US3829248A

US3829248A - Utility pump

Info

Publication number: US3829248A
Application number: US00320985A
Authority: US
Inventors: H Bright; L Davis; F Stanaszek
Original assignee: Little Giant Corp
Current assignee: LGC LIQUIDATING Inc; Little Giant Pump Co; Little Giant Corp
Priority date: 1973-01-04
Filing date: 1973-01-04
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13

Abstract

A self-priming pump assembly including motor means with a rotatable drive shaft extending therefrom and pump mounting means secured to the motor means with the drive shaft extending therethrough. A pump unit is demountably secured to the pump mounting means and includes an interchangeable pump cam with a pair of identical interchangeable pump cam with a pair of identical interchangeable wear plates disposed at each end thereof within a pump housing. A flexible vane impeller is secured to the drive shaft within the pump cam and between the wear plates. The pump housing has inlet and outlet fittings integrally formed therewith. The pump assembly is conformed such that it may be completely disassembled while the pump housing is left in assembled relation with the inlet and outlet fittings thereof connected to external inlet and outlet conduits.

Description

[ Aug. 13, 1974 ll'lllllLlTY PUMP [75] inventors: Hugh 11. Bright, Oklahoma City; Lee W. Davis, Del City; Frank ,1. Stanaszek, Bethany, all of Okla.

[73] Assignee: Little Giant Corporation, Oklahoma City, Okla.

[22] Filed: Jan. 4, 1973 [21] Appl. No.2 320,985

[51] lint. Cl. F041) 35/04 [58] Field 01 Search 417/410, DIG. 1;418/154, 418/178 [56] References Cited UNITED STATES PATENTS 2,971,469 2/1961 McLean 418/154 X 3,240,154 3/1966 Robbins 418/154 X 3,303,791 2/1967 Doble 418/154 3,390,638 7/1968 Adams 417/410 X 3,468,260 9/1969 Belden 417/410 7/1966 Great Britain 418/154 Primary Examiner-C Husar Assistant Examiner-Leonard Smith Attorney, Agent, or Firm-.lerry J. Dunlap ABSTRACT A self-priming pump assembly including motor means with a rotatable drive shaft extending therefrom and pump mounting means secured to the motor means with the drive shaft extending therethrough. A pump unit is demountably secured to the pump mounting means and includes an interchangeable pump cam with a pair of identical interchangeable pump cam with a pair of identical interchangeable wear plates disposed at each end thereof within a pump housing. A flexible vane impeller is secured to the drive shaft within the pump cam and between the wear plates. The pump housing has inlet and outlet fittings integrally formed therewith. The pump assembly is conformed such that it may be completely disassembled while the pump housing is left in assembled relation with the inlet and outlet fittings thereof connected to external inlet and outlet conduits.

8 Claims, 7 Drawing Figures UTHLHTY PUMP BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates generally to pumps and more particularly, but not by way of limitation, to a self-priming integral utility pump and drive motor assembly.

2. Description of the Prior Art The self-priming utility pumps currently available display a number of disadvantages. One available utility pump utilizes a pump head constructed of chrome plated brass which is subject to corrosion. This particular pump has the pump cam formed integrally with the brass pump head which results in the replacement of the entire pump head when the pump cam surface is worn out. This particular pump further utilizes no replaceable wear plates which again shortens the overall service life of the pump.

Another form of available utility pump employs a wear plate which is positioned such that the motor drive shaft can run on it making burrs which cause metal particles to get into the impeller thereby causing scoring and wear of the cam surface and wear plate. This particular pump does not employ interchangeable wear plates or a replaceable pump cam thereby shortening the overall service life of the pump. The pump housing of this particular pump is fabricated of a brittle plastic material and removal and reinstallation of the mounting screws readily causes the plastic to chip away from screw holes which can easily render the pump housing unserviceable. The shaft seal of this particular pump is retained in place by a metal washer which is difficult to remove for replacement of the seal. This particular pump further has no facility for direct connection into a rigid piping system.

A third known form of self-priming utility pump employs a thin cover and gasket over the outer portion of the pump housing thereby subjecting the pump the increased possibility of leakage. This particular pump employs brass inlet and outlet fittings which are subject to corrosion. The drive shaft seal employed by this pump comprises a hydraulic cylinder U type cup retained by a loose metal washer, which washer can be easily displaced to a position where it would rub against the rotating drive shaft, thereby causing grooving of the shaft and spreading metal burrs in the area of the seal thus shortening the service life of the pump. This particular pump further employs an additional spacer plate between the wear plate adjacent the drive motor and the shaft seal which must be removed and accounted for during repair or replacement of the seal.

SUMMARY OF THE INVENTION The present invention is directed to a self-priming utility pump assembly comprising motor means for driving the pump assembly, with the motor means including drive shaft means extending outwardly therefrom for drivingly rotating relative to the motor means. The pump assembly further includes pump mounting means fixedly secured to the motor means with the drive shaft means extending therethrough for mounting a pump unit on the motor means, and seal means carried by the mounting means for sealingly engaging the drive shaft means extending therethrough and providing a seal therebetween. The pump assembly also in- 2 cludes a substantially planar outer end face formed on the mounting means lying in a plane normal to the axis of the drive shaft means extending therethrough.

The self-priming pump assembly of the present invention also includes a pump unit carried by the mounting means adjacent to the outer end thereof, with the pump unit including a pump housing having an inner end face and an outer end portion with the inner end face thereof positioned adjacent to the mounting means. The pump housing has a cavity'formed therein intersecting the inner end face thereof and defined by a planar end wall lying in a plane substantially normal to the axis of the drive shaft means and by an inner peripheral surface traced by a straight line moving parallel to the axis of the drive shaft means and interconnecting the end wall and the inner end face of the pump housing. An inlet port is formed in the pump housing and communicates between the exterior thereof and the cavity formed therein, and an outlet port is formed in the pump housing communicating between the exterior thereof and the cavity formed therein. A pump cam having an outer end face and an inner end face is slidably disposed in the cavity, the pump cam having an outer periphery conforming to and slidably engaging the inner periphery of the pump housing, and having an inner periphery of non-circular cross-section and traced by a straight line moving parallel to the axis of the drive shaft means and intersecting the inner and outer end faces of the pump cam. An inlet port is formed in the pump cam and communicates between the inner periphery of the pump cam and the outer periphery thereof and the inlet port of the pump housing, and an outlet port is formed in the pump cam communicating between the inner periphery of the pump cam and the outer periphery thereof and the outlet port of the pump housing.

An impeller, having an inner end face and an outer end face, a hub portion, and a plurality of flexible vanes extending radially outwardly from the hub portion in spaced relation, is disposed within the inner periphery of the pump cam with the outer end portions of the flexible vanes slidably engaging the inner periphery of the pump cam and with the outer end portion of the drive shaft means extending into the center portion of the hub portion. The pump unit further includes means for demountably connecting the impeller to the drive shaft means for rotation therewith. Also included are a pair of identical wear plates each having an aperture formed therein for receiving the drive shaft means therethrough and disposed respectively between the outer end face of the mounting means and the inner end face of the impeller, and between the planar end wall of the pump housing and the outer end face of the impeller.

Accordingly, an object of the present invention is to provide a self-priming utility pump which is highly reliable and exhibits a long service life.

- Another object of the present invention is to provide a utility pump which may be quickly and easily disassembled and reassembled in the event repairs are required.

Yet another object of the present invention is to provide a utility pump which employs a minimum number of parts for simplified maintenance.

A further object of the present invention is to provide a utility pump which may be extensively repaired without removal of the pump housing from the piping system in which it is installed.

A yet further object of the present invention is to provide a self-priming utility pump which is not susceptible to corrosion damage.

A still further object of the present invention is to provide a self-priming utility pump which is economical to manufacture and maintain.

Other objects and advantages of the present invention will be evident from the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of the utility pump of the present invention.

FIG. 2 is a plan view of the utility pump of the present invention.

FIG. 3 is a partial cross-sectional view of the.utility pump of the present invention taken along line 3-3 of FIG. 2.

FIG. 4 is an enlarged portion of the partial crosssectional view of FIG. 3.

FIG. 5 is a front end elevational view of the utility pump of phe present invention with a portion of the pump housing shown broken away to more clearly illustrate details of internal construction.

FIG. 6 is an exploded view of the utility pump of the present invention.

FIG. 7 is an enlarged portion of the cross-sectional view of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, the self-priming utility pump assembly of the present invention is generally designated by reference character 10. The pump assembly 10 generally comprises a drive motor 12, a pump mounting adapter 14, and a pump unit 16.

The drive motor 12 is preferably an electric motor of either the AC or DC type. Suitable types of motors are found to be the 115 volt AC, 230 volt AC, and 12 volt DC types. The drive motor 12 is suitably equipped with a mounting bracket 18 which is rigidly secured thereto and which is equipped with a plurality of rubber vibration isolating grommets 20 to facilitate the installation of the drive motor 12.

A rotatable drive shaft 22 extends outwardly from the drive motor 12 and includes a water slinger 24 suitably installed thereon, such as by press fitting, adjacent to the drive motor 12. The outer end portion 26 of the drive shaft 22 includes a flat surface 28 formed thereon for engaging the pump impeller as will be described hereinafter.

The pump mounting adapter I4 is secured to the end of the drive motor 12 adjacent to the drive shaft 22, with the drive shaft 22 extending therethrough. The adapter 14 is preferably secured to the drive motor 12 by means of a pair of threaded screws 30 extending through the adapter 14 and threadedly engaging the drive motor 12. The adapter 14 includes a cavity 32 formed therein which surrounds a portion of the drive shaft 22 and the water slinger 24 secured thereto. An aperture 34 is formed in the lower portion of the adapter 14 through which fluid, which has been slung from the drive shaft 22 by the water slinger 24, may drain from the cavity 32.

A seal cavity 36, defined by a planar end wall 38 and a substantially cylindrically shaped inner periphery 40, is formed in the outer end portion 42 of the adapter 14. The cylindrically shaped inner periphery 40 communicates with a substantially planar outer end face 44 formed on the outer end portion 42 of the mounting adapter 14. The outer end face 44 lies in a plane normal to the axis of the drive shaft 22.

An annular shaft seal 46 is disposed within the seal cavity 36 providing a fluid-tight seal between the pump mounting adapter 14 and the shaft 22. The seal 46 comprises an annular reinforcing ring 48 having an L- shaped cross-section and preferably formed of a suitable metal such as steel. The shaft seal 46 further includes an annular elastomeric seal member 50, of U- shaped cross-section, which is integrally molded around and bonded to the reinforcing ring 48. An annular coil spring member 52 encircles the inner portion of the elastomeric seal member 50 and urges the inner portion thereof radially inwardly into sealing engagement with the drive shaft 22. The annular coil spring member 52 is preferably formed of stainless steel.

A substantially cylindrical outer peripheral portion 54 intersects the outer end face 44 of the pump mounting adapter 14 and extends a distance therefrom toward the drive motor 12. The peripheral portion 54 is interrupted at its uppermost portion by an arcuately shaped portion 56 defining a peripheral surface spaced radially inwardly from the outer peripheral portion 54. The arcuately shaped peripheral portion 56 has an arc length of approximately l/6th of the circumference of the outer peripheral portion 54. The arcuately shaped portion 56 provides a portion of a key way system for the pump assembly 10 to facilitate the alignment of various parts thereof as will be described more fully hereinafter.

The outer

peripheral portions

54 and 56 intersect an annular sealing surface 58 which extends radially outward therefrom and lies in a plane parallel to the outer end face 44.

The pump unit 16 includes a pump housing 60 which is rigidly secured to the pump mounting adapter 14 by means of a plurality of threaded screws 62 extending through the pump housing 60 and threadedly engaging the pump mounting adapter 14. When properly installed on the mounting adapter 14, the inner end face 64 of the pump housing 60 is positioned adjacent to the annular sealing surface 58 of the adapter 14 with a fluid-tight gasket 66 disposed therebetween to provide a seal between the pump housing 60 and the pump mounting adapter 14.

The pump housing 60 has a blind cavity 68 formed therein between the outer end portion 70 and the inner end face 64 thereof. The cavity 68 intersects the inner end face 64 and is defined by a planar end wall 72 lying in a plane normal to the axis of the drive shaft 22 and by an inner peripheral surface 74 traced by a straight line moving parallel to the axis of the drive shaft 22 and interconnecting the end wall 72 and the inner end face 64. The cross-sectional shape of the inner peripheral surface 74 is substantially identical to the crosssectional shape of the outer

peripheral portions

54 and 56 of the pump mounting adapter 14.

It should be noted that, as shown in FIG. 7, the

surfaces

58 and 64 preferably each have a plurality of

annular ribs

58a and 64a formed respectively thereon and extending longitudinally therefrom to mutually engage the gasket 66 to keep it from being forced radially outwardly out of position under conditions of elevated internal pressure within the pump unit. The

ribs

58a and 64a are spaced radially on the

respective surfaces

58 and 64 and follow the contour of the outer

peripheral portions

54 and 56 of the adapter 14 and the inner peripheral surface 74 of the housing 60. The

ribs

58a and 64a have been found to increase the maximum internal pressure which the gasket 66 can withstand by approximately 100 to 200 percent over the maximum pressure which can be withstood by an identical gasket installed between two similar sealing surfaces having no ribs formed thereon.

Two identical flat wear plates 76, preferably formed of sheet stainless steel, are disposed within the cavity 68 adjacent to the outer end face 44 of the pump mounting adapter 14 and the planar end wall 72 of the cavity 68, respectively. Each wear plate 76 includes an aperture 78 formed in the central portion thereof to permit passage of the drive shaft 22 therethrough. The

outer periphery 80 of each wear plate 76 is sized and shaped to be slidingly received within the cavity 68 of the pump housing 60 and conform to the crosssectional shape of the inner peripheral surface 74. The identical symmetrical configuration of the two wear plates 76 permits them to be interchanged or reversed when installed within the pump housing 60 to facilitate parts interchangeability and increase the service life of the pump assembly 10.

An inlet port 82 and an outlet port 84 are formed in the pump housing 60, each communicating between the inner peripheral surface 74 and the exterior of the pump housing 60. The inlet and outlet ports 82 and 84 include inlet and

outlet fittings

86 and 88, respectively. Each of the

fittings

86 and 88 includes a 3/4 inch standard garden hose external thread and a 3/8 inch F NPT internal thread. The inlet and outlet ports and fittings are preferably integrally formed with the pump housing 60 to form a one-piece unit.

A pump cam 90 is disposed within the cavity 68 of the pump housing 60 intermediate the two

wear plates

76, 76. The pump cam 90 includes inner and outer end faces 92 and 94 each positioned adjacent to a respective wear plate 76. The pump cam 90 is slidably disposed within the cavity 68 with the outer periphery thereof 96 sized and shaped to conform to and slidably engage the inner periphery 74 of the cavity 68. The pump cam 90 further includes an inner periphery 98 having a non-circular cross-section and traced by a straight line moving parallel to the axis of the drive shaft 22 and intersecting the inner and outer end faces 92 and 94 of the pump cam 90.

An inlet port 100 is formed in the pump cam 90 and communicates between the inner periphery 98 and the outer periphery 96 thereof and further communicates with the inlet port 82 of the pump housing 60. Similarly, an outlet port 102 is formed in the pump cam 90 and communicates between the inner periphery 98 and the outer periphery 96 thereof and further communicates with the outlet port 84 of the pump housing 60.

It should be noted that the outer periphery 96 of the pump cam 90 is configured such that it may be slidably received in the cavity 68 of the pump housing 60 only along a line parallel to the axis of the drive shaft 22. The non-circular contours of the inner peripheral surface 74 of the cavity 68 and the outer periphery 96 of the pump cam 90 prevent the possibility of any rotational displacement of the pump cam 90'relative to the pump housing 60.

, An impeller 104 is positioned within the inner periphery 98 of the pump cam 90 and between the two

wear plates

76, 76. The impeller 104 includes inner and outer end faces 106 and 108 which slidingly engage the respective wear plate 76. The impeller 104 includes a hub portion 110 and a plurality of flexible vanes 112 extending radially outward from the hub portion 110 in angularly spaced relation. An aperture 114 is formed in the central portion of the hub portion 110 for slidingly receiving the outer end portion 26 of the drive shaft 22. The aperture 114 includes a flat portion 116 formed therein for engaging the flat surface 28 of the drive shaft 22 to provide a suitable connection between the impeller 104 and the shaft 22 for rotation of the impeller therewith.

When the impeller 104 is installed, as described, on the drive shaft 22 within the inner periphery 98 of the pump cam 90, the outer end portion 118 of each flexible vane 112 slidingly engages the inner periphery 98 of the pump cam 90.

The pump mounting adapter 14 and the pump housing 60 are each preferably molded of thirty percent glass filled polypropylene. The

wear plates

76, 76 are preferably formed of 22 gauge 302 stainless steel. The gasket 66 is preferably formed of an elastomeric material such as Buna N of to durometer hardness having a thickness of approximately 0.063 inches. The hub portion 110 of the impeller 104 is preferably formed of brass while the remainder of the impeller 104, comprising the flexible vanes 112, is preferably formed of an elastomeric material such as Buna N of 70 to 75 durometer hardness.

The pump cam is preferably formed of a suitable synthetic resin material having high wear resistance. One such suitable synthetic resin material is a Teflon filled acetal resin which is marketed under the name of Fulton 404. Other suitable materials are Delrin and polypropylene.

Operation of the Preferred Embodiment To operate the pump assembly 10 of the present invention, a suitable conduit is threadedly secured to the inlet fitting 86 and is placed in communication with the fluid to be pumped. Similarly, a suitable conduit is threadedly secured to the outlet fitting 88 and directed to a suitable receiver for the fluid being pumped. The drive motor 12 is then energized thereby rotating the shaft 22 and the impeller 104 secured thereto. As the impeller 104 rotates within the pump cam 90 fluid is drawn through the first-mentioned conduit into the inlet fitting 86 and propelled through the pump unit 16 to exit from the outlet fitting 88 and the secondmentioned conduit to the receiver of fluid being pumped.

From the foregoing detailed description of the pump assembly of the present invention, it may be readily seen that the present invention obtains the objectives set forth herein. Changes may be made in the arrangement or combination of parts or elements shown in the drawings and described in the specification without departing from the spirit and scope of the invention as defined in the following claims.

What is claimed is:

1. A self-priming pump assembly comprising:

motor means for driving the pump assembly, said motor means including drive shaft means extending outwardly therefrom for drivingly rotating relative to said motor means;

pump mounting means fixedly secured to said motor means with said drive shaft means extending therethrough formounting' a pump unit on said motor means;

seal means carried by said mounting means for sea]- ingly engaging said drive shaft means extending therethrough and providing a seal therebetween;

a substantially planar outer end face formed on said mounting means lying in a plane normal to the axis of said drive shaft means extending therethrough; and

a pump unit carried by said mounting means adjacent to said outer end thereof, said pump unit comprising: a pump housing having an inner end face and an outer end portion with the inner end face thereof positioned adjacent to said mounting means, said pump housing having a cavity formed therein intersecting the inner end face thereof and defined by a planar end wall lying in a plane substantially normal to the axis of said drive shaft means and by an inner peripheral surface traced by a straight line moving parallel to the axis of said drive shaft means and interconnecting said end wall and said inner end face;

an inlet port formed in said pump housing and communicating between the exterior thereof and said cavity formed therein;

an outlet port formed in said pump housing and communicating between the exterior thereof and said cavity formed therein;

a pump cam having an outer end face and an inner end face and slidably disposed in said cavity, said pump cam having an outer periphery conforming to and slidably engaging the inner periphery of said pump housing, and having an inner periphery of non-circular cross-section and traced by a straight line moving parallel to the axis of said drive shaft means and intersecting the inner and outer end faces of said pump cam;

an inlet port formed in said pump cam and communicating between the inner periphery of said pump cam and the outer periphery thereof and the inlet port of said pump housing;

an outlet port formed in said pump cam and communicating between the inner periphery of said pump cam and the outer periphery thereof and the outlet port of said pump housing;

an impeller, having an inner end face, an outerend face, a hub portion, and a plurality of flexible vanes extending radially outward from the hub portion in spaced relation, disposed within the inner periphery of said pump cam with the outer end portions of the flexible vanes slidably engaging the inner periphery of said pump cam and with the outer end portion of said drive shaft means extending into the center portion of the hub portion;

means for demountably connecting said impeller to said drive shaft means for rotation therewith; and

a pair of identical. wear plates each having an aperture formed therein for receiving said drive shaft means therethrough and disposed respectively between said outer end face of said mounting means and the inner end face of said impeller, and between the planar end wall of said pump housing and the outer end face of said impeller.

2. The pump as defined in claim 1 characterized further to include:

an annular sealing surface formed on said mounting means and lying in a plane substantially parallel to the plane of said outer end face and spaced a distance therefrom toward said motor means;

annular seal means disposed between the inner end face of said pump housing and said annular sealing surface of said mounting means for providing a fluid-tight seal therebetween; and

at least one annular rib means formed respectively on said annular sealing surface and on the inner end face of said pump housing for mutually engaging said annular seal means to prevent radially outward displacement of said annular seal means under conditions of elevated internal pressure within said pump unit.

3. The pump as defined in claim 1 characterized further to include:

means for demountably securing said pump unit to said pump mounting means; and

seal means disposed between the inner end face of said pump housing and said pump mounting means for providing a seal therebetween.

4. The pump as defined in claim 3 wherein said means for demountably securing said pump unit to said pump mounting means is characterized further to include:

a plurality of threaded screws extending through said pump housing and threadedly engaging said pump mounting means.

5. The pump as defined in claim 4 wherein said pump housing is characterized further to include:

means communicating with the inlet port thereof for connecting said pump unit to a source of fluid to be pumped; and

means communicating with the outlet port thereof for connecting said pump unit to a receiver of fluid to be pumped.

6. The pump as defined in claim 5 wherein said means for connecting said pump unit to a source of fluid and said means for connecting said pump unit to a receiver of fluid are each characterized further to be threaded fittings integrally formed as a part of said pump housing- 7. The pump as defined in claim 6 wherein said pump mounting means and said pump housing are each further characterized as being formed of approximately 30 percent glass filled polypropylene.

8. The pump as defined in claim 7 wherein said pump cam is further characterized as being formed of Teflon filled acetal resin.

Claims

1. A self-priming pump assembly comprising: motor means for driving the pump assembly, said motor means including drive shaft means extending outwardly therefrom for drivingly rotating relative to said motor means; pump mounting means fixedly secured to said motor means with said drive shaft means extending therethrough for mounting a pump unit on said motor means; seal means carried by said mounting means for sealingly engaging said drive shaft means extending therethrough and providing a seal therebetween; a substantially planar outer end face formed on said mounting means lying in a plane normal to the axis of said drive shaft means extending therethrough; and a pump unit carried by said mounting means adjacent to said outer end thereof, said pump unit comprising: a pump housing having an inner end face and an outer end portion with the inner end face thereof positioned adjacent to said mounting means, said pump housing having a cavity formed therein intersecting the inner end face thereof and defined by a planar end wall lying in a plane substantially normal to the axis of said drive shaft means and by an inner peripheral surface traced by a straight line moving parallel to the axis of said drive shaft means and interconnecting said end wall and said inner end face; an inlet port formed in said pump housing and communicating between the exterior thereof and said cavity formed therein; an outlet port formed in said pump housing and communicating between the exterior thereof and said cavity formed therein; a pump cam having an outer end face and an inner end face and slidably disposed in said cavity, said pump cam having an outer periphery conforming to and slidably engaging the inner periphery of said pump housing, and having an inner periphery of non-circular cross-section and traced by a straight line moving parallel to the axis of said drive shaft means and intersecting the inner and outer end faces of said pump cam; an inlet port formed in said pump cam and communicating between the inner periphery of said pump cam and the outer periphery thereof and the inlet port of said pump housing; an outlet port formed in said pump cam and communicating between the inner periphery of said pump cam and the outer periphery thereof and the outlet port of said pump housing; an impeller, having an inner end face, an outer end face, a hub portion, and a plurality of flexible vanes extending radially outward from the hub portion in spaced relation, disposed within the inner periphery of said pump cam with the outer end portions of the flexible vanes slidably engaging the inner periphery of said pump cam and with the outer End portion of said drive shaft means extending into the center portion of the hub portion; means for demountably connecting said impeller to said drive shaft means for rotation therewith; and a pair of identical wear plates each having an aperture formed therein for receiving said drive shaft means therethrough and disposed respectively between said outer end face of said mounting means and the inner end face of said impeller, and between the planar end wall of said pump housing and the outer end face of said impeller.

2. The pump as defined in claim 1 characterized further to include: an annular sealing surface formed on said mounting means and lying in a plane substantially parallel to the plane of said outer end face and spaced a distance therefrom toward said motor means; annular seal means disposed between the inner end face of said pump housing and said annular sealing surface of said mounting means for providing a fluid-tight seal therebetween; and at least one annular rib means formed respectively on said annular sealing surface and on the inner end face of said pump housing for mutually engaging said annular seal means to prevent radially outward displacement of said annular seal means under conditions of elevated internal pressure within said pump unit.

3. The pump as defined in claim 1 characterized further to include: means for demountably securing said pump unit to said pump mounting means; and seal means disposed between the inner end face of said pump housing and said pump mounting means for providing a seal therebetween.

4. The pump as defined in claim 3 wherein said means for demountably securing said pump unit to said pump mounting means is characterized further to include: a plurality of threaded screws extending through said pump housing and threadedly engaging said pump mounting means.

5. The pump as defined in claim 4 wherein said pump housing is characterized further to include: means communicating with the inlet port thereof for connecting said pump unit to a source of fluid to be pumped; and means communicating with the outlet port thereof for connecting said pump unit to a receiver of fluid to be pumped.

6. The pump as defined in claim 5 wherein said means for connecting said pump unit to a source of fluid and said means for connecting said pump unit to a receiver of fluid are each characterized further to be threaded fittings integrally formed as a part of said pump housing.

7. The pump as defined in claim 6 wherein said pump mounting means and said pump housing are each further characterized as being formed of approximately 30 percent glass filled polypropylene.