An apparatus for mixing liquids under conditions of zero gravity is disclosed. The apparatus is comprised of a closed reservoir for the liquids, with a means for maintaining a positive pressure on the liquids in the reservoir. A valved liquid supply line is connected to the reservoir for supplying the reservoir with the liquids to be mixed in the reservoir. The portion of the reservoir containing the liquids to be mixed is in communication with a pump which alternately causes a portion of the liquids to flow out of the pump and into the reservoir to mix the liquids. The fluids in the reservoir are in communication through a conduit with the pump which alternately causes a portion of the fluids to flow out of the pump and into the sphere. The conduit connecting the pump and sphere may contain a nozzle or other jet-forming structure such as a venturi for further mixing the fluids

Booth, F. W.

Bruce, R. A.

English

NASA Technical Reports Server

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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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-1) ZERO GESVITY
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U.S. Patent No.
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NASA patent Case No.
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https://ntrs.nasa.gov/search.jsp?R=19730010731 2020-03-17T08:24:18+00:00Z
United States Patent
Booth et al.
tin 3,712,591
[45] Jan. 23, 1973
[54} ZERO GRAVITY LIQUID MIXER
[75] Inventors: Franklin W. Booth, Hampton;
Robert A. Bruce, Newport News,
both of Va.
[73] Assignee: The United States of America as
represented by the Administrator of
the National Aeronautics and Space
Administration
[22] Filed: Nov. 24, 1971
*
[21] Appl. No.: 201,782
[52] U.S. Cl 259/4
[51] Int. Cl BOlf 15/02
[58] Field of Search 259/1, 4, 18, 36, 2, 60
[56] References Cited
UNITED STATES PATENTS
[57] ABSTRACT
3,151,958 10/1964
3,567,185 3/1971
3,608,866 9/1971
3,672,643 6/1972
Bodine 259/1 R
Ross 259/1 R
Susanna 259/1 R
Bodine 259/4
Primary Examiner—Robert W. Jenkins
Attorney—Howard J. Osborn et al.
Apparatus for mixing liquids under conditions of zero
gravity is disclosed. The apparatus is comprised of a
closed reservoir for the liquids, having a means for
maintaining a positive pressure on the liquids in the
reservoir. A valved liquid supply line is connected to
the reservoir for supplying the reservoir with the
liquids to be mixed in the reservoir. The portion of the
reservoir containing the liquids to be mixed is in com-
munication with a pump which alternately causes a
portion of the liquids to flow out of the pump and into
the reservoir to mix the liquids. In a particular em-
bodiment disclosed, the reservoir comprises a sphere
having a flexible diaphragm across the diameter
thereof. A fluid pressure is applied to the upper side of
the diaphragm and the fluids to be mixed are pumped
into a section of the sphere on the opposite side of the
diaphragm from the fluid pressure. The fluids in the •
reservoir are in communication through a conduit
with the pump which alternately causes a portion of
the fluids to flow out of the pump and into the sphere.
The conduit connecting the pump and sphere may
contain a nozzle or other jet-forming structure such as
a venturi for further mixing the fluids. The reservoir
may be completely emptied of liquids stored therein.
13 Claims, 10 Drawing Figures
PATENTED JAH 2 31973 3,712,591
SHEET 1 OF 2
8
FIG.l
r-^—~~—~-^v U C
--=. -^,—_-> ^ SsJ/ «
FIG.3
FIG. 2
FIG.412
BY
2 INVENTORS
FRANKLIN W. BOOTH
ROBERT A. BRUCE
ATTORNEY
PATENTED JAH 2 31973
SHEET 2 OF 2
3,712,591
2'-
44
48
40
^38
H6 H6
FIG.5 63 58 FIG. 6
FIG. 9
FIG.7
BY
INVENTORS
FRANKLIN W. BOOTH
ROBERT A. BRUCE
ATTORNEY
3,712,591
1 2
ZERO GRAVITY LIQUID MIXER sure on liquids contained in the reservoir to facilitate
nRiriNmFTHFiNVFNTioiw the discnar8e of Ae licluids from ±e reservoir. TheORIGIN OF THE INVENTION ,jquids aie SUppiied to the reservoir through a valved
The invention described herein was made by em- supply line connected to the reservoir. The reservoir is
ployees of the United States Government and may be 5 provided with a conduit connecting the interior portion
manufactured and used by or for the Government for of the reservoir which holds the liquids that are to be
governmental purposes without the payment of any mixed with a pump. The pump is one which is capable
royalties thereon or therefor. of applying a second pressure to the liquids to be
mixed. The second pressure is alternately greater than
BACKGROUND OF THE INVENTION 10
 and ,esser Aan ^ first pressure appijed to the liquids
Field of the Invention in the reservoir. The pump causes a mass of said liquids
This invention relates to apparatus for the treatment Iess *an the total mass of the liquids in the reservoir
of liquids in space vehicles. Difficulties have been ex- together with the first pressure source alternately to
perienced in mixing liquids in reservoirs in space vehi-
 I5 flow between the reservoir and the pump through the
cles because of the zero gravity conditions which exist conduit, thus mechanically mixing the liquids,
during flight. Thus one liquid cannot simply be added
 BRIEp DESCRIPTION OF THE DRAWINGS
to a reservoir tank holding another liquid with the
result that the two liquids will mix within a reasonable In the accompanying drawings:
time. The liquids eventually will mix after an indefinite 20 FIG. I is a side sectional view of an apparatus ac-
period of time through molecular action somewhat cording to this invention in which the reservoir is emp-
similar to the mixing phenomenon when two inert gases ty.
are added to a vessel. Under zero gravity conditions, FIG- 2 is a side sectional view of the reservoir of FIG.
there is no stirring action as normally takes place when 1 which is partially filled with liquids to be mixed,
gravitational forces are active on the density gradients 25 FIG. 3 is a side sectional view of the reservoir in
within the liquids. There are many applications where it which the pump means has displaced additional liquid
is impractical or impossible to depend upon the 'n*o the reservoir.
molecular mixing of the liquids, since it is often neces- FIG. 4 is a side sectional view of the reservoir in
sary to thoroughly mix the liquids within a short period which liquids have been partially displaced from the
of time; for example, to react one liquid with another 30 reservoir into the pump means.
such as in the case of employing one liquid to "treat" FIG. 5 is a side sectional view showing an alternative
another liquid. For instance, to sterilize urine con- embodiment of the reservoir.
tained in a holding tank by mixing in a liquid sterilant, it FIG. 6 is a side sectional view of an additional em-
is necessary to mix the liquids within a short period of bodiment of the invention showing a nozzle means in
time. the conduit.
Experiments that have been conducted in the past FIG. 7 is a side sectional view of a further embodi-
show that the diffusion of chromic acid sterilant in ment which includes a venturi in the conduit,
urine contained in a holding tank under zero gravity FIG. 8 is a sectional view taken along the section line
conditions in life support systems takes many days to
 4Q 8—8 of FIG. 7.
reach equilibrium. Such time lapse is unacceptably FIG. 9 is a side sectional view of a further embodi-
long. In addition, since one liquid which it is desired to ment including an alternative form of nozzle,
treat must be used in later applications, it is not feasible FIG. 10 is a sectional view taken along lines 10—10
to employ mechanical agitators within the holding of FIG. 9.
tanks or reservoirs because of the impossibility of
 45
completely emptying such tanks under zero gravity
conditions or in the case of liquids such as liquid ox-
ygen, the presence of agitation devices in a liquid reser- The invention will be further apparent from the fol-
voir can constitute an explosion hazard. Therefore, lowing description of illustrative embodiments taken in
there exists the need for a means of efficiently mixing SO conjunction with the accompanying drawings,
liquids under zero gravity conditions in a reasonable Referring to FIG. 1, reservoir 2 for the liquids to be
length of time and storing the mixed liquids in a reser- mixed is shown in the form of a transparent acrylic
voir which can be completely emptied after the mixing. plastic sphere or other suitable material. The sphere is
SI IMMARY OF THF INVFNTION provided with a flexible diaphragm 4 which is secured
. SUMMARY OF THE INVENTION
 55 around itg periphery to the sphere across the diameter
The present invention is therefore directed to an ap- 6 of the sphere and serves upon completion of the mix-
paratus for mixing two or more liquids under zero ing process to be described, to discharge substantially
gravity conditions. In the specification, the term "zero the entire amount of liquid from the reservoir 2. An
gravity" is meant to include gravitational conditions in opening 8 is provided on the upper side of the sphere
which the action of gravitational forces on the mixed for supplying a fluid pressure P, from a suitable source,
liquids is zero or substantially negligible. It embraces not shown, to the portion 9 of the sphere which is on
the conditions normally referred to as the phenomenon the side of the flexible diaphragm 4 opposite the side of
of weightlessness experienced in space travel. The the diaphragm 4 where the liquids are mixed. The
present invention comprises an apparatus for mixing ,- liquids to be mixed in the reservoir are supplied to the
liquids under conditions of zero gravity which ap- reservoir 2 through a supply line 10 having a valve 12
paratus is comprised of a closed reservoir for liquids therein and communicating with the reservoir 2
and includes means for maintaining a first positive pres- through the conduit 14 at the base of the reservoir 2 on
3,712,591
3 4
the side of the flexible diaphragm 4 opposite the open- brane 67 covering only the peripheral opening around
ing 8. The other end of the conduit 14 is in comraunica- nozzle 66 is attached to the outer diameter of nozzle
tion with a pump 16. In the embodiment shown, the 66. This flexible flapper valve closes against arms 68
pump 16 comprises an upper chamber 22 on the top during a pressure stroke of piston 72 thus forcing the
side of a second flexible diaphragm 26 and a lower side 5 pressurized liquid through nozzle 66 at high velocity. A
24 which is in communication with a source of fluid suction stroke of 72 causes this flexible membrane 67
pressure Pj which pressure can be alternatively varied to bend away from arms 68 thus allowing passage of
to a pressure greater than or lesser than pressure P,. liquid from the outer diameter of primary storage con-
Optionally a valve 20 may be provided in conduit 14 tainer 2 back to top of piston 72, thus setting up a cir-
for isolating means 16 for repairs if necessary. culating pattern within tank 2. The pump 71 in this case
When it is desired to mix the two fluids, the valve 12 comprises a reciprocating piston 72 and rod 74.
is opened and the fluids admitted either together or The zero gravity operation of the apparatus of this in-
sequentially from the supply line 10 to partially fill the vention can be simulated under positive gravity condi-
reservoir 2 as shown in FIG. 2, the flexible diaphragm . - tions in the following manner. The reservoir comprised
being raised to the position shown at 30. The valve 10 is a sphere having a six inch internal diameter and con-
then closed. In FIG. 3, the flexible diaphragm 4 is posi- taining a rubber pressurizing diaphragm. The liquid dis-
tioned at 32 when the pressure Pt is raised to above P, placement of the pump means mixing diaphragm was
and the flexible diaphragm 26 is forced to the position about one and three-quarter cubic inches. The varia-
33, displacing the volume of liquid originally contained 20 t'ons m pressure P2 were controlled by a three-way
in the upper section 22 of the pump 16 and forcing it solenoid valve which pressurized the pump means to a
through the conduit 14 up into the reservoir 2 as shown pressure above P, and alternately vented the mixing
by the heavy arrows in FIG. 3. In FIG. 4 the condition diaphragm to the atmosphere.
of the apparatus is shown when the pressure P, has The mixing action of the apparatus of this invention
been lowered below that of P, thus displacing the flexi- 25 is demonstrated in the following manner: The reservoir
ble diaphragm 26 in the pump 16 to the position showri is filled with a first liquid which is water that is buffered
at 35. The pressure P, then forces the flexible with alcohol to equal the density of a second liquid
diaphragm 4 down against the liquids to the position which is then injected into the reservoir. The second
shown at 34 and causes the liquids to flow as shown by liquid is a similar alcohol and water solution containing
the arrows into the pump 16. 30
 a suspension of powdered black rubber to facilitate ob-
The alternating of the pressure P, is repeated a servation of the mixing of the liquids. Since the density
number of times and the liquids are thoroughly mixed of the two liquids are equal, they will act as though they
within a matter of minutes due to mechanical agitation were in zero gravity since gravity will have no mechani-
resulting from the flow of the liquids into and out of the cat mixing effect. When the second liquid is added to
reservoir 2. the reservoir, essentially no noticeable mixing of the
FIG. 5 shows an alternative embodiment of this in- liquids takes place. Upon operation of the pump means
vention wherein a supply line 48 to the reservoir 2' is in to alternately cause a portion of the liquids to flow into
direct communication with the reservoir 2'. In addi- and out of the reservoir, the liquids become thoroughly
tion, the reservoir 2' is in the form of a cylinder 38 and ,„ mixed within a few moments,
the means for maintaining the pressure Pt on the liquids What is claimed is:
is by means of the piston 40 connected to a pressure 1. Apparatus for mixing liquids under conditions of
source, not shown, by a connecting rod 44. zero gravity, comprising; a closed container for liquids;
In FIG. 6 there is shown an alternative embodiment first pressure means for maintaining a first positive
of the conduit 14. In this embodiment the conduit 14 is 45 pressure on liquids in said container; a liquid supply
provided with a jet-forming restriction 54 to concen- line connected to said container for supplying liquids to
trate the flow of liquids displaced from the pump 16 be mixed to said container; a conduit connecting the in-
into the center of the conduit 14 as shown by the heavy tenor portion of said container holding said liquids with
arrows. second pressure means; said second pressure means
In FIGS. 7 and 8 an additional embodiment is shown 50 being applied to the liquids to be mixed, which pressure
wherein a venturi 56 is provided within the conduit 14. is alternately greater than and lesser than said first pres-
The venturi 56 is comprised of walls 62 supported by sure means; said second pressure means displacing a
the arms 58 attached to the walls of the conduit 14 thus mass of said liquids less than the total mass of said
providing a space 63 between the exterior of the walls liquids in said container, alternately into and out of said
62 of the venturi 56 and the walls of the conduit 14 in 55 container, thereby mechanically mixing said liquids,
which liquid from the reservoir 2 is drawn down and 2. Apparatus as claimed in claim 1 wherein said first
then into the venturi 56. Liquid is caused to flow up- pressure means for maintaining a first pressure on said
ward from the pump 16 into the conduit 14 and the liquids includes a first flexible diaphragm, which
venturi 56 and through the center of the venturi 56, diaphragm divides said container into a side for said
thus forming a stream of the fluid directed into the 60 liquids and a side to which a fluid at said first pressure is
reservoir 2. The velocity of the fluid stream is such as to applied thereby transmitting said pressure throughout
cause a further mechanical mixing action to take place said first flexible diaphragm to said liquids,
within the reservoir 2. 3. Apparatus as claimed in claim 2 wherein said
A further modification of the apparatus of this in ven- second pressure means is pump means having a
tion is shown in FIG. 9 in which the reservoir 2 is pro- chamber divided into two sections by a second flexible
vided with a relatively wider conduit 64 which has a diaphragm, a first section in communication with said
nozzle 66 supported by the arms 68. A flexible mem- conduit and said liquids to be mixed, and a second sec-
3,712,591
tion in communication with a fluid pressure source
which alternately applies a pressure to said second flex-
ible diaphragm greater than and lesser than said first
pressure.
4. Apparatus as claimed in claim 1 wherein said
second pressure means is pump means having a
chamber divided into two sections by a flexible
diaphragm, a first section in communication with said
conduit and said liquids to be mixed, and a second sec-
tion in communication with a fluid pressure source
which alternately applies a pressure to said flexible
diaphragm greater than and less than said first pressure.
5. Apparatus as claimed in claim 1 wherein said
supply line for said container is in communication with
said conduit.
6. Apparatus as claimed in claim 5 wherein said
supply line contains valve means for controlling flow to
said container.
7. Apparatus as claimed in claim 1 wherein said con-
duit contains a jet-forming restriction.
8. Apparatus as claimed in claim 1 wherein said con-
duit contains venturi means at the end of said conduit
adjacent said container.
9. Apparatus as claimed in claim 8 wherein valve
5 means is associated with said venturi means to ensure
return flow to said second pressure means thereby
facilitating circulation of mixing liquids.
10. Apparatus as claimed in claim 8 wherein said
valve means is a flexible membrane.
10 11. Apparatus as claimed in claim 1 wherein said
second pressure means is pump means; said pump
means being of the type that employs a piston.
12. Apparatus as claimed in claim 1 wherein said first
pressure means is designed to discharge liquids from
15 said container to enable mixing of different liquids.
13. Apparatus as claimed in claim 1 wherein said first
and second pressure means are designed to purge said
apparatus for mixing liquids to enable mixing of dif-
ferent liquids.
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25
30
35
40
45
50
55
60
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Zero gravity liquid mixer

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