Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~ e illvelltion relates ~o a mctho(l or ~)roc(~;sin(3
supercooled fluids before the supercooled fluids are
packaged. The invention particularly relates to methods
of processing supercooled fluids to assure that the fluids
will be retained in a fluid state until such time as it is
desired to generate heat from the supercooled fluid. The
invention further relates to a method of processing super-
cooled fluids to assure that the generation of heat ~rom
~` the supercooled fluid will occur at a particular temperature.
~10 ~ The method also relates to supercooled fluids produced by
such methods.
There are many different instances where it is
desirable to generate heat for an extended period of time
at a substantially constant temperature. For example, it is
desixable to generate heat at a particular temperature for
an extended period of time w}ien babies are to be bathed or
otherwise administered to~in a hospital. It is further
des1rable to generate heat at~a~particular temperature at
the heél of a baby in order to facilitate the withdrawal
20~ of~b~1ood from the~véi~n or a~rte~ry of a baby for purposes of
testlng the physlcal well-being of the baby. ~ -
Various attempts have been made in the past to
enerate heat at a predetermined and 5ubstantially constant
temperature for an extended period of time. Until recently,
; it has~been difficult to provide such a generation of heat.
For example, chemicals have been mixed to produce an
exothermic chemical reaction but the heat generated has
peaked quickly at a relatively high value above the temper-
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1 ature desired and has then decreased progressively to a
2 temperature below that desired. When the temperature of
3 the chemical reaction is above that desired, the patient
4 can become burned or produce other detrimental effects.
When the temperature of the chemical reaction is below
6 that desired, the patient does not receive beneficial
7 results of an optimal nature.
9 Supercooled fluids have been known for some time
to generate heat at a substantially constant temperature.
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11 The supercooled fluids melt from a solid state to a liquid
I2 state at a particular temperature and then become triggered
13 from thé liquid state to a solid crystalline state at the
14~ particular temperature. During the time that the supercooled
fluid becomes triggered to the crystalline state, it generates
16 heat~.
r ~ 17
18 Although the desirable characteristics of supercooled
l9~ fluids have been known for some time, supercooled fluids have
20 ; had limited use. This has resulted~from certain disadvantages
21 ~in the supercooled 1uid. For example, although supercooled
22 fluids theoretically generate heat at a substant~ally constant
; 23 temperature, the temperature cannot always be pre-established
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24~ with great accuracy. As an illustration, under some conditions,
25 ~ a supercooled fluid wlll generate heat at a temperature of
26 118F. and at other times the supercooled fluid will generate
27 heat at a temperature of approximately 120F. When a precise
28 temperature is to be provided such as for medicinal purposes,
29 such variations ln temperature can cause great concern and
be somewhat detrimental to the well-being of a patient.
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1 There are other disadvantages to the use of super-
2 cooled fluid. Supercooled fluids tend to be somewhat unstable,
3 particularly when subjected to relatively low temperatures.
4 For example, when supercooled fluids tend to be subjected to
temperatures below the freezing point of water, they tend to
6 become automatically triggered from the fluid state to the
solid crystalline state.
~, g This invention provides a method of processing
supercooled fluids to overcome the above difficulties. When
li processed by the method constituting this invention, the fluid
12 tends to remain stable in the liquid state for extended periods
~ 13 of time, even when the fluids are subjected to temperatures
;~3~ 14 below the freezing temperature of water. Furthermore, the
fluids become triggered from the liquid state to the solid
16 crystalline state at a substantially constant temperature,
17 the value of which can be predetermined. The supercooled
18 ~ f~luid may constitute sodium thiosulfate pentahydrate.
20 ~ When supercooled~fluid lS processed by the method
constituting this ~invention, a suitable material such as
22 ethylene glycol may be added to the supercooled fluid to
25~ enhance the stability of the supercooled fluid and to provide
24 for the generation of heat in the supercooled fluid at a
desired temperature less than the melting temperature of the
26~ supercooled fluid. The mixture of the ethylene glycol and
27 the supercooled fluid is then heated to a relatively high
28 temperature considerably above the melting temperature of
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29 the supercooled fluid. With the mixture at the particular
temperature, water is added to provide a specific gravity of
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a particular value and a suitable material such as sodium
hydroxide or sodium carbonate is added to provide a particular
pH.
The mixture may then be poured into rupturable
packages while being maintained at the particular temperature.
The mixture is then allowed to cool slowly in the rupturable
packages to ambient temperatures and a trigger is added in a
separate container after the cooling of the mixture to ambient
temperature. The container then holds the package of the
supercooled fluid and the triggex in isolated relationship to
each other. The trigger may constitute a suitable material
such as sodium borate pentahydrate.
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More particularly, this invention provides a method of
producing thiosulphate having properties of crystallizing in an
aqueous solution in more than one crystalline phase and having
superior energy-transferring properties in the pentahydrate
phase and having properties of melting and crystallizing in a
particular temperature ;range to provide the pentahydrate phase
and having properties~of providing a second crystalline phase
20; with a second range of melting temperatures different from the
particular temperature range, including the following steps:
' heating the sodium thiosulphate to a temperatuxe of at
; ~ least 16SF. for a suf~iaient period of time to melt all of the
crystals in the sod~um thiosulphate,
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maintaining the pH of the fluid at a particular
alkaline value, and ~
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maintaining the specific gravity of the fluid at a
particular value.
In the drawings:
Figure 1 is a perspective view, partially broken
away, of one embodiment of the invention; and
Figure 2 is a sectional view substantially on the
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line 2-2 of Figure l; and
Figure 3 is a schematic view showing apparatus used
to provide the method constituting this invention.
In one embodiment of the invention, a pouch or
packet 10 contains a supercooled fluid 12. The pouch is
provided with a rupturable seal 14 along one edge, the seal
being ruptured when subjected to a particular pressure such
as results from a manual pounding or a manual squeezing
~ of the pouch. The pouch 10 is disposed in a container 16
S- ~ 10 which also contains a trigger material lB for the super-
~cooled fluid. As will be seen, the trigger material 18 is
disposed in isolated relationship to the supercooled fluid ~
; in the pouch 10.~ -
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1 A number of different materials can be used as the
2 supercooled fluid 12. These materials include sodium sulfate
3 decahydrate, sodium thiosulfate pentahydrate (hypo), sodium
4 hydrogen phosphate, sodium chromate decahydrate, calcium
chloride hexahydrate, magnesium chloride with water, magnesium
6 nitrate hexahydrate and urea/ammonium nitrate. The trigger
material 18 in the container 16 may be sodium borate.
g When the pouch 10 is ruptured, the supercooled fluid
12 in the pouch is mixed with the trigger material 18 and
1i becomes triggered from the liquid state into a solid crystalline
12 state. This causes heat to be liberated at a substantially
13 constant temperature during the time that the supercooled fluid
14 is being converted into the crystalline state. The conversion
f the supercooled fluid into the crystalline state occurs
16 over an extended period of time so that the temperature produced
17 at the surface of the container 16 is substantially constant
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for this extended period of *ime.
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20~ The particular temperature obtained ~y the triggering
21~ Of the supercooled fluid to the crystalline state can be con-
22 trolled by the addition of another material into the supercooled
23 fluid to form a mixture. ~or example, when ethylene glycol is
24 added to hypo, the temperature produced decreases in accordance
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~ 25 with the amount of the ethylene glycol added. When the mixture
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i~ 26 of the hypo and the ethylene glycol contains approximately ten
27 percent ~10%) of the ethylene glycol by weight, the temperature
28 produced from the triggering of the hypo into the crystalline
29 state is approxlmately 104F. This constitutes a decrease
from a temperature of approximately 116F. which is produced
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1 when the fluid in the pouch 10 is substantially only hypo.
2 A relatively small amount of ethylene glycol such as less
3 than approximately two percent (2%) by weight is also
effective in the hypo to limit the size of the crystals
produced from the hypo when the supercooled fluid is
6 triggered into the solid state. The amount of ethylene
7 glycol to approximately two percent (2%) tends to control
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8 the size of the crystals produced by triggering the super-
9 cooled fluid. The use of ethylene glycol for the above
~0 purposes is disclosed in co-pending application Ser
,; 3~ ~9
1i No. ~r64~ filed by Gustaf O. Arrhenius on l~ Lr-
12 ~ and assigned of record to the assignee of record of
13 this application.
1~
In order that the mixture in the pouch 10 is stable
16 under a wide range of conditions and that it will produce a
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~ 17 ~ predetermined temperature when triggered, the mixture is
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18 processed by the method constituting the invention. As a
lg~ first step, the mixture is disposed in kettles 20 made from a
;20~ suitable material such as stainless steel so that the super-
21 cooled fluid in the mixture will not become contaminated.
22 The kettle~ 20 may be electrically heated and may be provided
:
23 with closed tops to assure that contaminants are not introduced
24 into the kettles while the mixture in the kettles is processed.
The kettles are then heated electrically so that the mixture
26 in the kettles reaches a suitable temperature considerably
27 above the melting temperature of the supercooled fluid. For
28 example, the mixture may be heated to a suitable temperature
29 such as approximately 180F. An agitator 22 may be operated
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1 from the time that the melting of the supercooled fluid in
2 crystalline form is initiated. By heating the mixture
3 containing the supercooled fluid to a temperature consider-
4 ably above the melting temperature of the supercooled fluid
~ 5 and agitating the mixture during the heating operation, the
; 6 melting of all crystals, even those of minute size, is
7 facilitated. This assures that the supercooled fluid will
8 remain in liquid form even after being cooled since the
g minutes crystals might otherwise operate to initiate the
0 process of crystallization. Furthermore, by heating the
11 supercooled fluid at a temperature of approximately 180F.,
`~ ~ 12 the supercooled fluid tends to become pasteurized and thereby
13 inhibit bacterial growth.
- 14
When the temperature of the mixture has reached a
16 value such as approximately 180F. and the melting of the
17 crystals in the supercooled fluid at substantially that
18~ ~temperature has been completed, water is added at that
~l9~ temperature to~adjuYt the specific gravity to a particular
20 ; value~such as 1.595 + 0.005. ~The specific gravity of the
2~ mixture is adjusted in this manner to assure that the super-
22~ cooled fluid will remain in the supercooled state after the
23 fluid has been cooled to ambient temperatures. If insuffiaient
24 water is added to the mixture to provide the particular value
25~ desired for the specific gravity, the supercooled fluid will
26 tend to become self-triggered into the crystalline state,
2~ particularly when the supercooled fluid becomes cooled.
28 Furthermore, the insufficiency of water in the mixture causes
29 the supercooled fluid in the mixture to become crystallized
at a temperature of approximately 120F. instead of 118F.
31 which is normally the melting and crystallizing temperature
32 of hypo.
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1 It has been recently found that minute crystals
2 f the hypo in the dihydrate phase normally exist in hypo
3 which has been supercooled. Such minute crystals tend to
serve as nuclei in triggering the supercooled fluid into
crystals at times when the triggering is not desired. This
6 causes the supercooled hypo fluid to be unstable when the
7 minute crystals of hypo dihydrate exist in the supercooled
8 hypo.
. 9
0 It has also recently been found that the minute
11 crystals of the hypo dihydrate have a melting temperature of
12 approximately 74C. (167F.). In accordance with this
13 invention, a sufficient amount of water is added to the hypo
1~ to insure that aIl of the hypo will be in the e-pentahydrate
phase. It is desirable to maintain the hypo in the -pentahydrate
16 phase since the production of crystals in the -pentahydrate
17 phase causes five (5) to ten (10) times more heat ta be
18 liberated than the production of crystals in any other phase
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l9 including the dihydrate phase.
;21 As will be appreciated, only a sufficent amount
~22 of water is added to insure the maintenance of the hypo in
23 the i-pentahydrate phase If additional water is added
24 above the amount required, some additional assurance may be
provided of maintaining the hypo in the ~-pentahydrate phase
26 but the hypo is diluted so th:at the heat generated by
27 crystallizing a specified amount of fluid is decreased. The
28 hypo is then heated to a temperature of at least 74C. (165F.)
29 for a sufficient period of time to melt all of the minute
crystals of hypo in the dihydrate phase.
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1 The hypo is then cooled in air to ambient
2 temperatures and the hypo is maintained in a stable state
3 at ambient temperatures until it is desired to generate
4 heat by triggering the hypo in the crystalline phase after
such heat has been liberated and utilized. The hypo is
6 converted to the liquid state in the ~-pentahydrate phase
7 by heating the crystals to a temperature of at least 74C.
8 (167F.~ for a specified period of time. No water has to
9 be added if the hypo is maintained in a closed container.
0 In this way, the hypo can be recycled between the liquid
li s`tate with the ~-pentahydrate phase and the crystalline state
~ 12 with the -pentahydrate phase as many times as desired without
ll 13 the addition of any water.
14
The pH of the solution is also adjusted to a parti-
16 cular value during the time that the temperature of the mixture
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17 is maintained at the particular temperature such as approx- ~ `
18 imately 180F. For example, the pH of the mixture is adjusted
19~ to a value of approximately 8 to 8.5. By adjusting the pH to
20~ a value of approximately 8 to 8.5, the hypo is maintained
21~ n the~solution.~ For example, unless the pH of the hypo is
22 maintained at the specified value, the hypo may decompose
23 chemically and ~orm a colloidal suspension of sulfur. ~I~his
24, colloidal suspension of sulfur is capable of nucleating the
hypo at undesired times so that the solution of hypo becomes
26 unstable. Furthermore, a pH of 8 to 8.5 inhibits recrystal-
27 lization of the fluid after the temperature of the fluid has
28 returned to ambient values. The maintenance of the hypo at a
29 pH of approximately 8 to 8.5 has been obtained by adding
controlled amounts of a suitable material such as sodium
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1 hydroxide or sodium carbonate to the mixture. The sodium
2 hydroxide may have a concentration of approximately twenty-five
3 percent (25~) with the remainder constituting water. The sodium
4 carbonate may have a similar concentration.
6 The mixture is then pumped at the elevated temperature
7 of approximately 180F. through pipes 30 made from a suitable
8 material such as stainless steel to prevent contamination of the
9 mixture. The fluid is then introduced to a storage tank 32 also
lO made from a suitable material such as stainless steel to inhibit
11 the introduction of contaminants lnto the mixture. The
12 temperature of the storage tank 32 is controlled to maintain the
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13 solution at a suitable temperature considerably above the melting
14 temperature of the supercooled fluid. For example, the
}~ temperature of the storage tank may be maintained at a suitable
16 temperature of approximately 185F. + 5F.
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18~ The storage tank 32 is disposed above a packaging
l9~machine 34~to Lntroduce the mixture into the packagin~ machine.
20~The packaglnq machlne introduces the fluid into the pouches 10
21~and~fills the pouches with the mixture of the supercooled fluid,
22;water~ sodium hydroxide and ethylene glycol and then seals the
23 packages. The fIuid passing through the packaging machine into
24 the pouches is mai~ntained at a suitable temperature such as
25~approximately 180F. to inhibit bacterial growth in the fluid
26 during the fillin~ and sealing of the pouches 10 and to prevent
27 the reformation of minute crystals which subse~uently serve as
28 nuclei for produclnq crystallization of the supercooled fluids at
29 undesirable times~
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1 The pouches 10 are allowed to cool slowly under
2 ambient conditions to room temperature. This cooling process
3 may last for a period as long as four (4) days. One purpose
4 of this long cooling process is to provide ample opportunity
to determine integrity of the seals provided on the pouch 10.
6 Another purpose is to prevent the supercooled fluid from
7 forming small nuclei for subsequently producing crystallization
8 of the supercooled fluids at undesirable times. If the pouch
9 10 is introduced into the container 16 with the triggering
material 18 during the time that the mixture is above ambient
li temperature, there is a tendency for the supercooled fluid 12
12 to become triggered into the crystallized state. By insuring
13 that the supercooled fluid 12 has been cooled to ambient
1~ temperature before the pouch 10 and the trigger material 18
are inserted into the container 16, any tendency for the
16 supercooled fluid to become triggered into a state of crys-
17 tallization in the presence of the trigger material becomes `~
18 inhibited.
19
The material constituting this invention has certain
21 important advantages.~ It provides a supercooled fluid which
22 produces a substantially constant and predetexmined temperature
~3 to any temperature desired. Furthermore, the material is
24 quite stable at ambient temperatures even when the ambient
temperatures are below 32F., the freezing point o~ water.
26 In this way, the supercooled fluid can be shipped through
27 long distances and can be retained in the supercooled state
28 during such long shipments so that it is ready to be used
29 to generate heat at the end of such shipments. The advantages
of such material result in part from the methods used to
31 produce such materials.
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1 Although this application has been disclosed and
2 illustrated with reference to particular applications, the
3 principles involved are susceptible of numerous other applica-
4 tions which will be apparent to persons skilled in the art.
The invention is, therefore, to be limited only as indicated
6 by the scope of the appended claims.
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