US1972304A - Pump - Google Patents

Description

Sept. 4, 193.4. H. E. LA BOUR 9 PUMP Filed June 16, 1950 3She ets-Sheet 1 H. E. LA BOUR PUMP Filed June 16, 1930 3 Sheets-Sheet 2 Haaryff 43 50141 I 55 into the impeller chariib'erthrouiir "this threat,

Patented Sept. 4, 1934 UNITED STATES PATENT orrice 15 Claims.

My invention relates to pumps more particularly of the self-priming type first disclosed in my prior Patent No. 1,578,236, granted March 23, 1926, and constitutes more specifically an improvement upon the type of pump disclosed in my copending application 366,869, filed May 29, 1929.

In my prior patent, I disclose a centrifugal pump of self-priming type in which the mixture of gas and liquid discharged from the runner of the pump during the priming period is run into a. separating chamber wherein the gas is liberated from the liquid and the liquid returned to the runner chamber through a return passageway, which passageway also serves as an auxiliary discharge port when the pump has been primed and is pumping liquid. In certain instances this arrangement is disadvantageous be cause of the amount of space it requires, and in my copending application I combined the separating chamber with the structure of the pump, thereby eliminating the separate separator used in my prior patent, with a consequent reduction in the amount of space required by the pump in an installation.

In my present invention, I provide a pump of the type disclosed in my copending application, that is one in which the separating chamber is integral with the pump and in effect wrapped around the outside of the pump so that it requires a minimum space. In my present invention I modifythe separator of my prior pump to provide a more accurate control'of the return to the runner of the liquid that has been separated from the mixture of gas and liquid dis- I charged from the runner chamber during the priming period of the pump, this control, governing the amount of liquid so returned and thereby permitting the building up of a higher vacuum in the .runner chamber and consequent 40 increase inthe working range of the pump.

In self-priming pumps of the rotary centrifugal type disclosed in my prior patent-a certain amount of liquid is retained in the pump when it is shut down, and this liquid is revolved by the runner when the pump is re-started. The

liquid so revolved entrains gas in it and the mixture is discharged from the pump through a throat leading into the separating chamber. The

from "forcing the em in the pump is circulated through the pump by the runner without entraining gas, and consequently the pump is incapable of drawing a higher vacuum than is existing at the time that the runner chamber becomes overfilled with liquid. Furthermore, there is a definite ratio ofrgas to liquid at which ratio the maximum amount or gas that can be entrained is entrained, and consequently the pump is rendered capable of drawing its highest vacuum. For this reason it is as imperative that suflicient liquid be returned to the runner as it is that the return flow be limited, if this ratio of gas to liquid is to be maintained.

Obviously the retum' of liquid to the runner during priming may be controlled by suitable valves which may be either manually. operated or pressure operated to regulate that flow and maintain the ratio. However, such an arrangement adds to the complexity of the pump and makes its operation more intricate. In my present invention I have accomplished the results accomplished by the use of such valves without the use of valves.

As in my prior pumps of this type, I-have located the return passageway adjacent the throat and on the down side of the runner, that is, in the direction or the travel of the runner; so that a blade or bucket on the runner will first encounter the throat and then the return passageway during its revolution. In the present invention, the return passageway leads laterally into the running chamber at a point near the peripheral edge of the runner, this point being as hereinbei'ore explained adjacent the throat of the pump.

When there is an excess of liquid in the runner chamber, that is, more liquid than is required to seal the throat with mixture discharged ipto the useparating chamber, the excess liquid g'ed 'yjlthejrunner pinto the return pasfdl'scharge of liquidjrcmthe runm me ne s s r during age, ot. the pumpis an. indication Idisch 01 $1! EXQQSS Sll fiply oiliquidin the channel, and

I have, in the preferred embodiment of my invention, designed the port through which the return passageway entersthe channel in such a manner that the stream of liquid so discharged is bent into the path of the stream of liquid being returned to the channel through this passageway. The intermingling of these two liquid streams forms a hydraulic valve which regulates the amount of liquid that is returned to the channel. By .this arrang'ement, the

amount of liquid admitted to the channel is automatically regulated so as to prevent drowning the runner during the priming operation.

During the last part of the, priming stage of the pump. that is, when the vacuum in the runner chamber is relatively high and the pressure in the separator and consequently on theliquid in the return passageway is also high, the pressure difference between thevacuum in themnor channel and pressure in the separator tends to increase amount of liquid'retumed to the runner. This increase inthe amount of liquid increases the excessin the channel, so that more liquid is thrown over into the port leading to the return passageway and consequently the hydraulic valve produced is effective to reduce the how of return liquid. This arrangement permits drawing of higher vacuum in the runner chamber than has been heretofore ,possible, the

than the pressure in hydraulic valve in efl'ect serving as a gate in the return passageway which definitely restricts the return flow of liquid so that just enough is maintained in the runner chamber to properlyentrain gas and therefore draw a high vacuum.-

When the pump has been primed, and the runner channel is consequently full of liquid, the return passageway must serve as an auxiliary discharge port from the channel, since the amount of liquid thrown on bythe runner is in excess of .the carrying capacity of the throat or main discharge port. During this stage of the operation of the pump, the eifect of the hydraulic valve in the return passageway is to be avoided since it would impair the 'emciency of that passageway as a eway leading out of the runner channel. In the preferred embodiment of my invention, the throat or connection between the re turn passageway and the runner channel is i'ormed in such a manner that a hydraulic valve is produced only when the throat is partially full of liquid and when the throat is completely filled wl'th" 'liquid, as it will be during the pumping stage of the 'pumprthe'throat in efl'ect bends the stream" of liquid from the channel into the passageway without-producing the eiIect of the liy"- draulicvalve; By thlsarrangement, the full pressure developed by'the'runner'is maintained on the liquid flowing through the return passageway, and since this pressure is always higher g the separator, there is'no tendency for thepump to circulate liquid within itself during the pumping state. Suchcirchla- The arcuate path carries over so tion or liquid obviously reduces the eil'iciency of the pump. I In the preferred embodiment of my invention,

I have altered the construction. of the separator so that-its operation is improved during the priming period of the pump. During this period, the

mixture of air and gas thrown out of the throat.

of the pump is bent'in an arcuate path andsolid liquid, which is heavier than the and liquid, hugs the outer boundary of this path, and consequent ythemixture of gas and liquid follows the inside or concave portion of thezpath. that the heavy along the lineH of of gas:

ture of gas and liquid, thereby screening'the body of solid liquid collected in the bottom of the separator'to prevent the entraining of gas in it. This reverse position of the stream of solid liquid and mixture of gas and liquid places the latter on top of the former and permits separation oi gas from the mixture by gravity, whichgas is permitted to rise and flow out of the pump t with through its discharge port.

Now, to acquaint those skilled in the y the teachings of my invention, reference is made to the accompanying drawings in which a preferred embodiment of it is shown by way of example, and in which:

Figure 1 is a cross-sectional view through a completelyfassembled pump embodying the principles of my invention, taken longitudinally of x the axis or the shaft of the pump;

Figure 2 is a cross-sectional view of the pump taken substantially along the line 2-2 of Figures l and 3;

Figure 3 is a plan view of the pump shown in Figures 1 and 2;

Figure 4 is a de ail sectional view taken along the line 4-4 of Figure 3;

Figure 5 is a partial cross-sectional view taken Figure 2, looking in the direction of the arrows;

ill)

Figure 6 is a cross-sectional view of a pump employing a modified form of separator;

Figure 7 is a cross-sectional view of the pump shown in Figure 6 taken along the line 7-7, looking in the direction oi the arrows;

, Figure -8 is a cross-sectional view of the pump shown in Figure 8, taken along the line H, looking in the direction of the arrows; and

Figure 9 is a diagram illustrating the employ-v ment of a valve for regulating the return of liquid tothe runner.

Referring now to Figure l, the runner or impeller 1 is disposed in the casing 2 having a cover plate 3, which isbolted thereto by bolt 4 and is provided with an inlet opening 5 to which the inlet trap or strainer 8 is attached by bolts '1 ex tending through'the cooperating flanges 8 on the cover plate 3 and separator 6. The cover plate 3 is of general frusto-conical shape. which distributes the incoming liquid completely around the impeller 1.

The, trap 6 is not a part of my present invention, and need not be explained in detail herein, it being sufiicient to say that'it constitutes a strainer through whichtheliquid must pass in entering the trap, this strainer functioning to remove solid particles from that liquid and thereby prevent their entrance into the rimner channel.

The trap also contains a chamber or'cavity which As shown, the impeller comprises a hub 10 as.

; ingspokes l1 radiating therefrom, and rings .ioinf .ing free ends of.'the spokes. A plurality (SL blades or fins 1-3 are radially disposed on the ring 12 with their inner edges substantially'flush with the inner edge of thering, but with their outer edges extending beyond the-outer periphery of the ring, the lateral edges oi the flnsextending on opposite sidesrof the lateral facesof the ring 12. The fins or blades together with the walls of the casing 2 form a plurality of buckets which are U-shaped and disposed with the concave side of the U facing inwardly towards the axis of the hub 10. v

The particular type of runnershown asshown by wayof example only, as it is within the teachings of my inventionto modify therunner if desired; although I have. found that the type shown is satisfactory and gives excellent-results.

The hub 1 is preferably of smooth configuration and the spokes 11 radiating therefrom are shaped to minimize eddy currents in the liquid drawn into the impeller and deiiveredto the buckets of it. The hub is preferably formed integral with a shaft 14 which extends through a packing gland 15, in the back side of the casing 2, to prevent leakage of liquid past the shaft.

The particular type of packing gland employed for this purpose is not of the essence of the present invention and need not be described in detail herein.

As will be seen in Figure 1 when taken in conjunction with' Figure 2, the peripheral walls of the casing 2 are of general C-shape, and rather narrow, providing only suilicient seating for the bolts 4 which are employed to hold the cover 3 on the casing. Around the outside of the-casing and formed integral therewith are the walls 20, 21 and 22 which together define the outer limits of the separating chamber of the pump. The--- cover plate 24 that is attached to the flanges 23 by bolts 26 or in any other preferred manner. Suitable feet 27 and 28. are also formedintegral with the above walls, to provide for the support of the pump on a. suitable At the upper end of the pump, I have provided 4 a discharge port 29' which is flanged at so to provide for the attachment of the discharge pipe to casing 2 to'the separator chamber 41.

the pump.

Within the casing so formed, area -flanged bame 31 and side baflles 32 and a return pas-sage-v way 33, all being integrally formed into the walls of the casing.

' separating chamber 41 with the discharge chamher 43 located above thebaiile 31. The chamber 41 is shaped so that the mixture expelled by the runner travels in a path of single curvature, which path is disposed with its concave side adjacent the runner.

0n the opposite side of the casing are a return passageway 33 and auxiliary separating chamber 44 defined by the walls 22 and 2 of the casing, this chamber 44 terminating at its lower end with the return passageway 33 leading back into the nmner channel. The return passageway 33 is located in the side wall of the pump. preferably on the-back or side opposite the inlettrap 6.

' phragm to resist its downwardmovement.

The inner-end of this passageway connects with a lateral auxiliary throat 51' leading into the runner channel of the pump. This throat 51 is provided with a straight portion 52 disposed substantially tangential to the runner and a curved portion 53 connecting the outer end of the straight portion 52 with the edge of the runner channel. These walls 52 and 53 are both parallel to the axis of the pump and consequently at right angles to the plane of the runner 1. The inner or runner side of the straight wall 52 joins with the walls defining the throat 40, so that the auxiliary throat 51 is disposed immediately adjacent the main throat 40 and on the side of it toward which the runner is advancing.

As will be seen in Figures 1 to 4 inclusive, the

flanged baiile 31 is a tongue-like projection extending from the casing wall 21 inwardly across the chamber 41, the width of the battle 31 being approximately one-third of the width of the chamber orpassageway 41. The ports 42 formed on the opposite sides of the bailie 31 are each of aj vwidth approximately equal to the width of the baiile 31.

The inner end of the baffle 31 joins with side bames 32 on the top side of the casing 2 approximately at the middle of the pump. The two 'auxiliary separating chambers 44 located on the opposite side of the pump and behind the side bai'iles 32. From the foregoing it is apparent that the pump and separator structure comprise three members, the main casing consisting of casing walls 2, 20, 21 and 22, the inlet cover 3, and the separator cover. 24. Preferably each of these parts is a cast metal part, although, if desired, other forms of, fabrication may be used in lieu thereof within the teachings of my invention.

Referring now to Fgures 2 and 9, from which the operation of the pump during the priming period can be best understood, liquid thrown from the runner through the throat 40 passes into the separating chamber 41, where the majority of it passes through the lateral ports 42 into the out- .let chamber 43. A portion of this liquid hugs the outside wall 20 and is caught by the baffle 31 and forced through the narrow throat 45 into the auxiliary separating chamber 44, from which it returns to the runner chamber through the channel 33. As the pump builds up a vacuum, a pressure is built up in the separator, so that the "flow of liquid through the duct 33 is enhanced by the pressure difference on the two ends of the duct. To regulate this flow, I may employ a gate valve 100 connected to a diaphragm 101 spring 102. When the vacuum in the runner channel increases, the decrease in pressure is communicated through duct 104 to the under side 105 of the diaphragm 101, causing the air pressure on the outside of the diaphragm to move and urged outward with the diaphragm by a valve 100, so that the pressure in the separator' chamber and duct is not available to the dia- The auxiliary throat 51 leading from the runner channel is directly connected to the inside oi. the diaphragm through duct 104 so that the full force of high vacuum is on the under side of that diaphragm and the atmospheric pressure on the outside of the diaphragm is thereby rendered available to move it and the gate valve inward.

A suitable perforated cover 103 may be employed to protect the diaphragm from injury. 7

By this arrangement, when the pressure in the runner chamber is substantially equal to the pressure in the separator, the gate valve 100 will be completely open; and, conversely, when the vacuum is high and the pressure in the separator correspondingly high, the, gate valve will be practically closed and the flow of liquid through the duct 33 thereby diminished. This arrangement automatically regulates the return flow of liquid through the duct so that the ratio of liquid and gas in the runner channel is maintained at the value for maximum drawing of vacuum and the pump thereby rendered more efilcient during its priming stage.

When the pump has been primed and the runner channel is full of liquid more liquid is thrown from the runner than the throat 40 can handle and the full pressure of the runner is impressed upon the throat 51 and consequently upon the diaphragm 101, raising that diaphragm and opening the gate valve 100 fully, so that the auxiliary throat 33 may be efllciently employed to discharge liquid from the runner channel.

However, Figure 9 is merely a diagrammatic representation of the results that are accomplished in another manner.

In the operation of the preferred embodiment of my invention, when the pump is shut down a certain amount of liquid is entrained in the runner channel, the inlet trap 6, and separating chamber 41. When the pump is re-started, this liquid is whirled around the channel by the runner, and such operation entrains in the liquid the gas or air that is in the inlet or suction side of the pump, forming a mixture which is expelled from the runner through the tangential throat 40 into the separating chamber.

As the mixture enters the sepalating chamber, the liquid therein, being heavier than the gas, tends to move over towards the outside wall of the chamber, and the gas and some of mixture of gas and liquid towards the inner or concave side of the path of travel. This action produces a partial stratification of the mixture, and liberates a part of the gas from the mixture as soon as it has passed the throat section 40. The general path of travel taken by the mixture is arcuate and the liquid forming at the outer portion oi this path hugs the outer wall of the chamber, and a portion of it enters into the flange baille 31. where it is deflected inwardly in a path of substantially the same curvature. Any gas which may be entrained in the outer stratum of liquid is squeezed out when the liquid is forced through the port between the end of the baflle and the casing 22. The liquid that passes the port 45 strikes the casing 2 and is deflected across the auxiliary separating chamber 44, in a substantially horizontal'path.

Thus it will be seen that the mixture of gas and liquid in the separating chamber 41 is underneath the solid wall of liquid that hugs the outer wall and baffle 31 01 that chamber. This wall of solid'liqu-id in effect forms a screen whichpreven'ts a free escape. orgas'tromthe' mixture by g rayity action,- although a part: of thegasw may sozescape through the port 42. into the outlet chamber 43 of the separator.

By the action of the throat 45 squeezing gas out of any mixture that may enter the port, and by the' deflection of the stream of solid liquid by the baffle and this port as hereinbefore pointed out, the screening effect is maintained across the top of the auxiliary separating chamber 44. This chamber fills with liquid, and it is imperative for the proper priming of the pump that it be solid liquid, that is, liquid entirely free from gas. The motion of the stream of solid liquid deflected through the port 45 and across the top or the auxiliary separator 44 protects the liquid in the auxiliary separator 44 and guards against the entraining of gas in that liquid. Whereas the mixture of gas and liquid is stratified and moved to a position on the under side of the stream of solid liquid in the main separating chamber 41, through the action of the flow of liquid through the port 45, this condition is reversed in the auxiliary separating chamber 44; that is, the stream of solid liquid is underneath the stream of mixture of gas and liquid, so that the gas can escape from the latter liquid by gravity and flow out of the pump through the discharge port 29.

The mixture or gas and liquid which flows through the lateral port 42 into the discharge chamber 43 has some velocity and strikes against the baille 32 projecting inwardly into that chamber from the side walls of it, this bailie serving to break up the velocity of that liquid, so that the liquid in this mixture does not plunge into the liquid standing in the auxiliary separating chamber 44. For the successful operation of the pump during the priming period it is imperative that all plunging of liquid into this chamber be avoided. The stream of liquid flowing horizontally across the top of the auxiliary separating chamber 44 aids the baille 32 in preventing plunging of the liquid from the chamber 43 into the auxiliary separating chamber.

During the priming operation of the pump, no liquid is permitted to escape from it through the discharge port 29, so that the amount of liquid entrained in the pump casing and separator when the pump is shut down is sufiicient to draw a vacuum in the pump. Gas thus drawn from the impeller chamber is permitted to escape through the discharge port, and the liquid returned to the auxiliary separating chamber is entirely free from this gas so that it is capable of entraining more gas when it is again circulated in the runner chamber by the runner.

The continued discharge of mixture from the runner chamber through the port 40 into the separator builds up a pressure therein, which pressure is prevented from forcing the gas liberated from the mixture back into the impeller chamber by the seal formed by the passage of the mixture through the throat 40. As long as the runner channel is filled with liquid suiticiently to perinit the runner to discharge suiiicient liquid through the throat to completely close that throat, gas or liquid will not back up into the channel and the vacuum in the channel can be increased.

The liquid returned to the return passageway 33 from the auxiliary separator 44 flows through that passage to its end 50,?where it is deflected in a direction axially of the shaft of the runner, entering the latters channel through the lateral port 51 which is located adjacent the -throat;.4(l andalong the peripheral edge of the ychannel'.,;j-The,;liquidmust therefore change its to carry the excess liquid discharged from the direction twice in passing from the passageway 33 to the channel. When theamount of liquid in the channel is just suflicient to, or less than, the amount required to produce a mixture suflicient to completely close the throat 40, the liquid in the passage 33 flows freely into the channel. If, however, the amount of liquid in the channel is more than enough to produce the maximum amount of mixture that the throat can pass, the excess mixture is thrown into the tangential port 51. The liquid thus thrown from the runner through the tangential port 51 is bent by the curved wall 53 of that port and caused to re-enter the runner at a point adjacent this point of discharge. This re-entry of the liquid into the runner is across the path taken by the liquid flowing from the auxiliary separating chamber 44 through the duct 33 into the runner channel, an this cross flow serves to block the flow of liquid through this latter path. This action in effect forms a hydraulic valve regulating the amount of liquid that isreturned to the runner channel through the duct 33, thereby preventing drowning of the runner during the priming stages of the pump. The liquid discharged tar zentially along the wall 52 and deflected by the curved wall 53 is impelled by the full force of the runner so that its pressure is sufliciently high to effectually block the entrance oi liquid through the port 51.

In practicing my invention, I have found that by .proper design of the shape of the throat 51, the amount of liquid delivered to the runner channel can be automatically regulated so that there is at all times just sufficient liquid in the channel to produce enough mixture to completely fill the throat 40, and to maintain the ratio of liquid and entrained gas hereinbefore referred to. As a result of this operation, the vacuum that the impeller can draw is appreciably higher than has been possible of attainment in pumps of this design heretofore.

This vacuum in the impeller chamber, and the increase in pressure in the separator and consequently in the return passageway, cause a substantial pressure diflerence at the throat 51,

which, if it were not for the action of the hydraulic valve in this throat, would cause an in.-

. the entrance of liquid through the port 51 is thereby further reduced. This obstruction to the passage of liquid through the port 51 compensates for the pressure difference between the runner channel and the separator and the rapid ingress of liquid into the channel is therefore inhibited and the ratio of liquid to entrained gas in the runner channel thereby maintained and the runner made capable 0! drawing a still higher vac-- uum.

When the runner has drawn sufflcient vacuum to prime the pump, the runner channel becomes completely filled with liquid, and the throat 40 is therefore incapable of csrrying'away the liquid discharged from the revolving runner. The throat 51 and return passageway are now made and pressure that can be maintained by the pump impeller, the throat 51 being so designed that when it is completely fllled with liquid, as it will be. during the pumping operation of the pump, liquid is permitted to flow freely through the port 51 and passageway 33 into the auxiliary separator 44 without producing eddies or cross currents at the mouth of the port 51. This liquid of course travels upward in that separator and is discharged from the pump through the outlet port 29. Since the full pressure developed by the runner is impressed upon the liquid in passageway 33, and since thatpressure is higher than the pressure in the separators, obviously noliquid will be returned to the channel during the pumping period and circulation of liquid continuously through the pump is thereby inhibited.

When the runner is pumping sufllcient liquid that the auxiliary discharge port 51 is maintained full of liquid, some of that liquid may build up against the curved portion 53 of the wall of that port and remain practically immovable in this position. This effect, if it does exist, is beneficial in that it materially aids in bending the main stream of liquid through the port so that it may be carried through the auxiliary duct 33 into the auxiliary separating chamber 44 with a minimum loss of pressure and consequently the capacity is increased.

In the embodiment of the invention shown in Figures 1 to 5 inclusive, the auxiliary separating chamber 44 is placed on the opposite side of the pump casing 2 from the main separating chamber 41. This arrangement is arbitrary in the practice of my invention. In Figures 6, 7 and 8 I have shown a pump embodying the principles oi the invention and designed so that the main separating passage is located centrally of the pump and the auxiliary separating passage divided and located on opposite sides of the main passage and on the same side of the pump casing as the main passage.

In this embodiment, the impeller 60 is located within a casing 61, which casing and an outer casing 62 together form the main separating chamber 63, which is connected to the runner channel by the throat 64. The walls 62 of the separator chamber 63 terminate in a flanged baille 65, located centrally of the pump, that is with the meridian line in substantial alignment with the meridian planeof the impeller 60.

A second wall 66 disposed outside of the wall 62 is-joined to the wall 62 and to the casing 61 by parallel partitions 67 and 68 located in .the space between the walls 61 and 66. The discharge chamber 69 is formed within the walls 66 and 61 above the upper edges of the separators 67 and 68, terminating in the exhaust. port 70 through which the liquid-pumped by the pump is discharged.

The walls 6'7 and 68 also form the flanges on the bame 65, the free edge of this flange and the outer surface of the casing 61 together forming the lateral ports 71, through which liquid flows from the inner channel into the exhaust chamber 69. The exhaust chamber 60 is clmd at its bottom portion by an auxiliary wall "(2 which is located below the ports '11 and outside of the 14.1 separators 6'7 and'68. The auxiliary separating chamber 73 extends at its upper edge between the plate 67 and 68 and at its lower edge on the outside of the baiile 65 and toward the bottom of the pump in the space between the bane 65 and the other casing 66. From the lowermost portion of the outer auxiliary chamber '73, the return passageway 74 is led upward, terminating in the auxiliary port 75 leading into the runner channel and located adjacent port '15 leading into the runner channel and located adjacent the throat 84 as in the hereinbefore described embodiment.

The cover plate, inlet trap, and irusto-conical inlet port or this pump may be any preferred type such as that shown in detail in Figure 1, within the teachings of my invention.

In the operation oi. the pump shown in Figures 6 to 8 inclusive, the impeller forms a mixture of gas and liquid discharging it from the throat 64 into the separating chamber 74, the liquid of this mixture following the bottom and outside wall or the chamber while the gas and imperi'ectly stratifled mixture follow the inside wall 0! the chamber. The gas and latter liquid pass through the ports '71 laterally outward above the auxiliary wall '72 and into the discharge passageway 69 from which they are discharged from the pump through the port 70. The liquid trapped against the outside wall passes through the narrow orifice '16 which is located between the upper end or the. baflle 65 and the outer surface of the casing 61, flowing between the separators 67 and- 68 downward through the auxiliary separating chamber '73 into the return passageway 74 from which .the liquid re-enters the'runner channel through the auxiliary throat '15.

The auxiliary throat 75 is shaped in the hereinbefore explained manner, that is the same as throat 51 or the previously explained embodiment of my invention, so that excess liquid in the runner channel will be thrown into the throat '15 and made to form in a cross stream across the port, this stream obstructing the path or the liquid returning through the passageway 74, to thereby regulate the amount of liquid returned a to the runner channel.

After the priming state of the pump has been completed and the runner channel is filled with liquid, the excess liquid thrown on by the runner flows through the port .75 and the'passageway '74 into the auxiliary separator '13, through which it rises into the space between the separators 67 and 68 and eventually flows out or this space into the discharge chamber 69 and thence out of the pump through the port 70.

From the foregoing it is apparent that my invention is capable of being practiced in a number of different manners, and that certain features of theconstruction of a pump embodying the invention can be modified within the teach ings of the invention. I am not therefore to be limited to the specific details shown by way of example, as I am aware that many of the details may be modified.

Having thus described my invention, what I consider new and desire to have protected by Letters Patent is pointed out in the appended claims.

What is claimed is: 1. In a pump or the class'described, a casing having a channel, a runner disposed in the channel, a discharge throat leading from the channel through which a mixture of liquid and gas is expelled during the priming period and through which liquid is expelled during the pumping period, a return passage through which the liquid of said mixture is returned to the channel during the priming period and through which excess liquid is discharged-from the channel during the priming and pumping periods; said passageway being shaped to bend the excess liquid thrown through it during the priming period into a stream across the path of the returning liquid to thereby obstruct the return flow of liquid to the channel, said bending completely shutting off the return flow when the passageway is filled with liquid thrown from the channel during the pumping period.

2. In a pump of the class described, a casing having a channel, a runner disposed in the channel, a discharge throat leading from the channel through which a mixture of liquid and gas is expelled during the priming period and through which liquid is expelled during the pumping period, a return passage through which the liquid -0! said mixture is returned to the channel during the priming period and through which excess liquid is discharged from the channel during the priming and pumping periods, said passageway entering the channel laterally at the peripheral edge of the runner through a threat which bends the stream of excess liquid received during the priming stage in the path of the returning liquid to limit the amount returned, said bending of the liquid thrown out of the channel completely shutting oil the return flow when the passageway is fllled with liquid thrown from the channel during the pumping period.

3. In a pump of the class described, a casing having a channel, a runner disposed in the channel, a discharge throat leading from the channel through which a mixture or liquid and gas is expelled during the priming period and through which liquid is expelled during the pumping period, a return passage through which the liquid of said mixture is returned to the channel during the priming period and through which excess liquid is discharged from the channel during the pumping period, said passageway entering the channel laterally at the peripheral edge of the runner through a throat across which excess liquid thrown from the runner during the priming stage is directed in the path of the returning liquid to limit the amount returned, said second throat when full or liquid bending the liquid stream without whirling it to permit tree discharge of liquid from the channel through the passageway during the pumping period.

4. In a pump, a casing, a runner in the casing, said runner having a plurality of buckets, a chamber surrounding said casing and disposed concentric to it, a throat connecting said-chamber to said casing, said runner revolving to discharge a mixture oi gas and liquid through the throat intosaid chamber, means in the chamber for separating the gas from the liquid, a i

governing the amount or liquid returned to the runner.

5. In a pump, a casing, a runner in the cas-' ing, said rimner having a plurality of buckets, a chamber surrounding said casing and disposed concentric to it, a throat connecting said chamber to said casing, said runner revolving to discharge a mixture of gas and liquid through the throat into said chamber, means in the chamber for separating the gas from the liquid, a return passageway for returning the separated liquid to the casing, and means including cross flow formed by the excess liquid thrown from said runner striking the walls of said passageway and thereby deflected across it. for governing the amount 01 liquid returned to the runner. 5

6. Ida pump, a casing, a runner in the easing, said runner having a plurality of buckets, a chamber surrounding said casing and disposed concentric to it, a throat connecting said chamberto said casing, said runner revolving to discharge a mixture" of gas and liquid through the throat into said chamber, means in the chamber for separating the gas from the liquid, a return passageway for returning the separated liquid to the casing, said passageway having walls shaped to catch and deflect any liquid thrown from the runner in excess of that required to seal said throat to form it into a cross stream which obstructs the passage to lessen the amount of liquid returned to the runner. '7. In a pump, a casing wall defining a channel, a runner disposed in the channel, said runner having a plurality of buckets, a second casing wall forming with the first a. chamber, a throat connecting the channel to the chamber, said runner during the priming stage of the pump discharging a mixture of liquid and gas from its buckets through said throat into the chamber, said mixture sealing the throat to prevent the return of gas through it into the channel, and means in said chamber for separating the gas from said mixture, said'means including means for stratifying and then squeezing the mixture and ports for permitting the gas to escape from the chamber.

8. In a pump, acasing wall defining a channel, a runner disposed in the channel, said runner having a plurality of buckets, a second casing wall forming with the first a chamber, a throat connecting the channel to the chamber, said runner during the priming stage of the pump dis charging a mixture of liquid and gas from its buckets through said throat into the chamber to evacuate said channel and to build up a pressure in the chamber, said mixture sealing the throat to prevent the return of gas through it into the channel, a baflle formed integral with said second casing wall'and projecting across said chamber into juxtaposition to said first casing,

jsaid baflie deflecting the liquid in said mixture toward said first wall and permitting the gas which has been separated from that liquid to escape laterally around it, a passageway for re-.- turning the liquid separated from the mixture to the channel, and means in said passageway for causing the liquid thrown by the runner into the passageway to counteract the diiference in pressure between the chamber and channel to govern the quantity of liquid returned to the channel.

9. In a pump, a casing wall defining a cylindrical channel, a runner cooperating with said channel, said runner having a series of buckets, a second casingintegral with and concentric to the first casing, said casings between them forming a crescent-shaped chamber encircling said channel, a discharge port leading out of. said chamber, a throat leading tangentially from said channel into one end of said chamber, a return passageway connecting the opposite end 0! said chamber to said channel, said passageway: leading laterally into the channel at a point adjacent said throat in the direction of rotation of said runner, a baffle in said chamber adjacent said discharge port, said battle and outer casing together forming laterally disposed ports leading into said discharge port, said chamber, baille and lateral said throat during the priming of the pump to discharge the gas through the discharge port and to return the liquid to the channel through said return passage.

10. In a pump, a casing having a channel, a runner cooperating with said channel, said runner having a series of buckets, a crescent-shaped chamber encircling said casing, a throat connecting one end of said chamber to said channel, said throat leading'tangentially out of the chamber, a return passageway connecting the other end of said chamber to said channel, said pasand gas in a mixture discharged by a pump -dur-- ing its priming period, an arcuate wall for bending the stream of mixture to cause the liquid to form outside and above the mixture, a chamber in which gas-free liquid is stored for returning to the pump, said wall directing the liquid of said stream across said chamber to form a screen therein, and ports leading laterally. from the under side of said stream through which gas freed from said mixture flows to the space above said screen.

12. In a separator for separating the liquid and gas in a mixture discharged by a pump during its priming period, an arcuate wall for bending the stream of mixture to cause the liquid to formoutside and above the mixture, a chamber in which gas-free liquid is stored for returning to thepump, ports leading from the under .side'of said stream through which gas freed from said mixture escapes into a chamber located above said wall, and means for directing saidstream' across said chambers to separate them.

13. In a pump, a casing having a substantially circular outside periphery and a cylindrical channel within it, a runner in said channel, a throat leading from the channel, a separating chamber communicating with said throat, said chamber being bounded by an arcuate wall whose center is displaced from the center of saidchannel, said runner during the priming stage of the'pump' throwing a mixture of liquid and gas throughsaid port into said chambensaid mixture stratifying therein and a part of the liquid hugging said arcuate wall and traveling outside and over the remainder of the mixture, lateral ports leading out of said chamber through which gas freed from said mixture flows, a second chamber communicating with said channel and containing gas-free liquid to be returned to it, and a port through. which said arcuate wall directs said solid liquid stream across said second chamber to form a screen which prevents the plunging of said mixture into said gas-free liquid.

14. In a shelf priming pump, a pump casing having a channel, a single open impeller for the channel, a separator, a main tangential discharge throat between the channel and the separator,' an auxiliary" throat between the separator, and 1 a portion of the casing where pressure is deqveloped when the pump is primed said auxiliary throat returning liquid into the impeller during priming, said auxiliary throat having flow obstructlng means which acts progressively to compensate the return flow of liquid as the suction within the casing increases, to prevent excessive return flow which would tend to drown the air entraining action of the impeller before the pump casing is evacuated, said auxiliary throat serving as an additional discharge throat when the pump is primed.

; In a self priming pump, a pump casing having a channel, a single impeller for the channel, a separator, a main tangential discharge throat leading to the separator, an auxiliary said valve being removed by pressure developed in the pump when the pump is primed.

HARRY E. LA BOUR.

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