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Publication numberUS2119736 A
Publication typeGrant
Publication dateJun 7, 1938
Filing dateApr 11, 1934
Priority dateApr 11, 1934
Publication numberUS 2119736 A, US 2119736A, US-A-2119736, US2119736 A, US2119736A
InventorsClarence J Coberly
Original AssigneeRoko Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Governed fluid operated pump
US 2119736 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

June 7, 1938. BERLY 2,119,736

GOVERNED FLUID OPERATED PUMP Filed April 11, 1934 2 SheetsSheet 1 [/v ins/v TOR CLARENCE (1 (05mm; BY

: ATTORNEY.

June 7, 1938. c. .1. COBERLY GOVERNED FLUID OPERATED PUMP Filed April 11, 1934 2 Sheets-Sheet 2 Z/Vi/E/VTOR; CLARENCE d COBERL Y,

Patented June 7, 1938 UNITED STATES GOVERNED FLUID OPERATED PUMP Clarence J. Coberly, Los'Angeles, Calif., assignor to Roko Corporation, Reno, Nev a corporation of Nevada Application April 11, 1934, Serial No. 720,059

14 Claims.

My invention relates to fluid operated deep well pumps of the character shown in my copending application, Serial No. 623,171, filed July 18, 1932, and entitled Liquid operated pump, and

relates in particular to a fluid operated pump embodying a governing device.

Fluid operated pump mechanisms for use in deep wells ordinarily include a fluid motor with a pump unit connected to the moving part of the fluid motor and being adapted to pump oil from the well up through a tube leading to the top of the well. For operating the mechanism fluid, such as oil, is pumped under relatively high pressure through a tube which connects to the motor of the mechanism. As long as the device is pumping oil from the oil formation in the well, it will operate at a normal speed, but it often occurs that gas forms in or enters the pump unit so that instead of a liquid being pumped, the pumping mechanism is operating against a compressible gas, the result being that a material portion of the pumping load is removed and the pump then races or operates at high speed until the gas is removed from the pumping unit. Fluid operated deep well pumps, due to spacelimitations, are customarily of cylinder-piston type, both the fluid motor and the pump unit of the pumping mechanism having cylinders and pistons respectively. When a pump of this character is allowed to race, very great liability of injury is present. For example, the pistons will strike the ends of the cylinders in which they operate, battering the same and upsetting the ends of the pistons, and in some instances breakage of parts may occur.

It is an object of my invention to provide a fluid operated pumping mechanism for deep wells having means incorporated therewith for preventing the above discussed racing of the device, and for generally operating to cause the pump to maintain a constant speed despite variations in the working load placed thereon.

It is a further object of the invention to provide a simple form of governor for controlling the flow of a fluid under pressure, which governor operates in response to changes in theload against which the fluid pressure is working.

It is a further object of the invention to provide a governing device adapted to be placed in a pressure fluid delivery line ahead of the mechanism to which the fluid is being delivered, such governor having a moving body with one. face thereof exposed to the pressure of fluid in the delivery tube and the other face thereof exposed to a pressure which varies in accordance with the pressures existing in the mechanism which receives or is operated by the pressure fluid.

Further objects and advantages of the invention will be made evident throughout the following part of the specification.

Referring to the drawings, which are for illustrative purposes only,

Fig. 1 is a vertically sectioned view showing the manner in which a deep well pump embodying my invention is employed in a well.

Fig. 2 is a diagrammatic view showing the motor and pump unit of the fluid operated pump ing mechanism.

Fig. 3 is an enlarged, vertically sectioned view showing the governor of the pump mechanism with the parts thereof in one operating position.

Fig. 4 is a sectional view similar to Fig. 3, showing the parts in another extreme position of operation.

Fig. 5 is an enlarged cross section on a plane represented by the line 5-5 of Fig. 3.

Fig. 6 is an enlarged cross'section on a plane represented by the line 66 of Fig. 3.

Fig. 7 is an enlarged cross section on a plane represented by the line of Fig. 3.

Fig. 8 is an enlarged cross section on a plane represented by the line 8-8 of Fig. 3.

Fig. 9 is an enlarged cross section on a plane represented by the line 9- -9 of Fig. 3.

Fig. 10 is a projection of the upper portion of the movable valve member of the device showing the relative lengths of the flow controlling channels or orifices therein.

In Fig. 1 of the drawings I show a pump mechanism l5 disposed in adeep well having a casing l6 through which a. screen string of pipe I! is carried from a casing-head l8 situated at the top of the well down to the oil bearing formation. From an intermediate fitting IQ of the casinghead l8 an oil production pipe 2| is carried down through the screen string of pipe H to a point within the oil producing zone of the well. The production pipe 2| 'has a conical seat 22 in the lower end thereof in which a conical inlet plug 24 secured to the lower end of the pump mechanism is seated. The pump mechanism I5 is lowered into the position in which it is shown in the production pipe 2| by means of a pressure fluid delivery tube 25 which isconnected to a cap 26 forming the upper part of the casing-head l8 and having a passage 21 therein through which a pressure fluid, such as clean oil, may be delivered from a pipe 28 into the delivery tube 25. The pumping mechanism l5 includes a pump unit 30 at the lower end thereof, a motor element of the valve mechanism 42.

3| above and connected to the pump unit 38, and a governor 32 which connects to the upper or inlet end of the motor element through a tube 33 and has the upper end thereof connected to the lower end 34 of the pressure fluid delivery tube 25.

As diagrammatically shown in Fig. 2, the pump unit 30 comprises a cylinder 35 having a piston 36 operated by means of a piston rod 31 which projects upwardly intoa powercylinder 38 forming a part of the motor element 3| and having a power piston 40 therein which is connected to the piston rod 31. A pilot or valve control rod 4| projects upwardly through a valve device 42, also forming a part of the motor element 3|. When the piston 48 reaches the upper end of its stroke, as shown in Fig. 2, an external passage 43 in the valve control rod 4| connects a pressure space 44 at the lower end of a piston valve 45 with a discharge passage 46 so that at this time fluid may discharge from the space 44 and the piston valve 45 may be forced downwardly by fluid which is received through the tube 33 intoa space 41 formed within the upper end The piston valve 45 is shown in the position which it assumes after it has been moved downwardly by pressure of fluid in the space 41 after the opening of the space 44 to the discharge passage 46. In this lowered position of the piston valve, a port 48 therein aligns with a passage 58 which communicates with the upper end of the power cylinder 38. At the same time, a passage 5| which connects the valve mechanism 42 with the lower end of the power cylinder 38 is connected through an annular port 52 of the piston valve 45 with a discharge passage 53 so that as fluid pressure is delivered from the space 41 through the port 48 and the passage 58 into the upper end of the power cylinder 38 so as to force the power piston 40 downwardly, fluid may discharge from the lower end of the power cylinder 38 through the passage 5|, the annular port 52, and the discharge passage 53 into a space 54 external of the pump mechanism 5 and within the oil production pipe 2|. The pumping cylinder 35 has intake passages 55 connecting the upper and lower ends thereof with the inlet plug 24, such passages 55 being equipped with check valves 51. The upper and lower ends of the cylinder 35 are provided with discharge passages 58 connecting with the space 54 and having check valves 59 therein. During the downward stroke of the pumping piston 36, oil is forced from the cylinder 35 through the lower discharge passage 58 into the space 54, in which it combines with the discharge fluid issuing through the discharge passage 53 from the motor element 3| of the pumping mechanism. When the pistons 36 and 40 reach the lower ends of their stroke, the pilot rod 4| will be carried down to such position that a depression of the reduced diametral portion 68 at the upper end thereof will permit pressure fluid to flow from the space 41 and through a port 62 into the pressure chamber 44 at the lower enlarged end of the piston valve 45, this pressure fluid causing the piston valve 45 to move upwardly to such position that a lateral port 63 therein will deliver pressure fluid into the upper end of the passage 5| leading to the lower end of the power cylinder 38 so that pressure will be applied to the lower face of the piston 48 to move the same upwardly. The movement of the piston valve 45 to raised position places the annular channel 52 of the piston valve 45 in such position that it will connect the upper end of the passage 58 with the discharge passage 53, so that as the piston 48 moves upwardly, fluid may be discharged therefrom through the .passage 58 through which the pressure fluid was previously delivered to the upper end of the power cylinder 38 to force the piston 40 downwardly.

As hereinbefore mentioned, the entrance of gas through the inlet plug 24 into the pumping cylinder 35 results in a material reduction in the working load against which the pump mechanism I5 is operating, for the reason that the cylinder 35 becomes filled with compressible fluid instead of a relatively non-compressible liquid. This reduction in load produces a condition known as racing, the result being that there is great danger of injury to the pump and the striking of one or both of the pistons 36 and 40 against the ends of the cylinders 35 and 38. My pumping mechanism constitutes a direct improvement over the prior art in the provision of a means for maintaining the delivery of pressure fluid to' the motor element 3| so as to maintain a substantially constant motor speed even when the working load on the pumping mechanism is decreased, thereby preventing the pumping mechanism from racing in such a manner that injury to the pump structure may occur. The means which I employ for this purpose consists of a governor of the character of the governor 32, details of which are shown in Figs. 3 to 10 inclusive. Such governor comprises a tubular shell 64 having a threaded counterbore 65 at its upper end for connection to the lower end 34 of the pressure fluid delivery pipe 25. The lower portion 66 of the shell 64 is of externally reduced diameter so as to provide a fluid space 61 within the upper end of the tube 33 which connects to the upper end of the motor element 3|, the upper end of the tube 33 being threaded onto an intermediate portion 68 of the shell 64. The shell has a bore or axial opening 18 consisting of an upper major bore 1| and a lower smaller minor bore 12, the bores 1| and 12 being separated by a radial shoulder 13. Threaded into the lower end of the minor bore 12 is a plug 14 having a central extension 15 projecting upwardly therefrom to serve as a stop for the downward movement of a member 16 which is movable in the bores 1| and 12. Below the shoulder 13 the minor bore 12 is provided with lateral ports or openings 11 communicating with the space 61 of the connecting tube 33. Slidable within the major bore 1| is a body or piston 18 which in the present form'of the invention is directly connected to and forms the upper extremity of the member 16. This body 18 has metering orifices extending from an upper face 8| thereof to a lower face 82 thereof for the purpose of transmitting pressure fluid from the pipe 25 to the space 83 within the major bore 1| below the piston or body 18. The space 83 is connected by passage means to the lower space 84 below the member 16 in the minor bore 12. Such passage means may be conveniently formed from an axial passage 85 extending upwardly from the lower end of the member 16, and a lateral passage 86 connecting the upper end -of the passage 85 with the space 83. The pressure of the fluid in the pipe 25 is applied directly to the upper face 8| of the body 18, tending to move this body downwardly in the major bore 1|. Reacting against this downward pressure is the pressure of fluid against the face 82 of the body 18, the pressure of fluid against the u lower end face 81 of the member 16, and upward pressure of a spring 88 which extends within the lower chamber 84 and between the plug 14 and the member 16. Under normal conditions of operation, that is, with the reciprocating parts of the pump moving at a slow normal rate of speed, the upward pressure against the member 16, which is connected to or includes the piston 18, is slightly in, excess of the downward pressure exerted by the pressure fluid in the pipe 25 so that the member 16 may be held in raised position, as shown in Fig. 3, against a shoulder provided by an inserted ring 96. Should the pressure of fluid upwardly against the member 16 be decreased, as, for instance, by racing of the pump mechanism, the member 16 will move downwardly. The invention provides flow restricting means, or, in other words, velocity and pressure reducing means operating in consequence of the downward movement of the member 16 so that the flow of pressure fluid from the pipe 25 to the motor element 3| of the pumping mechanism wili be restricted in volume, thereby limiting the speed at which the reciprocating parts of the motor element 3| can be driven. In this manner, possibility of the operation at.high speed is entirely avoided, and safety from injury to the pump due to such case as hereinabove set forth is assured.

The flow restricting means which I employ is of simple character and consists essentially of channels or orifices 9| in the member 16 near the upper end thereof but spaced below the body or. piston 18. These grooves or orifices 9| lead upwardly from a vertically elongated annular channel 92 in the member 16'and increase in length progressively so that as the member 16 moves downwardly from the position in which it is shown in Fig. 2, the entering of the passages 9| into the upper end of the minor bore 12 will cause a gradual reduction in. the communication between the space 83 above the shoulder 13 and the space 93 formed by the channel 92 of the member 16 in the minor bore 12. When the member 16 is in its extreme lowered position, against the stop 15, the communication between the space 83 and the space 92 will be restricted to the groove or orifice indicated at 9|a, in Figs. 4 and 10, which is the only one of the grooves 9| which extends entirely to the shoulder 13 which is formed near the upper end of the member 16 in a position confronting the space 83. As shown in Fig. 3, when the pumping mechanism is operating at normal speed, so that the pressure in the connecting tube 33 and in the motor element 3| are correspondingly high, the raised position of the member 16 provides a free communication from the space 83, through the channel 92 and the port 11, with the space 61 of the connecting tube 33 leading to the upper end of the motor element 3|.

An especial feature of my invention is the provision of a structure wherein a control member 16 moves downwardly in proportion to the difference in pressures existing in the inlet and outlet portions of the governor valve. It will be perceived that as the member 16 moves downwardly, the movement of the orifices 9| into the upper end of the minor bore 12 proportionately restricts the escape of fluid from the space 83, and that as the restriction of the escape of fluid increases, the pressure in the spaces 83 and 84 is increased until such time as the fluid pressures acting upwardly against the member 16 balance the fluid pressure acting downwardly thereon. Accordingly, therefore, the reduction in the pressure of fluid in the outlet space 61 of the governor 32 causes a movement of the member 16 downwardly into a flow restricting position controlled by the relative dif- 5 ferences in pressure in the pipe 25 and in the connecting tube 33. When the working load of the pump increases, as by discharge of gas from the pumping cylinder and replacement of the gas with oil, the pressure in the connecting tube 33 will increase, which increase in pressure will be transmitted through the ports 11 and the space 93 to the lower ends of the orifices 9| where the pressure will cooperate with the frictional head produced by the orifices 9| to increase the 15 pressure in the space 83, the result being that the member 16 moves upwardly until a balanced condition of operation is again attained.

Although I have herein shown and described my invention in simple and practical form, it is recognized that certain parts or elements thereof are representative of other parts, elements, or mechanisms which may be used in substantially the same manner to accomplish substantially the same results; therefore, it is to be understood that the invention is not to be limited to the details disclosed herein but is to be accorded the full scope of the following claims.

I claim as my invention: 1. A fluid operated deep well pump of the character described, including: a pump mechanism adapted to be placed in the lower part of the well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending down through said well to deliver pressure fluid to said pump mechanism; and a governor disposed between said pump mechanism and said delivery pipe constructed and arranged sothat, throughout its effective operating range, it maintains such volume of flow of fluid to said motor as to maintain a substantially constant motor speed regardless of fluctuations in load on said pump unit so as to prevent a harmful racing of. said pump mechanism.

2. A fluid operated deep well pump of the character described, including: a pump mechanism adapted to be placed in the lower part of the well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending down through said well to deliver pressure fluid to said pump mechanism; and a governor in saidwell disposed between said pump mechanism and said delivery pipe, said governor being responsive to a drop in fluid pressure in said fluid motor and automatically restricting the flow of pressure fluid into said fluid motor as the load on said pump unit decreases.

3. A fluid operated deep well pump of the character described, including: a pump mechanism adapted to be placed in the lower part of-the well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending down through said well to deliver pressure fluid to said pump mechanism; and a governor connected to said delivery pipe so that pressure fluid will pass therethrough, said governor being constructed and arranged so that, throughout its effective operating range, it maintains such volume of flow of fluid to said fluid motor as to maintain a substantially constant motor speed regardless of fluctuations in load on said unit.

4. A fluid operated deep well pump of the character described, including: a pump mechanism adapted to be placed in the lower part of the well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; .a pressure fluid delivery pipe extending down through said well to deliver pressure fluid to said pump mechanism; and a governor having its inlet connected to the lower part of said delivery pipe and its outlet connected to said pump mechanism, said governor comprising a casing, a movable body in said casing having one face thereof subject to pressure of fluid in said delivery pipe and the other face thereof subject to pressure, of fluid in said outlet and moving in response to the change in relative pressures in said pipe and said outlet, and valve means controlled by said movable body operating to control the flow from said delivery pipe to said pump mechanism.

5. A fluid operated deep well pump of the character described, including: a pump mechanism adapted .to be placed in the lower part of the well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending down through said well to deliver pressure fluid to said pump mechanism; and a governor having its inlet connected to the lower part of said delivery pipe and its outlet connected to said pump mechanism, said governor comprising a casing, a movable body in said casing having one face thereof subject to pressure of fluid in said delivery pipe and the other face thereof subject to pressure of fluid in said outlet and moving in response to the change in relative pressures in said pipe and said outlet, there being spring means urging said movable body in a direction against the pressure of fluid from said fluid delivery pipe, and valve means controlled by said mov'able body operating to control the flow from said delivery pipe to said pump mechanism.

6. A fluid operated deep well pump of the character described, including: a pump mechanism comprising a fluid operated motor and a pump unit connected to said motor so as to be driven thereby, said motor having a fluid inlet; a pressure fluid delivery tube extending down through said well to deliver pressure fluid to said fluid motor; and a governor device connected to the lower end of said pressure fluid delivery tube so as to receive pressure fluid therefrom and connected to said fluid inlet of said fluid motor so as to deliver pressure fluid thereto, said governor device having a valve structure operated in response to a decrease in pressure in said inlet to apply a restraint to the flow of pressure fluid through said governor device from said pressure fluid delivery tube to said inlet in a fixed relation to the decrease in pressure in said inlet.

7. A fluid operated deep well pump of the character described, including: a pump mechanism adapted to be placed in the lower part of the well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending down through said well to deliver pressure fluid to said pump mechanism; and a governor in said well and connected to said delivery pipe so that pressure fluid will pass therethrough, said governor automatically maintaining the flow of pressure fluid into said motor at a predetermined constant rate regardless of changes in the load on said pump unit.

8. A fluid operated deep well pumping mechanism of the character described, including: a pump mechanism adapted to be placed in a well,

said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending from a source of supply of pressure fluid to said pump mechanism for delivering said pressure fluid thereto; and a governor connected to said delivery pipe so that pressure fluid will pass through said governor, said governor normally maintaining the flow of pressure fluid into said motor at a substantially constant rate but being constructed and arranged so that, throughout its effective operating range, it maintains such volume of flow of pressure fluid to said pump mechanism as to maintain a substantially constant speed of operation of said pump mechanism regardless of changes in load on said pump mechanism.

9. A fluid operated deep well pumping mechanism of the character described, including: a pump mechanism adapted to be placed in a well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending from a source of supply of pressure fluid to said pump mechanism for delivering said pressure fluid thereto; and a governor connected to said delivery pipe so that pressure fluid will pass through said governor, said governor including a valve member adapted to permit the passage of said pressure fluid therethrough and being movable from open position to any degree of closure in response to changes in the rate of said fluid flow, said governor being constructed and arranged so that it automatically adjusts the position of said valve member, throughout its eifective operating range, to maintain such volume of flow of pressure fluid to said motor as to maintain a substantially constant motor speed regardless of fluctuations in load on said pump.

10. A fluid operated deep well pumping mechanism of the character described, including: a pump mechanism adapted to be placed in a well, said pump mechanism comprising a fluid motor and a pump unit connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending from a source of supply of pressure fluid to said fluid motor for delivering said pressure fluid thereto; and a governor through which said fluid passes, said governor including a valve member adapted to throttle the flow of said pressure fluid, a cylinder having a piston therein operatively connected to said valve member, walls forming an orifice through which said fluid passes, and means for applying the differential pressure on said orifice to the faces of said piston so as to control the action of said valve member.

11. In a fluid operated deep well pumping mechanism, the combination of: a pump mechanism including a fluid motor and a pump unit in a well connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending from a source of supply of pressure fluid to said motor for delivering pressure fluid thereto; and a governor through which said fluid passes, said governor including a throttle valve and walls forming a metering orifice adapted to have a differential pressure thereon, said orifice being connected in series with said valve, and

means for applying said diiferential pressure onsaid orifice to control the throttling action of said valve.

12. In a fluid operated deep well pumping mechanism, the combination of: a pump mechanism including a fluid motor and a pump unit in a well connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending from a source of supply of pressure fluid to said motor for delivering pressure fluid thereto; and a governor through which said fluid passes including a throttle valve member and walls forming a metering orifice adapted to have a differential pressure thereon through which said fluid is adapted to pass, a cylinder having a piston therein operatively connected to said valve member, resilient means tending to hold said throttle valve member in an open position, and

means for applying said differential pressure on said orifice to said piston so that the resultant force opposes the action of said resilient means.

13. In a fluid operated deep well pumping mechanism, the combination of: a pump mechanism including a fluid motor and a pump unit in a, well connected to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe extending from a source of pressure fluid to said motor for delivering pressure fluid thereto; and a governor through which said fluid passes including a throttle valve and walls forming a metering orifice through which said fluid passes,

a cylinder having a piston therein operatively connected to said throttle valve, fluid from the ends of said orifice communicating with the faces of said piston so that the resultant force from the difierential pressure on said oriflce tends to close said throttle valve, and resilient means for oppos ing the action of said piston.

14. A fluid operated deep well pump of the character described, including: a pump mechanism adapted to be placed in the lower part of the well, said pump mechanism comprising a fluid motor, and a pump arranged relatively to said fluid motor so as to be driven thereby; a pressure fluid delivery pipe connected to said pump mechanism for delivering pressure fluid to said fluid motor; and a governor connected tosaid pressure fluid delivery pipe and actuable by pressure fluid, said governor being constructed and arranged so that, throughout its effective range of operation, it maintains snort volume of flow of pressure fluid to said moto as to maintain a substantially constant motor speed regardless of changes in load on said pump.

- CLARENCE J. COBERLY.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2589668 *May 5, 1947Mar 18, 1952Dresser Equipment CompanyControl governor for fluidoperated pumps
US2637276 *May 10, 1947May 5, 1953Dresser Equipment CompanyMethod of and apparatus for hydraulic pumping
US2639609 *Jun 3, 1947May 26, 1953Du PontApparatus for determining boiling points
US2703585 *Dec 1, 1949Mar 8, 1955Kobe IncControl valve for fluid-operated motors
US3865516 *Aug 3, 1973Feb 11, 1975Roeder George KFluid actuated down-hole pump
US4597722 *Mar 22, 1985Jul 1, 1986Tichy James BLong-stroke downhole pump
US4792291 *Sep 9, 1987Dec 20, 1988Graco Inc.Viscous damped valve for hydraulic pump
US4820135 *Feb 9, 1987Apr 11, 1989Shell Oil CompanyFluid driven pumping apparatus
US4828036 *Jan 5, 1987May 9, 1989Shell Oil CompanyApparatus and method for pumping well fluids
US4871302 *Jan 26, 1988Oct 3, 1989Milam/Clardy, Inc.Apparatus for removing fluid from the ground and method for same
WO1989007201A1 *Jan 19, 1989Aug 10, 1989Milam/Clardy, Inc.Apparatus for removing fluid from the ground and method for same
Classifications
U.S. Classification91/335, 91/446, 91/319, 92/112, 91/300, 417/404, 137/517
International ClassificationF04B47/04
Cooperative ClassificationF04B47/04
European ClassificationF04B47/04