A sensor for measuring the mass of fluids, is described which includes a housing having an inlet and outlet for receiving and dumping the fluid, a rotary impeller within the housing for imparting centrifugal motion to the fluid and a pressure sensitive transducer attached to the housing to sense the rotating fluid pressure. The fluid may be drawn into the housing by entrainment within a gas stream. The resulting mixture is then separated into two phases: gas and liquid. The gas is removed from the housing and the pressure of the liquid, under centrifugal motion, is sensed and correlated with the mass of the fluid

Fogal, G. L.

English

NASA Technical Reports Server

United States Patent [191 
Fletcher et al. 
[ 1 11 3,988,933 
[451 Nov. 2, 1976 
FLUID MASS SENSOR FOR A ZERO 
GRAVITY ENVIRONMENT 
Inventors: James C. Fletcher, Administrator of 
the National Aeronautics and Space 
Administration with respect to an 
invention of; G. L. Fogal, Wayne, 
Pa. 
Filed: Nov. 7, 1974 
Appl. No.: 521,816 
U.S. CI ................................... 73/432 R; 17711; 
177/208 
Int. c1.* ......................... GolL 19/14; G01G/5/04 
Field of Search .............. 177/1, 208; 731194 M, 
731214,432 R 
References Cited 
UNITED STATES PATENTS 
1,956,309 411934 Borden ................................. 731214 
Primary Examiner-George H. Miller, Jr. 
Attorney, Agent, or Firm-Marvin J. Marnock; John 
R. Manning; Marvin F. Matthews 
ABSTRACT [571 
Apparatus and method for determining the mass of a 
fluid comprising: a housing having an inlet and outlet 
for receiving and dumping the fluid, a rotary impeller 
within the housing for imparting centrifugal motion to 
the fluid and a pressure sensitive transducer attached 
to the housing to sense the rotating fluid pressure. In 
the method the fluid may be drawn into the housing 
by entrainment within a gas stream. The resulting mix- 
ture is then separated into two phases: gas and liquid. 
The gas is removed from the housing and the pressure 
of the liquid, under centrifugal motion, is sensed and 
correlated with the mass of the fluid. 
3 Claims, 2 Drawing Figures 
https://ntrs.nasa.gov/search.jsp?R=19770012441 2020-03-20T07:30:28+00:00Z
U.S. Patent Nov. 2, 1976 3,988,933 
1 
FLUID MASS SENSOR FOR A ZERO GRAVITY 
ENVIRONMENT 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 
BACKGROUND OF THE INVENTION 
The present invention relates to apparatus and meth- 
ods for the accurate measurement of the mass of a 
fluid. In particular this invention pertains to accurate 
real time mass measurement of fluids at remote loca- 
tions. 
The invention is particularly directed to the real time 
measurement of the mass of urine discharged by astro- 
nauts. It is also useful in the separation and determina- 
tion of the mass of a liquid mixed with a gas immedi- 
ately at the time of separation. 
In the past few years man has made great strides in 
exploring outer space. The NASA space program has 
been characterized by continuous and sometimes spec- 
tacular advances. Of course, in making advances in 
such a program, many problems have been encoun- 
tered. 
One such problem in space travel is the ability to 
accurately measure and keep bio-medical data on each 
astronaut to make sure he is in good health. It has been 
observed that the mass of urine discharged during each 
micturition of an astronaut is significant as a good diag- 
nostic indicator of whether an astronaut is having some 
biological malfunction. Thus, it has been found to be 
important to have an accurate measure of the mass of 
urinary discharges each time an astronaut urinates. 
Another such problem is how to make astronauts as 
comfortable as possible on long space trips. One way to 
keep astronauts comfortable is to make the normal 
body functions of eating and excreting as earth-like as 
possible. The currently used roll-on cuff for urination 
in space leaves much to be desired in making the astro- 
naut feel comfortable and earth-like in his environ- 
ment. 
The problem of accurate measurement is further 
compounded by the necessity of providing a way to 
accurately measure the urine mass of an astronaut in 
his zero gravity environment. Most scales, as we known 
them today, are gravity dependent. The lack of gravity 
in space creates additional problems in that fluid to be 
collected will not collect and stay in a container while 
the measurement of its mass is being made. 
Prior methods used in the determination of the mass 
of urine have been post-flight gravimetric determina- 
tion based on the mass of the fluid being collected, 
during flight, but this post-flight bio-medical data does 
not provide the inflight data which is needed to keep 
real time medical checks on the astronauts. 
Another problem associated with post-flight urine 
analysis is the filling of the containers without the astro- 
nauts having to handle the container. In addition, the 
astronaut has had to wear a roll-on cuff in order to feed 
urine into a post-flight collection system. In order to 
solve these problems it is important to find a means 
whereby the astronaut can automatically fill the device 
to be used in measuring the mass of the urine and also 
to provide the astronaut with a means of collecting 
85-568 (72 Stat. 435; 45 U.S.C. 2457). 
2 
wherein the discharge of urine can be more earth-like. 
Further, as the space hardware designers have begun to 
develop pneumatic collection systems for urine and 
fluids, it has become important that the device devel- 
oped for the measurement of the mass of the urine also 
be compatible with a pneumatic collection, and yet not 
sacrifice the accuracy of the measurement of the mass 
of an astronaut’s urine. 
IO SUMMARY OF THE INVENTION 
In the present invention, apparatus and methods are 
provided for accurate measurement of a fluid mass in 
real time. Further, this invention is compatible with a 
pneumatic fluid collection apparatus to be used in zero 
l 5  gravity. To these ends the present invention provides a 
collection system for fluid which is not dependent on 
gravity for collection or for accurate determination of 
the fluid mass. 
The invention provides an air transport or draft of gas 
2o to draw fluids into an inlet of a housing of the invention 
because there is no gravity to do so in space. After the 
fluids are drawn into the housing, they are separated 
into their respective gas or liquid phases by using a 
25 multibladed rotor which imparts centrifugal motion to 
the fluid in the housing and creates a rotating fluid 
vortex against the inside of the housing. The transport 
air or gas phase is driven out and a liquid pressure is 
generated on the inside of the housing. A pressure 
3o sensitive transducer is connected to the inside of the 
housing wall to sense the pressure of the rotation fluid 
vortex and to correlate it into accurate mass measure- 
ments. This operation can occur as an astronaut uri- 
nates thus providing timely data on the mass of urine 
This particular invention is perfectly compatible with 
other pneumatic type collection systems and frees the 
astronaut because he does not have to handle any urine 
collection hardware. Also as the urine mass is automat- 
40 ically determined and then dumped into a disposal 
system, after the mass reading is made, the astronauts 
do not have to perform any work functions such as 
mass determination. Also as the accuracy of the liquid 
mass determination of this invention is excellent, it 
45 provides the necessary data for the bio-medical analysis 
and monitoring of the astronauts. 
Another feature of this invention relates to providing 
the astronaut as earth-like an environment as possible 
by using the pneumatic system to collect the urine. This 
50 eliminates the need for use of the roll-on cuff which has 
been used in the past. 
35 discharged by each astronaut. 
DRAWINGS 
FIG. 1 is a function diagram of the method of opera- 
FIG. 2 is an elevation in cross-section of the appara- 
55 tion of this invention; 
tus of this invention. 
DESCRIPTION OF THE PREFERRED 
60 EMBODIMENT 
FIG. 1 is a general diagramatic view of the general 
features and operation of the apparatus of this inven- 
tion. In FIG. 1 the apparatus of this invention has pro- 
vided a urinal into which an astronaut can urinate. 
65 Under zero gravity the urinal 10 is fluidly connected 
through a housing 11 to a draft blower 13 which draws 
a draft of cabin air into the urinal 10 and thus feeds the 
urine and cabin air into the housing 11. 
3,988,933 
3 4 
As the cabin air and urine are fed into the housing 11, transducer head 33 and for insulation between the wall 
a multi-bladed rotary impeller 12 creates a centrifugal of housing 11 and the transducer head 33 is to prevent 
rotating vortex of urine and cabin air, indicated gener- the effect of thermal drift, in interpreting the data as 
ally in FIG. 1 at f, against the wall of the housing 11. read from the transducer 14. It has been found that the 
This rotating vortex of urine and cabin air creates the 5 fluid entering the housing 11, if it is generally warmer 
centrifugal forces necessary to separate the urine and than the walls of the housing 11 and the transducer 
cabin air and to hold the urine against the wall of the head 33, creates an artificially high reading, as shown 
housing 11 by centrifugal force, while the separated by the data in Table I. 
TABLE I cabin air is drawn out of the housing 11 by the draft blower 13 and discharged. 10 
While the urine is held against the walls of the hous- 
ing 11 by centrifugal force and after completion of 
urination by the astronaut, a pressure-sensitive trans- 634 (Sample injection Complete) 
15 625 
30 619 
the centrifugal pressure created by the mass of the 15 45 616 
urine as it is rotated at a constant impeller speed. The 60 615 
75 612 (2% error) 
pressure sensitive transducer 14 then transmits a signal 90 610 
to a scaler 15 which amplifies the pressure signal trans- 120 609 
150 608 
180 607 
mine the mass of the urine for a given speed of rotation 20 240 606 
of the impeller 12. In the more general case, with the 300 605 (Water Temperature = 87" ) 
FLUID TEMPERATURE 
Time Meter Reading 
0 sec. 
ducer 14 connected to the wall of the housing 11 senses 
mitted by the pressure sensitive transducer 14 to deter- 
impeller speed uncontrolled, the scaler would correlate 
upon spin with pressure signal to determine mass. A 
resultant signal from the scaler 15 is then transmitted to The faster the transducer head 33 and fluid become 
a read-out indicator 16 which indicates the mass of the 25 more nearly the same temperature, the faster and more 
urine collected. accurate the reading of the mass of the urine present. 
After the mas  of the urine has been determined, the The tapered faces 31 and 32 and the insulation 30 are 
astronaut activates a dump valve 17 which discharges designed to Prevent heat transfer from the transducer 
the urine from inside the housing 11 into a disposal 14 to the outer Parts Of the Wall of the housing 11 and 
system, not shown, for treatment or storage. 30 to provide the transducer with the maximum exposure 
Referring to FIG. 2 in the illustrated embodiment, to the Warm Urine which is collected in the housing 11, 
the principal apparatus of the invention includes a thus reducing the time required for the hardware and 
cylindrical housing 11 with an inlet 18 leading inside fluid temperature to equalize. 
the housing 11 for the introduction of fluid therein. The The housing 11 is also provided with an exhaust man- 
housing 11 also has mounted at its center a multi- 35 ifold 34 which is in communication with an outlet 35 of 
bladed rotary impeller 12 which has flowways 19 there- the housing 11 for the discharge Of gases from within 
through and is in fluid communication with a hollow the housing 11. 
hub 20 of the multi-bladed rotary impeller 12. A dy- In the Operation Of this invention, the user actuates 
namic seal is formed at the union of the inlet 18 and the the motor 24, the speed controller 27, and a blower 13 
hub 20 by a ring seal 21. An additional ring seal 22 is 40 which is connected to the outlet 35 and then the user 
fitted around a drive shaft 23 which is connected to a proceeds to urinate into a urinal 10. It should be appre- 
motor 24 at one end and connected to the multi-bladed ciated that in zero gravity the draft of air by the blower 
impeller 12 at the other end for rotation of the multi- 13 feeds the urine by entrainment into the urinal 10 
bladed impeller 12. which is in fluid communication with the inlet 18. The 
Intermediate the connection point of the motor 24 45 urine is then passed through flowways 19 of the multi- 
and the shaft seal 23 are bearings 25 and 26 which bladed rotary impeller 12 and spun against the wall of 
allow the shaft 23 connected to the motor 24 to easily housing 11 (as shown in FIG. 1) at points along the wall 
turn a constant number of revolutions per minute. To in line with where the pressure transducer 14 is 
further aid the motor in turning the shaft 23 at a con- mounted. AS the urine is fed into the housing 11, it is a 
sbnt number of revolutions per minute, the motor 24 50 combined mixture of air and urine, but as rotation is 
may be connected to a speed controller 27 as shown continued, the centrifugal force of the urine presses the 
diagramatically in FIG. 1. It should be understood that urine against the Wall Of housing 11. The air is dis- 
a constant and exact speed of rotation is preferable for placed by the centrifugal forces of the urine and al- 
accurate computation of the mass of the liquid because lowed to escape from inside the housing 11, passing 
the centrifugal pressure exerted by the liquid against 55 through the outlet 35 for discharge through the mani- 
the housing 11 is a function of the speed of rotation and fold 34. 
the mass of the fluid. Consequently, a measure of cen- As the user continues to urinate, the device continues 
trifugal liquid pressure is also a measure of fluid mass. to collect the urine along the wall of the housing 11, the 
Mounted on the wall of the housing 11 opposite the multi-bladed rotary impeller 12 setting up a centrifugal 
multi-bladed rotary impeller 12 by bolts 28 and 29 is 60 rotating vortex of fluid over the pressure sensitive 
the pressure sensitive transducer generally referred to transducer exerting a pressure against the pressure 
at 14. It should be noted that bolts 28 and 29 pass sensitive transducer head 33. It should be understood 
through an insulation barrier 30 which prevents the that the pressure exerted by the fluid in zero gravity is 
transducer from contacting the housing 11. Also, it a function of the specific gravity of the urine and the 
should be noted that the inside wall of housing 11 is 65 speed of rotation of the impeller, and thus can be corre- 
recessed along surfaces 31 and 32 to expose the maxi- lated in terms of the mass of the fluid. 
mum surface area of a transducer head 33. The pur- The pressure sensitive transducer head 33 which is 
pose for exposing the maximum surface area of the located in the wall of the housing 11 senses a pressure 
3,988,933 
6 
connected to said 
means and to separate said fluid into its gas and 
liquid phases; 
Power 
means for effecting rotation thereof; 
speed controller means operatively associated with 
said power means for maintaining the rotary speed 
of said impeller means at a constant number of 
revolutions per minute; and 
pressure sensitive transducer means mounted in said 
housing for sensing the centrifugal liquid pressure 
and producing an electrical signal indicative of said 
pressure and representative of said fluid mass. 
2. An apparatus as described in claim 1 wherein said 
I claim: means for introducing a liquid-gas stream into said 
1. An apparatus for sensing and measuring fluid 15 housing means includes a draft blower means for draw- 
ing a liquid-gas fluid mixture into said housing means 
housing having inlet for receiving a whereby said apparatus is operative in gravity and zero 
gravity environments. 
3. An apparatus as described in claim 1 wherein said 
munication with said inlet means and flowways through 
the blades thereofand in fluid communication with 
hub whereby fluid received through said inlet means is 
dispensed through the blades of the impeller means 
5 
and relays it to a scaler 15 which correlates the pres- 
sure relayed into a read-out 16 of the niass of urine 
collected in housing 11. After the mass of the urine has 
been determined the user trips the discharge valve 17 
which dumps the urine from inside chamber 11 to an- 
other chamber not shown, either for storage of treat- 
ment. 
Only One preferred embodiment of the 
invention has been described herein, many other varia- 10 
tions will be apparent to those skilled in the art. It is 
therefore intended that the scope of the invention be 
limited only by the claims which follow. 
5 
mass, said apparatus comprising: 
liquid-gas fluid stream into said housing means; 
of fluid from said housing means; 
housing means through said inlet means; 
ing means for imparting centrifugal motion to said 25 into said housing means. 
Outlet in said housing for the dumping 2o rotary impeller means has a hollow hub in fluid corn- 
means for introducing a liquid-gas stream into said 
multi-bladed rotary impeller means within said hous- 
fluid to form a liquid vortex within said housing * * * * *  
30 
35 
40 
45 
50 
55 
60 
65 


Fluid mass sensor for a zero gravity environment

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