US2005466A - Self priming pump - Google Patents

Description

June 18, 1935. H. E: ,LA BOUR I SELF PRIMING PUMP Filed sea. a, 1931 :s Sheets-Sheet 1 i I J22 092205 Jamel 8,1935. H. E. M Bonn 2,005,466 SELEPRIMING PUMP Filed Sept. s,- 1931 3 snets-sne t 2 Jung 18, 1935. H 5 LA S U 2,005,466

SELF PBIMING PUMP Filed Sept. 8, 1931 3 s eets-sheet 5 Patented June 18, 1935 SELF PRIMING PUMP Harry E. La Bour, Elkhart, Ind. Application September 8, 1931, Serial No. 561,516

15 Claims.

This invention relates to pumps, more specifically to self-priming pumps of the centrifugal type. v

There is shown in my Patent No. 1,578,236 a centrifugal pump having a pump chamber in which a multi-vane runner is revolved to draw liquid into the pump casing and to discharge that liquid through a substantially tangential opening leading out of the runner chamber. An entrance or inlet trap is provided to trap a quantity of liquid when the pump is shut down, which liquid is available when the pump isagain started for entraining and removing the gas in the pump casing, to cause the pump to draw a partial vacuum and thereby prime itself. Pumps of this type are provided with separators into which the mixture thus formed in the runner chamber is discharged, the separator permitting or causing the gas to escape from the mixture and providing for the return of liquid substantially free of gas to the runner chamber during the priming period.

My present invention which comprises certain improvements in pumps of this kind aims among other objects to reduce the entrance losses in the intake and also those occasioned in the separator, and thereby to increase the efficiency of the pump particularly when it is pumping liquid. My invention further provides a new and improved separator and a novel method of separation which provides the capability of satisfactory operation over a wider range of conditions in relatively restricted space than devices of the prior art.

I have discovered that considerable hydraulic loss can be traced to the action of the liquid-in passing from the intake trap into the pump runner. The liquid must pass from a state of rest or minimum rate of motion in the intake trap to a relatively high velocity when it is engaged by the runner. This motion is not only longitudinal of the intake but also angularly due to the rotation of the runner. I have found that by providing a gradual acceleration of the liquid axially and angularly the liquid may be brought to the runner speed with little loss due to shock and eddies.

In my present invention I have provided a relatively long tubular inlet which flares outwardly into the eye of the runner and through which the liquidis drawn by the runner. The liquid flowing through this inlet is whirled prior to its entrance into the runner channel and as a consequence follows a helical path and has an appreciable velocity prior to its entrance into that channel. As a result the liquid enters the channel without appreciable shock and the entrance losses of the pump are therefore decreased. v

(Cl. l03-113) I may shape the inlet neck like a Venturi tube with a relatively restricted portion defining a high velocity region when the liquid passes into the impeller and a suitable flare or taper extending to the inlet end. a

Entrance losses are further avoided by providing a new and improved strainer which holds out any solid matters of a character which could not freely pass through the runner.

In pumps operated to handle liquid contain- 10 ing suspended-abrasives the pump casings and impeller wear out and must be replaced. In the prior art pumps in which the impeller chamber is formed partly by a wall of the inlet trap, wear of the casing involves the provision of a 1 new inlet trap, although the trap itself is not worn out. This increases the cost of repair of the pump. According to my present invention I provide a mechanical construction which permits replacement of the worn parts of a pump 30 at a minimum expense.

One of the most importantfeatures-of the present pump. is an improvement in the method of and means for disentraining gas from the liquid during the priming stage of operation.

In the self-priming pump of my invention the medium by which evacuation of the pump and suction line is secured must be retained for each priming operation. It must then be caused to pass through a closed circuit in one part of 30 which by kinetic action gas is entrained in the liquid medium. Then the medium charged with gas is driven through a throat or its, equivalent. This throat separates the entrainment and pressure-building action from the next stage, which is disentrainment. According to the present invention disentrainment is secured by either one or both of two distinct actions which occur in succession: One action is a kinetic separation and the other is a static separation. The kinetic 40 separation is preferably a centrifugal separa-- tion which separates gas from liquid by the difierence ininertia between a particle-of gas and a particle of liquid. Such centrifugal 'separation may be performed in a. whirl or partial whirl or vortei: lying in any plane or warped from any plane. In the present preferred form the whirl is vertical but it might equally well be horizontal. The static separation which is combined with the kinetic separation brings the 5 liquid from a condition of velocity to a condition of relatively slow motion or substantial quies cence. The peculiar virtue of this combination of actions resides in the virtual interchangeability of action and the fact that the static separation brings the liquid substantially to rest and any gas which has been held entrained by the velocity of the liquid may escape by gravity or static separation before the liquid medium is returned to the inside of the pump casing for re-entrainment of gas. It is difficult to disentrain gas from liquid moving at high velocity, and particularly so when the stream of mixture has considerable radial or cross-sectional depth.

According to my invention the mixture is driven out of the throat of the pump at a high velocity and kinetic separation immediately takes place. The velocity is gradually diminished, thus permitting space or gravity separation to occur. The liquid is then returned through a controlling throat to the pump substantially free of. gas. Thus a compact and highly effective separation or disentrainment of gas from the liquid is secured. The physical arrangement of the preferred form herein disclosed is highly advantageous in saving head room and floor space by simple effective means.

After priming is accomplished the return throat becomes a secondary discharge throat.

Further objects of my invention will be apparent from the detailed description and claims which follow, reference being had to the accompanying drawings in which:

Figure l is an elevational view partly in section showing the details of my improved pump;

Figure 2 is a cross sectional view through the runner channel taken along the line 2-2 of Figure 1 looking in the direction of the arrows;

Figure 3 is a cross sectional view of the pump taken along the line 3-3 of Figure 1 looking in the direction of the arrows;

Figure 4 is a plan view of the drip pan of the pump;

Figure 5 is a fragmentary cross sectional view of the inlet trap taken along the line 5-5 of Figure 1 looking in the direction 'of the arrows and showing details of the improved strainer;

Figure 6 is an end elevational view of the strainer and inlet or the pump;

Figure 7 is a schematic longitudinal section of a modified form of pump embodying the present invention;

Figure 8 is a diagram of the action of my pump during the priming stage.

Referring now to the drawings in detail, the pump comprises a suitable base I upon which is mounted the bracket 2 which contains a bearing 3 and a split collar 4 for embracing the hub of the pump casing 5. The casing 5 contains a central hub 6 which is gripped in the split clamp collar 4 to hold the casing upon the mounting bracket. A suitable shaft packing I- is confined within this hub, as will hereinafter appear. The particular details of these parts of the pump are shown more ,completely' in my Patent No. 1,922,050, issued August 15, 1933.

The pump casing 5 contains a cylindrical channel or raceway 8 in which is located the pump runner 9, this runner fitting within the chamber preferably as closely as a free running fit will permit. The channel 8 is defined in part by a, suction or inlet member which consists of a front plate I fitting in the open side of the channel 8 to form a wall thereof, and a substantially cylindrical suction inlet tube I I concentrically located in that plate. The junction of these two parts of the suction inlet is flared as at l2 for the purpose of allowing the liquid to pass smoothly into the impeller. Shock and. eddy current losses are thereby reduced. A modified form of intake passageway and impeller is shown in Figure '7, to which reference will be made later. The outer periphery of the plate I0 is conical in shape to fit the conical seating face I3 of the pump casing 5, and is flanged as at I4 to accurately locate the plate in the casing member and to reenforce the outer rim of the plate portion II}.

The suction inlet thus formed is held upon the pump casing by the trap indicated generally at I5 and comprising ageneraliy cylindrical portion disposed with its axis vertical and a second cylindrical portion I6 disposed with its axis horizontal, this latter portion being flanged as at H and registered with a corresponding flange on the pump casing over the peripheral edge of the front plate Ill, where it is held in place in any preferred manner such as by bolts I8 projected through its flange and through a corresponding flange I9 upon the pump casing 5. By this arrangement the suction inlet is securely attached to the pump casing, and the joint between the hub and the casing is made liquid tight by means of a gasket The flange I? and intervening gasket make a tight joint between the inside and outside of the trap and also seal off the channel 8 from both the trap and atmosphere. By thus disposing the flange ll over both the flange I9 of the pump frame 5 and the flange IQ of the plate 58, the intervening gasket performs the dual purpose of sealing the inlet to the frame, to avoid leaks on the suction side of the pump, and sealing the channel 8, which is on the pressure side of the pump, from leakage on the discharge side.

It is further to be noted that the thickness of the interposed gasket has no effect upon the position of the plate It. Hence, no matter howthick or thin the said gasket, or no matter how tightly the clamping bolts are drawn up, the position of the plate Ill, and hence the width of the runner channel, is not varied. This constitutes an improvement of practical importance.

The trap 85 comprises an inlet opening 2 I which is flanged and against which the flanged coupling plate 22 of the inlet pipe 23 is registered and secured to form a suction line for the pump.

Located within the vertical cylinder of the inlet trap is a frusto-conical strainer 24 through which the liquid must pass before reaching the runner chamber of the pump.

This frusto-conical strainer, best seen in Figures 5 and 6, contains an outwardly projecting flange 25 which is cut away at 26 to permit the strainer to be positioned in the inlet trap over the lugs 2i. This is accomplished by inserting the strainer in the trap through the large opening bordered by the flanged portion I I, and bringing the notches 26 into registration with the supporting bosses 21 which are located on the interior surface of the vertical cylinder of the trap. The strainer is then elevated to the position in which it is shown in Figure 1, and rotated through a suitable angle, in this case approximately 45, to bring the notches 26 in the flange out of register with the lugs or bosses 21. The strainer is thus supported in the vertical portion of the inor when a back flow of liquid occurs as on stopping of the pump. The slotted connection 29 prevents. accidental rotation and dislodgment of the strainer 24.

The inlet trap I is provided with a hand opening 3| normally closed by a suitable cover that is held in place by an inverted U-clamp 32, the cover being removable to give access to the top side of the screen or strainer 24 to permit of access to the interior of the trap, the suction line 23 and the strainer 24 and the removal of solid matter accumulated thereon. Hook-shaped lugs 32' project from each side of the trap I5 and they are engaged by the hooked ends of the clamp 32 which is held thereagainst by the compression screw bearing centrally against the cover. clamp and cover are removed by loosening this screw to drop the ends of the clamp below the hooked ends of the lugs 32 and rotating the clamp to disengage it from the lugs 32. The hook-shaped lugsmay both face in the same direction, in which event the clamp 32 need only be dropped to clear the hooked end and then shifted sidewise to clear the hooked lugs-32'. The trap I5 is also provided with a suitable foot 33 which rests upon a boss 34 of the base I, where it is held by any preferred means such as the cap screw 35 to securely mount the trap upon the base. The inlet trap is also provided with a cleanout duct 36 projecting downward from its bottom wall and normally closed by a cover plate 31! which is held in place by bolts 38.

The pump casing 5' is provided with a main discharge passage 40 which starts as a relatively small substantially tangential throat 4| at the peripheral wall of the raceway 8, the cross sectional area of which increases as the distance from the chamber increases. v

Preferably the outer wall 42 of this discharge throat is disposed tangential to or substantially tangential to the runner chamber 8.

The discharge throat 40 opens into a separator indicated generally at 44, in which the mixture expelled from the runner is separated into gas and gas free liquid, which liquid is returned through a return passageway 45 to the runner chamber during the priming period of the pump. This passageway 45 is optionally divided into an anterior passage 46 and a posterior passage 41 by a battle means 48, which means 48 may consist of a single bafile as shown in Figure 2 or a plurality of baffles, aswill presently appear. The baffle 48 is not essential and in some cases I omit the same.

Preferably the casing 5 and walls of the discharge throat 40 and return passageway 45 are cast as a single unit, as shown, this unit terminating in a flat flanged portion 49 to which a cooperating flange of the separator 44 isattached, the separator having suitable passageways forming continuations of the dischargeand return passageways of the pump casing.

The separator consists of a generally cylindrical body preferably located with its axis substantially horizontal, in this case parallel to the axis of the runner 9 of the pump, and with the major portion of the body of the separator located over the pump and its bearing 3, this arrangement being economical-of both floor space and head room. As will be seen in Figure 2, the inlet passage 58 of the separator registers with theportion. of the discharge passageway 49 of the pump casing and is shaped so that the increase in cross sectional area noted in the discharge passageway 49 is continued throughout the en- The trance of the separator. The inside surface of wall 5| of the inlet passageway is preferably disposed substantially tangential to the interior surface of the cylindrical wall of the separator so that mixture leaving the runner chamber substantially tangentially will enter the separator separator itself.-

The first chamber 55, which may be designated as the kinetic separating chamber, communicates with the inlet passage 59 of the separator at its one end and with the posterior or static separating chamber 56 at its other end. This latter chamber communicates through an opening 58 with the third sub-chamber 51, which is in reality a passageway, and also with the discharge opening 59 through which gas and liquid are expelled from the separator. The walls of the separator adjacent this discharge opening 59 are flanged as at 60 to provide for the attachment of a discharge pipe, not shown, to the separator structure.

The walls 44 of the separator are provided with I lugs 6| located directly beneath the discharge passageway 59 and adapted to receive bolts 62 by which a U-shaped supporting bracket '63 is attached to the separator. The bottom of the U- shaped bracket rests upon the bearing housing 3 of the mounting bracket 2 and is secured thereto by a cap screw 64. The bracket 63 thereby serves to support the free end of the separator through the bearing bracket 2 upon the base I.

The base I is adapted to mount a motor, not shown, which has its shaft directly coupled to the shaft I9 as by a suitable flexible coupling, or the like, so that when the motor is operated the shaft and impeller 9 are rotated in the clockwise direction as shown by the arrow in Figure 2.

The packing member I which surroundsthe shaft of the impeller 9 seals the impeller casing at this point, the gasket between the flanges I! and I9 seals the trap to the impeller casing, and a gasket BI between the separator and pump casing seals the casing at that point so that infiltration of air and/or loss of liquid are both avoided. The packing I and gland construction may be of the type shown in my Patent No. 1,922,050, issued August 15, 1933, or any other suitable type desired. This packing gland forms .gland and .the shaft of the pump. The drip pan is flanged as at 85 and hangs between the clamp 4 and bearing 3 of the mounting bracket 2, beneath the shaft of the pump. A spout 86 leading out of the bottom of the drip pan projects through an opening in the side wall of the bracket 2 so that whatever liquid does escape and is collected-by the pan drops down onto the inclined top surface of the base I of the pump. It is to be noted that the central part of this base I within the flanges about its edges slopes as shown at' 85, Figure. 1, to a low end from which a drain pipe 88 leads, so that any escaping liquid may be carried from the pump.

The operation of the pump is as follows:

When the pump is shut down, a certain amount ofliquid is trapped in the inlet trap and the pump casing, this liquid constituting the medium or means'by which air is entrained and transferred from the intake side to the discharge side of the pump by rotation of the impeller during the air handling or priming stage. The trap is of such size as to contain a quantity of liquid great enough to supply the necessary priming medium, and it is great enough in cross section between the suction pipe 23 and the openof the inlet tube ii to reduce the velocity of flow to a low value. This reduction of velocity, and the right-angle relation of the suction tube H with the body of the trap, hinder the production or formation of a whirl in either the trap or the suction pipe As the impeller or runner S is rotated. liquid in the runner chamber is intermingled with gas contained therein, and that gas is entrained in the liquid to form a mixture which is expelled from the runner chamber through the discharge throat M. The mixture thus discharged is directed to the separator, where the gas is caused to be separated from the liquid, and the liquid which should contain a minimum of gas is returned to the runner chamber through the return passage 85. The liquid trapped in the inlet trap and pump casing is continuously recirculated, carrying out air until the pump has drawn sufficient vacuum to draw fresh liquid in through the inlet pipe 23. As explained in my Patent No. 1,972,304 issued Sept. 4, 1934, and Patent No. 1,915,678. issued June 27, 1933, there is a certain optimum ratio between air or gas and liquid in the stream discharged by the impeller during the priming period, for realizing the maximum ability to entrain and remove air or gas. This depends upon a number of factors. Thesize of the discharge throat M is made such that when liquid and gas are in the proper ratio, the mixture thrown from the impeller will be sufficient to fill the throat 4| of the discharge passageway 40 for minimum pressure difference. As suction is built up by the pump, pressure difference bethe two ends of the return passageway increases and there is a tendency for theliquid to be returned to the runner chamber through return passageway 51 more rapidly, with the result that too much liquid may be present therein and maximum entraining of air cannot be achieved. In otherwords, as the pressure difference increases there is a tendency to drown the air entrainment. This tendency is in the present pump compensated for or reduced by the divided return throat or secondary discharge throat construction, As the proportion of liquid in the runner chamber increases more mixture willbe formed and the discharge throat 4| will not be able to carry all of it, with the result that part of this mixture will be carried past the throat 4| and discharged from the runner chamber through the anterior passageway 46 of the return passageway. Obviously the presence of mixture at the end of the anterior passageway 46 restricts or decreases the return flow of gas freed liquid to the runner chamber either by opposing return flow or by compelling the liquid that returns to pass through the posterior channel 41. This tends to check or limit the return flow of liquid. However, if this checking is,not sufficient and more liquid enters the pump than is necessary and the amount of mixture thrown into the anterior passageway 46 is increased, then the upwardly flowing stream of mixture in that passageway will interfere with return flow and act as a throttle valve toregulate the return flow of gas-freed liquid' 'through the posterior passageway fill. This operation is more fully brought out in my above mentioned copendirig applications.

Obviously, for the satisfactory operation of pumps of this kind, eflicient separation of the gas and liquid composing the mixture discharged by the runner during the priming period is essential. In the present invention, the separator secures an efficient separation of gas and liquid in a novel manner, this separator functioning in two stages or two distinct steps of separation. The first of these, a kinetic or dynamic separation, is produced in the chamber 55, into which the liquid discharged through the discharge passageway 46 of the pump enters tangentially of the walls of that chamber because of the shape of the inlet passage 50. This liquid rises to the top of the separator and follows the interior peripheral cylindrical wall of that separator, with the result that a whirling helical motion is imparted to the mixture, that motion being about an axis parallel to or substantially coinciding with the axis of the separator and serving to secure separation by a centrifugal action. Obviously as the mixture is whirled or subjected to centrifugal action the heavier liquid will tend to hug the outside of the path and the lighter mixture will be forced to the inside of the path and the still lighter gas will escape from the mixture through the vortex or the concave free surface of the stream of fluid. Baffle 53 forming the end wall of the chamber 55 is provided with a port 53 through which the gas thus separated out of the whirling mixture can escape into the upper 4 part of the chamber 56, from which it escapes through the discharge port 56.

After the stream of mixture has made one or more turns on the inside cylindrical wall of the chamber 55, it has lost much of its velocity and hence its kinetic separating ability. Thereupon it passes through the space between the baffles 56 and 52 into the chamber 56, where the second or static or gravity stage of separation occurs. The mixture in the chamber 56 is relatively quiescent, and gravity separation can readily occur. There is a relatively large free surface in chamber 56 from which surface gas can easily escape. The height of the bafiie 52 regulates the maximum depth of the liquid in the static separation chamber 56. This baflle is preferably extended to approximately the middle of the cylindrical separator 44 and its upper edge therefore lies on substantially a diameter of that cylinder. The area of the upper surface of the liquid in the chamber 56 isample for efficient static or gravity separation. The volume of that part of the chamber 56 occupied by the liquid is relatively large and the speed at which the liquid is moving is therefore so slow as not to retain the gas therein, which condition aids materially in the gravity separation. The liquid collected in the bottom of the chamber'56 is free to flow through the port or opening 58 into the passageway 51 which communicates with the return passageway 45, through which the liquid returns to the pump chamber. Gas escaping from the mixture in the chamber .56 rises in that chamber and escapes or is forced through the outlet 59.

I have shown, in diagrammatic form in Figure 8, the course of travel of the gas and liquid during the air pumping or priming operation of the pump. The rotor is turned at a suitable speed in the clockwise direction as viewed in Figures 2 and 8, the liquid which is trappedcin the inlet trap and the pump casing being caused to entrain air in the pump casing, and the same is discharged out through the throat II as indicated by the lines and arrowheads, making one or more helical turns at relatively high velocity to give a centrifugal separating effect 'in the chamber 55, the'liquid thereupon being delivered at reduced speed into the chamber 56 which, in effect, forms a pan or open receptacle, from the surface of which air can readily be freed. The bottom of the open-topped receptacle has the port 58 from which liquid substantially free of gas is returned through the throat 45 into the pump casing and there again caused to entrain air which is carried out as above described. It is to be noted particularly that if the volume of mixture discharged is relatively small as at the first part of the priming stage when the pressure difference is the minimum, most of the action of separating gas from the liquid may occur in the chamber 55 due to the centrifugal action. If, howeyer, the volume ofmixture is greater so that the centrifugal action is not able to free the liquid of sufiicient gas to accomplish the purpose, then a greater part of the separation than previously occurs in the chamber 56 due to the relatively large exposed surface and a tendency for the surface to be lowered by the dilference in pressure. The space thus devoted to the two actions may be occupied more by one or more by the other as the case arises.

After the pump has drawn sufiicient vacuum to draw liquid into itthrough the inlet pipe 23, the inlet trap I5 becomes again filled with water. that water passing through the strainer 20 prior to its entrance into the lower part of the trap.

The strainer 20 being shaped as a frustumof a cone and provided with a plurality of slots 80, affords little resistance to the flow of the liquid and entrance losses are thereofore reduced. As the column of liquid in the suction inlet II is in contact with the revolving runner-at one of its ends, that runner will tend to revolve the entire column of liquid contained within this inlet, and I have found that the liquid in the inlet flows through it'in a spiral path, so that the velocity ofthe liquid at the eye of the pump is high and that liquid enters the runner without shock. It will be noted that the suction inlet is flared at 62. so that as the liquid in the spiral path approaches the runner, the radius of that path is increased and the liquid is moving radially and angularly when it enters the runner. The inlet II is relatively long and smooth. This provides space within which angular acceleration can occur as the liquid travels toward the runner, without too abrupt a change in velocity at any point. The arrangement of the suction inlet therefore further reduces the entrance losses of the pump and insures a uniform supply of liquid to the runner of the pump, with the result that when the pump is pumping liquid, it is operating at an efficiency higher than has been achieved heretofore.

In Figure 7 I have showna modified form of inlet throat for the pump casing, wherein the entrance tub'e I is shapedlike a Venturi tube in order to gain the maximum velocity at the point I02 which is substantially the section of minimum area just in advance of the liquid entering the vanes of the impeller I03 which is constructed differently from that shown in Figures 1 and 2. In this case the impeller carries, on the ring I04, not only the series of short blades I05, but also a series of blades I05 extending radially from the ring I04 to the throat I02 so that these ex tended blades I06 which correspond somewhat to the spider arms 9 (shown in Figure 2) pick up i r the liquid at substantially its innermost position, that is, the position where it is substantially nearest the axis, and tend to give it angular motion very early in.its travel from the inlet tube I00 into the channel 8 in which the runner travels. Thus, the liquid which tends to whirl as it is carried through the inlet tube I00, starts out at a relatively low velocity and acquires velocity both angular, radial and axially in agradual progression or acceleration to the point of discharge. Otherwise, the pump shown in Figure 7 is substantially the same as that shown in Figures 1 and 2. In this case, however, a slotted boss I01! is formed on top of the tube to receive the T-head 28 of the screen 24 instead of having the T-head extend into the tube itself.

When the pump is pumping the liquid. the runner 9 discharges more liquid than can be passed through the discharge throat 40 and the excess is passed through the anterior passageway 46 and posterior passageway ll, both of which communicate with the return channel 45, and that liquid therefore flows through it and the return passageway 51 of the separator and through the opening 58 into the sub-chamber 56 from which it escapes through the discharge port 59. The walls of the channels through which this stream of liquid is conducted are shaped so that there are no sharp turns and the amount of pressure lost by the liquid is low. The liquid discharged from the runner through the main discharge throat il fills the chamber 55 and joins the liquid through the auxiliary discharge port 45 into the chamber 55 and flows out of the port 59. The separator fills with liquid during the pumping period of g the pump.

When the pump is shut down the liquid in the separator drains back through it through the channels 50 and i5, and, since in the preferred form the separator is located entirely above its discharge opening, that is, entirely above the channel SI and the inlet channel 50, no air or liquid is trapped in the pump, and the separator V and pump are therefore capable of operating efficiently when re-started. The separator need not be located on top of the pump so far as functional requirements go but the particular arrangement shown has important advantages. The separator could be disposed at the side of the pump to save head room but more floor space would be required. The liquid in the separator drains back through the pump inlet trap and out of the inlet pipe 23, beingurged by the siphon action of the descending column of liquid in that pipe. As soon as air is drawn into the pump this suction is broken and the back flow ceases while the inlet trap is substantially filled with liquid, i. e., retains suficient liquid to provide the air evacuating medium.

This reverse flow of liquid through the inlet trap builds up a force on the under side of the strainer 2 which tends, to liftvthat strainer ofi of the bosses 21. However, since the T-shaped projection 28 of the strainer is engaged by the suction inlet cylinder I I, the strainer is prevented from being lifted or turned by this force.

Pumps of this type are frequently used to move corrosive liquids such as acids, and all parts of the pump coming into contact with such liquid obviously must be made of an acid-resistant material. The design herein disclosed permits an emcient use of this material by minimizing the size and weight of the parts which must be composed of it. Parts of the pump not engaged by the liquid are made of cast iron or steel, as required, to reduce the cost of the pump as much as possible.

Pumps of this type are also used extensively to pump liquids containing abrasives such as sand, and naturally the runner and the pump casing will be worn by this material. In the pump disclosed herein, it is only necessary to replace the pump casing 5, the runner 9, and the suction inlet member consisting of the front plate it and the inlet cylinder M, these being the parts that will most rapidly wear. The trap i5, while it is worn somewhat by the passage of this liquid through it, is not worn as rapidly as the runner and pump casing because the liquid is moving at a much lower velocity, and since the suction in let is not an integral part of the trap, the latter may be replaced without replacing the former. Obviously this reduces the cost of repairing the pump structure.

Since the separator M is disposed above the pump casing and the bearing 3, no additional floor space is needed for mounting it upon the pump. In many instances this is a decided advantage. Since the separator is disposed with its longitudinal axis horizontal, the amount of head room that'it requires is minimized, and the pump can therefore be installed in many locations that have been too small for the prior art pumps of which I am aware.

While I have chosen to show my invention by illustrating a preferred embodiment of it, I have done so by way of example only, as there are many modifications and adaptations which canbe 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 embodiment of 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 self-priming centrifugal pump the combination of a pump casing containing a runner chamber, a runner disposed in said casing, a horizontal shaft for said runner, a tubular suction inlet opening concentrically into said chambema discharge throat leading substantially tangentially out of said chamber, a cylindrical separator and discharge chamber disposed with its longitudinal axis extending horizontally above the axis of said runner, transverse longitudinally spaced baiiie means in said separator dividing it into a plurality of communicating sub-chambers, said discharge throat lying substantiallyin a vertical plane and leading substantially tangentially into the first one of said sub-chambers, and a return passage leading from another one of said sub-chambers into said runner chamber. said return passage serving as a liquid discharge throat during the operation of liquid pumping, and a discharge outlet from the top of said separator communicating with said last named sub-chamber for discharging gas during the prim ing operation of the pump and for discharging liquid during the liquid pumping operation.

2. In a self-priming centrifugal pump the combination of a pump casing containing a runner chamber, a runner disposed in said casing, a

tubular suction inlet opening concentrically into said chamber, a discharge throat leading substantially tangentially out of said chamber, a horizontally extending separator and discharge cham-.

ber connected to said discharge throat and located above the axis of said runner, vertically-disposed longitudinally spaced baflle means in said separator dividing it into a plurality of communicating sub-chambers, said discharge throat leading substantially tangentially into a first one of said chambers, said first chamber opening into the top portion of a second chamber, said second chamber being connected at its bottom portion to the top portion of a third chamber, and a return passage leading from the bottom of said third separator chamber to said runner chamber, said return passage serving as a liquid discharge throat during the operation of liquid pumping, and a discharge outlet from the top of the third chamber for discharging gas during the priming operation and for'discharging liquid during the liquid pumping operation.

3. In a self-priming centrifugal pump the combination of a pump casing containing a runner chamber, a runner disposed in said casing, a tubular suction inlet opening concentrically into said chamber, a discharge throat leading substantially tangentially out of said chamber, a horizontally extending separator and discharge chamber communicating with said chamber through said discharge'throat, longitudinally spaced means in said separator dividing it into a kinetic separation chamber and a communicating gravity separation chamber disposed side by side, and a repriming operation and for discharging liquid during the liquid pumping operation.

4. In a centrifugal pump, a casing having a shallow cylindrical opening in one of its faces, said casing having a discharge throat, a suction inlet plate fitted in said opening and with said casing defining an annular runner channel, an inlet trap registered with said casing, means for holding said trap on said casing, said means also holding said inlet in place on the casing and within said trap by engagement with the margin of said plate, and a strainer in said trap, said inlet engaging said strainer to assist in holding it in place in the trap.

5. In a centrifugal pump, a casing having a shallow cylindrical opening in one of its faces, a suction inlet plate fitted in said opening and with said casing defining an annular runner channel, an inlet trap registered with said casing, means for holding said trap on said casing, said means also holding said inlet in place on the casing and within said trap, bosses projecting into said trap, a frusto conical strainer supported on said bosses, 2. lug projecting from the bottom of said strainer, said inlet engaging said lug to hold said strainer down on said bosses and against rotation thereon.

6. In a centrifugal pump, a casing containing a runner chamber, a runner concentrically located in said chamber and rotatable within it, an inlet trap connected to said casing, a suction inlet disposed within said trap, said inlet being generally cylindrical and flaring outwardly at the eye of iii) the runner chamber, and a strainer in said trap, said strainer being supported in the trap and keyed against rotation therein by said inlet.

7. A self-priming centrifugal pump comprising a base, a casing mounted on said base, a bearing mounted on the base, a shaft rotatably mounted in said bearing, a runner supported by said shaft and disposed in said casing, a suction inlet registered with said casing and cooperating with it to form a channel, an inlet trap registered with said casing, means for-holding the trap in place on the casing, said means also holding said suction inlet in place on the casing, a strainer in said trap, said suction inlet engaging. said strainer to hold it in place, a cylindrical separator disposed above said casing and with its axis substantially parallel to the axis of said runner, a discharge throat leading substantially tangentially out of said chamber into one end of said separator, means attached to said bearing and the other end of the separator for supporting it, an outlet leading from the top of said other end of said separator, and a return passage leading from the bottom of said other end of said separator to said chamber.

8, A self-priming centrifugal pump comprising a base, a casing mounted on said base, a bearing mounted on the base, a shaft rotatably mounted in said bearing, a runner supported by said shaft and disposed in said casing, a cylindrical suction inlet registered with said. casing and cooperating with it to form a runner, said inlet flaring outward at its junction with the casing, means for holding the trap in place on the casing, said means also holding said suction inlet in place on the casing, a strainer in said trap,saidsuctioninlet engaging said strainer to hold it in place, a cylindrical separator disposed above said casing and with its axis substantially parallel to the axis of said runner, a discharge throat leading substantially tangentially out of said chamber into one end of said separator, means attached to said bearing and. the other end of the separator for supporting it, an outlet leading from the top of said other end of said separator, and a return passage leading from the bottom of said other end of said separator to said chamber.

9. A self-priming centrifugal pump comprising a base, a casing mounted on said base, a bearing mounted on the base, a shaft rotatably mounted in said bearing, a runner supported by said shaft and disposed in said casing, a suction inlet registered with said casing and cooperating with it to form a channel, an inlet trap registered with said casing, means for holding the trap in place on the casing, said means also holding said suction inlet in place on the casing, a frusto conical strainer in said trap, said suction inlet engaging said strainer to hold it in place, a cylindrical separator disposed above said casing and with its axis substantially parallel to the axis of said runner, a discharge throat leading substantially tangentially out of said chamber into one end of said separator, means attached to said bearing and the other end of the separator for supporting it. an outlet leading from the top of said other end of said separator, and a return passage leading from the bottom of said other end of said separator to said chamber.

iii. In a self -priming centrifugal pump, a casing eontaining'a runner chamber, a rotatable runner in said chamber, a discharge port leading substantially tangentially out of said chamber, a substantially cylindrical separator and discharge chamber into which said port openstangentially,

transverse longitudinally spaced baffles dividing said separator into sub-chambers, said runner during the priming operation throwing a mixture through said port and into said separator, said mixture traveling in a helical path tangentially of the wall of the first of said sub-chambers to effect a kinetic separation of the gas from it, there being ,a gas escape port in one of the baflies defining said first chamber, the helical path taken by. said mixture terminating in a second sub-chamber in which static separation of gas from it occurs, and a return passage leading from the bottom of said second sub-chamber to said runner chamber, said return passage serving as a liquid discharge throat during the operation of l quid pumping, and a discharge outlet from the top of the second sub-chamber for discharging gas during the priming operation and for discharging liquid during liquid pumping operation.

11. The method of evacuating a centrifugal pump of air to prime the same, which comprises sealing the pump with liquid, rotating the pump runner, circulating a body of priming liquid through the pump in contact wu'th the runner to entrain air and form a mixture, discharging the mixture at a relatively high velocity, guiding the mixture at said relatively high velocity in a curved path to develop centrifugal force, separating a part of the entrained air by said centrifugal force, reducing the velocity of the mixture, discharging the liquid at reduced velocity into an open toppedcontainer permitting the formation of a free surface of the liquid to promote gravity separation of air, therefrom and returning liquid from the bottom of said container into a portion of the pump casing where the runner develops hydraulic pressure when the pump is operating to pump liquid and again entraining air in the pump.

12. In a self-priming pump, a pump casing having a runner with a horizontal axis, a channel in the casing for said runner, said channel having a discharge throat extending in substantially a vertical plane, a cylindrical separator and discharge chamber having its longitudinal axis extending horizontally and parallel to the runner axis, said separator having a tangential inlet opening at one end connected to the discharge throat and having an upwardly directed outlet at its opposite end, there being a passageway extending longitudinally of the chamber from said lower part of the opposite end back to the interior of the pump casing for forming a priming pas! sageway during priming of the pump and serving as a liquid discharge throat during the operation of liquid pumping, the discharge throat of the pump casing directing the fluid stream discharged therethrough substantially tangentially into the separator, and the walls of the separator directing the fluid-stream in a helical path toward the opposite end of the separator and a discharge outlet from the top of said opposite end of the separator for discharging gas during the priming operation and for discharging liquid during the pumping operation.

13. In a self -priming pump, a pump casing hav-.- ing a runner with'a horizontal axis, a channel in the casing for said runner, said channel having a discharge throat extending in substantially a vertical plane, a cylindrical separator and discharge chamber having its longitudinal axis extending horizontally, said separator having an inlet opening at one end connected to the discharge throat and having an upwardly directed outlet at its opposite end'for discharging gas durg aooaeee liquid during the liquid pumping operation, there being a passageway extending from said lower part of the opposite end back to the interior of the pump casing serving as a return passage during priming and serving as a liquid discharge throat during the liquid pumping operation, the discharge throat of the pump casing directing the fluid stream discharged therethrough substantially tangentially into the separator, and the walls of the separator directing the fluid stream in a helical path toward the opposite end of the separator, there being transverse bafiles in said separator extending from top and bottom respectively toward the central part of the separator for directing said fluid stream, said bafiles being spaced apart longitudinally to permit helical travel of the stream between them.

14. In a self-priming pump, the combination of a substantially cylindrical pump chamber having a horizontal axis, a substantially cylindrical separator and discharge chamber having a horizontal axis. said separator chamber being above the pump chamber and having a single discharge outlet at the end thereof which is remote from the pump chamber, connections between said chambers comprising walls defining a discharge way leading tagentially from a wall of the pump chamber substantially vertically into the separator chamber substantially tangential to the inner wall of the separator chamber, said passageway lying at one side of the axes of both chambers, and an auxiliary passageway constituting a priming passageway during priming of the pump, said last named passageway connecting'the-upper part of the pump chamber with the lower part of the separating chamber, the connections of said passageways with said separator chamber being spaced apart longitudinally of the separator chamber and a bafile wall in the separating chamber between the ends of both of said passageways to compel a helical travel of the priming liquid from the discharge throat to the priming passageway during the priming operation, and permitting parallel flow of liquid discharged.

from said passageways to the outlet during the liquid pumping operation.

15. In a centrifugal pump, the combination of a main frame having a cylindrical bore, one end of which is closed by an integral'end plate, the other end terminating in a flat annular clamping face, an inlet plate seated in the open end of said bore and having at its margin a flat annular face in the same plane as said clamping face, said plate having a central tubular inlet, said cylin-' drical bore between said end plate and said inlet plate comprising a runner chamber having a tangential discharge passageway, a runner in said chamber for moving liquid entering through said inlet and discharging the same through said tangential discharge passageway, an inlet trap comprising a hollowbody loosely enclosing said tubular inlet and having an annular fiat clamping face overlying both the flat annular clamping face of the frame and the flat annular face on the inlet plate, a fiat gasket between the clamping face of the trap on one side and the coplanar clamping faces of the frame and of the inlet plate respectively on the other side, and clamping means between the frame and the inlet trap for clamping said parts together to seal the inlet trap to the frame and the inlet plate to the frame, independently of the thickness of the gaslret.

HARRY E. LA BOUR.

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