 44 and an inlet line 45 which is also provided with a safety relief valve 46. This liquid is preferably preheated before or during introduction so that the liquid is saturated at the operating pressure desired for dispensing the liquid into the container 10, as described, for example, in US Pat. No. 2,951,348. For example, the desired oxygen vapor pressure 2.0 kg / c where: n is saturated, liquefied oxygen at -l68 ° C (105 ⁰ K) liquid contents are introduced into the reservoir of 17.5 liters, equipped with an isolation of alternate layers of aluminum foil and glass paper 10 mm thick corresponding to a thermal conductivity of 0.062 cal / hr / m / ° C (0.040 XlO " ⁵ Btu / hr. χ ft. ² χ ° F / ft.) in the evacuated room at a Density of approximately 60 foils / in. Alternatively, supercooled liquid oxygen can be introduced into the same reservoir and, with gentle, occasional shaking of the reservoir, a sufficiently saturated pressure can finally be obtained to operate the system If the pressure is much lower than 2.8 kg / cm above atmospheric pressure, a corresponding change must be made

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can be made in the setting of the liquid sensor when the pneumatic system of Fig. 3 is used. It will shown in greater detail below.

Another way of ensuring that the steam pressure in the container 41 for the discharge of liquefied gas into the container 10 is allowed into it at the desired pressure and temperature, means can be provided to controllably introduce external heat into the container 4l. More accurate in other words, when the vapor pressure falls below a predetermined limit, the liquid can be controllably flowed through line 50 be pulled by opening a valve 51 in this line whereupon the liquid evaporates in the evaporator 52 and returned as vapor to the upper end of the inner vessel 42 will. A gentle shaking of the contents prevents layering and the result is a uniformly saturated one Condition over the entire body of liquid. Of course, the pressure build-up circuit just described is 50-52 not required if the liquefied gas to container 40 is poured into the preheated saturated container.

To fill the container 10, this is turned over and with his brought the upper end into flow communication with the reservoir 40. The latter is with a liquid dispensing line 53 provided, which has a first end 54 which is at the bottom

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end of the inner vessel 42 opens, as well as with a second end 55 which opens outside the top of the container. A first coupling device 56 is at the second end 55 of the conduit provided and connected to second coupling devices 19, preferably in such a way that when manufacturing the connection creates a fluid connection.

Liquefied gas flows upwardly through the conduit 53, through the second coupling means 56, through the first coupling means 19 through conduit means 16 for the vapor vent, and the liquid filling and then exits from the first end 17 dev latter in the lowest zone of the inverted container 10 with the lowest zone usually representing the top i4. The line 16, which previously served as a gas vent during the liquid storage and dispensing operation and during the gas supply operation, is now used to fill the liquid.

As the filling of liquid proceeds, vapor of the liquefied gas must be in the highest zone of the inverted container 10, which normally represents the lower end 15, should be dispensed to prevent the pressure in the 15 µm area becomes a value lower than the pressure in the container 4l, which is greater is than the hydrostatic pressure to be overcome. To ensure, that such a pressure difference occurs becomes steam

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from the container 10 to the first end 22 of the line 21 for liquid extraction and gas venting, so that it flows through the reversed circuit 24 past the liquid sensing device 25, continues to be heated in the first evaporator 26 and is finally released into the atmosphere through the open gas vent valve 27. Correspondingly, during the liquid filling operation, the reverse circuit 2h, which was previously used during the gas supply operation for liquid discharge and evaporation, is now used for gas venting.

The liquefied gas discharged from the inverted container 10 during the liquid filling operation is sensed by the element 25a. When the container 10 is filled with liquid, the liquid to penetrate into the reverse control circuit 2 ^l \ for liquid evaporation and gas venting begins. The element 25a detects the presence of liquid before it reaches the first evaporator 26 and this detection is used as a signal to automatically close the gas vent valve 27. For this purpose, for example, the wire 28 that receives an electrical signal, the controller 29 and a wire 30 that transmits an electrical signal can be used. Once the valve 27 is closed, the pressure difference between the containers 10 and 40 drops to a value which is substantially equal to the hydrostatic pressure which is generated by the

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Difference between the two interfaces between liquid and gas in the two containers is determined. When this occurs the fluid transfer ends. The first coupling device 56 and the second coupling device 19 are now separated, the container 10 is rotated to its normal upright position and the previously described gas supply operation resumes recorded. The first and second coupling devices 56 and 19, respectively, are preferably of the type that automatically closes, when it is disconnected, so that in line 16 for gas venting and liquid filling and in line 53 no shut-off valves are necessary for the liquid discharge.

FIG. 3 illustrates another particularly preferred system for controlling liquid loading termination, this being System is based on the fact that a pressure rise occurs when circuit 2-4 detects fluid, and that instead of an electrical one Signal transmission a pneumatic signal transmission to the gas vent valve 27 is used. The 10. container for the Storage and delivery of liquefied gas, the line device 16 for gas venting and liquid filling, and the line device 21 for the removal of liquid and gas venting are essentially identical to the corresponding ones Devices in Fig. 1 and operate in the manner already described.

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The control circuit 24 for liquid evaporation and gas venting according to FIG. 3 comprises a liquid control line of smaller diameter which, with its one end acting as a liquid filling device 25, connects to the second end 23 of the line 21 for liquid removal and gas venting outside and above the normally upper end 14 of the Container 10 is arranged upstream of the first evaporator 26. A smaller third evaporator 62 is arranged in the control fluid line 60, and a first flow restrictor, such as a nozzle 63, is arranged between one end 25 of the line and the second evaporator 62. The second flow limiter 64 is between the third evaporator 62 unc? the other end 65 of the fluid control line 60 is arranged. This other end 65 is connected to the gas vent valve 27 which, as shown, is preferably a four-way valve. With such a valve, during the filling of the container 10 with liquefied gas, venting can be carried out simultaneously through a larger venting gas circuit and through a smaller venting gas circuit. When the liquid filling is completed, the four-way valve 27 closes the two separate gas venting circuits from communication with the atmosphere by connecting them together. More specifically, a first flow passage is created through the valve which connects the first inlet port 27a and the first outlet port 27b and which allows a major portion of the vent gas to be vented

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the primary evaporator 26 enables. A second throughflow opening is also formed which connects the first inlet opening 27c and the second outlet opening 27d and enables a smaller proportion of the deaeration gas to be vented through the control fluid line 60. To end the liquid filling, the flow openings are placed parallel to one another so that the e: * ste and the second inlet opening 27a or 27c are connected to one another. A pressure transmission line 66 with a small diameter has one end which is connected to the control fluid line 60 between the flow restrictors 63 and 64, preferably between the third evaporator 62 and the second flow restrictor 6k , while the other end is connected to the pneumatic actuator 67, which is mechanically connected to the ^ ler-Weger valve 27. The size of the first flow limiter 63 and the second flow limiter 6k is selected so that a pneumatic signal is transmitted through the line 66 to close the valve 27 when the pressure in the control fluid line 60 between the third evaporator 62 and the second flow limiter 6 ¹ J rises to a certain level.

When the container 10 of FIG. 3 and the control ^{circuit 2 2} I for the liquid evaporation and gas venting are in the inverted position with the bottom upwards, and with a storage container for liquefied gas in the one analogous to FIG

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Way connected, the four-way valve 27 is opened manually the open position. The vent gases flow from the inverted container 10 through both the larger and the larger one smaller vent circuit to atmosphere. During this filling operation for liquefied gas, the resistance is for the fluid flow in the smaller gas vent circuit is much greater than that in the larger circuit due to the first and second flow restrictors 63 and 64, respectively, most of the vent gas flows through accordingly the first evaporator 26. During the subsequent gas supply operation, all of the liquefied gas flows from the upright container 10 is dispensed by the first evaporator 26.

When the inverted container 10 of FIG. 3 with liquefied gas is filled, this liquefied gas begins to exit through both the larger and smaller vent circuitry. Again, most of the liquid will flow through the larger circuit including the first evaporator 26, evaporated there and finally released into the atmosphere as a warm gas. Some of the overflowing liquid is carried into the control fluid line 60. Compared with the previously flowing cold gas, the first flow restrictor 63 allows relatively more fluid mass than liquid with one much lower pressure drop and delivers this fluid

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to the third evaporator 62. The liquid therein is rapidly evaporated and warmed up and increases in volume several hundred times. Suddenly a much larger volume of gas flows through the second flow restrictor 64, which is now the main resistance in the line 60 is. The pressure in this line between the first and second flow restrictors 63 and 64, respectively increases abruptly to compensate for the new flow of inlet liquid (rather than inlet gas). This pressure increase will transmitted through the line 66 to the pneumatic actuator 67, the four-way vent valve 27 in a closed position brings. When this occurs, the pressure levels in the supply and dispensing containers 10 and 40 and in 'len are equal to one another associated fluid diversions, with the exception of the aforementioned hydrostatic pressure, and the liquid filling stop.

The elements of the control circuit 24 for the liquid evaporation and gas vent are sized to provide the pressure level necessary to operate the pneumatic system to close the gas vent valve 27 easily and reliably within the permissible pressure limits for the containers 10 and 40 is obtained. Furthermore, the circuit elements are preferably sized so that the liquid sensing response is sufficient is fast to prevent liquefied gas spillage from vent valve 27. For example is the

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first flow restrictor 63, preferably of such a size that, when the liquefied gas, the control circuit 24 for the Liquid evaporation and gas venting achieved at the end of the liquid filling, only a small amount of liquid through passes through the limiter and the capacity of the third evaporator 62 is not exceeded * The second flow limiter 64 downstream of the evaporator 62 is of such a size that a sufficient flow resistance of the now evaporated liquid is opposed so that the gas pressure level between the two flow restrictors quickly increases to the desired level increases and produces a reliable signal.

The advantages of the invention have been demonstrated in an experiment in which a dispensing container for liquefied oxygen and the Gas venting circuit for all positions, which is shown schematically in Fig. 3 and that in the assembly drawings of Figures 5 to 7 is shown · in a horizontal position

• f.

has been brought. The container was provided with an insulation, which consisted of alternating layers of fiberglass paper and aluminum foil, and which was wrapped around the inner vessel as thermal insulation, with approximately I ¹ J layers

all in all

with a thickness of / about 9.5 mm were used. The isolation room was also with a molecular sieve zeolite adsorber and equipped with a hydrogen-selective getter material and evacuated to an absolute pressure of less than 10 "· ^ mni Hg.

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The thermal conductivity of the insulation at this pressure was approximately 0.04 cal / hr / m / ° C (2.5 x 10 ~ ⁵ Btu / hr. X ft. X ° P). The oxygen gas pressure inside the container and the container weight were recorded as a function of time, and the results were shown in FIG. The container contained approximately 1.5 kg of oxygen when full, its total weight

's

was approximately 7.1 kg. The second evaporator 35 (substantially the entire length of line 3 ¹ J for low relief pressure) comprised approximately a six and a half inch long tube of aluminum with an outside diameter of approximately 6.35 mm and a wall thickness of 0.81 mm. The second relief valve 36 for low pressure was adjusted to ¹ 1.36 kg / cm pressure, the Durchflußbenchtänkungselement 36a consisted of a porous disc of 2.5 mm thick sintered stainless steel with a porosity of 2 '% and an average pore size of 7 to A very similar and successfully used restrictor 36a had the following flow properties and is commercially available as "Pressure Snubber / Number 0014-8CIl" from Pacific Sintered Metals Company, Gardena, California.

Flow Characteristics Flow Rate

Overpressure in kg / cm ² l / min. (O_ gas)

Upstream Downstream

0.35 0.0035

0.7 0.0038

1.05 0.0044

1.4. 0.0050

ο, 76 ι, 92 2, 33

δ'09840 / 0350

- 3β -

The first evaporator 26 was made from aluminum tube 6.35 mm (0.25 inch) outer diameter and 0.81 mm wall thickness, so that the heat transfer capacity of the second evaporator is approximately 0.12 times the capacity of the first evaporator (based on comparison of the outer surfaces)

wore. The high pressure relief valve 32 was set to 4.71 kg / cm " overpressure set «However, it is preferable to have a wider range of pressure settings between the first and the second To maintain relief valve 32 or »36, whereby typically

2 2

see settings 4.78 kg / cm and 3.66 kg / cm overpressure

With reference in particular to FIG. 4, it should be said that it took about 1 hour for the container pressure to be pulled after the container had been pulled the horizontally aligned container the setting of 4.36

kg / cm has been reached for the second low pressure relief valve 36 as shown by the vertical dashed line (a). During this initial period there was of course no loss of stored oxygen so the total weight shown in the lower curve remained constant. During the subsequent 1 1/2 hours resulted in an average loss of oxygen by boiling of 1.52 liters of oxygen per minute, the leaked through this valve, wherein the tank pressure to 4.71 kg / cm, the setting of the first relief valve 32 for high Pressure, increased. The valve

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opened as shown by the vertical dashed line (b) is and both relief valves were now open for the following hour and the average oxygen evaporation loss through these valves was 6.84 liters of oxygen per minute, after a total time of 210 minutes, see vertical dashed line (c), the second end 22 of the line 21 for liquid extraction and gas venting was nicat more immersed in liquid oxygen »After a period of total. 254 minutes, see vertical dashed line (d), v; ar the oxygen boiling rate equal to the normal evaporation rate at an overpressure of 4.36 kg / cm for the container in vertical upright position.

At no time was liquid oxygen exposed during this test submitted. The total boiling of gas reached the value of 0.82 kg. 0_; thus a loss of about 54 # had occurred, however, 7 kg of 0 “remained in the container. The remaining amount of liquid corresponds to the respiratory atmosphere of 1 hour duration with the relatively high requirement of 7 liters of oxygen per minute for a patient with lung or heart problems. This amount roughly corresponds to the maximum rate at which oxygen can according to U.S. Patent 3,199,303.

The above results show that with the gas relief circuit according to the invention for all positions of the dispensing container for

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liquefied gas remains operational even if it is placed horizontally for an extended period of time. It was shown, that the gas relief circuit has the ability for all positions to prevent the release of liquefied gas, without sacrificing the overall size of the arrangement for liquid storage, evaporation and gas venting control this additional gas vent circuit would be enlarged for all positions.

In the following table I are the essential sizes of the arrangement specified, consisting of a container for the storage and delivery of liquid oxygen, from the circuit for the Evaporation and for gas vent control, as well as from the previously described control circuit for gas venting, which is effective in all positions.

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Tabel

characteristic

Essential sizes of the arrangement

data

Dispensing container 10:

Contents: liquid oxygen Contents: equivalent oxygen gas inner diameter wall thickness

height

Overall arrangement:

height

broad

Depth·

Oxygen gas withdrawal rates (through valve 31):

normal evaporation rate

Line for gas venting and liquid filling inner diameter outer diameter

Line 21 for fluid extraction and gas venting
inner diameter outer diameter

First evaporator inner diameter outer diameter length

Second evaporator inner diameter outer diameter length

First nozzle 63
diameter

Second nozzle 64
diameter

ι, 36 kg cm 1026 1 46-0.76 mm 10 cm ο, cm 20th cm 34 cm 24 14th

1,2,3,4,5,6,7 1 / min. 0.15 kg O "/ day

2.9 mm 3.2 mm

4.25mm 4.76mm

4.7 mm 6.3 mm. 4.9 to 5.5 m

4.7mm 6.3mm 6l cm

0.4mm 0.66mm

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Table I feature continued

Dater

First. Nozzle 63 diameter

Second nozzle 64 diameter

Second relief valve set overpressure

First relief valve set overpressure

Breakthrough disk setting overpressure

maximum venting rate for second overload valve / normal evaporation rate

Heat transfer capacity from second evaporator to first evaporator

0.4 mm 0.66 mm 3.66 kg / cm 4.78 kg / cm 7.38 kg / cm

17.5 1 / 8.5

Heat transfer capacity of the

second vaporizer for vaporizing and heating up the liquid oxygen:

Liquid oxygen flow rate / maximum venting rate for two oars

Relief valve * 1.15

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- 13 -

In the assembly drawings of FIGS. 5 through 7, the same have been made Reference numbers are used for the elements which correspond to the corresponding elements in the schematic drawing of FIG. 3, and the system works in the manner already described. The entire functional arrangement is within of a carrying case 70 »The phase separation arrangement also secures 71 that any entrained liquid accidentally discharged through valve 27 during a fill does not is sprayed outside of the carrying case 70. This liquid is separated from the high-speed steam and falls harmlessly on the bottom of the envelope.

S09840 / 0350

Claims (1)

- 44 - Claims / IJ method of supplying gas from a thermally insulated Dispensing container for the storage and dispensing of liquefied gas, the container having an upper and a lower Has end and from an upright output position-in an inverted filling position can be inverted and in which gas liquefied during the gas delivery operation due to is pressed upwards by the vapor pressure above the liquid from the lowest zone of the container, flows off and from is discharged from the top of the container and evaporated by ambient heat to form a gas source, characterized in that in the upright • gas delivery position (a) when a gas is not supplied, steam is vented through a passage from the highest zone of the container at a flow limited maximum rate which is three to twenty-five times the normal rate of evaporation of the container, that the steam is warmed by ambient heat and the heated steam is released when the container pressure is above a first relief pressure above atmospheric pressure; and C υ;? ^ 2 (b) when gas is supplied, liquefied gas flows through vapor pressure above the liquid level upwards from the lowest zone of the container, dispensing this liquid from the upper end of the container, Evaporation of the thus dispensed liquid by ambient heat, heating of the vapor and extraction of the heated one Steam as the gas supply and simultaneously venting the steam in accordance with step (a); and (c) in the non-vertical position so that the liquid flows through the passage of step (a) and the Container gas pressure above the first lowest, above atmospheric pressure lying relief pressure increases: dispensing the first liquid from the normally upper one Terminating the container at a first low flow limited rate, vaporizing the dispensed first liquid, Warming up the cold first steam to ambient temperature and releasing the first heated one Steam at a pressure above the first lowest, above atmospheric, relief pressure; and when the case pressure rises to a second, higher relief pressure above atmospheric pressure, that is 1.08 and 1.75 times the first above atmospheric relief pressure 509840/0350 measured on an absolute basis, is simultaneous dispensing of the second liquid from that normally Bottom end of the container with a second, higher one. Rate, vaporize and dispense the second liquid by atmospheric heat, warming up the cold second steam and releasing the warmed up steam at one Pressure that is above the second relief pressure, which is above atmospheric pressure * 2. The method according to claim!., Characterized in that that the steam is vented during step (a) at a flow limited maximum rate, those between five and twenty times normal vaporization rate of the container is, 3. The method according to claim 1, characterized in that that the second, above atmospheric pressure relief pressure between the 1.15 and the 1.4 times the first relief pressure, which is above atmospheric pressure, measured on an absolute Base* 509840/0350 Apparatus for carrying out the method according to claim 1, having a storage and supply system for liquefied gas, including a thermally insulated storage and dispensing container for liquefied gas, which has an upper and a lower end and is reversible between an upright dispensing position and an inverted filling position with conduit means for gas venting and liquid filling with a first end which opens into the container at its upper end, and with a second end which lies outside the container at its upper end, with conduit means for liquid extraction and gas venting, with a first End opening inside the container at its lower end and having a second end outside the container at its upper end with a reversible control circuit for liquid evaporation and gas venting external to the container and on one first inlet end with the second n end of the line means for the liquid extraction and the gas venting is connected and comprises a first vaporizer, with gas flow control devices between the first vaporizer and with the other end of the circuit for the gas discharge, characterized by a gas relief circuit for 'the container, which in all positions is effective, and the
Ib.) A first Druokentlastungssinricbtiang between the. he- ϊ- * " ί I - l | 8th - includes, furthermore (b) Manifolds one end of which is in flow communication with the second end of the conduit for gas venting and liquid filling, Farther (c) second flow restriction and pressure relief devices in the branch pipe (b), which are designed to vent gas at a lower pressure as the first pressure relief device at a maximum rate three to twenty-five times is the normal evaporation rate of the container, and with (d) a second evaporator, which at its inlet end is in flow connection with one end ίύΓ branch line (b), and in flow communication at its discharge end with the second flow restriction and Pressure relief device, and which is so constructed that its heat transfer capacity is not greater is than one third of the heat transfer capacity of the first evaporator and is sufficient to liquefy Vaporize gas entering its inlet end and exhaust the gas at a rate 1.4 to 1.3 times is the maximum venting rate of (c). 509840/0350 5. Apparatus according to claim 4, characterized in that that the second flow-restricting and pressure-relieving device (c) is constructed so that gas vented at a maximum rate five to twenty times the normal rate of evaporation from the container amounts to. 6. Apparatus according to claim!, Characterized in that that the second evaporator has a heat transfer capacity which is not greater than one fifth the heat transfer capacity of the first evaporator. 7 »Device according to claim 4, characterized in that ■ shows that the heat transfer capacity of the second evaporator is sufficient to evaporate liquefied gas entering the inlet end and this gas to spend at a rate between 1.08 and 1.25 times is the maximum venting rate of (c). 8 «Device according to claim ^, characterized in that that a pressure relief valve and a separate flow restriction element in flow communication coexist that the second flow restriction and make up pressure relief device (c). 509840/0350 9. Apparatus according to claim 4, characterized in that that a pressure relief valve and a porous member in downstream flow communication with the container pressure relief valve constitute the second flow restriction and pressure relief device (c). 10 »Apparatus according to claim 4, characterized in that the second flow restriction and pressure relief device is constructed so that gas is vented at a maximum rate which is five to twenty times the normal rate of evaporation of the container, and that the second evaporator is such a Heat "has a thermal capacity no greater than one fifth of the heat transfer capacity of the first evaporator and sufficient to vaporize liquefied gas entering its inlet and releasing that gas at a rate between 1.08 and 1 , 25 times the maximum venting rate of (c) with a pressure relief valve and porous member disposed in downstream flow communication with the pressure relief valve _s and including the second flow restricting and pressure relief means (c). 509840/0350 Blank page