US 3157201 A
Description (OCR text may contain errors)
Nov. 17, 1964 D. LITTMANN 3,157,201
FLUID EXCHANGE VALVE Filed April 12, 1962 2 Sheets-Sheet l DRIP HEPARIN IN SALINE OR GLUCOSE FIGI FIG2 C8 INVENTOR WWW*W ATTO R N EYS Nov. 17, 1964 D. LlTTMANN 3,157,201
FLUID EXCHANGE VALVE Filed April 12. 1962 2 Sheets-Sheet 2 203 RESERVO! R 200204 ,lol 51.000 DONOR [O5 2O x I02 //L/ 212 cl-iii 12- SYRINGE am 2 CATHETER 402 F|G.5 20| 4 I03 403 DISCARD 404 oydfw ATTORNEYS United States Patent 3,157,201 FLUID EXCHANGE VALVE David Litimann, Belmont, Mash, assignor to Cardiosonics Medical Instrument Company, Belmont, Mass a partnership Filled Apr. 12, 1962, Ser. No. 37,099 ll Qiairns. (ill. list-625.4%
Fluid exchange valves which have heretofore been used in medical procedures are diificult to use, particularly under the strain of operating conditions. Further such earlier valves are uncertain of accurate positioning and are difiicult to disassemble for cleaning and sterilization.
It is an object of the present invention to provide an improved multip-osition fluid exchange valve particularly useful in connection with medical procedures such as catheterization and exchange transfusion. In a preferred embodiment, the fluid exchange valve of the present invention has four positions controlled by a single lever. This multiple position valve permits filling and/or flushing of a transducer from a saline solution; maintenance of a continuous protective drip from a reservoir to a catheter while qualitatively monitoring samples by such means as an oscilloscope; recording by interconnecting a transducer and a catheter through the valve; and, sampling by connecting the catheter to a syringe.
It is another object of this invention to provide a simple, efficient, accurate and time saving method of blood exchange transfusion employing a valve of this invention.
In a preferred alternative embodiment, the valve of the' present invention has three positions controlled by a single lever. The valve of the alternative embodiment is particularly useful for exchange transfusion procedures and permits, removal of blood from a recipient, donor or blood reservoir, discard of recipientblood, injection of donor blood to the recipient, and flushing of the valves with, or injection into the recipient of an anti-coagulant fluid.
The valve of this invention is designed for ease and certainty of operation. Both limiting stops and click stops are used to permit the operating attendant or doctor to determine with'certainty the position of the valve. The strucure of the fluid exchange valve also minimizes the likelihood of clotted passageways, contaminated samples and damped pulse curves.
The device of this invention is compact but is capable of passing relatively large quanties of fluid. The fluid exchange valve, having fewer parts than conventional valves may be easily and quickly dismantled, cleaned an reassembled, without'specialized training. The components of the fluid exchange valve are designed to minimize wear and avoid corrosition and tarnish. The fluid exchange valve is also designed to be made at costs favorably comparable to other less des rableprior art fluid exchange valves.
Generally this invention provides a valve for selectively connecting plural fittings into plural arrangements for fluid exchange. The valve comprises a valve housing including a substantially annular collar having plural spaced passageways extending therethrough and stops mounted thereon; a valve rotor having passageways extending therethrough for interconnecting the valve housing passageways into plural arrangements for fluid exchange on selective rotation of the rotor, and means for removably securing the rotor within the housing ice whereby the fluid exchange valve is held positively in assembled relation and may be quickly and easily disassembled for cleaning and/ or sterilization.
In its preferred embodiment, this invention provides a fluid exchange valve particularly useful in heart catheterization procedures for selectively connecting four fittings into four different arrangements for fluid exchange with one arrangement interconnecting a first and second fittings, a second arrangement interconnecting the first and second and fourth fittings, a third arrangement interconnecting the fourth and second fittings, and a fourth arrangement interconnecting the third and fourth fittings. The valve of the preferred embodiment comprises a valve housing including an annular collar with four spaced passageways extending therethrough and stops located thereon, a valve rotor having a side wall shaped and dimensioned to fit in rotatable sliding and facing relation with an inner surface of the annular collar and passages in the rotor for interconnecting the passageways into four di ferent arrangements for fluid exchange on selective rotation of the rotor; means for selectively rotating the rotor relative to the housing into four different positions, and means for removably securing the rotor in the four positions and/ or securing the rotor within the housing.
In a preferred alternative embodiment, this invention provides a fluid exchange valve forselectively connecting five fittings into three different arrangements for fluid exchange with one arrangement interconnecting a first and fourth fittings, a second arrangement interconnecting a second, fourth and fifth fittings, and a third arrangement interconnecting a third and fourth fittings. The fluid exchange valve of the preferred alternative'embodiment of this invention comprises a valve housing including an annular collar with five spaced passageways extending therethrough and stops thereon; a valve'rotor having a side wall shaped and dimensioned'to fit in rotatable, sliding and facing relation to an inner surface of the annular collar with passages in the rotor for interconnecting the passageways into three different arrangements for. fluid exchange on selective rotation of the rotor; means for selectively rotating the rotor relative to the housing into the three difierent positions, and means for removably securing the rotor in the three positions and/ or for securing the rotor within the housing. t p
Numerous other features, objects and advantages of the present invention will become apparent fromfthe'following specification when read in connection with the accompanying drawing, in which:
FIG. 1 is a top plan view of a preferredembodiment of the present invention shown in a system for cardiaccatheterization.
FIG. 2 is an exploded view of the preferred embodiment of a fluid exchange valve of this invention. 5 FIG. 3 is a bottom view of the fluid exchange valve of FIG. 2.
FIG. 4A is a top view of the preferred embodiment of the valve of this invention showing a first positioning of the elements thereof.
FIG. 4B is similar "to FIG. 4A and shows a second position.
FIG. 4C is similar to FIG; 4A and shows a third position.
FIG. 4D is similar to FIG. 4A and shows 'a fourth position. FIG. 5 is a top plan view of a preferred alternative embodiment of the fluid exchange valve of the present invention. 7 I I p The preferred embodiment of the fluid exchange valve of this invention, designated generally at. 15, may be used as a cardiac catheterization valve in conjunction with "an anticoagulant reservoir 16 containing heparin in saline or glucose, a conventional fluid electrical signal transducer :3 12 operatively connected to a conventional oscilloscope recorder 11, a syringe such as a common Luer syringe 13 and a conventional cardiac catheter 14.
The fluid exchange valve 15 comprises three major components. A valve rotor 24, a valve housing 25, a means 32 for removably securing the rotor in the housing and securing the rotor in various positions.
The valve housing includes an annular collar or ring 26 having four radially extending passageways 4t), 41, 42 and 43 extending therethrough. Tubular female fittings 29, 30 and 31 extend radially outwardly of passageways 43, and 41, respectively. A tubular male fitting 28 is axially aligned with passageway 42. The fittings 28, 29, 3t), and 31 may be attached to the an nular collar 26 by screwing the threaded ends of the tubular members into female threaded holes provided on the member 26. Alternatively, other modes of attachment may be employed if desired. A truncated conical inner wall of the housing provides a seat for engaging a wall 22 of rotor 24 in sliding and facing relationship therewith.
Limiting stops preferably comprising spaced upwardly extending pins or projections 68 and 61 are aifixed to a top wall of annular collar 26. Click stops 37 and 38 are provided on a lower wall 98 of the annular collar 26. Preferably 37 and 38 are indentations or grooves in wall 98.
The valve rotor 24 comprises a rotor base 99 having a truncated conical side wall 22 adapted for sliding and facing relationship with the wall 80 of the valve housing.
Radially extending tubular passages 44, 45, 46, 47, 43 and 49 interconnect with each other at the center of the rotor 99. The passages are angularly arranged so as to interconnect preselected ones of passageways 4t 41, 42 and 43 upon selected positioning or rotation of rotor 24 into positions prescribed by the arrangement of the limiting and click stops provided. Preferably all of the passageways employed in the valve are made large enough to minimize resistance to fluid fiow. Normally diameters of 0.093 inch are employed for the passages and passageways.
An integral boss 21 is located at the top of the base 99 and carries a firmly affixed control lever 20 which provides a means for rotating the rotor. Preferably the control lever 20 is bent upwardly at a slight angle as shown in FIG. 2 in order to facilitate movement thereof in use of fluid exchange valve. The particular control lever may be varied if desired. For example, a winged projection or fiat bar means may be advantageously utilized.
The lower portion of the rotor base comprises a substantially fiat section extending under the rotor with inwardly hooked or L-shaped walls 23 on either end of the fiat section 90. Inwardly hooked walls 23 are adapted to engage a means for removably securing the rotor in varying positions and for securing the rotor within the valve housing as will be described hereinafter. The fluid exchange valve 15 is preferably designed so that the flat portion 90 lies in substantially the same plane as the bottom of the collar 26 when the two elements are assembled.
Preferably a durable, tarnish resistant material such as stainless steel is employed as the material of the valve rotor and the valve housing. Aside from durability and tarnish resistance, stainless steel may be easily cleaned and sterilized in conventional hospital autoclaves. Other materials may be employed if desired. For example, in certain applications, plastic materials such as Teflon or similar plastic materials may be employed. Teflon materials or similar plastic materials are advantageous in that they may be easily cleaned and sterilized and provide a completely self-lubricating valve.
A spring detent 32, means for removably securing the rotor in varying positions and/or for securing the rotor within the housing. In effect, the conical walls 22 and 8t) secure the rotor from shown in FIGS. 2 and 3, forms 4 movement in one axial direction with respect to the housing while the spring detent urges the rotor towards movement in that direction.
The spring detent 32 is preferably composed of a hardened spring material such as steel alloy, although other materials such as plastics may be used if desired. The spring detent 32 has substantially parallel side walls 91 and 92, substantially arcuate end walls 93 and 94 and a tongue stop 36 projecting laterally from one end thereof. The spring detent is bowed downwardly or arced across its length between end walls 93 and M as indicated by the downward bow of side walls 91 and 92. The spring detent is also preferably bowed or arced along its width as indicated by the downward bow of walls 93 and A stop comprising a keyhole slot 33 is provided extending inwardly from wall 1 on an end of the spring detent opposite torque stop and an upwardly depending click stop or detent such as ridge 34 is provided adjacent wall 94. A cutout circular portion 35 located substantially centrally within the spring detent enables manual gripping of the spring detent and ease of depressing the spring detent as will he described hereinafter. The circular cutout portion is particularly desirable when a convex leaf spring as above described is employed.
it should be understood that although I have described specific preferred configurations and elements of the spring detent 32, these elements may be varied in certain applications. For example, the spring need not be bowed in multiplanar directions, the keyhole slot 33 may be eliminated if desired, or other stop means may be employed in its place. Further, the rounded ridge 34 may be replaced with dimples or other click-stop means or entirely eliminated if desired, for certain applications. Alternatively, the housing collar 26 may have projections instead of depressions 37 and 38, and the spring detent may have a downwardly depending indentation for operatively engaging such projections.
The preferred embodiment of the fluid exchange valve of the present invention may be assembled in a simple and efiicient manual operation. The rotor 24' is mounted coaxially on the valve housing 25' by engaging walls 86 and 22 in sliding and facing relationship, with the control lever 2% located between stops 6t) and 61 on the same side of the annular collar 2-6 as tubular member 28. As best seen in FIG. 3, the spring detent 32 is then manually slid into engaging relationship with the rotor 24 and a lower wall 98 of the valve housing 25. The spring detent 32 is biased between the hooked lower portions of the walls 23 of the valve rotor and the lower wall '38 of the valve housing. Tongue stop member 36 is engaged with one end of a wall 23 and prevents movement of the spring dctent in a direction opposite arrow 1% and the lip 95 of the keyhole slot 33 is automatically snapped into engagement with a second side Wall 23 to prevent movement of the spring member in the direction of arrow iii-f).
The cleaving or disassembly of the valve may be simply and manually performed by a reversal of the above procedure. The spring detent 32 is removed manually by depressing lip 95 while manually depressing the center of the spring member and sliding the spring detent 32 in the direction of the arrow shown at 10th in FIG. 3. In this manner the valve may be simply and efiiciently disassembled and cleaved for cleaning or sterilization purposes.
The operation and positioning of the valve of this in vention is certain, simple and efiicient. The valve may be positively positioned in various fluid exchange arrange ments by manual actuation of control lever 29 into positions defined by the limiting stops 6t) and 61 and the click stops 37 and 38. When the control lever is in its first position as shown in FIG. 4A, the position of the valve elements are determined by limiting stop 61. In the first position a passageway is provided interconnecting fittings 29 and 30 with all other passageways being blocked. This position may be employed for filling and/ or flushing the transducer from the heparin or saline or glucose reservoir.
On counterclockwise movement of the rotor by manual actuation of control lever 20, projection 34 slides along the lower wall 98 of-the valve housing collar until it reaches depression 37 whereupon it clicks into a second position and is spring biased within the groove 37. As shown in FIG. 4B, the second position is reached with the control lever 20 in the position shown. In the second position, the cathter fitting 28 is interconnected with the reservoir 29 and the transducer 3 by interconnecting passageways. In this position, the valve may be employed to maintain a continuous protective drip from the reservoir through the catheter while permitting qualitative monitoring (by oscilloscope) of the transducer output. The second position is the normal position of the valve during cardiac catheterization. However, the positioning of the valve elements may be changed when recording pressure pulses, drawing blood samples or injecting dyes or contrasting substances into the catheter.
Further rotation of the control member 20 in a counter clockwise direction causes projection 34 to leave the groove 37, slide along the lower wall 98 of the valve housing collar and click into engagement with the groove 38. At this point the control lever reaches a third position as shown in FIG. 4C. The third position interconnects the catheter to the transducer and excludes all other connections. This position is used during recording of pressure pulses emanating from the catheter.
Upon further movement of a control lever 2% in a counterclockwise direction, it meets limiting stop all and the fourth position of the valve is thereby reached. In this position the catheter fitting 28 and syringe fitting 31 are connected by interconnecting passageways. This position may be employed for sampling body fluids withdrawn from the catheter or for injecting iiuids into the body.
From the above description it will be readily understood that the novel fluid exchange valve of the present invention provides ease and certainty of operation. The limiting and click stops permita doctor or operating attendant to determine with certainty the exact position of the elements of the valve. Assembly and disassembly of the-valve for cleaning or other purposes may be accomplished manually by a depression and sliding action of the spring detent member. Due to the fact that there are only'three major components in the valve, which may be formed of stainless steel or other materials, the valve is easily cleanable, durable, inexpensive and relatively simple to manufacture.
An alternative embodiment of the invention is illustrated generally at 20% in FIG. 5. Fluid exchange valve 2% is particularly adapted for usage as a blood exchange'transfusion valve.
Blood exchange transfusions are frequently employed in cases of Erythroblastosis Fetalis in infants. in such transfusions the infants blood is exchanged with donor blood by removing the infants blood a syringeful at a time and replacing it with fresh RH- donor blood. Known valve systems have been employed to enable a single syringe to be used for withdrawing infant blood and injecting donor blood. However, in the known systems it has been found that the syringe employed tend to block as a result of blood clotting. Thus, it is common to employ as many as or more changes of syringes in a single blood exchange transfusion. Each time the syringe is changed, valuable time is lost and dangerous possibility of introducing air intothe infant exists. The fluid exchange valve of this invention enables rapid, accurate blood exchange transfusion and the employment of a novel procedure substantially eliminating disadvantages of known blood exchange transfusion valve systems and methods. I
The fluid exchange valve 206 is constructed in the same manner as the fluid exchange valve described with certain modifications as will be described hereinafter.
The valve housing comprises an annular collar or ring i236 having five fittings radially extending therefrom and interconnecting with radial passageways located in said annular wall. Tubular female fittings are provided at Hill and N52 with a male catheter fitting being provided at sea. A tubular fitting is provided having a one way valve comprising a plastic member 2tr2 spring biased between a narrow shoulder portion 203 and a hollow plug 284. Fitting is screw threaded into the annular collar 126 by thread means. As clearly seen in FIG. 5, fitting M5 allows passage of fluid from a blood donor or reservoir to the valve rotor but prevents fiuid passage opposite to the direction of the arrow shown at 299. Fitting 103 is similar to fitting 105 and contains a one way valve thereon which allows passage of fluid out of the rotor 1% in the direction of the arrow shown at 2&1 and prevent passage of fluid into the rotor. The one Way valve elements comprise a plastic stopper 492 spring 403 and a female Luer ending 40-4. The particular construction of one way valves 105' and 103 may be varied and other conventional one way valve means may be employed if desired.
The rotor 1% employed in the valve 2% is similar to element 2.4 above described. However, only four radially extending interconnecting passages 210, 211, 212 and 213 are provided. A spring detent 32 as above described is employed to position the rotor in three different operating positions and secure the rotor within the housing as described above.
The blood exchange transfusion valve 2% has three different positions. The first position is shown in REG. 5 with control lever 2% in the position illustrated and passageways Zld'and 212 connecting catheter fitting th t with syringe fitting m2, all other passageways being closed. The first position is located by a clicl: stop arrangement on the spring detent and valve housing as above described. In this position,'bl'ood may be withdrawn through the catheter fitting 194 into a syringe connected to fitting 192. A second position is reached by rotating lever 2i) clockwise until radially extending passageway 219 is aligned with the passages through fitting 1625 and the control lever 2% is prevented from further clockwise movement by a limiting stop suitably rovided on-a top surface of annular collar 126. In the second position, blood may be transferred from a syringe connected to fitting 102 into the discard fitting 1'83. It should be noted that although fittings 1 95, 162 and 103 are interconnected by radially extending passages of the rotor, no blood or other liquid can flow past the fitting H35 due to the action of the one way valve incorporated therein. After the syringe has been emptied, withdrawal of a plunger in the syringe enables blood to flow into the syringe from the reservoir or donor through passageway or fitting 1%, while the one way valve 193 prevents return of discarded blood. The control lever 20 is then rotated counterclockwise to the first noted position whereupon the donor blood within the syringe may be injected into the catheter. A third positioning of'the lever is accomplished by counterclockwise movement of control lever 20 until it meets a second limiting stop 61. At. this point the anticoagulant reservoir is connected through fitting 1G1 to the syringe fitting 1&2. Anticoagulant may be drawn into the system by the syringe and upon appropriate repositioning of the rotor means, by rotation of control lever 26, the anticoagulant solution may be discarded, or if desired, injected into the catheter through fitting 164.-
and. stop-means and employment of only four radially extending passages in the rotor.
The preferred method of employing the valve ass for blood exchange transfusions enables rapid and efficient exchange transfusion. The method of this invention comprises attaching fitting 104 to a catheter injected into a blood vessel of a recipient or body to be transfused, attaching fitting M by suitable fluid transmission tubing to a blood donor vessel or alternately to a blood reservoir, attaching fitting 101 by suitable fluid transmission tubing to an anticoagulant reservoir such as a heparin in glucose or saline solution, attaching fitting 162 to a syringe such as a conventional Luer syringe and attaching fitting 163 to a discard receptacle.
After the proper connections have been made to the valve fittings (or before), the control lever is clicked into the clic; stop and positioned in a first position as shown in FIG. 5. Blood is then withdrawn from the catheter into the syringe. The control lever is then moved clockwise to the second position of the valve. At this point the recipient blood is discarded from the syringe through the discard fitting 1% into a suitable receptacle. The syringe is then actuated in a second step by withdrawing a plunger therein to withdraw blood from the donor or reservoir through fitting 105 and into the syringe. The control lever is then actuated and moved counterclockwise to the first position described. At this point the syringe is depressed and the donor blood injected into the recipicut. The valve rotor may be rotated successively to the first and second positions carrying out the steps noted above in succession. However, it has been found that blood within the valve and syringe will tend to coagulate upon successive repositioning of the valve. In order to prevent coagulation and subsequent blockage of the valve passageways and the syringe, it has been found desirable to employ a third position of the valve rotor interconnecting fittings 1M and 1% and to fill the syringe with anticoagulant solution. The anticoagulant solution is discarded by moving the valve rotor means to the second position and emptying the syringe. In some cases small amounts of anticoagulant may be injected through the catheter into the recipient by employing the first position of the valve.
This method is extremely advantageous in that by simple repositioning of the valve rotor, continuous blood exchange may be accomplished without unnecessary time delay caused by coagulation or blocking of blood within the passageways of the valve system or the catheter.
While specific embodiments of the invention have been described and illustrated, it will be obvious that many variations of the invention are possible. For example, the number and type of fitting may be varied, the number and positions of stops and resulting connections employed may be varied and varying dimensions may be employed. All such variations and modifications are intended to be covered by the present invention which is to be limited only by the scope of the following claims interpreted in the light of the prior art.
What is claimed is:
1. A catheterization valve having means for selectively connecting four fittings into four different arrangements for fluid exchange with one arrangement int rconnecting a first and second fittings, a second arrangement interconnecting said first, second and fourth fittings, a third arrangement interconnecting said second and fourth fittings and a fourth arrangement interconnecting said third and fourth fittings, said valve comprising, a valve housing including an annular collar with four spaced radially arranged passageways extending through said angular collar,
four fittings each comprising a tubular member aligned and interconnected with one of said passageways and secured at one end to a first surface of said annular collar,
a valve rotor having a sidewall shaped and dimensioned to fit in rotatable sliding and facing relation to a second surface of said annular collar with passages in said rotor extending to said rotor sidewall for interconnecting said passageways into said four different arrangements for fluid exchange on selective rotation of said rotor, said passages comprising a plurality of passages exceeding in number the number of said fittings with one end of each of said passages extending to an opening on the surface of said rotor sidewall and the other end of each of said passages opening on at least one of said other passages within said rotor, said one end of each of said passages being spaced from said one end of at least one other passage a distance corresponding to the distance on said second surface of said annular collar between at least two of said passageways,
means for selectively rotating said rotor relative to said housing into said four different arrangements, and
means for interlocking said rotor and said housing with said second collar surface in engagement with said rotor sidewall.
2. A oathcterization valve in accordance with claim 1 wherein said last mentioned means for interlocking includes stop means for locating said rotor in selected positions in said housin whereby said passages are positioned in selected positions.
3. A cathcterization valve in accordance with claim 1 wherein limiting stops are provided on said valve housing.
4. A device as set forth in claim 1 having six passages in said rotor.
5. A device set forth in claim 4 wherein said six passages are all interconnected within said rotor.
6. A device as set forth in claim 1 wherein said interlocking means includes a spring resiliently urging said second surface and rotor sidewall together.
7. A device as set forth in claim 6 wherein said spring is a leaf spring extending across said rotor and is in engagement therewith with a portion engaging said annular collar, said leaf spring having a detent in said portion and said annular collar having means engageable by said dctent on rotation of said rotor to generate a clicking sound.
8. A blood exchange transfusion valve having means for selectively connecting five fittings into three different arrangements for fluid exchange, with one arrangement interconnecting a first and fourth fittings, a second ar rangement interconnecting a second, fourth and fifth fittings and a third arrangement interconnecting a third and fourth fittings,
slid valve comprising a housing with an annular collar having five spaced radially arranged passageways extending through said annular collar,
five fittings each comprising a tubular member aligned and interconnected with one of said passageways and secured at one end to a first surface of said housing annular collar, a valve rotor having a sidewall shaped and dimensioned to fit in rotatable sliding and facing relationship to a second surface of said annular collar with passages in said rotor extending to said rotor sidewall for interconnecting said passages and said passageways with said fittings aligned therewith into said three ditferent arrangements for fluid exchange on selective rotation of said rotor, said passages comprising four in number with one end of each of said passages extending to an opening on the surface of said rotor sidewall and the other end of each of said passages opening on at elast one of said other passages within said rotor, said one end of each of said passages being spaced from said one end of at least one other passage a distance corresponding to the distance on said second surface of said annular collar between at least two of said passageways,
means for selectively rotating said rotor relative to said housing into three different positions, and
means for interlocking said rotor coaxially with said housing.
9. A blood exchange transfusion valve in accordance with claim 8 having a leaf spring interlocking and tensioning said rotor and annular collar together.
10. A device as set forth in claim 8 wherein said four passages are all interconnected within said rotor.
11. A fluid exchange valve including, a housing having a truncated conic opening therein, a rotor positioned coaxially within said opening and having a truncated conic sidewall in facing relation with said opening, means forming passages in said housing and rotor adapted to be selectively aligned on rotation of said rotor and housing with respect to each other, said rotor having a pair of integrally formed L-shaped members extending from its narrower end and forming opposed parallel channels normal to the axis of said rotor and forming means for receiving and securing a leaf spring in a position transverse with respect to the axis of said rotor and with portions of said spring projecting into engagement With said housing, said leaf spring engaged at its side edges by said channels with portions thereof engaging said housing, said spring being secured in fixed relation to said rotor and in rotational relation to said housing, said leaf spring also exerting axial forces on said rotor and housing in opposite directions with the force on said rotor in an axial direction toward the narrower diameter of said truncated conic sidewall.
References Cited by the Examiner UNITED STATES PATENTS 508,365 11/93 Bothwell 251-297 X 1,170,958 2/16 Butler 128-214 1,224,959 5/17 Rosenfeld 251-181 X 1,561,867 11/25 Larsen 251-181 1,832,426 11/31 Roberts 251-297 2,505,145 4/50 Ryan 251-297 2,842,124 7/58 James 128-214 2,854,027 9/58 Kaiser et a1. 128-214 X 2,881,802 4/59 Crawford 251-297 3,048,192 8/62 Murphy 137-625.42
FOREIGN PATENTS 632,579 9/36 Germany.
M. CARY NELSON, Primary Examiner.
JORDON FRANKLIN, Examiner.