High pressure liquid flow sight assembly for wide temperature range applications including cryogenic fluid

Hobart, H. F.

Minkin, H. L.

English

NASA Technical Reports Server

REPLY ro 
ATTNOF GP 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON, D.C. 20546 
October 16, 1970 
TO : USI/Scien t i f ic  & Technical Information Div is ion  
FROM s" GP/Office of A s s i s t a n t  General 
At ten t ion :  M i s s  Winnie M. Morgan 
Counsel f o r  Patent Matters 
SUBJECT: Announcement of NASA-Owned 
U,S. P a t e n t s  i n  STAR 
I n  accordance wi th  t h e  procedures con-ained i n  ,,,e code G P  
t o  Code U S 1  memorandum on t h i s  subject, dated June 8, 1970, 
t h e  a t t ached  NASA-owned U . S .  p a t e n t  i s  being forwarded f o r  
a b s t r a c t i n g  and announcement i n  NASA STAR., 
The following information i s  provided: 
U.S.  Pa t en t  No. : 3,323,484 
Corporate Source : L e w i s  Research Center  
Supplementary 
Corporate Source 
NASA Pa ten t  Case No.: XLE-02998 
Gay le  Parker  
NASA-HQ 
https://ntrs.nasa.gov/search.jsp?R=19700032758 2020-03-17T02:15:56+00:00Z
H. b. MINKIN ETAL 
x. 
Filed Dec. 27, 1965 ‘ .‘? 
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3,323,484 
of the Nationall Aeronautics and Space Administration 
Filed Dee. 27, 1965, Ser. No. 516,794 
10 C l h s .  (C1. 116-117) 
The invention descrbed herein may be manufactured 
and used by or for the Government of the United States 
of America for Governmental purposes without the pay- 
ment of any royalties thereon or therefor. 
This invention relates to  a liquid flow sight assembly 
and more particularly to a high pressure cryogenic ob- 
servation window for viewing the flow of pressurized 
fluids. In conventional fluid flow sight indicators, the 
flowing pressurized fluid is channeled through a thin- 
walled glass tube through which the fluid is directly 
viewed. Such structures are limited to low pressure fluids 
because of the inherent weakness of the glass tube. Addi- 
tionally, such prior structures cannot handle extremely 
hot or extremely cold fluids because of undue expansion 
and/or contraction of the parts thereof. Also, prior struc- 
tures contain obstructions in the line of fluid flow causing 
eddying and turbulence at the viewing sight. 
An object of the present invention is to provide a fluid 
flow sight assembly of thin-walled glass tube construc- 
tion that can accommodate high pressure fluids. 
A further object of the invention is to provide a fluid 
flow sight assembly of the above type that can accommo- 
date fluids of a wide range of temperatures. 
A further object of the invention is to provide a fluid 
flow sight assembly of the above type that is simple in 
construction, inexpensive to manufacture, and highly ef- 
fective in operation. 
A further abject of the invention is to provide a fluid 
flow sight assembly of the above type effecting uninter- 
rupted or streamlined flow of fluid through the sight as- 
semb!y thereby preventing eddying and turbulence 
therein. 
Briefly, the foregoing objects are accomplished by the 
provision of a fluid flow sight assembly including a fluid 
conduit having an enlarged portion with oppositely dis- 
posed sight members therein for viewing fluid flow. The 
enlarged portion contains a thin-walled glass tube (of 
preselected length and of less cross-sectional size than the 
conduit) longitudinally disposed in the enlarged portion 
and extending, at each of its ends, into the adjacent con- 
duit. The glass tube is retained in position by snap rings 
detachably secured to the inner conduit wall at each end 
of the tube, with at least one end of the glass tube being 
spaced from its adjacent snap ring. The glass tube is di- 
mensioned in length and in cross-sectional size to provide 
a controlled leak for flow of pressurized fluid to the con- 
duit enlarged portion (to the exterior of the glass tuibe) 
to equalize fluid pressure interiorly and exteriorly of such 
tube to prevent breakage thereof. The fluid flow sight as- 
semb may be retained in a vacuum jacket containing a 
vacuum for minimizing heat transfer, such being a neces- 
sary requirement in cryogenic flow. The vacuum jacket 
has oppositely disposed sight members in alignment with 
the conduit sight members for viewing liquid flow ex- 
teriorly of the jacket. 
Thus, with the above structure, fluids having a wide 
range of pressures and temperatures can be accommo- 
dated and fluid turbulence is eliminated, such structure 
being formed entirely of relatively inexpensive com- 
ponents. 
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Other objects and advantages of the invention will be 
apparent from the following description taken in con- 
junction with the drawings wherein: 
FIG. 1 is a front elevational sectional view of a fluid 
flow sight assembly constructed in accordance with the 
invention; 
FIG. 2 is a portional top view of the assembly shown 
in FIG. 1 and taken along the line 2-2 thereof; 
FIG. 3 is an enlarged broken sectional view of the right 
portion of the upper conduit sight member shown in 
FIG. 1; and 
FIG. 4 is a view taken along the line 4-4 of FIG. 1. 
Although the invention is shown and described herein 
with reference to a fluid flow sight assembly for viewing 
liquid hydrogen, it will be understood that the invention 
may be applied to any type of fluid flow sight indicator 
accommodating fluids of very wide ranges of tempera- 
tures and pressures. 
Referring to the drawings, there is shown a fluid flow 
sight assembly, generally designated as A, and which is 
enclosed in a vacuum jacket designated as J. 
The assembly A, in the preferred form, includes a 
fluid conduit 10 having an enlarged portion 12 with 
aligned oppositely spaced sight openings 14 and 16 there- 
in. A substantially transparent tube P8, of preselected 
length, is longitudinally disposed in the bore 19 of the 
conduit 10 with the central portion of the tube being 
positioned in the conduit enlarged portion 12 and with 
the end portions of the tube being positioned in the 
conduit as shown. Thus, the tube 18 conducts the pres- 
surized fluid in series with the conduit 10. The tube 18 
is preferably formed of thin-walled glass, although any 
similar substantially transparent material may be used 
such as, for example, Pyrex (registered trademark). 
Also, the tube 18 is of less cross-sectional size than the 
conduit BO to provide a clearance 20 between the outer 
longitudinal wall of the tube and the inner longitudinal 
wall of the )conduit, such clearance, in the preferred 
form, being on the order of 0.005 inch. 
The tube 18 is retained in the conduit 10 by a conduit 
retaining means in the form of a pair of spaced snap 
rings 22 and 23 which are positioned in annular trans- 
verse grooves 26 and 27, respectively, formed in the inner 
longitudinal wall of the conduit 10. Suitable annular 
semi-resilient buffer lings 31 and 32, of preselected size, 
are interposed between the snap rings 22 and 23 and 
the respective ends of the tube. 18. The glass tube 18 is 
of preselected length to provide a passageway 34 thereby 
allowing the tube to float or move longitudinally back 
and forth between the snap rings a limited amount to 
allow for temperature expansion and contraction of the 
tube. This construction also permits slight fluid flow 
through a controlled leak around the end of the glass 
tube and/or around the buffer rings and thence through 
the clearance 20 to the enlarged portion 12, thereby 
equalizing fluid pressure interiorly and exteriorly of the 
tube to  prevent breakage of the same. Also with such 
structure the sight assembly is free of internal fluid flow 
obstruction, thereby preventing eddying and turbulence 
therethrough. 
The sight openings 16 and 14 contain aligned oppo- 
sitely disposed sight members, generally designated as 38 
and 39 respectively, for viewing the flow of pressurized 
fluid in the glass tube 18. Although only one of the sight 
members (sight member 38, for example) is necessary 
for viewing fluid flow, the use of a second oppositely dis- 
posed sight member 39 permits the use of an associated 
source of light to be shown through the second sight 
member and onto the glass tube 18 to better view fluid 
3,323,484 
3 4 
flow therethrough. Since both sight members 38 and 39 flow exteriorly of the tube thereby equalizing pressure 
are similar in construction, only one will be described in interiorly and exteriorly of such tube to prevent break- 
detail. age thereof by the pressuribed fluid, and means for re- 
The sight member 38 includes a first annular plate 42 taining the tube in the conduit. 
secured to the periphery of the sight opening 16 to form 5 2. The structure of claim 1 wherein said conduit and 
a fluidtight seal therewith. The plate 42 has a centralized said tube are circular in cross-section and said means in- 
aperture 43 in line with the sight opening 16, said plate cludes a pair of spaced annular transverse grooves 
having a series of preconfigured serrations 44 around formed in the inner longitudinal wall of the conduit, and 
the periphery of the aperture 43. Disposed above the snap rings disposed in said grooves, said tube being dis- 
plate 42, in parallel spaced relation thereto, is a second 10 posed ibetween the snap rings whereby at  least one end 
plate 46 having a centralized aperture 47 in line with the of the tube is spaced slightly from the adjacent snap ring 
aperture 43 and the sight opening 16. Interposed between to provide a passageway for the pressurized fluid to  flow 
the plates 42 and 46 is a substantially transparent means around the end of the tube to the tube exterior to equalize 
such as, for example, the quartz glass plate 50. A lead pressure on the same. 
gasket 52 is positioned on the serrations 44 between the 15 3. The structure of claim 2 wherein the tube is di- 
lower surface of the glass 50 and the plate 42 t o  form a mensioned cross-sectionally to provide a clearance be- 
fluid-tight seal therebetween. A resilient gasket 54 is in- tween the inner longitudinal wall of the conduit and the 
terposed between the top surface of the glass 50 and the outer longitudinal wall of the tube of approximately 
plate 46. The plates 42 and 46, with the glass 50 and 0.005 inch. 
its respective gaskets 52 and 54 therebetween, are 20 4. The structure of claim 2 wherein an annular semi- 
clamped together under controlled compression by any resilient buffer ring is disposed between each snap ring 
suitable means such as the bolts 58. and the adjacent end of the tube, said buffer ring being 
For minimizing the heat transfer by gas conduction of preselected size to permit fluid flow therearound to 
to the fluid conduit, assembly A is maintained in a vac- the tube exterior to equalize pressure thereon. 
uum contained in a vacuum jacket J which encloses the 25 5. The structure of claim 1 wherein said transparent 
assembly A. Disposed on the jacket J are a pair of aligned tube is a Telatively thin-walled glass tube. 
oppositely disposed jacket sight memtbers, designated gen- 6. The structure of claim 1 wherein said fluid conduit 
erally as 62 and 63, which are positioned in line with the has a second sight opening transversely and oppositely 
sight members 38 and 39. Although only one of the disposed from the first-named sight opening, and a sight 
jacket sight members (sight member 62, for example), 30 member disposed in said second opening whereby the 
is necessary for viewing fluid flow, the use of a second flowing pressurized fluid may be viewed from either side 
oppositely disposed sight member 63 permits the use of of the conduit and whereby light may be directed on the 
an associated source of light to be shown through the tube through one of the sight openings to better view 
second sight member to better view fluid flow. Since fluid flow through the tube. 
both of sight members 62 and 63 are similar in construc- 35 7. The structure of claim 1 wherein said conduit has 
tion, only one will be described in detail. an enlarged portion containing at least the central portion 
Sight member 62 includes a sleeve 70 having a bore of the transparent tube and containing said sight opening 
72 and having a restricted portion 74 disposed in the with the sight member therein, said tube being dimen- 
jacket sight opening 76. The restricted portion 74 has a sioned cross-sectionally to provide a controlled leak from 
bore 75 in line with the sight member 38. A substantially 40 the conduit interior t o  the enlarged portion to  equalize 
transparent member in the form of the glass plate 78 pressure on the tube. 
is disposed in the bore 72 and retained therein lby the 8. The structure of claim B wherein said sight mem- 
annular plate 80 which is secured to the sleeve 70 by ber comprises, a first plate secured to the periphery of 
the bolts 82. The plate 80 has a centr&ed aperture 83. the sight opening and having a centralized aperture in 
An O-ring 84 is disposed ibetween the glass plate 78 and 45 line with the sight opening, said plate having precon- 
the shoulder 86 of the sleeve 70 to provide a vacuum- figured serrations formed around the periphery of the 
tight seal therebetween. aperture, a second plate spaced from the first plate and 
In practice, the present construction is adapted to having a centralized aperture in line with the sight open- 
accommodate liquid hydrogen flowing through the con- ing, substantially transparent means disposed between 
duit 10 and through the thin-walled glass tube 18 at  pres- 50 said plates in line with said aperture, a semi-resilient 
sures up to 50 p.s.i.a., free of turbulence. Ordinarily, gasket disposed between the transparent means and the 
such pressures would easily break the glass 18 if pressure plate serrations, and means for securing the plates to- 
interiorly and exteriorly thereof were not equalized as gether with the transparent means and the gasket inter- 
provided by the present structure. The invention obviates posed therebetween under controlled compression. 
'the necessity of bonding glass tubing to metal which is 55 9. The structure of claim 1 wherein said sight assembly 
a difficult and expensive operation. Also, thin-walled glass is enclosed in a vacuum jacket containing a vacuum for 
tubing does not impair observation as is the case with minimizing heat transfer to the sight assembly, said vac- 
thick or heavy-wall glass tubing. uum jacket having at least one sight member in line with 
The terms and expressions which have been employed the sight assembly sight member for viewing fluid flow 
are used as terms of description, and not of limitation, 60 in the tube. 
and there is no intention, in the use of such terms and ex- 10. The structure of claim I wherein said conduit has 
pressions, of excluding any equivalents of the features an enlarged portion containing the central portion of the 
shown and described, or portions thereof, but it is rec- transparent tube, said conduit and its enlarged portion 
ognized that various modifications are possible within and said tube being circular in cross-section, said tube 
the scope of the invention claimed. 65 being dimensioned cross-sectionally to provide a clear- 
What is claimed is: ance between the inner longitudinal wall of the conduit 
1. A fluid flow sight assembly for viewing the flow and the outer longitudinal wall of the tube d approxi- 
of pressurized fluid comprising, a fluid conduit for con- mately 0.005 inch, said enlarged portion having aligned 
ducting pressurized fluid and having a sight opening oppositely-disposed sight openings therein, a sight mem- 
therein, a sight member disposed in said opening, a sub- 70 ber disposed in each of said sight openings, said means for 
stantially transparent tube of preselected length and of retaining the tube in the opening including a pair of 
less cross-sectional size than the conduit and disposed spaced annular transverse grooves formed in the inner 
longitudinally in the conduit opposite said sight member longitudinal wall of the conduit, snap rings disposed in 
for conducting the pressurized fluid in series with the said grooves, said tube disposed between the snap rings, 
conduit, said tube dimensioned to provide slight fluid 75 an annular semi-resilient buffer ring disposed between 
3,323,484 
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each snap ring and the adjacent end of the tube, said 
buffer ring being of preselected size and said tube being 
of preselected length to provide a passageway for the 
pressurized fluid to flow around the end of the tube to 
the sight assembly, and a pair of aligned oppositely- 
disposed sight members contained in said vacuum jacket 
and in alignment with said first-named sight members for 
viewing fluid flow in the tube. 
No references cited, the exterior of the tube t o  equalize pressure on the same, 5 a vacuum jacket containing a vacuum enclosing said 
fluid flow sight assembly for minimizing heat transfer to LOUIS J. CmOzI, primam E ~ ~ ~ i n e r .  


Liquid flow sight assembly Patent

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