US1915678A

US1915678A - Pump

Info

Publication number: US1915678A
Application number: US470559A
Authority: US
Inventors: Bour Harry E La
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-07-25
Filing date: 1930-07-25
Publication date: 1933-06-27
Anticipated expiration: 1950-06-27

Description

June 27, 1933.

H.E.LABouR rum Filed July 2 5, 1930 2 Sheets-Sheet 2 p2 $672307 flaw" EMOW Patented June 27, 1933 PATENT OFFICE Bazaar 1i. LA noun, or mm, mnium PUMP Application filed July 25, 1930. 'Serial No. 470,559.

This invention relates to improvement in pumps. In centrifugal pumps of the self priming type, a quantity of liquid is trapped in the .pump when it is shut down and when the pump is re-started this liquid is whirled by the runner to entrain air and draw vacuum into the pump. The mixture of air and liquid is discharged from the pump into a separator in which the gas entrained in the liquid is permitted to escape therefrom and the liquid is returned to the pump to be recirculated by the runner and again discharged into the separator. In pumps of this kind, it is essential that the throat through which the mixture is discharged be of such cross sectional area that the mixture discharged during priming will completely fill it and-thereby seal it against the gas in the separator from being forced into the pump by the pressure built up in the separator by the discharge of the mixture into it. It is furthermore essential in the'priming of 'a pump of this kind that a certain quantity 0 liquid be returned to the runner channel for mixing with the gas in that channel. If this quantity of liquid'is excessive the pump becomes drownednd incapable of drawmg'a higher vacuum on its intake or suction side.

If the quantity of liquid is insufficient the pressure in the separator forces the mixture and gas back into the runner channel and the vacuum which-has been drawn therein i's'c'on s uently reduced v n the prior art of which I am aware various arrangements have been provided to.

regulate this. return flow of liquid and to .inslirethat the main discharge throat of the 40 pump will be completely sealed by the mixture of gas and liquid discharge from the runner. In certain of these prior art pumps, it has been noted that the pump will-start drawing a vacuum, proceed successfully in this manner for a short interval of time, then drop its vacuum, and subsequently again continue with the drawing of a vacuum in the runner channel. This operation produces a surging in the pump and it'has been noted that this surging is due to a variation 1? this'tendency of'a centrifugal pump to sur -mixture thrown into the return passa away in the runner channel becomes excessively high, the quantity of mixture thrown into the return port is great and the return of gas free liquid to the channel is thereby diminished. In certain instances its return flow may be momentarily entirely cut oil with the result that the excess quantity of liquid in the channel is soon exhausted and the quantity of mixture thrown into the return throat thereby eatly diminished or entirely'elimic nated. idly'into the runner and a eye 0 of the surge is thus completed.

In my present invention I have corrected during its priming period by providing t e usual discharge port of such cross sectional area that it can be readil maintained full of mixture by the runner uring the priming period; I also provide the usual return passage 'through which gas free li uid is returned to the runner in a path su stantially radial of that runner. I also provide a baflle or bafiles in the return throat which divides that throat into two or more sections. The

by the runner strikes against this ba e and is thereby deflected into such a path that it isincapable of completely shutting off the return flow of gasfree liquid to the runner. While the mixture is incapable of cornsletely shutting off the flow of gas free liqui it is still capable of opposing that flow to thereby form a hydraulic valve which regulates the return flow of gas free liquid so that the ratio of liquid to gas in the runner chamber can be accurately maintained at the proper value for the efiicient drawing of a vacuum by the pump. Since uid is never interrupted, there will always be, suflicient liquid in the channel to. enable d s a result gasfree 1i uid flows rap-,

the return flow of gas freeliqand improved separator of this type, one

which is more efficient and therefore capable of being'built as a unit substantially smaller than the separators used heretofore, such reduction in size being accomplished without a reduction in the efficiency of the separator.

Separators in the prior art have provided for whirling the mixture discharged by, the pump runner about anaxis located substantially normally to theaxis of rotation of the runner. I have found that by providing a separator in which the axis of the whirling mixture is parallel to and above the axis of the rotating runner, the over-all dimensions of the separator can be materially reduced without reducing its efiiciency in any way. Other advantages resulting from this construction will be apparent from a reading of the detailed description and claims which follow.

Now to acquaint those skilled in the art in 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 an elevational View, partly in section, of a pump and separator;

Figure 2 is a cross sectional view taken along the line 2-2 of Figure 1;

Figure 3 is a cross sectional view taken along the line 33 of Figure 2;

Figure 4 is a cross sectional view taken along the line 44 of'Figure 1 and showing the return passageway;

Figure 5 is asimilar view taken along the line 5-5 of Figure 1 showing the discharge passageway;

Figure 6 is a cross sectional view taken along the line 6-6 of Figure 2 looking into the direction of the arrows;

Figure 7 is a fragmentary cross sectional view taken along the line 77 of Figure 2 looking in the direction of the arrows; and

Figure 8 is an elevational view of a modlfied form of separator.

Referring to the drawings now in more detail, the pump comprises a casing 1 consisting of a generally cylindrical casting which may be supported upon feet 2-2 and which contains a central cylindrical runner channel 3 in which the runner or impeller 4 'is supported to rotate about a horizontal axis.

The runner casing 1 is provided with an inlet cover 5 which is preferably of conical shape form a mounting for-the inlet trap of the.

The inlet trap is not of the essence of the present invention and'any preferred type of inlet trap may be used, for example the inlet trap shown in my copending application Serial No. 374,409, filed June 28, 1929 (Case 29) may be successfully employed within theteachings of my invention. The use of bolts 6 to attach the cover 5 to the-pump casing 1 is optional, as the member may be secured together by any other suitable arrangement such as the clamps shown in my above mentioned copending application. Preferably the cover plate and casing are both castings made of metal suitable for the use to which the pump is to be placed, the metal preferably being iron when the pump is to be employed in pumping noncorrosive liquids and of being an acid resisting alloy if the pump is to pump corrosive liquids,

The pum discharge tiiroat 11 which is formed in the walls of the casing itself. This discharge throat leads tangentially out of the runner channel 3 and is provided with a restricted port or opening 12 adjacent the peripheral edge of the runner 4. The cross sectional area'of this port is carefully calculated with respect to the impeller speed and pump capacity and the flare of the throat 11 to increase its cross sectional area likewise carefully proportioned to the cross sectional area of the The outer wall 14: of this dischargeport. throat is straight and is disposed as a tangent to the runner channel 3, and the increase in cross sectional area of thethroat is obtained by suitable shaping of the opposite wall 15 which defines the passageway.

A'return'p'assageway 16 is also provided in the projection of the casing 1 which houses the discharge passageway 11, this return passageway being formed between thewall 17 which is located substantially radially of the runner 4 and the wall 18 located substantially tangential to the runner. A. dividing baffle 19 or plurality of such bafiies separates thereturn passageway 16 into a plurality of portions, for a purpose which will be hereinafter explained. The number of such passageways varies with the capacity of the pump and the two shown in the drawings are shown by way of example only.

The cross sectional area of the return pasemma] than the cross sectional area of the main discharge throat 11, and the walls 17 and 18 are so shaped that the return passageway 16 has its maximum cross sectional area at the upper flange 13 of the pump.

The upper surface of the flange 13 is machined flat to provide a seating surface-for the separator'which is attached thereto, the

' flange 13 preferably being provided with a plurality of holes, not shown, through which suitable bolts are projected to attach the separator to the casing.

The separator indicated generally at 20 consists of a cylindrical drum 21 from the lower side of which the inlet passage 22 and the outlet passage 23 are projected. The wall 24 of the separator is a flat wall terminating in the flange 25 which registers w th the flange 13 of the pump casing. The 1nner surface of the wall 24 accurately aligns with the inner surface of the wall 14 of the pump casing and is therefore tangential to the pump runner'4. The upper part of the separator consists of a cylin rlcal wall section 26 joined at one end with the straight wall section 24 and at the other end. with a second straight wall section 27, wh ch latter section terminates in a continuation 25' of the flange 25 whichtin turn registerspwith the flange 13 on the pump casing.

At the bottom of the separator and'between the

walls

24 and 27 is a triangular wall member one side 28 of which forms a bounding wall of theinlet passage 22, and the other wall 29 forms a bounding surface of the outlet 23 of the separator. The .third wall 30 of this triangular member is arcuate ahd 1ts center coincides with the center of the cylindrical wall 26 thereby completing the cylindrical chamber at'the upper part of the separator.v

As will be seen

wall sections

24 and 27 in Figure 3.the straight and the cylindrical wall section 26 are joined by

side walls

31 and 32 which together with the

wall sections

24, 26 and 27 form the separator as .a sub-' stantially cylindrical member whose axis is parallel to the axis of the pump runner.

Side walls

31 and 32 are provided with

lateral ports

33 and 34 over which are cast the

walls

35 and 36 of the discharge duct 37, this duct branching out of the central chamber 21 ofthe separator laterally at the upper part of that chamber and ing transversely of the chamber 21 across the top of it and above the cylindrical wall 26. The discharge duct 37 terminates in a member 38'which is provided with suitable holes through which a discharge pipe may be connected to the separator in any preferred I manner such as by bolting. Obviously the shape and position of the duct may be altered within the teachings of my invention, and the position of changed. In certain instances it may be adseparator omitted if then preferably extendtheflange 38 may also bevantageous

wall sections

24 and 27 and the cylindrical to'place this flgnge 38 in a horizontal position above the separator or to one wall section 26, these openings being provid- I ed with threaded plugs 42 which. are normally in place to seal the openings. These openings permit inspection and cleaning of the separator when necessary. The triangular member consisting of walls 28, 29 and-30 1s provided with acentral opening 43 which is so placed merely to reduce the amount of metal and consequently the weight of the" desired within the teachings of my lnvention.

In the operation of the pump and separator shown in the drawings, when the pump is shut down a certain amount of liquid is trapped in the pump and the inlet trap, not shown, and when the runner 4 is revolved this liquid is circulated to entrain gas in it there by forming a mixture which is expelled from the peripheral portion of the runner through the throat 12., the discharge duct ll'into the inlet 22 of the separator. This mixture of gas and liquid'is traveling at a high speed and as it passes through the restricted area this opening of course can be of the throat 12 it. squeezed somewhat and 1 completely seals that port against the entrance of gas or liquid from the separator.

As the liquid travels into the larger portion 11 of the discharge throat it ispermitted to expand somewhat thereby permitting the gas in it to collect in the form of bubbles in which condition it is better able to escape from tlia liquid.

As thliquid is thrown tangentially from the runner it flows along the

tan ential walls

14 and 24 until it strikes the'cyhndrical wall 26 which bends it in anarcuate path whose axis is parallel to the axis of the pump runner.

The bending of the mixture of'gas and liquid in an arcuate path causes the heavier liquid of the mixture to hug the outside wall producing thereagainst a stratum of gas free liquid. The lighter gas andmixture of gas and liquid flows along the inside of the arcuate path forming a layer or stratum of mixture beneath and inside of the stratum of solid liquid. In Figure 1 I have illustrated this action by the closed barb arrows 80'representing the mixture of gas and liquid, -and the open barb arrows 81 representing the gas free liqu d. Thus it will beseen that asithe mixture flows upward frompor't 12 through.

throats-11 and 22, no separation occurs As .the mixture is bent in an arcuate path by the wall 26, the heavier gas free liquid, arrows 81', is thrown to the outside of the path, and

,from the liquid during this stratification readily escapes laterally through the

ports

33 and 34 and thence into the discharge duct 37 from which it escapes from the pump through the discharge piping, not shown.

With the stratum of solid liquid above-and outside of the stratum of gas and liquid, gravity separation of the gas from the liquid is greatly hindered. As the mixture and solid liquid flows onward around the arcuate path 26 and against the wall 27. the relative position of the two is reversed so that the solid liquid is beneath the mixture and free separation of the gas from the liquid by gravity is thereby enhanced.

By the time the mixture and solid liquid have reached the Wall section 27 of the separator they have lost the greater part of the velocity imparted to them by the runner so that their movement is at a relatively low speed. The solid liquid thus separated from the mixture is returned to the impeller chamher through the duct 23 leading out of the separator.

When there is a minimum suction at the eye of the impeller chamber, that is, the inlet port 8, there is also a minimum pressure in .the separator 21, and consequently a minimum force urging fiow of solid liquid through the duct 23 back intotheimpeller chamber. For .maximum efiiciency the quantity of liquid maintained in the impeller chamber under these conditions should be such that the impeller will throw out just suthcient mixture to completely fill the dis charge throat 12 with no excess; As the vacuum increasesv the pressure in the separator 21 either remains the same if the discharge is open to atmosphere or increases it closed and the pressure difference on the opposite ends of the duct 23 is therefore increased in either event and the flow of liquid through it correspondingly increased. The

quantity of liquid in the impeller chamber is therefore increased and the proportions of air and liquid discharged thereby changed. and the impeller discharges more mixture than can be handled by the throat 12' and some excess is discharged-through the throat 44 as will presently appear. As the pressure differencebetween the opposite ends of the return duct increases the excess of mixture will likewise increase and some will tend to enter the passage or throat 44 retarding or shutting off return flow through this passage or throat. If this does not compensate for the tendency to increase return flow by increase in pressure difference between separator and pump casing, the amount of liquid in excess of that going out the main throat 12 will be driven up through the passage or throat 44, thereby shutting ofl not only any return flow through throat 44 but throttling down by interference the return flow through

passages

23 and 12. Thus there is an automatic and inherent tendency to maintain approximate the return flow at a value which will give the maximum entraining ability.

When the runner 4 is rotating and a sulficientsupply of liquid is present in the runner channel 3, to cause the runner to expel slightly more mixture than the throat 12 can carry, the excess is thrown through the passage formed by the wall 18 and the bafie 19, which passage is substantially tangential to the runner 4 and through the other passageways between adjacent baflies if more than one bafiie is used. The throat 44 of this passage is narrow and the passage is therefore completely sealed by this mixture. The presence of mixture in the throat 44 obviously reduces the area through which returning liquid can flow and the return of liquid to the impeller chamber is thereby decreased. As the pressure difference between the separator and impeller chamber increases more liquid is returned to the impeller chamber and the quantity of mixture thrown into the throat 44 is increased, that mixture being directed by the baiile 19 upwardly in the passageway 23 where itencounters the returning liquid and its pressure opposes the pressure of that returning liquid. If the quantity of mixture is relatively small and its pressure correspondingly low, the solid liquid fiowing downwardly in the passageway 23 will predominate and the mixture will not reach the separator but rather will be returned to' the impeller chamber with the solid liquid. If the quantity of liquid in the impeller chamber is larger the quantity of mixture in the throat 44 will be greater and its pressure higher and this overflow of mixture will be thrown upward in the return passageway 23 with suflicient force to create a pressure opposing the flow of liquid from the separator into the runner chamber through the return passageway 46 by forming an eddy. This eddy obviously interferes withthe return flow of liquid to the impeller chamber, and is, in eflect, a throttle valve by which that return flow is governed. As the distance from the throat 44 increases the velocity of the mixture is diminished and its resistance to the flow of gas free liquid accordingly decreases. Usually the force of the mixture is overcome and the mixture stream is bent back toward the runner before the junction 47 of the return passage and separator is reached;

however when the quantity of liquid in the channel is high, sufficient mixture will be thrown into the return passage to enablethe stream of it to rise to the separator. The rising mixture and down traveling solid liquid from the cylindrical wall. section 26 again oppose each other at the junction of throat 23 and the separator forming in e'flect a valve which restricts the flow of solid liquid through the throat 23 and causes a portion of that liquid to continue in its travel in an arcuate path to the Wall section of the divider between the inlet and outlet passa es of the separator. This cross flow of so id liquid across the opening 47 in effect screens that opening thereby preventing the down flow of mixture from the separator into the passage.

4 The mixture thrown upward in the passage 23 by the runner 4 is entrained in this cross flow of liquid across the-port 47 and squeezed between that liquid and the wall 30, which squeezing action facilitates the separation of gas from the mixture, which gas is permitted to rise in the separator and escape from the outlet port 37. If the velocity of the liquid across the wall section 30 is sufficient to carry that liquid completely across that wall, the

liquid is caught in with the onrushing mixture through the inlet 22 of the separator and is whirled thereby, which whirling obviously materially assists in the liberation of gas from the mixture.

If a plurality of bafiles 19 are inserted in the return passageway, the quantity of mixture carried by the passages between them decreases with number of passages intervening to the wall 18. Normally not all of the passages so formed'will be filled with mixture and the unfilled ones are available to carry gas free liquid to the runner. If the quantity of excess mixture increases the number of passages filled by it increases and the number of passages left for the returning liquid decreases, so that the quantity of liquid returned to the runner is of course decreased. This throat action assists the hydraulic valve formed in the return passageway 23 in controlling the quantity of liquid returned to the runner.

Despite the fact that mixture is flowing upward through the passage 23, a stream of solid liquid will continuously flow downward through that passage along the walls 27 and v 17, entering the runner channel through the radial passageway 46. The force of the mixture thrown-into the auxiliary discharge port 44 is taken up by the baflle 19 and made to flow along the walls 18 and 29 of the passageway so that it causes a minimum of interference with it reaches the discharge passageway 23 ofthe separator, where it forms the hydraulic valve hereinbefore mentioned. By this arrangement, a substantially constant return flow of gas free li uid from the separator to the channel is achieved and therefore a correct supply of liquid is at all times maintained in the runner channel so that the runner will al.-

ways be supplied with suflicient liquid to enable it to entrain the maximum amount of the down flow of solid liquid until gas. The pump is therefore enabled to continuously increase the vacuum in its runner channel to thereby prime the pump. At no time is the quantity of returning liquid completely shut off and there is therefore no tendency for the pump to surge during its priming period.

As the vacuum on the suction face of the runner 4 increases the pressure in the separator also increases due to the pumping of mixture into it, and there is therefore a substantial pressure difference between the opposite ends of the passageways 23 and 46 so that there will be a tendency for more liquid to fiow into the runner channel. This increase in the amount of liquid in the runner channel causes the'runner to throw more mixture into the port 44, this mixture aiiordinga greater opposing pressure to the returning liquid so that the How of that returning liquid is thereby slightly diminished. This hydraulic valve action, more fully explained in my copend ing application Serial No. 461,313, filed June 16, 1930 (Case 32), accurately regulates the return flow so that'the proper amount 0 liquid is at all times maintained in the runner channel and the proper ratio between volume of entrained gas and liquid is therefore always maintained, and the pump is therefore in condition for eflicient priming.

Ordinarily the velocity of the solid wall of liquid flowing along the straight wall section 27 is so low that there is no tendency for the liquid to plunge into the passageway 23 under great pressure. However in certain instances the velocity of the liquid at the junction of the cylindrical wall 26 and the straight wall section 27 may be too high for eilicient operation of the separator, which high velocity would tend to force too much liquid down into the throat 23 and prevent the free flow of mixture through the throat 47 with the result that the pump would soon become drowned and incapable of drawing further vacuum. To guard against contingencies of this kind in certain adaptations of my invention I contemplate providing the wall 27 with an inwardly depending arcuate boss 50, Figure 8, formed integral with the wall at the unction ofthe cylindrical section 26 and the straight section 27. The liquid traveling downward past this bot-s 50 is deflected upward out of the throat 47 leading into,the passageway 23 and against the wal 3O striking that wall and'being deflected upward thereby.

The end of the wall 30 adjacent the inlet passageway 22 of the separator may be extended upwardly as at 57 to deflect the liquid so thrown "across the port 47 upward in the separator chamber 21 and against the upwardly moving stream of liquid against the wall 24 of. the separator. I In this embodiment of my" invention, the stream of solid flowing crosswise 0f the throat 47 definitely fQO,

screens that throat from downwardly traveling mixture so that it is impossible for mixture .to flow downwardlythrough that throat 47 and the passageway 23 into the runner channel. This crosswise moving stream of solid liquid also serves as a support for .the mixture of gas and liquid above it, that mixture being the inner stratum of the mixture thrown around the cylindrical wall 26, this support holding the mixture in a relatively quiet position so that the gas can efiieiently separate out of the mixture and pass out of the port pump through the discharge port 3 The mixture expelled by the runner and carried through the auxiliary discharge throat 16 to the separator is'carried transversely along the wall 30 by this cross flow and entered thereby into the stream of mixture flowing through throat 22. This mixture' is of course squeezed between the wall 30 and the cross stream of gas free liquid and bent in an upward direction by the tip portion 57 of that wall so that When it enters the upward stream of mixture it expands and the gas in it is thereby permitted to escape.

While I have chosen to illustrate my invention by showing a preferred embodiment of it, I have done so by way of example only as there are many modifications and adaptations which can be made by one skilled in the art without departing from the teachings of the invention.

Having thus complied with the statutes and shown and described a preferred embod- 2. In a centrifugal pump of the self priming type, a runner chamber, a rotatable runner disposed in said chamber, a discharge throat leading from said chamber through which said runner throws a mixture of gas and liquid during its priming period, a separator in which the gas in said mixture is liberated from the liquid, a return passage through which said liquid is returned to said runner and through which excess mixture thrown from the runner is carried to the separator independently of said throat, and means in said passage for dividing the same into a passageway leading tangentiallylout.

of said chamber and a passageway leading aeiaevs radially into said chamber to prevent said mixture from mixing with said returning liquid. i

3. In a centrifugal pump of the self priming type, a runner chamber, a rotatable run,- ner disposed in said chamber, a discharge throat leading from said chamber through which said runner throws a mixture of gas and liquid during its priming period, a separator in which the gas in said mixture is liberated from the liquid, a return passage through which said liquid is returned to said runner during the priming period of the pump and through which excess mixture thrown from the runner is carried to the separator, and means in said excess passage for preventing said mixture from completely obstructing the flow of said returning liquid.

4. In a centrifugal pump of the self priming type, a runner chamber, a rotatable runner "disposed in said chamber, a discharge throat leading from said chamber through which said runner throws a mixture of gas and liquid during its priming period, a separator in which the gas in said mixture is liberated from the liquid, a return passage through which said liquid is returned to said runner and through which excess mixture thrown from the runner is carried to the separator, and means in said excess passage for preventing said mixture from forming an eddy at the junction of said passage and chamber and completely obstructing the flow of said returning liquid.

5. In a centrifugal pump of the self priming type, a runner chamber, a rotatable runner disposed in said chamber, a discharge throat leading from said chamber through which said runner throws a mixture of gas and liquid during its priming period, a separator in which the gas in said mixture is liberated from the liquid, a return passage through which said liquid is returned to said runner and through which excess mixture thrown from the runner is carried to the sepa rator, and bafile means in said return passage cooperating with the walls thereof for intercepting and directing the mixture thrown into the passage to cause it to throttle and regulate the flow of said returning liquid.

6. In a centrifugal pump of the self priming type, a runner chamber, a rotatable runner disposed in said chamber, a discharge throat leading from said-chamber through which said runner throws a mixture of gas and liquid during its priming period, a separator in which the gas in said mixture is liberated from the liquid, walls defining a return passage through which said liquid is re; turned to said runner and through whichexeess mixture thrown from the runner is carried to the separator, and means in said pas sage cooperating with the walls thereof for maintaining the flow of mixture in a path substantially tangentially to and the flow of liquid substantially radially of said runner adjacent to it to prevent surging of the pump during its priming stage.

'7; In a centrifugal pump of theself priming type, a runner chamber, a rotatable runner disposed in said chamber, a discharge throat leading from said chamber through, which said runner throws a mixture of gas and liquid during its priming period, a separator in which the gas in said mixture is liberated from the liquid, a return passage through which said liquid is returned to said runner and through which excess mixture thrown from the runner is carried to the separator, and baffle means located in said return passage and cooperating with the walls thereof for intercepting and directing the mixture the pump during its priming period an arcuate path a thrown into it by said impeller to regulate 8. In a self priming centrifugal pump, the combination of a pump casing, a runner mounted therein and adapted to be rotated about a horizontal axis, a throat leading upward tangentially of said casing, said throat carrying the mixture of gas and liquid discharged by said runner during the priming period of the pump, a separator communicating with said throat, said separator having means for bendin the stream of mixture in %out an axis parallel to the axis of the runner to stratify it and bring a stratum of solid liquid bove a stratum of mixture, lateral ports through which the gas in said mixture stratum is permitted to escape, a return passage leading from said separator into said casing radially of said runner, and means in said separator for deflecting said stratum of solid liquid across said return passageway to screen it from said mixhire.

9.- In a self priming centrifugal pump, the combination of a pump casing, a runner mounted therein and adapted to be rotated about a horizontal axis, a throat leading upward tangentially of said casing, said throat carrying the mixture of gas and liquid discharged by said runner duringthe priming period of the pump, a separator communicating with said throat, said separator having means for bending the stream of mixture in an arcuate path about an axis parallel to the axis of the runner to stratify it andbring a stratum of solid liquid above a stratum of mixture, a lateral port through which the gas in said mixture stratum is permitted to esa return passage leading from said sepcape,

arator into sald casing radially of said run aner, and meansin said separator for deflect- "charged by said runner 10. In a self priming centrifugal pump,

the combination of a pump casing, a runner mounted therein and adapted to be rotated about a horizontal axis, a throat leading upward tangentially of said casing, said throat carrying the mixture of gasand liquid disduring the priming period of the'pump, a separator communicating with said throat, said separator having means for bending the stream of mixture in an arcuate path about an axis parallel to the axis of the runner to stratify it and bring a stratum of solid liquid above a stratum of mixture, lateral ports throughwhich the gas in said mixture stratum is permitted to escape, and a return passage leading tangentially from said separator into said casing radially of said runner and a branch of said return passageway leading tangentially out of said casing to convey excess mixture expelled by the runner into said separator.

11. In a self priming centrifugal pump, a casing, a runner disposed in said casing and rotatable about a horizontal axis, a discharge throat in said casing leading upward tangentially of said runner, a separator conond fiat wall aligned with the opposite end of said cylindrical wall and disposed at an angle wlth respect to said first flat wall, a return throat in said casing having a wall alignedv with said second flat wall and disposed radially of said runner, and side walls on said separator joined with said flat and cylindrical walls and having discharge ports adjacent said cylindrical walls.

12. In a self priming centrifugal pump, a casing, a runner disposed'in said casin and rotatable about a horizontal axis, a disc arge throat in said casing leading upward tangentially of said runner, a separator connected to said throat, said separator consisting of a flat wall aligned with said throat, a cylmdrical wall disposed with its axis parallel to the axis of said runner and having one of its ends aligned with said flat wall, a second flat wall aligned with the opposite end of said cylindrical wall and disposed at an angle with respect to said firstvfiat wall, a return throat in said casing having a wall aligned with said second flat wall and disposed radially of said runner, side walls on sa d separator joined with said fiat and cylindr1cal. walls and having discharge ports adjacent said cylindrical walls, and a triangu-.

lar wall section disposed between said side walls and separating said discharge and re turn throats. j x

1 3. In a self priming centrifugal pump, a casing, a runner disposed in said casing and rotatable about a horizontal axis, a discharge throat in said casing leading upward tangentially of said runner, a separator connectcylindrical wall and disposed at an angle with respect to said first fiat wall, a return throat in said casing having a wall aligned with said second fiat wall and disposed radially of said runner, side walls on said separator joined with said flat and cylindrical walls and having discharge ports adjacent said cylindrical walls, and a discharge duct located above said cylindrical wall and communicating with said discharge ports.

14. In a self priming centrifugal pump, a casing, a runner disposed in said casing and rotatable about a horizontal axis, a discharge throat in said casing leading upward tangentially of said runner, a separator connected to said throat, said separator consisting of a fiat wall aligned with said throat, a cylindrical wall disposed with its axis parallel to the axis of said runner and having one of its ends aligned with said flat wall, a second flat wall aligned with the opposite end of said cylindrical wall and disposed at an angle with respect to said first flat Wall, a return throat in said casing having a wall aligned with said second flat wall and disposed radially of said runner, side walls onsaid separator joined with said flat and cylindrical walls and having discharge ports adjacent said cylindrical walls, and hollow semi-cylindrical bosses raised out of said side and cylindrical walls to form a discharge duct located above said separator and communicating with said discharge ports.

15. In a self priming centrifugal pump, a casing, a runner disposed in said casing and rotatable about a horizontal axis, a discharge throat in said casing leading upward tangentially of said runner, a separator connected to said throat, said separator consisting of a flat Wall aligned with said throat, a cylindrical wall disposed with its axis'parallel to the axis of said runner and having one of its ends aligned with said flat wall, a second fiat wall aligned with the opposite end of said cylindrical wall and disposed at an angle withrespect to said first flat wall, a return throat in said casing having a wall aligned with said second fiatwall and disposed radially of said runner, side walls on said separator joined with said flat and cylindrical walls and having discharge ports adjacent said cylindrical walls, a triangular remove wall section disposed between said side walls and separating said discharge and return throats, and an arcuate boss projecting inwardly from the junction of said cylindrical and second flat walls to deflect liquids hugging said wall across the opening of said return throat and against said triangular wall section.

16. A pump casing containing a cylindrical runner channel and having a projection forming a discharge throat of small cross sectional area at the junction of the channel and throat, the .walls on three sides of said throat flaring to increase the cross sectional area of said throat, the wall on the fourth side of the throat being tangential to said channel, a return throat formed in said projection by one flaring wall of said discharge throat and the walls of said projection, said flaring wall being tangential to the channel on the side forming said return throat and said projection-walls being radial of said channel, and a battle wall in said return throat dividing it into two passageways which lead into the channel.

17. In a self priming pump, the combination of a pump casing containing a runner chamber, a discharge leading tangentially out of said chamber, a cylindrical separator attached to said casing and disposed with its axis horizontal and above the axis of said chamber, an entrance passage for said separator, said passage connecting with said discharge throat and leading substantially tangentially into said separator, a port leading out of said separator, a return passageway leading from said separator into said chamber, and means in said'return passageway cooperating with the walls thereof for.

regulating the flow of liquid through it during the priming period of said pump.

18. In a self priming pump, the combination of a pump casing containing a runner chamber, a discharge leading tangentially out of said chamber, a cylindrical separator attached to said casing and disposed with its axis above the axis of said chamber, an entrance passage for said separator, said passage connecting with said discharge and leading substantially tangentially into said a separator, a port leading out of said separator, a return passageway leading from said separator into said chamber, and baflie means in said return passageway cooperating with the walls thereof for regulating the flow of 3 liquid through it during the priming period of the pump.

In witness whereof, I hereunto subscribe my naine this 21st day of July, 1930.

HARRY E. LA BOUR.

CERTIFICATE or connncrron.

Patent No.. 1,915,678. v M 1m 27, 1933.

HARRY E. LA BOUR.

it is hereby certified that error appears in the printed specification of the *above numbered patent requiring correction as follows: Page 6, lines 81 and 95, claims 3 and 4, strike out the word "excess" and insert the some otter "sairl'I in lines 82 and 96, respectively; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed. this 15th, dayof August, A. D. 1933.

M. J. Moore. (Seal) Acting Commissioner of Patents;