US3741298A

US3741298A - Multiple well pump assembly

Info

Publication number: US3741298A
Authority: US
Inventors: L Canton
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-05-17
Filing date: 1971-05-17
Publication date: 1973-06-26
Anticipated expiration: 1990-06-26

Abstract

An adapter housing for mounting an auxiliary well pump in a bore hole to supplement the production of, and act as a standby for, the main well pump. The adapter housing is mounted above the main pump in the bore hole and comprises an elongate tubular member having a diameter preferably no greater than that of the main pump. Inside the housing are a longitudinal chamber for mounting an auxiliary pump smaller than the main pump and a longitudinal bypass portion for conducting fluid under pressure upward from the main pump. The lower end of the housing is coupled with the discharge port at the top of the main pump, and the upper end of the housing is coupled with the well discharge pipe which extends to the ground surface. The two ends of the housing communicate through the bypass portion to form a continuous conduit from the main pump to the surface. The auxiliary pump chamber runs almost the entire length of the housing and has a cross section smaller than that of the housing to allow room for the bypass portion. The chamber is completely sealed from the bypass portion but is exposed to the surrounding well fluid by means of a window in the side of the housing. The small auxiliary pump mounted within the chamber draws fluid through the window and discharges it under pressure through a discharge port into the bypass portion of the housing. There the fluid mixes with and supplements the fluid discharged by the main pump, and the combined discharge of the two pumps is conducted by pump pressure to the ground surface, through the well discharge pipe. The interior of the bypass portion of the housing is provided with streamlined surfaces to minimize turbulence and is coated with a suitable material to reduce flow friction and resist corrosion. Power means are provided for running both pumps simultaneously to augment production for peak flow requirements, or alternatively for running each pump separately when lower volume is required or when one of the pumps breaks down.

Description

United States Patent Canton [451 June 26, 1973 MULTIPLE WELL PUMP ASSEMBLY [76] Inventor: Lawrence .1. Canton, 1713 N. E. 94th Street, Vancouver, Wash. 98665 [22] Filed: May 17, 1971 [21] Appl. No.: 143,787

Arutunoff 417/201 2,215,505 9/1940 Hollander 417/426 516,713 3/1894 Waite 166/65 R 2,204,857 6/1940 Hollander 417/62 2,242,166 5/1941 Bennett 166/105 2,682,225 6/1954 Coberly 417/203 2,931,304 4/1960 Massey l66/54.1

Primary Examiner-James A. Lepp'ink Attorney-Daniel P. Chernoff and Jacob E. Vilhauer, Jr.

[57] ABSTRACT An adapter housing for mounting an auxiliary well pump in a bore hole to supplement the production of, and act as a standby for, the main well pump. The adapter housing is mounted above the main pump in the bore hole and comprises an elongate tubular member having a diameter preferably no greater than that of the main pump. Inside the housing are a longitudinal chamber for mounting an auxiliary pump smaller than the main pump and a longitudinal bypass portion for conducting fluid under pressure upward from the main pump. The lower end of the housing is coupled with the discharge port at the top of the main pump, and the upper end of the housing is coupled with the well discharge pipe which extends to the ground surface. The two ends of the housing communicate through the bypass portion toform a continuous conduit from the main pump to the surface. The auxiliary pump chamber runs almost the entire length of the housing and has a cross section smaller than that of the housing to allow room for the bypass portion. The chamber is completely sealed from the bypass portion but is exposed to the surrounding well fluid by means of a windowin the side of the housing. The small auxiliary pump mounted within the chamber draws fluid through the window and discharges it under pressure through a discharge port into the bypass portion of the housing. There the fluid mixes with and supplements the fluid discharged by the main pump, and the combined discharge of the two pumps is conducted by pump pressure to the ground surface, through the well discharge pipe. The

interior of the bypass portion of the housing is provided I with streamlined surfaces to minimize turbulence and is coated with a suitable material to reduce flow friction and resist corrosion. Power means are provided for running both purnps simultaneously to augment production for peak flow requirements, or alternatively for running each pump separately when lower volume is required or when one of the pumps breaks down.

14 Claims, 4 Drawing Figures June 26, 1973 Unified States Patent [191 Canton PAIENTEUmzs ms 3. 741. 298

MULTIPLE WELL PUMP ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to improvements in well pump assemblies of the type where multiple pumps are positioned one above the other in a well bore hole, and conduit means are provided in the bore hole for conducting the fluid discharged by the pumps to the ground surface. More specifically, the pump assembly is of the type particularly adaptable for use in water wells where the pumps draw from the same fluid source and supplement one anothers flow production.

Well pump assemblies of the type commonly used in water wells usually consist of a single elongate cylindrical pump, normally electrically powered, immersed in water at the bottom of the well bore hole. The volumetric flow capacity of the pump under given discharge pressure and depth conditions depends on its diameter, horsepower rating and number of stages, greater diameters and horsepower rating and fewer stages generally corresponding to greater flow capacity. The size of pump required is determined by the estimated peak flow demands which may occur during the year. Pump size is also determined by the well bore diameter, which must be of sufficient size to house a pump capable of satisfying such peak flow demands.

The drawbacks of this common approach to water well pump design are threefold. First, the provision of only one pump in the bore hole does not provide any emergency or standby pumping capacity if the pump should fail. Such failure, for only 1 days time, might for example cause a dairyman the loss of an entire days milk crop. The dairyman might, for emergency requirements, drill a separate bore hole for a second pump, but this would be inordinately expensive. I

Second, the size of the pump and bore hole are determined by peak flow requirements which may typically arise only three or four times a year during periods of high irrigation demand. The high cost of providing a large enough pump and bore hole to satisfy these peak flow demands must be borne even though normal everyday volume requirements are much lower and require a substantially smaller pump and bore hole.

Third, a pump large enough to satisfy peak flow demands is not particularly efficient for satisfying everyday low flow demands, requiring costly excess power to do so. Moreover, a high flow capacity pump can be allowed to run only for short periods of time when small flow volumes are required, and such intermittent operation can be harmful to the pump and shorten its useful life.

Multiple well pump assemblies have on occasion been utilized in a single well bore hole in an attempt to overcome the above-mentioned difficulties. These prior art arrangements comprise two pumps of the same size and flow capacity positioned one above the other, immersed in water at the bottom of the bore hole. The pumps are plumbed in parallel to discharge into a common well discharge pipe and are individually actuated for low flow demands and jointly actuated for high flow demands. These systems do overcome several of the disadvantages inherent in the single pump assemblies inasmuch as one pump can act as a standby or emergency pump if the other breaks down, and only one pump need be actuated to satisfy small flow requirements while both may be run simultaneously for peak flow requirements. However, these assemblies require parallel plumbing which is difficult and expensive to install. Moreover, the additional plumbing causes operational problems not found in single pump assemblies by introducing turbulence and pipe friction pressure losses, particularly in the regions of the elbows and tees commonly utilized in such plumbing. These pressure losses tend to reduce the flow capacity of the pump assembly.

Furthermore, the expense of drilling an excessively large bore hole is not overcome by the multiple pump assemblies of the prior art, even though smaller diameter pumps can be used in combination for peak requirements. This results from the fact that a conduit must be provided bypassing the upper pump to conduct fluid discharged by the lower pump. Since both pumps are of the same diameter, the bypass circuit creates a bulge in the pump assembly adjacent the upper pump. This requires that the bore hole be of sufficient diameter to house the bulge, which necessitates the provision of a hole diameter greater than that otherwise required merely to house the pumps themselves. Many existing wells do not have bore holes of sufficient diameter to accommodate such a bulge.

SUMMARY OF THE PRESENT INVENTION The present invention is directed to a multiple well pump assembly of the general type described in which upper and lower pumps are both housedin a single well bore hole and the pumps are connected in parallel so as to supplement each others output. The upper pump, which is smaller in diameter and has a flow capacity less than the lower pump, is mounted in a prefabricated tubular adapter housing preferably having a diameter no greater than the diameter of the lower pump. The housing is positioned above the lower pump and contains a chamber exposed to the surrounding well water for mounting the upper pump, together with a conduit portion bypassing the chamber and coupled to the discharge end of the lower pump. Both pumps discharge into the bypass circuit of the housing where their fluid outputs mix with and supplement each other. The combined discharge of the two pumps is conducted to the ground surface through a well discharge pipe connected to the upper end of the housing. The interior of the bypass portion is provided with streamlined surfaces to reduce turbulence and is coated with a suitable material to minimize flow friction and resist corrosion. Power means are provided for running both pumps simultaneously to augment production for peak'flow requirements, or alternatively for running each one separately when lower volume is required or when one of the pumps breaks down.

The combination of features contained in the well pump assembly of the present invention provide it with several important advantages not found in well pump assemblies of the prior art, with respect to both initial installation and operation. First, the presence of two pumps supplementing each other and producing a peak flow rate equal to the sum of their individual discharge flow rates provides a substantial reduction in the diametric size of the pump means needed to satisfy peak flow demands, which in turn reduces the size of the bore hole diameter required. More importantly, the bore hole size is further minimized by the fact that the upper pump of the present invention has a smaller diameter than the lower pump and thus provides room for a bypass conduit without thereby creating a bulge adjacent the upper pump as is found in prior art upper and lower pump assemblies. Accordingly, the adapter housing need be no larger than the lower pump, and the bore hole therefore need only be large enough to house the lower pump. This advantage is particularly critical when it is desired to modify an existing well to increase output capacity, provide a standby pump, and supply multiple flow rates. The assembly of the present invention can accomplish this without need for enlarging the bore hole or well casing since the hole is already large enough to house the lower pump and therefore large enough to receive the adapter housing.

Second, the provision of a prefabricated upper pump housing having an integral bypass conduit for the lower pump and a mounting chamber for the upper pump, readily installable merely by coupling the housing with the discharge end of the lower pump without the need for any other plumbing, allows rapid, simple and inexpensive installation and removal.

Third, the provision of streamlined and coated surfaces within the bypass conduit of the housing minimizes the pressure losses in the fluid produced by the two pumps by reducing flow friction and turbulence below the levels encountered with prior art multiple pump devices.

Fourth, the provision of two pumps having different flow capacities coupled with power means for running each pump individually or both simultaneously provides a well pump system capable of selectively delivering three different effective flow rates from a single well bore hole to satisfy varying flow demands.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of the well pump assembly installed in a well casing, with portions of the casing cut away to expose the elements of the assembly.

FIG. 2 is an enlarged extended detail view of a portion of the assembly taken along line 2-2 of FIG. 1, with the casing and portions of the assembly cut away to show inner parts.

FIG. 3 is a top sectional view of the assembly taken along lines 33 of FIG. 2.

FIG. 4 is a bottom sectional view taken along line 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The well pump assembly, designated generally as in FIG. 1, comprises a main pump 12 and an auxiliary pump adapter housing 12 containing an auxiliary pump 14 mounted above the main pump 12. The entire pump assembly is mounted in a well bore hole lined with a conventional tubular well casing 18, the interior of which is exposed to the surrounding well fluid. Both main pump 12 and auxiliary pump 14 are positioned below the level of the water or other fluid within casing 18.

Main pump 12 and auxiliary pump 14 are conventional, electrically powered submersible turbine pumps of the type for example manufactured by Fairbanks Morse of Kansas City, Kans. The main pump 12 is of elongate, generally cylindrical shape with a series of rotary impellers 22 driven by an electric motor 20. Impellers 22 draw the surrounding well fluid from the interior of casing 18 through intake strainer 24 and discharge the fluid under pressure through threaded discharge conduit 26. Auxiliary pump 14 is similar in construction having electric motor 28 and impellers 30 which draw surrounding fluid through intake strainer 32 and discharges it through discharge conduit 34.

Each of the pump motors is connected to a source of electrical power through waterproof electrical cable 36 which contains a separate set of leads 37, 37a respectively for each pump. Each set of leads is coupled with a separate

electrical switch

39, 39a respectively at ground level operable either to conduct or interrupt the flow of electrical current to each pump individually. Thus, with a single switch in the closed position only the pump coupled with that switch is driven, while with both switches in the closed position both pumps are driven simultaneously.

The discharge conduits of main pump 12 and auxiliary pump 14 are connected in parallel by fluid passageways so as to discharge into a common well discharge pipe 38 which extends to ground level. This parallel plumbing, plus the means for mounting auxiliary pump 14 between main pump 12 and well discharge pipe 38, is provided by a novel auxiliary pump adapter housing 16 which will now be described in'detail.

Adapter housing 16, as best seen in FIG. 2, comprises an elongate tubular shell 40 with a threaded inlet port 42 at its bottom end for coupling with the threaded discharge conduit 26 of main pump 12, and a discharge port 44 at its upper end for coupling with the well discharge pipe 38. The shell 40 also contains an elongate opening or window 46 in one side of the shell forming a passageway between its exterior and interior.

Inside the shell is a wall assembly comprising upper streamlining member 48, U-shaped channel member 50 and lower streamlining member 52 which are sealingly joined with each other and with the interior of shell 40, as for example by welding, so as to divide the interior of the shell into two portions. The channel member 50 is of smaller width and depth than the diameter of shell 40 and has an upper end plate 54 sealing its upper end and a lower streamlining portion 56 sealing its lower end. Both plate 54 and streamlining portion 56 have flat edges 54a and 56a respectively, as best seen in FIGS. 3 and 4. Streamlining

members

48 and 52 have

flat sides

48a and 52a respectively which mate with and are sealingly joined with edges 54a and 56a respectively to form a continuously sealed wall. The pair of longitudinal edges 50a of channel member 50 are sealingly joined along their entire length with the inside surface of shell 40 and encompass the longitudinal edges of opening 46 so as to expose the concave side of channel member 50 to the opening while sealing its convex side from the opening. The sealing of the wall assembly with the interior of shell 40 is completed at the juncture of peripheral edges 48b and 52b of streamlining

members

48 and 52 respectively (FIG. 2) with the inner surface of shell 40.

From the above description of the wall assembly and the manner in which its components are sealingly joined with one another and with the interior of the shell, it is seen that the wall assembly seals the two interior portions of the shell from one another so as to prevent the passage of fluid between them. The portion exposed to opening 46 in the side of the shell and formed by the concave side of channel member 50 comprises a chamber 58 for housing auxiliary pump 14. The other portion comprises a longitudinal bypass conduit 60 which circumvents chamber 58 and connects inlet port 42 with discharge port 44 through their sealed junctures with streamlining

portions

52 and 48 respectively.

Shell 40 has an outside diameter and a transverse cross sectional area preferably no larger than the out side diameter and transverse cross sectional area, respectively, of main pump 12 so as not to require a casing or bore hole larger than that necessary to house main pump 12. Since both bypass conduit 60 and auxiliary pump 14 are housed within shell 40, pump 14 has a smaller transverse cross section and a smaller diameter than that of main pump 12. This is convenient since it is desirable that auxiliary pump 14 also have a dis charge flow rate capacity less than that of main pump 12 to provide a choice of flow rates from the well in a manner to be explained hereafter.

Auxiliary pump 14 is mounted within chamber 58 with its discharge conduit 34 sealingly joined with and penetrating through upper end plate 54 of channel member 50. Chamber 58 is exposed to the surrounding well water in casing 18 by virtue of opening 46, en abling pump 14 to draw from the surrounding fluid and discharge through upper end plate 54 into bypass conduit 60. Since bypass conduit 60 is also coupled with discharge conduit 26 of main pump 12 via inlet port 42, the discharge ends of the two pumps are connected in parallel for emptying into discharge pipe 38 via discharge port 44. Thisplumbing' arrangement, together with the aforementioned electrical switches which control the pumps, enables either pump to be actuated separately to discharge at their respective different flow rates into discharge pipe 38 or, alternatively, to be actuated simultaneously to discharge jointly into pipe 38 to produce a third flow rate greater than the individual flow rates obtainable from either pump individually. Thus, during periods of high irrigation demand, it might be desirable to drive both pumps simultaneously to achieve the highest flow rate possible. At other times, for example when washing a barn, a somewhat'lesser but still substantial flow rate might be desired in which case main-pump 12 alone might be actuated. At still other times, when water is needed only for low volume domestic uses, auxiliary pump 14 alone might be actuated. In each case the pump system would be delivering fluid at a rate consistent with its most efficient and economic capacity, thus helping to conserve power and lengthen pump life.

Housing 16 is provided with several internal features designed to maximize the flow rate of fluid discharged by

pumps

12 and 14 by minimizing pressure losses incident to such flow. For example channel member 50 is provided with a lower streamlining portion 56 in the shape of a flattened cone with its pointed end facing inlet port 42. Streamlining portion 46 reduces the turbulence and consequent pressure loss which might otherwise result from the directional deviation of flow through bypass conduit 60 caused by the protrusion of auxiliary pump chamber 58 into the bypass conduit. Moreover, upper and

lower streamlining members

48 and 52, each formed in the shape of a flattened truncated cone, minimize the turbulence which might otherwise be caused by the change in conduit cross section at the inlet and

discharge ports

42 and 44 of housing 16.

In addition, the interior surfaces of bypass conduit 60 are preferably coated with a suitable material such as PVC (polyvinyl chloride) or Teflon (polytetrafluorethylene) to reduce pipe friction pressure losses in the conduit and, at the same time, help to resist corromen.

It should be noted that the flattened sides of upper streamlining member 48 and lower streamlining member 52 respectively provide a pair of

cavities

62 and 64 within shell 40 through which electrical cable 36 can be threaded for connection with

pumps

12 and 14. This ensures that the cable is protected by shell 40 and that no additional space for the cable within the well casing is required exterior of shell 40.

The terms and expressions which have been employed in the foregoing abstract and specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

What is claimed is:

1. A well pump adapter housing for mounting an auxiliary pump above a main pump in a well bore hole and conducting the fluid discharged from both pumps into a well discharge pipe comprising:

a. an elongate shell having an inlet port adjacent its bottom end for coupling with the discharge conduit of said main pump, a discharge port adjacent its upper end for coupling with said 'well discharge pipe, and a passageway between the exterior and interior of said shell;

b. wall means Within said shell for dividing its interior into two portions sealed from one another to prevent the passage of fluid therebetween;

c. one of said portions comprising a chamber for housing said auxiliary pump exposed to the exterior of said shell through said passageway;

d. the other said portion comprising a longitudinal bypass conduit circumventing said chamber and connecting said inlet port and discharge port of said shell for conducting the fluid discharged by said main pump toward said well discharge pipe; and

e. auxiliary pump discharge conduit means coupled with said auxiliary pump for conducting the fluid discharged by said auxiliary pump toward said well discharge pipe.

2. The adapter housing of claim 1 wherein said auxiliary pump conduit means penetrates through said wall means into said bypass circuit.

3. The adapter housing of claim 1 comprising a tubular shell having an opening in one side thereof and an elongate channel member therein, said channel member being of a width and depth smaller than the inside diameter of said tubular shell and fitting within said shell with its concave side exposed to said opening, said concave side of said channel member forming said chamber for mounting said auxiliary pump and the portion between the convex side of said channel member and the interior of said shell forming said bypass conduit.

4. The adapter housing of claim 3 wherein said main pump is generally cylindrical in shape and wherein said tubular shell has an outside diameter no greater than the outside diameter of said main pump.

5. The adapter housing of claim 1 wherein the side of said wall means facing the interior of said bypass conduit includes streamlining means .for minimizing turbuto fluid discharged through said bypass conduit and for resisting corrosion.

7. A well pump assembly for drawing underground fluid and pumping the fluid through a well bore hole toward ground level comprising:

a. a first pump housed within said bore hole having a cross-section transverse to said bore hole;

b. a second pump housed in said bore hole at a higher elevation than said first pump and having a cross section transverse to said bore hole smaller in area than said cross section of said first pump;

0. bypass conduit means sealed from the intake of said second pump for conducting fluid discharged from said first pump upwardly past said second pump in side-by-side relation with the latter; and

d. conduit means for joining the fluid discharged from said second pump with said fluid discharged from said first pump.

8. The well pump assembly of claim 7 wherein the cross sectional area of said bypass conduit means transverse to said bore hole is sufficiently small that, when added to the corresponding side-by-side transverse cross sectional area of said second pump, the total area of the combined said cross sections is no larger than the transverse cross-sectional area of said first pump.

9. The well pump assembly of claim 7 wherein the greatest outside transverse width of said first pump is at least as large as the greatest outside transverse width of said second pump and bypass conduit assembly taken together.

10. A well pump assembly for drawing fluid from an underground fluid source and pumping the fluid through a well bore hole toward ground level comprismg:

a. a main pump means and an auxiliary pump means,

each comprising a vertically elongate pump member, both housed in said bore hole with their discharge ends connected by fluid conduit means with a common well discharge pipe for pumping said fluid from said fluid source through said well discharge pipe, said auxiliary pump means being mounted vertically above said main pump means and having a discharge flow rate capacity and a transverse cross sectional area less than that of said main pump means;

b. power source means selectively coupled with said pair of pump means and operable, in a first selective mode, for driving said main pump means to produce a relatively high discharge flow rate of said fluid through said discharge pipe and operable, in a second selective mode, for driving said auxiliary pump means without thereby driving said main pump means to produce a lower discharge flow 1 rate of said fluid through said discharge pipe; and

c. a bypass conduit for conducting fluid discharged from said main pump means upwardly past saidauxiliary pump means in side-by-side relation therewith.

1 1. The well pump assembly of claim 10 wherein said selectively coupled power source means is operable, in said first selective mode, for driving said main pump means without thereby driving said auxiliary pump means to produce said relatively high discharge flow rate of said fluid.

12. The well pump assembly of claim 11 wherein said selectively coupled power source means is operable, in

, a third selective mode, for driving said main pump means and said auxiliary pump means simultaneously to produce a total discharge flow rate of said fluid greater than the flow rates obtainable from either said main or auxiliary pump means individually.

13. The well pump assembly of claim 10 wherein said selectively coupled power source means is operable, in said first selective mode, for driving said main pump means and said auxiliary pump means simultaneously to produce said relatively high discharge flow rate of said fluid.

14. The well pump assembly of claim 10 wherein said main pump member is generally cylindrical in shape and wherein said auxiliary pump member and said bypass conduit are housed within a tubular member having an outside diameter no larger than that of said main pump member.

TINTTTD STATES PATENT @FFECE CERHHCATE CF CQRRECEWN Patent No. 3 741 298 Dated June 26 1973 lnventol-(s) Lawrence J, Canton It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. '2 Line 17 Change "circuit" to --conduit-;

Line 42 Change cxirc'uit" to -conduit.

Col 3, Line 52 7 Change adapter housing 12" to ---adap'ter housing l6-.

Col. 5, Line 53 Change "portion 46" to portion 56-.

C01. 6, Line 49 Change circuit" to -=--conduit-.

Signed and sealed this 20th day of November 1973'.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. RENE Du TEJGTMEYER Attesting Officer Acting Commissioner of Patents FORM PO-IOSO (10-69) USCOMM-DC 60376-1 69 9 U 5. GOVERNMENT PRINTING OFFICE I I965 0-366-334

Claims

1. A well pump adapter housing for mounting an auxiliary pump above a main pump in a well bore hole and conducting the fluid discharged from both pumps into a well discharge pipe comprising: a. an elongate shell having an inlet port adjacent its bottom end for coupling with the discharge conduit of said main pump, a discharge port adjacent its upper end for coupling with said well discharge pipe, and a passageway between the exterior and interior of said shell; b. wall means within said shell for dividing its interior into two portions sealed from one another to prevent the passage of fluid therebetween; c. one of said portions comprising a chamber for housing said auxiliary pump exposed to the exterior of said shell through said passageway; d. the other said portion comprising a longitudinal bypass conduit circumventing said chamber and connecting said inlet port and discharge port of said shell for conducting the fluid discharged by said main pump toward said well discharge pipe; and e. auxiliary pump discharge conduit means coupled with said auxiliary pump for conducting the fluid discharged by said auxiliary pump toward said well discharge pipe.

5. The adapter housing of claim 1 wherein the side of said wall means facing the interior of said bypass conduit includes streamlining means for minimizing turbulence with respect to fluid discharged through said bypass conduit.

6. The adapter housing of claim 1 wherein the portions of said shell and wall means facing the interior of said bypass conduit are coated with a layer of material for minimizing pipe friction pressure losses with respect to fluid discharged through said bypass conduit and for resisting corrosion.

7. A well pump assembly for drawing underground fluid and pumping the fluid through a well bore hole toward ground level comprising: a. a first pump housed within said bore hole having a cross-section transverse to said bore hole; b. a second pump housed in said bore hole at a higher elevation than said first pump and having a cross section transverse to said bore hole smaller in area than said cross section of said first pump; c. bypass conduit means sealed from the intake of said second pump for conducting fluid discharged from said first pump upwardly past said second pump in side-by-side relation with the latter; and d. conduit means for joining the fluid discharged from said second pump with said fluid discharged from said first pump.

10. A well pump assembly for drawing fluid from an underground fluid source and pumping the fluid through a well bore hole toward ground level comprising: a. a main pump means and an auxiliary pump means, each comprising a vertically elongate pump member, both housed in said bore hole with their discharge ends connected by fluid conduit means with a common well discharge pipe for pumping said fluid from said fluid source through said well discharge pipe, said auxiliary pump means being mounted vertically above said main pump means and having a discharge flow rate capacity and a transverse cross sectional area less than that of said main pump means; b. power source means selectively coupled with said pair of pump means and operable, in a first selective mode, for driving said main pump means to produce a relatively high discharge flow rate of said fluid through said discharge pipe and operable, in a second selective mode, for driving said auxiliary pump means without thereby driving said main pump means to produce a lower discharge flow rate of said fluid through said discharge pipe; and c. a bypass conduit for conducting fluid discharged from said main pump means upwardly past said auxiliary pump means in side-by-side relation therewith.

11. The well pump assembly of claim 10 wherein said selectively coupled power source means is operable, in said first selective mode, for driving said main pump means without thereby driving said auxiliary pump means to produce said relatively high discharge flow rate of said fluid.

12. The well pump assembly of claim 11 wherein said selectively coupled power source means is operable, in a third selective mode, for driving said main pump means and said auxiliary pump means simultaneously to produce a total discharge flow rate of said fluid greater than the flow rates obtainable from either said main or auxiliary pump means individually.

14. The well pump assembly of claim 10 wherein said main pump member is generally cylindrical in shape and wherein said auxiliary pump member and said by-pass conduit are housed within a tubular member having an outside diameter no larger than that of said main pump member.