US2477079A

US2477079A - Pump

Info

Publication number: US2477079A
Application number: US670657A
Authority: US
Inventors: Alexander V Mueller
Original assignee: Individual
Current assignee: Deming Co
Priority date: 1946-05-18
Filing date: 1946-05-18
Publication date: 1949-07-26
Anticipated expiration: 1966-07-26

Description

July 26, 1949. A. v. MUELLER PUMP 6 Sheets-Sheet 1 Filed May 18, 1946 .1 m a M Z "July 26, 1949. A, v. MUELLER PUMP Filed May 18, 1946 6 Sheets-Sheet 3 INVENTOR. Amamwnn V. Hue-um g, hall, 121% F I TORNEX A. V. MUELLER July 26,1949.

PUMP

6 Sheets-Sheet 4 Filed May 18, 1946 ji 37 I INVENTOR.

Irromvzrl A. v. MUELLER PUMP 6 Sheets-Sheet 5 Filed May 18, 1946 M 1 1 M l l 4 z 8 J 9 Wm 4 3 4 VI I M I V m/ l H \41 n 0 1 0 J 5 W 75 w w w w x F! n 6 J 3 a 2 J .3 f 6 N. Z H Al! 4 J M w VVlMl/VVJ & M u m u w l. f V (p/ f a M N M H M U 9 F. 1 m w M H .Ill

2 v 2 1 J L nrroANf/ July 26, 1949. A. v. MUELLER PUMP Filed May 18, 1946 6 Sheets-Sheet 6 INVENTOR. AL EXA N051? V. flueLLe/t Y lafia, 6w MM? Patented July 26 1949 Alexander V. Mueller, Salem, Ohio, asslgnorto R he Deming Company, Salem, Ohio, a corporan of Ohio Application May 1a, 1946, s ria No. 570,657

18 Claims. (Cl. 103-113) Thislinvention relates to improvements in self priming pumps, and particularly to a self-priming rotary pump which, after the pump is initially primed, wil1 reprime itself automatically. These, therefore, are the general objects of this invention. s l

Repeated attempts have been made to provide a self-priming pump which, when either the source of power or the supply of liquid at the pump intake is for any reason interrupted, will reprime itself automatically, consequent upon the correction of such interruption. One of the difficulties encountered has been the siphoning of all of theliquid, including the priming liquid from the'pump through the suction line when an interruption in the functioning of the pump occurs. At the present time, pumps which are designated as self-priming, generally rely upon a check valve at the foot of the suction line and/or in the pump itself to prevent this siphoning action. In some instances special air inlet or snufile valves have been arranged to admit air to the suction line of the pump to therebyprevent the withdrawal or. siphoning of the priming liquid from the pump when the supply of liquid to the suction line becomes exhausted.

This use of check valves and the like to facilitate the priming of the pump is far from satisfactory. Such valves are generally subjectto failures particularly s'eepageand therefore are generally, if at all, efi'ective only for interruptions of relatively short periodsQof time. Further, when pumps are used to pump materials containing solids, foreign matter and the like, such as when pumping from sumps. as m mines, excavations, and thelike where sand and other foreign matter is encountered, check valves frequently are held open by particles of non-fluid matter. accessible and diflicult to repair or replacewithout dismantling the entire pumping system. The

Further, such valves are generally in -v equipment of the foot of the suction line with screens sufficientlyfine to prevent particles of foreign matter from reaching the check or foot snuflle valve causes'the failure of the pump immediately. v 7

It is an object of the present invention to provide a pump, and particularly a valveless pump such 'as "a rotary or centrifugal pump, which pump "will overcome the disadvantages above mentioned and, when once primed and interrupted, will reprime itself automatically. consequent upon the elimination of the cause of interruption. I

A further object of the present invention is to provide a pump of the valveless type which reprimes itself automatically, and without the aid of foot valves, check valves, and the like.

Another object of this invention is'to provide an'improved centrifugal pump having a minimum number of moving parts, and which may be readily and economically manufactured and assembled. 1 e

A more specific object of the invention is to provide a pump which may be used to pump liquids containing foreign. matter such as weeds, solid particles, and the like, and which pump will reprime itself des'plte the presence of such foreign matterinthe pumping system.

A further object is'to provide a pump which may be readily convertedfor various types of uses and capacities. I o

Other objectsand advantages of this invention will become more apparent from the followin description, reference being had to a preferred embodiment thereof illustrated in the accompanying drawings. The essential features of the invention will be summarized'in the claims.

In the drawings, Fig. 1 is 'afperspective' view of one form of the improved pump, certain portions thereof being broken away to more clearly illustrate the internal construction; Fig. 2 is a side elevation of the pump on a scale somewhat smaller than that of Fig. 1 and looking at the right-hand side of such figure; Fig. 3 isa vertical section taken in substantially the plane indicated by the lines 3-3 on Figs. 2, '7, 8 and 9; Figs. 4 and 5 are sectional views similar to Fig. 3 .butillustrating the arrangement of the pump I for different uses and capacities; Fig, 6 is a vertical section'through the pump casing and is indicated by the lines 6+6 on Figs. 2, 7, 8 and 9; Figs. 7 and 8 are'substantially horizontal sections as'indicated by the correspondingly numbered lines on Figs. 2 and 9; Fig. 9 is a vertical section taken thorugh the axis of the pump, the plane of the section being indicated by the lines 9-9 on Figs. 7 and 8; and Fig. 10 is a fragmentary vertical section, the plane of the section being indicated by the lines Ill-l on Fig. 6.

Referring now to the drawings and particularly to Figs. 1, 2 and 9, it will be seen that my improved pump has a housing l0 provided with a pump chamber II, a suction passageway l2, a stilling chamber l4, and a pair of supplemental suction or priming chambers l5 and I5. As illustrated, the pump is of the centrifugal or impeller type having an open type impeller I! provided with vanes IS. The impeller is mounted on and driven by a horizontally extending shaft l9 which extends through a stufllng box formed in a boss-like formation 2| on a plate 22. This plate is secured to the open face of the housing I 0 by bolts 23, thereby closing the pump chamber. Any suitable bearing structure for the shaft l9 may be carried by the plate 22 and a driving connection may be established with the shaft IS in the usual manner.

The pump chamber H is provided with the customary cut-on tongue 24. As shown in Figs. 3, 4 and 5 this cut-oi! is formed by a wall or web formed on a plate 28. This plate forms the inner wall of the pump chamber, being clamped against a wall 2'! of the housing III by the closure plate 22. The cut-oi! tongue 24 is preferably located in one side of the impeller, that is, disposed in a horizontal plane substantially passing through the axis of rotation of the impeller. The wall 25 forms a continuation of a wall 28 formed by the pump housing. As shown in Figs. 3 and 4, the plate 25 is provided with a plurality of Webs 29 which extend across the pump chamber and which form difluser passageways 3B.

The diffuser passageways 30 increase in cross sectional area as they recede from the periphery of the impeller, and extend to a point spaced from the circumferential wall 3| of the pump chamber The wall 2| is formed in the nature of a volute and is eccentric relative to the pump axis so that the space 22 between the periphery of the diffuser member and the wall increases in cross sectional area in the direction of rotation of the impeller indicated by the arrow in Fig. 3. The wall 28 of the housing, heretofore mentioned, is shaped so that the discharge passageway 32 of the pump leading from the volute passage 33 upwardly into the stilling chamber l4 also increases in cross sectional area as it passes from the pump chamber II to the stilling chamber I4. The diffuser passageways an together with the volute chamber 23 and the discharge passageway 32 act to transform the kinetic energy imparted to the fluid by the impeller ll into fluid pressure efficiently.

The stilling chamber l4, as shown in Figs. 2, 3 and 9, is positioned above the pump chamber ll The chamber I4 is of at least a sufficient size to contain a quantity of fluid which will insure priming of the pump, that is, a quantity of liquid more than sumcient to maintain the level of the liquid above a horizontal line passing through the pump above the pump inlet opening or eye 35.

Fluid is drawn into the pump through the suction passageway I! which extends from the eye 35 of the impeller axially, thence upwardly to a point above the impeller eye 35 where a suitable flange or threaded opening 36 is provided to facilitate the connection on a suction conduit (not shown) to the housing l0. Generally the suction conduit extends downward a considerable distance from the pump to a wall or sump. A screen 21 is shown in the passageway l2. How- '4 ever, the screen may be eliminated as heretofore mentioned.

The supplemental suction or priming chambers I5 and I6, are, as shown in Figs. 1 and 6, pcsitioned above the pump eye 35 and below the stilling chamber l4. As illustrated, these chambers lie back of the pump chamber I I. The combined area of the chambers l5 and I5 is such that they may contain a quantity of liquid suflicient to prime the pump, that is, to submerge the impeller to such an extent as to completely separate the suction passageway l2 from the pump outlet 32, and the stilling chamber 14 is of sufllcient size to retain such quantity of liquid.

The priming chambers l5 and I6, as illustrated in Figs. 6 and 8, are separated from each other by the walls 38 of the suction passageway I2 and by a wall 39 which extends from one of the walls 38 to the wall of the pump chamber ll. Communication is provided between the two chambers i5 and I5 by ports 40 and II (Fig. 10) in the wall 39, the port 40 being located adjacent the top of the chambers and the port 4| adjacent the bottom thereof. The cross sectional area of the ports 40 and 4| may be comparatively small so that only a restricted communication may be established between the two chambers.

The priming chambers I5 and I5 communicate with the suction passageway l2. As shown in Fig. 6, the walls 38 of the suction passageway are each provided with a port 42 and a port 43 located adjacent the top and bottom respectively of the chambers l5 and IS. The

ports

42 and 43 provide restricted and independent passageways between each priming chamber and the suction passageway |2. Thus, the only communication with the chambers l5 and I5 is via the ports 40 and 4| which afiord intercommunication between the chambers, and the

ports

42 and 43 which atford a restricted and independent communication between each chamber and the suction passageway l2. The priming chambers l5 and I6 serve, as will hereinafter be more fully described, to store priming liquid in the pump despite siphoning actions.

The automatic repriming of the pump utilizes a recirculation of liquid from the stilling chamber l4 to the suction passageway I 2. As shown in the drawings, and particularly in Fig. 6, the stilling chamber M has a port 5|! communicating with a small chamber 5| formed in the housing ID. The chamber 5| is provided with a port 52 which forms a passageway through the external wall of the pump housing. This passageway communicates with a port 53 in a recirculating valve housing 54 which is secured to the exterior of the pump housing Ill. The housing 54 is provided with upper and

lower chambers

55 and 56 separated by a partition 51. Liquid enters the upper valve chamber 55 through the port 53 and passes into the lower chamber through a valve port 58 formed in a partition 51. A conduit 59 extends from the chamber 55 through the priming chamber l5 and discharges into the suction passageway |2 as indicated in Fi 6. Thus, so long as the valve port 58 remains open a portion of the liquid being pumped to the stilling chamber [4 will recirculate to the pump intake.

The flow oi the recirculating liquid through the port 58 is controlled by a valve 6|) mounted on a valve stem Bl which is carried by a spring pressed diaphragm 62. This diaphragm is exposed to the pressure in the upper portion of the valve housing which is at all times substantially equal to that in the stilling chamber. The spring 63, which may, if desired, be adjustable, preloads the diaphragm 82 such that the valve 60 will be held open until the desired discharge pressure is reached in the chamber ll whereupon the action of this pressure against ,tlie diaphragm 62 will raise the valve 60 closing the port 58 and stopping the recirculation of the liquid. The use of the conduit 59 is preferable; however, recirculation may be eflected by omitting this, conduit whereupon the recirculating fluid will pass to the passageway I2 through the chamber I5. The use of the conduit 59 adds to the efllciency of the pump.

As heretofore mentioned, when the pump is initially placed in operation, a quantity of liquid, sufficient to prime the pump, is placed in the stilling chamber I4. Generally speaking, the amount of liquid required is an amount sufflcient to maintain liquid at the pump eye. and to enable recirculation of 'liquid from the stilling chamber through the recirculating valve to the pump eye.

After the pump has been initially primed and placed in operation it will .evacute the suction passageway and the suction line of air, pumping the air and some liquid into the stilling chamber where the air separates from the liquid. The liquid passes through the recirculating valve and back through the conduit 59 into the suction passageway I2 to maintain the pump primed. The air passes outward from the chamber through the discharge opening 65 thereof. As soon as the suction line and passageway I2 have been pumped free from air, liquid flows into the pump and, due to the restricted nature of the discharge opening 65 relative to the stilling chamber I4, a pressure is built up in the stilling chamber whereupon this pressure acts on the diaphragm 62 to close the recirculating valve 60 and stop the recirculation of the liquid, thereby preventing loss of efiiciency of the pump. When the flow of liquid from the suction line fills the suction passageway I2 it likewise fills the priming chambers I5 and I 6. Such chambers are subjected to the substantially same degree of vacuum or suction as the passageway I2. Accordingly they quickly fill with'liquid.

As heretofore mentioned, neither the pump nor the discharge conduit is provided with a check valve to prevent the flow of fluid in the reverse direction through the pump housing and the discharge .conduit, should for any reason the pump impeller cease its rotation or materially slow down. Accordingly, any interruption of the rtation of the impeller i'l, whether intentional or unintentional, will result in a siphoning action.

In the normal operation of the pump the stilling chamber I4 is substantially filled with liquid under discharge pressure while the suction passageway I2 and the priming chambers I5 and I6, which are under the influence of a partial vacuum also, are also substantially filled with liquid and the recirculating valve is held closed by the discharge pressure in the chamber I4. When the impeller II ceases to rotate or has its speed of rotation materially decreased, the pressure in the stilling chamber immediately drops, and the spring 63 opens the recirculating valve 60. Simultaneously a siphoning action takes place in the suction line and the liquid normally flowing from the suction line through the suction passageway I2 and the eye of the pump into the pump chamber I I, immediately reverses its direction of flow, so that it flows from the pump chamber through the suction passageway I2 into the suction line which, ordinarily, is located some distance below the pump level. This reversal of liquid flow through the pump is almost instantaneous and is accompanied by an almost instantaneous change in pressure. When the pump impeller I] is stopped, the pressure in the suction passageway I2 immediately rises to atmospheric pressure and then quickly drops below atmospheric pressure. The amount of this drop depends somewhat upon the height of the pump above the liquid level from which it was pumping.

The pressure in the priming chambers I5 and I6 during the normal pumping operation is .below atmospheric pressure and changes with the change of pressure in the suction passageway. However, during this change in pressure, the passageway I2 is filled with liquid. Accordingly no liquid flows from the chambers I5 and I6. Indeed as the chambers I5 and I6 are under a subatmospheric pressure or vacuum during the normal pumping and as they have no communication except with each other and with the suction passageway I2, liquid tends to enter these chambers during the reversal of the direction of flow in the passageway I2. As the reversal of direction of flow of liquid in the passageway I2 is almost instantaneous, and as the chambers I5 and I6 are out of the path of liquid flowing through the passageway I2, the liquid content of such chambers remains substantially unchanged while there isliquid in the passageway I2, regardless of the direction of flow of such liquid.

During the siphoning action liquid flows from the stilling chamber I4 and the pump chamber II through the suction passageway I2 and the suction conduit into the well or sump. As soon as the liquid is exhausted from the stilling chamber I4 and the pump chamber II, air reaches the suction passageway I2 and immediately breaks the siphoning action. The pressure in the passageway i2 accordingly falls to atmospheric pressure whereupon the liquid from the chambers I5 and I6 drains through the openings 43 into the passageway I2 and thence to the eye of the impeller. The chambers I5 and I6 contain sufficient liquid to prime the pump in the manner heretofore described. Therefore, consequent upon the restoration of the power the rotor or impeller will cause the pump to prime as heretofore explained and as soon as liquid flows from the suction line into the suction passageway I2, the chambers I5 and I6 will refill with liquid, and the pressure will be restored in the stilling chamber I4, causing the recirculation valve to automatically close.

Should for any reason the liquid in the sump or well drop below the bottom of the suction conduit the pump ceases to function. However, upon the restoration of the liquid supply, the pump of the present invention will reprime itself automatically.

When no more liquid is available, either from the suction line, the passageway I2 or the chambers I5 and I6, the continued rotation of the impeller I'I acts as a fan and retains liquid in the stilling chamber I 4 above the pump chamber II. Inasmuch as the impeller is air bound it can generate no liquid pressure. Accordingly, there is no liquid flow from the pump and no pressure in the chamber I4. Consequently, the recirculating valve 55 automatically opens, causing the liquid to recirculate from the chamber I l into the suction passageway I2. Thus the pump in efiect draws some air from the suction conduit through the passageway and discharges it with liquid into the chamber I4 which acts as a stilling chamber. The air passes out of the pump and the liquid returns through the recirculation valve to the pump intake. Thus, as long as the liquid in the sump or well is below the level of the bottom of the suction line, the pump merely recirculates liquid through the pump itself.

When the liquid in the sump or well rises to again cover the bottom of the suction conduit, the

recirculating liquid automatically reprimes the pump, and as soon as liquid again reaches the passageway 12 it fills the chambers Ii and I8. Accordingly, it will be seen that the improved pump reprimes itself even when, for any reason, the pump rotor ceases its rotation or when the supply of liquid pumped becomes exhausted, and

the pump will immediately and automatically reprime itself consequent upon the restoration of the power or the restoration of the source of liquid being pumped.

While I have described the use of two priming chambers, namely the chambers I! and it, the pump will operate with one chamber. Under some conditions, the use of a plurality of chambers, each independently connected with the suction passageway I 2, is an advantage. To facili-' tate illustration, only two such chambers have been described. The passageways which connect these chambers (l and It) with the suction passageway l2 are restricted in cross sectional area so as to insure retention of liquid therein during the siphoning action. During the siphoning each chamber acts quite independent of the other. so far as the relation of their liquid contents and the effect of the siphoning fluid thereon are concerned. However, the size of the openings into the chambers remains constant whether one or a plurality of chambers are used.

While I have utilized a valve in the recirculating passageway, a failure of'this valve to close. unlike the failure of check valves to close, does not materiallyailect the operation of the pump. Should the valve 68 for an reason fail to close, the pump will operate to reprime itself equally as well as though this valve had closed. Therefore, seepage through the valve in is immaterial so far as the repriming operation is concerned. Indeed as the sole purpose of this valve is to increase the efliciency of the pump during normal operations it may be eliminated.

A strainer is disposed in the passageway-in the chamber II leading from the stilling chamber I to the recirculating valve to protect this valve against the flow of foreign particles. While this strainer is shown as being positioned in the chamber 5| it may be inverted and positionedin the chamber I, as indicated by the dot and dash lines in Fig. 6, and when in the latter position the flow of liquid in the stilling chamber will prevent clogging of the strainer.

Inasmuch as fluid cut-off 24 is positioned substantially upon a horizontal axis, I may provide the pump chamber H with a vent I2. This vent permits the filling of the pump chamber with liquid to a point above the eye of the pump by permitting the escape of trapped air. This vent is normally sealed by the liquid in the chamber l4 and is comparatively small so that it has practically no efiect upon the efficiency of operation of the pump.

The pump is arranged so that it may be readily adapted for different capacities. This is ordina'rily accomplished in pump structures by reducing the size or diameter of the pump impeller and generally requires an entire new pump casin for each size of impeller. However, in the present structure a different sized impeller may be substituted for the one in use by merely removing the diifuser plate and replacing it with another having diffusing passageways of a somewhat greater length to thereby compensate for the dilference in size or diameter of the impeller. This feature forms the subject matter of my divisional application, Ser. No. 1,729, filed January 12, 1948. Herein, it is best illustrated in Figs. 3 and 4 where it is evident than the'impeller in Fig. 4 is considerably smaller in diameter than in Fig. 3, and the width of the annulus of the diffuser vanes has been enlarged to compensate for the decrease in the diameter of the impeller.

The pump may alsobe used as a contractor's pump where it is desired to pump from sumps or excavations where foreign material, such as weeds and the like, are apt to exist. Under these conditions the diffuser plate is removed and a plate substituted therefor which has merely the cut-oi! member 24. Such a construction is shown in Fig. 5.

From the above description it will be seen that I have provided a pump which will reprime itself automatically and which does not rely on check valves and the like to prevent siphoning, and which pump is readily adapted for diil'erent capacities and uses. Thus the pump may be used at one time for one purpose and for one capacity. and it may be readily changed for use either at another capacity or for another purpose without necessitating the replacement of the entire pump structure.

Iclaim: i

1. A centrifugal pump, a pump chamber having an inlet and an outlet, rotary impeller means in said chamber, a substantially enclosed stilling chamber positioned above the pump communicating with the outlet of the pump and having a discharge opening whereby pressure may be built in said chamber by said pump, a suction passageway communicating with the pump inlet and having a suction inlet positioned above the pump inlet whereby liquid may be trapped in the pump, a liquid storage chamber out of the path of fluid flowing through the suction passageway and out of communication with the stilling chamber, a restricted passageway between the storage chamber and the suction passageway, a recirculating conduit between the stilling chamber and the suction passageway said chambers being arranged to permit the flow of liquid from the stilling chamber through the recirculating passageway to the suction passageway and from the storage chamber to the suction passageway under the influence of gravity.

2. A rotary pump, a pump chamber, a rotary impeller therein, said pump chamber having an inlet opening and an outlet opening, a stilling chamber communicating with the outlet of the pump and having a discharge opening, a storage chamber positioned below the outlet opening of the pump and above the inlet thereof, a suction passageway for said pump communicating with the pump inlet and having a suction inlet positioned above the pump inlet, a. restricted passagewa between the storage chamber and the suction passageway, a liquid recirculating passageway between the stilling chamber and said suction passageway, said recirculating passageway connecting with the suction passageway at a point below the top of the storage chamber.

3. A centrifugal pump having a pump chamber having an inlet and an outlet, a rotary impeller in said chamber, a stilling chamber communicating with said pump outlet and provided 9 V i with a discharge opening, a suction passageway communicating with said pump inlet, an inlet for the suction passageway positioned above the pump inlet, a plurality of fluidstorage. chambers positioned out ofthe line. of flow through said suction passageway, an independent restricted passageway between each of said storage chambers and said suction passageway, a fluid recirculating conduit between said stilling chamber and said suction passageway, said chambers being arranged to permit the flow of liquid from the stilling chamber to the suction passageway and from the storage chambers tothe suction passageway solely under the influence of gravity.

4. A centrifugal pump having a. pump chamber provided with an inlet and an outlet, a rotary impeller in said chamber, a stilling chamber comaeraorc g I 10 L sive to fluid pressure in thcstiliing chamber to control the operation of saidvalve'."

1 '7. A centrifugal pump having a pump :chammunicating with said pump outlet and. having a discharge opening, a suction. passageway/communicating with said pump inlet, an inlet port for the suction passageway positioned above the pump inlet, a plurality of fluid storage chambers positioned out of the line of flow of fluid through said suction passageway, an independent restricted passageway between the top of eachof said storage chambers and said suctionjpassageway, an independent passageway between the bottom of each of said storage" chambers and 7 formed in said housing, a rotary pump member I,

in said pump chamber,'a stilling chamber formed in said housing and provided with a discharge opening, said stilling chamber positioned above said pump chamber and directly connected therewith, a fluid inlet passageway formed in said housing and terminating at the inlet of the pump chamber and having a fluid inlet port positioned above the pump inlet, a storage chamber formed in said housing and positioned above the inlet to the pump chamber, a restrictedpassageway between the top of the storage chamber and the suction passageway, a restricted passageway between the bottom of the storage chamber and the suction passageway, and a recirculating conduit extending between the stilling chamber and the suction passageway.

6. In a pump, a housing, a pump chamber formed in said housing, a rotary pump member in said pump chamber, a stilling chamber formed in said housing and provided with a discharge and inlet openings, said stilling chamber being positioned above said pump chamber and directly connected therewith, an inlet passageway terminating at the inlet to the pump chamber and having a fluid inlet at a point above the bottom of the stilling chamber, a pair of storage chambers formed in said housing and positioned intermediate the bottom of the stilling chamber and the inlet to the pump chamber, an independent passageway between the top of each of the storage chambers and the suction passageway, an independent restricted passageway between the bottom of each of the storage chambers and the suction passageway, and a recirculating conduit extending between the stilling chamber and the suction passageway, a valve in said recirculating passageway, and means responto the suction passageway ber provided with an inlet port and adischarge passageway,---a rotary-impeller in'said chamber, a stillingv chamber positioned above and communicating with said passageway, said'discharge passageway increasing in cross-sectiona1 area as it approaches said stillingchamber, said stilling chamber having a: discharge opening adjacent its .upper end, a suction passageway communicatingwith said pump inletpa fluid inlet opening into the suction passageway and positioned above. the pump inlet, a fluidstorage' chamber positioned out of the line of flow of'fluid through said passageway, arestricted passageway between the said storage chamber and said suction passageway, a recirculating conduit between said stilling: chamber and said suction" passageway, said chambers being arranged to permit the flow of liquid from the stilling chamber to themetion passageway and from'the' storage chamber solelyunder the influence of gravity.

8'. A' centrifugal pump'havingj a pump chamber provided with aninlet and an outlet,-rotary impeller means in said chamber, 'a's'ubstantially enclosed stillingchamber positioned above the pump and in communication with the outlet thereof, said i chamber having a' restricted 'discharge opening whereby pressure may 'be 'built in said chamber by said-pump, a suctionpassa way communicating with the pump inlet and having a fluid inlet positioned above the pump inlet whereby liquid-may be trapped in the pump, a pair of storage chambers positioned on opposite sides of said suction passageway, a restricted passageway between each of the storage chambers and the suction passagwayfla recirculating conduit between the's'tilling chamber and the suction passageway, said chambers being'arranged to perm-it the flow of fluid from the stilling chamberthrough the recirculating passageway to the suction passageway and from the storage chambers to the suction passageway under the infiuence of gravity. I

9. In a pump ahousing having a pump chamber arranged to receiveja rotary impeller mounted with its axis ina horizontal plane, said housing having a stilling chamber above said pump chamber and directly connecting with the discharge thereof, said stilling chamber being provided with a discharge opening, an inlet opening into said pump chamber substantially along the axis of rotation of the impeller, a suction passageway formed in said housing and having one end in communication with the inlet opening to the impeller, a suction inlet for said passageway positioned above the bottom of said stilling chamber, a storage chamber positioned at one side of said suction'passageway having its bottom positioned above the top of the pump inlet and its top below the stilling chamber, a restricted opening between the top of said storage chamber and said suction passageway, a restricted opening between the bottom or said storage chamber and said passageway, I

10. In a pump, a unitary housing, a pump chamber formed in said housing, a rotary impeller mounted in said pump chamber with its axis in a horizontal plane, a stilling chamber formed insaid housing ram; above said pump chamber, the walls of the pump chamber forming a passageway which discharges upwardly directly into said stilling chamber, a dispositioned substantially along the axis of rotation of the impeller, a suction passageway formed in said housing and'ieading from the inlet port oi the pump chamber upwardly to a plane above the pump chamber inlet port, a suction inlet into said passageway. positioned above said inlet port, a storage chamber formed in said housing and positioned at either side of said suction passageway and having a portion thereof extending from substantially the inlet port substantially to the bottom wall of the stilling chamber, a restricted opening between the top of said storage chamber and said suction passageway, a restricted opening between the bottom of said storage chamber and said suction passageway, a recirculating passageway extending between said stilling chamber and said suction passageway, a

valve in said recirculating passageway to control the flow oi. fluid therethrough, and means responsive to pressure in said stilling chamber to control the operation of said valve.

11. In a pump, a unitary housing, a pump chamber formed in said housing, a rotary impeller mounted in said pump chamber with its axis in a horizontal plane,, a stilling chamber formed in said housing immediately above said pump chamber, the walls of the pump chamber forming a volute which discharges upwardly directly into said stilling chamber, a discharge port adjacent the top of said stilling chamber, an inlet port for said pump chamber positioned substantially along the axis of rotation of the impeller, a suction passageway formed in said housing and leading from the inlet port of the pump chamber upwardly to a plane above said inlet port, a suction inlet into said passageway positioned above said inlet port, a pair of storage chambers formed in said housing and positioned at either side of said suction passageway and having their top walls below said stilling chamber, a restricted opening between the top oi-each of said storage chambers and said suction passageway, a restricted opening between the bottom of each of said storage chambers and said suction passageway, a restricted passageway between the tops of said storage chambers, a restricted passageway between the bottoms of said storage chambers, a recirculating passageway extending between said stilling chamber and said suction passageway.

12. In a. pump, a unitary housing, a pump chamber formed in said housing, a rotary impeller mounted in said pump chamber with its axis in a horizontal plane, a stilling chamber formed in said housing immediately above said pump chamber, the walls of the pump chamber forming a passageway which discharges upwardiy directly into said stilling chamber, a discharge port adjacent the top of said stilling chamber, an inlet port for said pump chamber positioned substantially along the axis of rotation of the impeller, a suction passageway formed in said housing and leading from the inlet port of the pump chamber upwardly to a plane above the bottom of said stilling chamber, a suction inlet into said passageway positioned above the bottom wall of said stilling chamber, a pair of storage chambers formed in said housing and positioned at either side of said suction passageway and extending at least from the region of the inlet port to that of the stilling chamber, a pair of restricted vertically spaced openings between each of said storage chambers and said suction passageway, a pair of restricted vertically spaced passageways between said storage chambers, a recirculating passageway extending between said stilling chamber and said suction passageway, a valve in said recirculating passageway to control the flow of fluid therethrough, and means responsive to pressure in said stilling chamber to control the operation of said valve.

13. In a pump, a unitary housing, a pump chamber formed in said housing, a rotary impeller mounted in said pump chamber with its axis in a horizontal plane, a stilling chamber formed in said housing immediately above said pump chamber, the walls 01' the pump chamber iorming a volute which discharges upwardly directly into said stilling chamber, a discharge port adjacent the top of said stilling chamber, an inlet port for said pump chamber positioned substantially along the axis of rotation of the impeller, a suction passageway formed in said housing and leading from the inlet port of the pump chamber upwardly to a plane above the bottom of said stilling chamber, a suction inlet into said passageway positioned above the bottom wall of said stilling chamber, a pair of storage chambers formed in said housing and positioned at either side 01' said suction passageway and having their bottom walls above the top of the inlet port of the pump chamber and their top walls below said stilling chamber, a restricted opening between the top of each of said storage chambers and said suction passageway, a restricted opening between the bottom of each or said storage chambers and said suction passageway, a restricted passageway between the tops oi said storage chambers, a restricted passageway between the bottoms of said storage chambers, a recirculating passageway extending between said stilling chamber and said suction passageway, a valve in said recirculating passageway to control the flow oi fluid therethrough, and means responsive to pressure in said stilling chamber to control the operation of said valve.

14. A centrifugal pump having a pump chamber provided with inlet and outlet ports, rotary impeller means in said chamber, passageway for recirculating a portion 01' the liquid discharged from said pump back to the pump, a suction chamber connected with the pump inlet port and extending upward therefrom and having a fluid inlet port positioned above the pump inlet, a fluid storage chamber at least a portion of which is disposed above the pump inlet and below the suction chamber inlet, a passageway between the upper portions of said storage chamber and said suction chamber, a passage extending from the lower portion of said storage chamber and communicating with said suction chamber at a point below the point of communication of the first named passageway, said passageways being small in comparison to the suction chamber and pump inlets.

15. A centrifugal pump having a pump chamber provided with inlet and outlet ports, rotary impeller means in said chamber, a passageway for recirculating a portion of the liquid discharged from said pump back to the pump, a suction chamber connected with the pump inlet port and extending upward therefrom and having a fluid inlet port positioned above the pump inlet, a fluid storage chamber at least a portion of which is above the pump inlet and below the suction chamber inlet, a passageway between the upper portions of said storage chamber and said suction chamber, a passage extending from the lower portion of said storage chamber and communicating with said suction chamber at a point below the point of communication of the first named passageway, said passageways being small in comparison to the inlets to suction chamber and pump and providing the only fluid communicating passageways into or out of said storage chamber.

16. A centrifugal pump having a pump chamber provided with inlet and outlet ports, rotary impeller means in said chamber, a passageway for recirculating a portion of the liquid discharged from said pump back to the pump, a suction chamber connected with the pump inlet port and extending upward therefrom and having a fluid inlet port positioned above the pump inlet, a fluid storage chamber positioned between a horizontal plane extending through the pump inlet and a horizontal plane extending through the suction chamber inlet, a passageway between the upper portions of said storage chamber and said suction chamber, restricted passages extending from said storage chamber and communicating with said suction chamber, said passageways being small in comparison to the inlets to suction chamber and pump, said storage chamber being in communication with said suction chamber only and being out of the normal path of fluid flowing through said suction chamber.

17. A centrifugal pump having a pump cham- .ber provided with inlet and outlet ports, rotary impeller means in said chamber, a passageway for recirculating a portion of the liquid discharged from said pump back to the pump, a suction chamber connected with the pump inlet port and extending upward therefrom and having a fluid inlet port positioned above the pump inlet, a fluid storage chamber positioned between horizontal planes passing through the pump inlet and the suction chamber inlet respectively, a passageway between the upper portion of said storage chamber and said suction chamber, a passage extending from the lower portion of said storage chamber and communicating with said suction chamber at a point below the point of communication of the first named passageway, said passageways being small in comparison to the inlets to suction chamber and pump and providing the only fluid communicating passageways into or out of said storage chamber, said storage guaidiiber being out oi the path of recirculating 18. A centrifugal pump having a pump chamber provided with inlet and outlet ports, rotary impeller means in said chamber, a stilling chamber into which said impeller discharges, a passageway between said stilling chamber and the inlet of said pump chamber for recirculating a portion of the liquid discharged, a. suction chamber connected with the pump inlet port and extending upward therefrom and having a fluid inlet port positioned above the pump inlet. a fluid storage chamber positioned above the pump chamber inlet port and below both the stillin chamber and the suction chamber inlet port, a

passageway between the upper portions of said storage chamber and said suction chamber, a passage extending from the lower portion of said storage chamber and communicating with said suction chamber at a point below the point of communication of the first named pmsageway. said passageways being small in comparison to the inlets to suction chamber and pump, said passageway providing the only fluid communicating passageways into or out of said storage chamber, said storage chamber being in communication with said suction chamber only and out of the normal path of fluid flowing through said suction chamber from the suction chamber inlet to the pump chamber inlet and out of the path of recirculating fluid.

ALEXANDER V. MUELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 958,765 Pindle May 24, 1910 1,118,070 Sulzer Nov, 24, 1914 1,909,517 Bird May 16, 1933 1,910,531 Ferguson May 23, 1933 1,997,418 Horschurch et a1. Apr. 9, 1935 2,005,466 La Bour June 18, 1935 2,061,521 Saxe Nov. 17, 1936 2,075,315 'I'eel Mar. 30, 1937 2,181,792 Rupp et a1. Nov. 28, 1939 2,224,615 Stratton Dec. 10, 1940 2,313,403 Ungar Mar. 9, 1943 2,389,753 Babb Nov. 27, 1945 2,416, Mueller Feb. 25, 1947