US2312455A

US2312455A - Intermitting system for flowing wells

Info

Publication number: US2312455A
Application number: US355274A
Authority: US
Inventors: Lynn M Trawick
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-09-03
Filing date: 1940-09-03
Publication date: 1943-03-02
Anticipated expiration: 1960-03-02

Description

March 2, 1943- l.. M. TRAwlcK l INTERMITTING SYSTEM FOR FLOWNG WELLS Filed sept. 3, 1940 2 Sheets-Sheet .L

o/o y Rw M w /Mwwww m c@ f w wm mwm; g J BK A March 2, 1943. L, M, TRAwlcK l l INTERMITTING SYSTEM FOR FLOWING WELLS 'Filed Sept. 3, 19110A 2 Sheets-Sheet 2 .III

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INVENT Patented Mar. 2, 1943 INTERMITTING SYSTE WELLS FOR FLOWING Lynn M. Trawick, Stroud, Okla.

Application September 3, 1940, Serial No. 355,274

(Cl. 10S-233) 15 Claims.

This invention relates to the flowing of liquid from wells and more particularly, but not by way of limitation to an automatic intermitting apparatus for controlling the admission of a gas under pressure into a column of liquid to raise the liquid out of the well. This application contains subject matter disclosed but not claimed in applicants co-pending application, Serial No. 355,273, filed September 3,1940, patented July 14, 1942, No. 2,289,603.

In the pneumatic displacement or gas lifting of liquid from oil wells, mechanical devices such as kick off, flow or starting valves for flowing the well have been used in wells where the bottom hole pressure is insufficient to provide a natural flow to raise the liquid level to the surface. With the event of proration in most of the oil bearing states, intermitting systems for flowing the Wells have been utilized wherein a liquid is displaced through the eduction tubing by injecting gas through a selectively disposed valve at timed intervals, the operation of the valve being affected by a time signal control installation at the top of the Well.

Heretofore, mechanical installations for the displacement of oil from wells has disregarded to a great extent the importance of gas lifting as an aid to preserving the bottom hole pressure or formation energy of the well. Furthermore, little consideration has been given the gas-oil ratio in producing the well since the motive fluid or input gas in usually injected into the well at sufficiently high pressures to ilow the well under any condition, which obviously in many instances causes unnecessary waste or use of motive fluid.

The present invention utilizes the arrangement of a plurality of automatic kick off or flow valves whose operation is based on the principle of constant submergence pressure. By constant submergence pressure is meant the pressure as determined by calculating the number of feet of liquid which the motive fluid operating in the well will suspend, minus the distance from a particular valve receiving the motive fluid to the liquid level below which the valve is arranged.

It is therefore an important object of this invention to provide means for controlling the admission of motive fluid under pressure into a column of liquid to raise the same from a well.

Another object of this invention is to provide means which will control the admission of motive Huid into a column of liquid in such a manner that the control means is governed by the hydrostatic pressure due to the column of oil.

A further object of this invention is to provide a fluid lifting assembly of an entirely automatic intermitting type which will be subject in its operation to the pressure of the column of liquid in the well, and to the motive fluid utilized in flowing the wen.

Another object of this invention is to provide a plurality of differential type fluid controlling valves having a dual seating arrangement, Whereas a valve is moved to a neutral position either by the hydrostatic level of the fluid or the pressure of the input gas, depending upon in which position the valve is seated.

An additional object of this invention is to provide an automatic intermitting apparatus arranged in the eduction tubing employed in the flowing of liquid from a well in such a manner that the apparatus acts as a choke for decreasing the volume of liquid to be lifted, thereby conserving the amount of motive fluid necessary to lift the liquid.

A further object of this vinvention is to provide an automatic intermitting apparatus in the eduction tubing employed in the flowing of liquid from an oil well, said apparatus including a plurality of control units determining the flow of liquid into the tubing, as well as discharging the liquid into the eduction tubing in a vertical upstream direction in order to prevent any distortion or turbulence of liquid below a control unit.

And still an additional object of this invention is to provide an automatic intermitting apparatus arranged in the eduction tubing of a well so as vto provide a proper gas-oil ratio by displacing as much liquid as possible with as little use of motive fluid as is economically feasible. Furthermore, the motive fluid is directed in a vertical upstream from the intermitting apparatus to prevent any pressure acting against the oil not being lifted and preventing any counterforce disturbing the normal back pressure of the well.

Other objects and advantages of the invention will be evident from the following detailed description read in conjunction with the accompanying drawings which illustrate one form of my invention.

In the drawings:

Fig. 1 is a fragmentary vertical sectional view with certain parts in elevation of the intermitting system shown disposed in a well hole.

Fig. 2 is an enlarged front elevational view of one of the lower valve collars and valve unit associated therewith.

Fig. 3 is an enlarged vertical elevational view of the collar and valve unit shown in Fig. 2. V

Fig. 4 is a View similar to Fig. 1 with the surface shown disposed in the well with the lower end in`v proximity of the shot hole 4. The upper end of.. the casing 2 is secured to a suitable casing head 8 cooperating with an apertured tubing head |0 suspending a string of tubing 6 in spaced relation to the casing 2.

The casing head s is provided with ports l2` and |4 receiving conduits I6 and I8 respectively. A tubing head T is disposed above head |0rand receives conduits 24 and'rr26 "respectivelyr A*rl/'heV conduit ,24is connected by the {T-connectionZ- tonoonduit I6.,A However, a suitable valve is interposed in line 24 for Vcontrolling the `flow of fluid through Vconduit 24. Valves 32 and 34fare interposed inline I6 on opposite sides of'Tconnection 28 for determining flow through' conduit I6. Apressure gauge 36 is interposed in line I6. Conduitl is provided fwith'valvfe 4 0 determining flowtherethrough,V while condit'ZGl is provided with a valve 42 closing olf or allowing discharge' of fluid therethrough;Y From the abovef'it will be apparent that the actuating 'uid from any suitable source (not shown) can be directed into the well, either into the casing 2 or the' tubing 6,

depending upon 4regulation of AValves A30; 32fandai.V oni die 'other hand; the' iijtebelifteq from the well may be discharged through rthe casing 2 or tubing 6 depending upon regulationA of the VallYS. and 4,2m Y i For the purpose of this invention, it is preferred that valve 80 be closed while valves 32v and 34 are open,allowinginotivemfluidto Ybe discharged into casing 6. A Similarly, valve 40is closed while'valve 424 is open .allowing` oil to b e discharged from tubing 6 through;A conduit 26v leading to-separators. storage'tanks, or the like (not shown). ./.fipressure` gauge 44 isv disposed at the top of tubingheadri.'v (Y i vThe intermitting unit or system is arranged in the lower sections of the tubing string 6, and comprisesl a collar interposed in the tubing 6, which for practical purposes is usually at a point from Iifty to one hundred feet abovethe normal liquid level of the well. The collar 50, as clearly shown in detailin Fig. 6, is provided with acentraily disposed spider' 52 having av vertical threaded passagewayor bore 54. The boreY 54- intersects with a transverse passageway or bore 56 providing communication therebetween. Sleeves or bushings 51 are threadedly secured at opposite ends of the passageway.

As clearly shown in Figs. 1 and 5, the upper portion of bore 54 receives a cylindrical housing 58 containing an intermittingV valve unit'to be later described. A string of smaller sizedl tubing 60 is secured in thelower portion of -the bore 56 and extends vertically downward from the collar 50 in spaced relation to an extension of eduction tubing 6 extending downwardly from thecollar 50. The tubing 60 is interconnected by aplurality of valve collars 62 (see Figs. 2 and 3b) having associatedV therewith adiierential valve unit 64 to beihereinafter described. l As shown in Fig. 1, conventional packing 66 is disposed between the tubing 6 and casing 2 immediately below the collar 50 to block off incoming gas pressure from the shot hole. The disposition of the packing provides a denite directional flow of input pres.. sure gas through the passageways 56 of the collar 50 for a purpose to be hereinafter described. The lower end of the tubing 60 is closed off by any conventional bull plug 68. The lowermost portion'of tubing 6 is provided with perforations 10 to allow flow of oil therethrough, and a valve cage 12 and ball valve 14 are disposed in tubing 6 for controlling the entrance of the oil into the tubing. The end of the tubing is closed oir by a plug 15.

"Referring to the intermitting unit in detail (Fig. 5),thehousing 58 comprises two sections 16 and 18 threadedly secured together at 80. A removable annular valve seat 82 is disposed betweenfthe'top of cylinder 16 and an annular flange 84 provided on the inner periphery of cylinder 18. The seatis provided with a dual bevelledv aperture 86 cooperating with a pair of semi-circular members forming a dual seating valvel88 `disposed on a stem 80. The stem 90 extendsrthrough an apertured valve stem guide 92 vprovided inthe interior of the cylinder 16. A helical tension spring 94 surrounds the stem and is anchored between the lower end of guide 92 and a pair of adjusting nuts 96 threaded on the lower end of stem 92. The spring 94 is adjusted to provide tension to assist seating of the upper portion of valve 88 in seating position. A housing 98 surrounding the spring is threaded at |00 to the guide. W A plurality of circumferentially spaced apertures |02 provides communication between the passageway 54 and valve 88. Y A cylinder I 04 is threadedly secured to the upper end of cylinder A18, and is provided with outlet apertures |06. Y y

The collars 62 connecting thesmaller sized tubing 60 areusually disposed from fifty to one hundred feet apart. Each of the collars 62 is provided with a reduced portion |08 in which is disposed the vertically arranged valve unit 64.

In Fig. 4 the arrangement of the intermitting system is exactly as that shown in Fig. l except that the standing Valve 14 in the lower section of the tubing 6 is omitted, as well as the packing 66, in order that the bottom hole pressure of the well can be utilized as a motive iluid maintained between the tubing 6 and the casing 2 and allowed to flow into the collar 50. It is to be understood that the lcasing 2 is closed off at the surface of the well (not shown).

Operation In operation it is intended in either of the illustrations shown in Figs. 1 or 4 that high pressure motive nuid such as gas or air shall be maintained at a substantiallyV constant pressure within the annular space I 40 between the tubing 6 and the casing, so as to be discharged into the passageway 58 of the collar 59. The installation of the intermitting system as in Fig. 4 is such that the collar 5|) is normally disposed above the liquid level of the well, thereby preventing any liquid flowing into passageways 5'5 and the interior of the tubing 60. a

The construction of the valve unit 58 or anyone of the units 64 is vsuch that the tension of their respective springs at all times tends to close the valve. The seating of a valve is assisted by the hydrostatic head of the column of well iluid assisting the action of the spring. It will be apparent that in any valve not submerged within the well fluid the dual seating aspect of the valve allows the injected motive fluid to close the valve against the tension of its respective spring. In an installation wherein the collar 5U is above the liquid level, the motive uid maintains Valve g3 in closed position and is directed from collar 59 for automatically unseating the first valve unit 64 disposed immediately below the liquid level. It will be apparent that the unseating action of a valve IIB is against the tension of a spring itil andthe hydrostatic head of the weil liquid. With the valve off its seat, motive fluid is injected into the oil stream in an upward vertical direction, lifting the column of liquid within the tubing. As the liquid flows upward, the hydrostatic head above the particular valve gradually falls due to the decreased amount of liquid thereabove, therefore force exerted upon the valve tending to hold it in closed position is obviously decreased while at the same time the velocity of gas entering the tubing 6 will increase due to the greater differential between the pressure existing in the tubing E and that existing in the casing 2. The `motive Huid will therefore exert an ever increasing force upon the valve tending to close it against the tension of spring |23 and the decreasing hydrostatic head within the tubing E. With sufficient depletion of the hydrostatic head the valve unit is closed and the gas is then directed downward through the tubing 6i) to a valve unit VEll immediately below the last unit to function, where the operation is repeated. This operation is repeated in the plurality of valve units 65 until `the liquid is lifted to a point above collar 5i).

The arrangement of the smaller tubing Sii and the valve units 64 in the space |42 ,provided by the interior of the lower sections of tubing 6 acts as a choke to decrease the volume in space lli2, which in turn decreases the amount or volume of liquid to be lifted by the units 64 to an elevation above the collar 50, It will thus be apparent that it will take less amount of gas at a constant -pressure to lift the oil in space |42, thereby providing an economical and conservative use of the motive fluid. As lon 1r as the hydrostatic head is sufficient above each of the valve units Sli, they will automatically function to lift the liquid in space |42 to an elevation above collar 50.

As soon as the hydrostatic head of the uid above the collar 5S, plus the tension of spring Sill becomes greater than the motive fluid pressure in the passageway 54, the lower` portion of the valve 88 will be moved downward off its seat for allowing passage of motive uid into the cylinder E04, through ports |06 and vertically upward into the oil stream, causing it to be aerated upward to the surface of the Well.

The disposition of outlet ports |05 directs the motive fluid in a vertically upward stream as well as effect-s a jetting action for increasing the velocity of the motive fiuid discharging into the eduction tubing 6. The lifting gas discharging at below the ports. The directional `path of the motive fluid does not contact the liquid below the ports |06, thereby preventing any counteracting force against the natural or bottom hole pressure of the well, and thus prevents any turbulence or distortion of the liquid standing at an elevation lower than the ports |66. With the liquid being caused to flow in space |44 above valve unit 58, to the surface, the hydrostatic head is decreased whereby the lower portion of valve E3 is closed against the bevelled seat 86.

The dual seating aspect of valve S3 and each of valves ||6 prevents an unnecessary Waste of motive fluid by closing the valve and substantially providing the proper gas-oil ratio necessary to lift the oil whether it be in space |132 or |44.

From the foregoing it will be apparent that the construction and arrangement of the intermitting system is simple and efficient in that once the submergence level of the well fluid is known, the tension on the various valve springs can be adjusted prior to putting the system in the well. Furthermore, the disposition of the collar 5i) determines the substantially constant pressure submergence necessary to slug or flow the liquid in space |42. For all practical purposes, in the average oil well it requires one hundred pounds per square inch of motive iiuid pressure to displace three hundred feet of oil. If the well liquid contains both oil and water, one hundred pounds of pressure will displace approximately two hundred feet. The smaller sized tubing E!) and its cooperating valve units 64 act as a choke for decreasing the volume of space for lifting less Volume of oil which obviously decreases the frictional resistance of liquid iiow, as Well as conserves the volume of gas in cubic feet for lifting a smaller volume of liquid above the collar 5B where it is then slugged to the surface of the well by the valve unit 53. From the normal submergence level of the well liquid and the disposition of the collar 5G, plus the number of valve units 64, it can be easily determined the time it takes to elevate the liquid above the collar in suiiicient quantities to cause an intermitting action of the valve 88 for slugging the oil to the surface of the well. Furthermore, any disturbance of the natural pressure of the well is eliminated, thus providing longer life to the sand pressure and substantially constant submergence liquid level. The well can thus fiow continuously by the automatic predetermined intermitting of the system for iiowing the liquid to the surface under any proration requirements.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims without departing from the spirit of the invention.

What I claim is:

l. A system for controlling the lifting of well liquid including an eductio-n tubing disposed in a well, motive iiuid inlet means interposed in the eduction tubing, intermittent means communicating with the inlet means and controlling the admission of motive fluid into the liquid at a point below the normal liquid level, said last mentioned means arranged in spaced relation in the eduction tubing and providing a choke for decreasing the volume of liquid to be lifted, differential means normally above the liquid level responsive to the hydrostatic head of the liquid being lifted for admitting motive fluidinto the eduction tubing above the differential means and causing aerating of the liquid, and means for increasing the velocity of the motive fluid discharging into the eduction tubing. V

2. A system for controlling the lifting of well liquid including an eduction tubing disposed in a well, motive fluid inlet means interposed in the eduction tubing, intermittent means communicating with the inlet means and controlling the admission of motive fluid into the liquid at a point below the normal liquid level, said last mentioned means arranged in spaced relation in the eduction tubing and providing a choke for decreasing the volume of liquid to be lifted, differential means normally above the liquid level responsive to the hydrostatic head of the liquid being lifted for admitting motive fluid into the eduction tubing above the valve and causing aerating of the liquid, and means directing the discharging motive fluid in a vertical path upward.

3. A system for the intermittent lifting of well liquid including an eduction tubing disposed in the well, motive fluid inlet means interposed in the eduction tubing at a point above the normal liquid level of the well, a plurality of differential valves communicating with the inlet means and arranged in spaced relation in the tubing and normally disposed below the liquid level to admit pressure fluid to the liquid in the tubing, said valves providing a choke for decreasing the volume of liquid to be lifted, each of said differential valves having a dual seating arrangement responsive to either hydrostatic head of liquid or pressure of motive fluid for controlling admission of motive fluid through the valves into the liquid for increasing the level thereof, an intermitting valve associated with the inlet means and responsive to an increased liquid level for admitting motive fluid into the eduction tubing for flowing the liquid.

4. A system for the intermittent lifting of well liquid including an eduction tubing disposed in the well, motive fluid inlet means interposed in the eduction tubing at a point above the normal liquid level of the well, a plurality of differential valves communicating with the inlet means and arranged in spaced relation in the tubing and normally disposed below the liquid level to admit pressure fluid to the liquid in the tubing, said valves providing a choke for decreasing the volume of liquid to be lifted, each of said differential valves having a dual seating arrangement responsive to either hydrostatic head of liquor or pressure of motive fluid for controlling admission of motive fluid through the valves into the liquid for increasing the level thereof, an intermitting valve associated with the inlet means and responsive to an increased liquid level for admitting motive fluid into the eduction tubing above the intermitting valve for flowing the liquid, and means for directing the flow of motive fluid in a vertical path upward and at an increased velocity.

5. A system for controlling the lifting of well liquid including an eduction tubing disposed in the well, a collar interposed in the eduction tubing and having an inlet passageway for motive fluid, a string of small tubing communicating with the passageway and extending downwardly from the collar in spaced relation in the eduction tubing, a plurality of couplings connecting sections of the small tubing, a differential valve associated with each of the couplings, an intermitting valve arranged above the collar and communicating With the passageway, said differential valves controlling admission of motive fluid for lifting the liquid level above the collar, said intermitting valve responsive to the hydrostatic head of the liquid being lifted for admitting motive fluid into the eduction tubing and causing flow of the liquid upward.

6. In a system for controlling the lifting of well liquid including an eduction tubing disposed in the well, a collar interposed in the eduction tubing permitting passage of motive fluid therethrough, a plurality of differential valves communicating with the flow passage in the collar and disposed below the collar in spaced relation in the eduction tubing an providing a choke for decreasing the volume of space below the collar, an intermitting valve communicatively associated with the collar and normally held in seated position by the pressure of the motive fluid, said differential valves responsive to the hydrostatic head of liquid for admitting motive fluid into the liquid for increasing the liquid level, said intermitting valve responsive to the hydrostatic head created by the increased liquid level for admitting motive fluid into the liquid stream above the intermitting valve and causing the liquid to be aerated in the eduction tubing.

7. In a system for controlling the lifting of well liquid including an eduction tubing disposed in the well, a collar interposed in the eduction tubing permitting passage of motive fluid therethrough, a plurality of differential valves arranged below the collar in spaced relation in the eduction tubing and providing a choke for de` creasing the volume of space below the collar, an intermitting valve associated with the collar and normally held in seated position by the pressure of the motive fluid, said differential valves responsive to the hydrostatic head of liquid for admitting motive fluid into the liquid for increasing the liquid level, said intermitting valve responsive to the hydrostatic head created by the increased liquid level for admitting motive fluid into the liquid stream above the intermitting valve and causing the liquid to be aerated in the eduction tubing, and a plurality of outlet ports associated with the valve for directing the flow of motive uid in a vertical upstream path.

8. In a well flowing apparatus including an eduction tubing, a collar interposed in the tubing, motive fluid inlet means in the collar, a plurality of differential valves arranged below the collar in spaced relation in the eduction tubing and communicating with the inlet means, an intermitting valve disposed above the collar and communicating with the inlet means, said differential valves controlling flow of motive fluid for lifting liquid above the intermitting valve, said intermitting Valve responsive to the pressure of the increased liquid for admitting motive fluid into the eduction tubing and lifting liquid therefrom.

9. In a owing apparatus for wells, an eduction tubing extending downwardly into the well liquid, an inlet collar in the tubing for admitting motive fluid, a plurality of vertically arranged differential valves extending downward from the collar in spaced relation in the tubing and providing a liquid choke below the collar, said valves in. fluid communication with the collar, an intermittlng valve associated with the collar and communicating therewith, said differential valves having a dual seating arrangement responsive to either hydrostatic head of liquid or pressure of motive iiuid for opening the valves to admit motive fluid into the liquid stream and increase the height of the liquid level, said intermitting valve responsive to the increased liquid level for admitting motive fluid into the eduction tubing above the valve and flowing the liquid to the surface.

10. In a owing apparatus for wells, an eduction tubing extending downwardly into the well liquid, an inlet collar in the tubing for admitting motive iluid, a string of small tubing extending downward from the collar and in iiuid communication therewith, a plurality of vertically arranged differential valves provided in the small tubing and arranged in spaced relation in the tubing and providing a choke below the collar, an intermitting valve associated with the collar and communicating therewith, said differential valves having a dual seating arrangement responsive to either hydrostatic head of liquid or pressure of motive fluid for opening the valves to admit motive uid into the liquid stream and increase the height of the liquid level, said intermitting valve responsive to the increased liquid level for admitting motive fluid into the eduction tubing and flowing the liquid to the surface, and jetting means cooperating with the valve for increasing the velocity of the discharging motive fluid.

11. In a flowing apparatus for wells, an eductiontubing extending downwardly into the Well liquid, an inlet collar in the tubing for admitting motive fluid, a plurality of vertically arranged differential valves extending downward from the collar in spaced relation in the tubing and providing a choke below the collar, an intermitting valve associated with the collar and communicating therewith, said differential valves having a dual seating arrangement responsive to either hydrostatic head of liquid or pressure of motive fluid for opening the valves to admit motive fluid into the liquid stream and increase the height of the liquid level, said intermitting valve responsive to the increased liquid level for admitting motive uid into the eduction tubing and flowing the liquid to the surface, and outlet means directing the motive fluid into the eduction tubing in a vertical path upward.

12. A well flowing apparatus including a tubing for conducting liquid from the well, an inlet collar for motive fluid interposed in the tubing, a plurality of kick ofi valves arranged below the collar and disposed in spaced relation in the tubing at successive elevations below the liquid level, said valves in fluid communication with the inlet collar an aerating valve disposed in the tubing above the collar and communicating therewith, said kick off valves successively responsive to the motive fluid whereby the motive fluid forces the liquid from the standing level in the well upward to a point in the tubing where the hydrostatic head of the liquid will move the aerating valve to a neutral position for admitting motive fluid into the tubing above the aerating valve.

13. A well flowing apparatus including an eduction tubing for conducting liquid from the well, an inlet collar for motive fluid interposed in the tubing, a plurality of kick off valves interposed between strings of smaller tubing at successive elevations below the collar and in spaced relation in the eduction tubing, said smaller tubing and kick off valves communicating with the collar and adapted to provide a choke for the normal liquid level standing in the eduction tubing, an aerating valve disposed in the eduction tubing above the collar, said kick off valves successively responsive to motive uid whereby motive fluid pressure forces the liquid from the standing level in the well upward to an elevation in the eduction tubing above the collar, said aerating valve responsive to the hydrostatic head of the lifted liquid for admitting motive uid into the eduction tubing above the aerating valve.

14. A vwell flowing apparatus including an eduction tubing for conducting liquid from the well, an inlet collar for motive iuid interposed in the tubing, a plurality of kick oli valves interposed between strings of smaller tubing at successive elevations below the collar and in spaced relation in the eduction tubing, said smaller tubing and kick off valves communicating with the collar and adapted to provide a choke for the normal liquid level standing in the eduction tubing, an aerating valve disposed in the eduction tubing above the collar, said kick olf valves successively responsive to motive fluid whereby motive fluid pressure forces the liquid from the standing level in the well upward to an elevation in the eduction tub-ing above the collar, said aerating valve responsive to the hydrostatic head of the lifted liquid for admitting motive fluid into the eduction tubing above the aerating valve, and outlet means for directing the motive iiuid in a vertical upward path.

15. A system for controlling the lifting of a well liquid including an eduction tubing disposed in a well, motive fluid inlet means interposed in the eduction tubing, means communicating with the inlet means and controlling the admission of the motive fluid into the liquid at a point below the normal liquid level, said last mentioned means arranged in spaced relation in the eduction tubing and providing a choke for decreasing the volume of liquid to be lifted, and differential means communicating with and receiving motive fluid from the inlet means disposed normally above the liquid level and responsive to the hydrostatic head of liquid being lifted for admitting motive uid into the eduction tubing and causing aerating of the liquid.

LYNN M. TRAWICK.