US2275502A - Priming system for centrifugal pumps - Google Patents

Description

"Nimh 41o, 1942. F. s. BROADHURST 2,275,502

PRIMING SYSTEM FOR CENTRIFUGAL PUMPS Filed Dec. 6, 1959 5" Sheets-Sheet 1 March 10, 1942. F, s BRQADHURST 2,275,502

PRIMING SYSTEM FOR CENTRIFUGAL PUMPS Filed Deo. 6, 1939 5 Sheets-Sheet 3 WIr/V555.'

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MarchlO, 19.42. F. s. BRoADHURsT PRIMING SYSTEM FOR CENTRIFUGAL PUMPS Y 5 Sheets-Sheet 4 Filed Dec. 6, 1939 Mmh 1o, 1942.

F. s. BRoADHuRsT PRIMING SYSTEM FOR CENTRIF'UGAL PUMPS A Filed Dec. 6, 1939 5 Sheets-Sheet 5 y ra wir.;

Patented Mar. 10, 1942 UNITED .STATES PATENT OFFICE Frank S'. Broadhurst, Watertown, Mass., assgnor to De Laval Steam '.,lurbine Company, Trenton, N. J., a corporation of New Jersey Application December 6, 1939, Serial No. 307,743

(Cl. M13- 113) 9 Claims.

This invention relates to priming systems for centrifugal pumps.

In cases where there is no, supply of liquid available to prime, a centrifugal pump by gravity flow, or where it is undesirable or impossible to prime the pump by the use of an auxiliary water pump, it has been customary to provide the centrifugal pump with an air pump in the same casing to evacuate the main pump andso render it self-priming.- A system of this character is usually unsatisfactory for several reasons, among which may be mentioned the fact that most centrifugal pumps may not be driven for an appreciable time without priming without resulting` damage to their labyrinth packing, the fact that there is absorptionof considerable power by the air pump which is running throughout operation of the main pump, and the fact that scoring and plugging of the air pump may occur due to grit, dirt, seaweed, etc., in the water being pumped, some of which is passed through the air pump for sealing purposes.

It has also been customary to prime centrifugal pumps on the delivery side, sometimes with the provision o'ffloat valves or the like designed to prevent the passage `of liquid to a vacuum pump after the centrifugal .pump is primedand' operating. The valves under such conditions are exposed to high pressures and are liable to damage by impact and plugging by solid or semi-solid material jammed against them, for example, in the handling of sewage.

" having as their ends the proper rapid, reliable In general pumping, and particularly in the pumping of driven wells, air is carried into the centrifugal pump with the liquid. This air is separated by the centrifugal action of the pump and accumulates adjacent the shaft. When the accumulation reaches such extent as to substantially cut off the intake passages, the pump will lose its prime, and, with previous priming systems, it was necessary to shut down the pump, reprime, and then restart the pumping operations. In my Patent No. 2,144,613, there are disclosed priming arrangements for centrifugal pumps which overcome the aforementioned objections to prior priming arrangements.

The present invention relates to priming systems of this general type in which priming is effected by evacuation of the suction side of a centrifugal pump, and relates more particularly to improvements on the priming systems disclosed in my application Serial No. 260,469, filed March 8, 1939. .'IheV present invention involves, for example, various improvements whereby the operation of the vacuum pumps may be reduced to a minimum, normal operation, eventhough it involves a considerable accumulation of gas, being accompanied with no operation of the vacuum pump or pumps unless abnormally high quantities of gas enter the system. Under normal conditions, the evacuation only takes place in the initial priming of the system on starting. Thereafter, accumulated gas is removed automatically by the action of the centrifugal pump itself.

subsidiary to the broad objects of the-invention just indicated are various secondary objects operation of the priming systems to take care of modern centrifugal pumping operations which are designed to operate automatically over long periods with little or no attention. Specically, the subsidiary objects of the invention relate to the provision of arrangements for taking care-of abnormal gas accumulation, for handling water carrying sediment or floating material, for maintaining proper operation despite surges attending unusual conditions in the supply or discharge lines, for securing rapid and positive operation of valves, and for the priming of centrifugal pumps used in marine installations in which the splashing of water in priming chambers in heavy seas would be likely to disturb the operation of the priming system. Additionally, provision is made for the operation of pumps in parallel or the operation of pumps receiving their liquid from different supplies.

The primary andA specific objects of the invention will be clear from the following description, read in conjunction with the accompanying drawings in which:

Figure 1 illustrates diagrammatically an embodiment of the invention applied tothe priming of a plurality of centrifugal pumps and specifically pumps used in a marine installation;

Figure 2 is a vertical section illustrating the elements associated with one of the priming chambers of Figure 1;

Figure 3' is a similar vertical section taken at right angles to the section of Figure 2;

Figure 4 is a wiring diagram adapted to installations of the general type illustrated in Figure l, but showing electrical rather than vacuum control of an evacuating pump;

Figure 5 is a diagrammatic view illustrating a modification of the invention particularly applicable to the pumping of liquid containing relatively large quantities of gas or dirt;

Figure 6 is a wiring diagram of the installation of Figure 5;

Figure 7 is an elevationillustrating a vertical ning to the vacuum tank 38. with this vacuum tank are vacuumswltches 40V pumpingarrangement applicable particularly to marine use;

Figure 8 is a partial vertical section through the pump of the unit of Figure 7;

Figure 9 is a view somewhat similar to Figure '7, but showing a `modified arrangement suitable for marineuse;

Figure 10 is a fragmentary vertical section through the upperportion of the priming chamber of Figure 9; and

Figure 11 is a Wiring diagram of the installation of Figure 9.

effective to start the motors 44 and 46 at a vac- Referring first to the modification of Figures 1, -2 and- 3, there is illustrated therein a priming system designed for marine service, though it will be readily understood that it is applicable to land service as well. Briefly stated, it involves a censpectively, by motors 3 and 3', are provided with connections 4 to their sources of supply and are adapted to discharge through the usual discharge check valves, not illustrated. Each of these pumps comprises a rotor 6 provided with the impeller passages and receiving liquid from suction bells 8 and discharging the liquid through the discharge volute I0. If the pumps are of double suction type, as illustrated, a pair of suction bells arelocated at each end ofl the rotor. It will be obvious, however, that the invention is applicable to a single suction pump4 and to multiple.stage centrifugal pumps as well as the type illustrated. K

Located above the pumps are priming chambers I2 and I2', respectively, the arrangements of` While any 4number of pumps may be.

dicated at 2 and 2'. These pumps driven, re-

which are shown more particularly in Figures 2 and 3. Chamber I2 is supported on the pump by means of pipes I4 communicating with the chambers through openings I5 and with the upper portions of the suction bells 8. Extending through the pipes I4 are smaller pipes I1, which open within the suction bells closely adjacent the shaft. These tubes are conveniently mounted by being upset at their upper ends so as to be hung `from a baille plate I6 having a central opening I8 and, except for such opening, substantially closing the chamber I2. Above the baiileplate I6 is a second baille plate 20 provided with a skirt portion 22 approaching the plate I6 and having y openings 24 outside the skirt to furnish communication with the uppermost portion of the chamber I2 beneath its cover into which is tapped a .nipple 26 communicating with a valve v28 controlled by a solenoid 30. Beneath the bame plate I6 the pipes I1 are slotted as indicated at I3. As will be pointed out, the high water level is at the level of these slots, `and by reason of the presence of the bailles, water is prevented from splashing out through the outlet 26 despite rolling and pitching of the ship.

In the line running from the chamber I2 above the valve 28 are, in order, a check valve 3 2 and a stop valve 33. Similar valves, indicated with these numerals primed, are indicated as associated with the priming chamber. I2'. From the valves 33 and 33', respectively, extend the pipes 34and 34', connected to a common pipe 36, run- Communicating uum of 18 inches of mercury and to stop these motors at 26 inches of mercury, while the other may' start the motors at a vacuum of 16 inches and stop them at 26 inches. Thus the former will normally be the controlling switch, while the latter serves to effectits control only under emergency conditions. Both of these should be of a snap type to avoid any instability of operation. The motors 44 and 46 driving the vacuum pumps 48 and 50, respectively, areprovided in duplicate for safety purposes. The vacuum pumps 48 and 58 are connected with the tank 38 through the lines 52 and 54 with the interposition of diaphragm controlled check valves 56 and 58 connected through a common balancing connection 60 to the tank 38. Such valves are of conventional type, insuring that the slightest increase of pressure in the lines 52 and 54 will result in a differential action on the diaphragm positively closing communication' to the tank 38. Thus the vacuum in the tank is maintained from the instant the motors 44 and 46 cease operating.

In the event that the pumps 48 and 50 are of the type not designed to handle liquid except, for example, for sealing purposes, it is necessary that any flow of liquid to them should be prevented. Accordingly, not only is the flow of liquid to the tank 38 carefully prevented, but provision is made to remove from the tank 38 from time to time such liquid as may condense therein from the air. A drain pipe 62 is accordingly connected to a three-way valve 64 which, in turn, communicates with a chamber 66 provided with a sight glass 61 and adapted to drain through a check valve 68. By turning the three-way valve 64, liquid may be permitted to flow into the chamber 66 While the vacuum is held in 38, the check 68 then being closed. Moving the valve to another position opens the chamber 66 to the atmosphere s'o that the liquid may flow therefrom through the check valve 68. The sight glass 61 permits note to be made of the amount of water which has collected in the chamber 38 and thus serves to advise an operator of any abnormal accumulations of liquid.

Extending into the priming chamber I2 are lower and upper electrodes 18 and 12, respectively, which electrodes function as will be best understood from a modied arrangement illusy trated in Figure 4 which would be vapplicable if the vacuum pumps were controlled not by the vacuum in a tank such as 38, but by the liquid level in a priming chamber. l

Passing for the moment the electrical considerations, it may be stated that the arrangement of Figures l, 2 and 3 operates as follows:

When the pumps 2 and 2' are stationary, they may be empty, and through disuse ak substantial pressure may exist in the vacuum tank 38.

tank 38, the liquid to be pumpedwill rise into the.

pumps -2 and 2' and through the pipes I4 and I1- into the chambers I2 ,and I2',V iirst submerging the lower electrodes without any actions taking place, and iinally reaching the electrodes 12. As soon as an electrode 12 is submerged, its corresponding solenoid 30 will be deenergized, and its valve will close, preventing any further withdrawal of air from its priming chamber. Thereafter, air will be pumped out of chamber 38 until the vacuum'pumps are shutl down by the action of one or `the other of the switches 40 or 42. Normally, this vacuum will be maintained over very long periods, since, except for leakage. the pumps will maintain their prime during operation.

When the valves 28 and 28 close, the pumps and chambers I2 are isolated from each other and from the tank 38. As soon as the electrode 12 is submerged, the corresponding pump driving motor is either automatically started, or its circuit is put into condition to be manually closed. As the pump operates, a high velocity of ow, due to the rotation of the shaft, occurs at the lower ends of the pipes I1, producing an ejector action creating in the pipes I1 a lower pressure than that existing in the pipes I4 opening in the upper portions of the suction bells where the liquid is relatively quiet and ejector action is not occur-A ring. Accordingly, the liquid in the chamber I2 is caused to rise until it can flow through slots I8 into the pipe I1, and thereafter a recirculation continues to occur upwardly through pipes I4 and down through I1. The pressure differential producing this circulation iis suiilclent to draw downwardly through the pipe I1 any air which might ow from the upper portions of the suction bells into the chamber I2, and accordingly small accumulations oi air are continuously removed. If air centrifugally separates about the shaft, as sometimes occurs when large quantities enter the centrifugal pumps, the ejector action ceases, and this air will pass upwardly through the pipes I1 into the upper portion oi' the chamber I2. By

Vthis action, however. liquid is again caused to submerge the" lower end of the pipes I1, whereby the ejector action is renewed to gradually Withdraw through the pipes I1 the air Whichhas accumulated in chamber I 2.H The air thus withdrawn by ejector'action is in the form of iine bubbles and readily passes through the pump. Thus the prime of the pump-is maintained despite relatively large accumulations of air. Only Vii? accumulations are such as tocause the liquid level to drop below the lower electrode 10 will the solenoid controlled valve open andpermit such air to ilow to the vacuum tank 38. 'I'he valve 28 is immediately closed as soon as the liquid level is restored to the level oi' the electrode 12. l

The action of the electrodes in effecting this control will be clear from consideration of Figure 4V in which, in view of the somewhat more elabrorate controls involved, the electrodes 10' and 12' corresponding to 10'and 12, respectively, are shown associated with means for controlling a vacuum pump operation. In this arrangement a solenoid controlled valve 28' is villustrated and corresponds to the valve 28, the corresponding solenoid being indicated at 30', and operative upon energization to open the valve 28'. At 14 there is illustrated a relay of the well known Bender-Warrick induction type. 'I'his relay is through a switch 82.

when the'coil provided with an A-shaped core having a coil `84 on its crossbar portion grounded at one end and connected at its other end to the electrode 12 and also to the contact element 86 of the armature-18. The upper connecting element of the core is provided with a coil 18 permanently connected to the alternating current power line '80 The legs of the core are adapted to attract the armature 18, which is conventionally illustrated as adapted to close a single contact at 88 by engagement with its contact portion .88 thereby connecting the electrodes 10 and 12'-, together. When thearmature 18 is not attracted, it closes at 90 a circuit including the coil 92, which is adapted toclose a switch 84 in series with a manually operated switch 88 to control a vacuum pump motor 88 operating a vacuum pump adapted to produce, either with or without the interposition of a vacuum tank, a vacuum in the priming chamber such as I2. Also involved in the circuit closed at 90 is the solenoid 30' controlling the valve 28.

When the armature `16 is attracted, there is closed at I 00 a circuit including a coil |02 adapted to close a switch at I04, which switch will open |02 is deenergized only after a delay by reason ofthe provision of a dash pot II2 controlling the movements of the switch. "I'he switch |04 controls the circuit of a starting relay |06, conventionally illustrated as adapted to` controlling the motor IIO op.

vacuum pump motory 98 is immediately closed.

and the valve 28 is open. Accordingly, a vacuum is produced to cause rise of liquid into a chamber such as I2. At this time, when neither of the electrodes 10l nor 12 is immersed in liquid, the path of the magnetic iiux Ais through the crossbar ofthe core 14 and the armature 18 is not attracted. Accordingly, the coil |02 will not be energized and the starter |08 will remain open.

When vthe liquid rises to a point to submerge electrode 10", nothing occurs, but as soon as 12 -is submerged, a current is introduced in the secondary coil 84 producing a ux bucking the ux tending to ilow through the crossbar, so that the path of the flux must now be through the armature which is attracted opening the circuit at 90 and closing the circuit atv |00 and connecting the electrode 10' to the electrode 412 by making contact at 88. As soon as the contact at is broken, the valve 28' closes, and the vacuum pump motor 96 is stopped. The coil |02 is now energized and serves either to operate thefstarter conventionally illustrated at |08, or close a switch naking it possible to start the motor IIO manu- E 1y.

If the liquid level`now drops below the level 10', the secondary circuit of the relay is opened and contact at made to eil'ect opening of'the valve'28' and renewed operation of the motor 98. The `motor IIO, however, is not immediately stopped by reason o1' the time delay action afforded by the dash pot II2. Preferably a delay oi', say, 30 seconds or the like is provided, during which most centrifugal pumps may safely operate without damage due to overheating, even if they do not contain water. Inv this limited time, ii' merely a surge hasA occurred rather than something serious, such as failure of the water supply, the vacuum pump will be able to restore the VUgal pump motor.

On the other hand, if, in the limited time, the liquid level is not restored to submerge the electrode 12', the main pump motor will stop and will only restart when the water level is properly restored or when manual starting occurs. Y

In Figures y and 6 there is illustrated an alternative form of the invention, particularly designed for use in connection with driven wells, in which sand or other sediment may be carried by the inflowing water together with large quantities of air. In such case, it is desirable to have a separating tank precede the centrifugal pump, and it becomes impractical to provide a time delay arrangement, as in the previous modification, by reason of the very considerable volume oi' air which must be pumped to restore an abnormally low liquid level to its normal height.

The inlet ||5 communicating with the well or the like from which pumping is taking place, communicates with a chamber |01 of large capacity, provided with a baiiling arrangement, indicated at |03, for preventing as much sediment as possible from entering the intake piping |03 of the centrifugal pump |0|, in which piping there is interposed a stop valve |05. The pump delivers water through the passage and the check valve ||3 and stop valve Hd.

Provided preferably as an upper unit of the separating tank, though it may be separate, is a vacuum tank |||6communicating through connections ||8 with a motor driven vacuum pump, indicated at |20. A vacuum controlled diaphragm type check valve |2d is interposed in the line |I8 having a controlling connection |23 with the vacuum tank. A stop valve |22 is preferably provided in the same line. In an arrangement such as this, particularly where operation of the centrifugal pump must be maintained despite possible failures of the electrical supply, the centrifugal pump or pumps, since a plurality may be' connected to the same separating chamber, may

provided with energizing coil |32 permanently connected to the power line |44, which may be connected to the main power supply through a switch |48. The armature |60 of this relay has one contact permanently connected to the electrode |38 and the coil |52 on the cross member cf the relay, the other end of which is grounded. When the armature |33 is attracted by the core, a contact is made at |563 serving to connect the electrodes |36 and |33 together, as in the case of r the modification of Figure 4.

The armature |03 has. another contact making portion |50 designed to connect the contacts at |53 to energize the coil |32 of -the valve |30 to open that valve.

For the purpose of control of the motor driving the centrifugal pump, there is provided a second relay of the same Bender-Warrick type provided with a core |63 and an energizing coil |32, connected to the line |44. The secondary coil is connected at one end of the electrode |33 and at its other end to ground. The armature it, of this relay is of the type requiring manual resetting, i. e., when once dropped it can be reset only by manual manipulation of the button |65. When this armature is attracted by the core it is adapted to close the switch con` trolling the circuit through the starter coil |12 controlling the' switch |14 in the line |16 to the centrifugal pump motor. Automatic starting may be thus effected, orthe arrangement may be such as merely to place the motor circuit in condition for manual starting.

In the operation of this arrangement, assumingthe electrical supply is operating, the valve |33 will be closed, and the vacuum pump |20 operating. ,This vacuum pump may be controlled by the pressure in the tank H6 as in the l case of a modification of Figure'l, or, alternabe arranged to be alternatively driven by a motor.

or motors and a gasoline or similar engine. Likewise, in such cases, provision is made for driving one or more vacuum pumps alternatively either by an electric motor or motors or by a gasoline or similar engine. If a plurality of vacuum pumps are provided, then they should be provided with independent connections such as I0 to the vacuum tank H6. In such case, the valve |22 serves to isolate either of the pumps for repair purposes or, in the event, for example, 'that only one of them is operated by a gasoline engine in an emergency, the other may be cut out of the system.

A connection |20 is provided between the upper end of the separating tank |01 and the 'vacuum tank H6, there being interposed in this connection a valve |30 controlled by a solenoid V|32 and adapted to be opened when the solenoid is energized. To permit proper operation in the event of failure of the electrical supply, an auxiliary connection is provided between the separating tank and the vacuum tank and is controlled by a stop valve |39. Also provided for emergency operation is a tank |33, connected at its upper and lower portions to the separating chamber |01 and housing a float |35 adapted to open an air vent |31. y

Extending into the separating chamber are three electrodes indicated at |34, |36 and |38. These are electrically connected into the system, as illustrated more particularly inFigure 6.

A Bender-Warrick relay, indicated at |40, is

tively, by the rise of liquid level asdescribed in the modification of Figure 4. At any rate, it will tend to cause rise of liquid past electrode |34 without effecting any result, since the relay |60 is of the manual resetting type, and

" then past |36 without eiecting any result until the electrode |38 is submerged. Thereupon, the

armature |48 is attracted by the core closing the' contact at |54, thereby connecting the electrodes |36 and |38 together. At the same time, the

' contact at |58 is broken so that the solenoid |32 releases the valve |30 to closed position. At thesame time, the vacuum pump motor may be stopped, or it may be stopped only after a predetermined vacuum is produced in the chamber H6. Whenever desired the main pump motor or motors may be started by moving the armature |64 into the field of attraction ofv the core |60 which is now in attracting position by reason of submersion of the electrode |34. As the centrifugal pump operates a circulating effect is produced as in 'the case of the modification of Figure 1, by reason of the approach of the connection ||1`Yto the shaft of the pump within its eye. Accordingly, a partial vacuum is produced in the-line ||1 tending to raise the liquid in the tank |01 to the level of the connection H1, whereupon flow of liquid from the tank through the connection ||1 takes place with withdrawal of air whenever any accumulation occurs in the tank |01 to cause the liquid level to tend to dropv beneath the connection I|1. Preferably this connection opens into the tank a substantial distance above the uppermost electrode |38. Thus the pump maintains itself primed and lthe level of the liquid in the tank.

.vent |31 to the atmospher an installation of this character I tinuously operated and' is indicated at |88 asv Under these conditions, no liquid enters the float chamber |33.

In the event that an abnormal accumulation of air occurs, or, for some other reason, a surge occurs tending to drop the liquid level, the valve |30 will not reopen until the liquid level drops below the middle electrode |36. When such drop occurs. however, immediately opening will take place so that air may ow into the vacuum tank and the level will be restored. As soon as |38 is again submerged, the valve |30 will close. If the surge or accumulation of air is abnormal and the liquid clears the electrode |34, the core Ill will drop its armature and the centrifugal pump motor will be stopped and can be restarted only by manual intervention.

If for some reason the valve |30 should stick in open position, liquid might enter the chamber ||6 and cause damage to the vacuum pump. To avoid any possibility of the occurrence of this, the oat valve |35 is provided which, if the liquid level rises abnormally, will open the so that air will 110W through this vent into the upper portion of tank |01 and -then into the vacuum tank, preventing any liquid from rising therein and at worst merely producing an abnormal continued operation of the pump |20.

The float valve |35 has another emergency function coming into play when the electrical supply fails. Under such conditions, the valve |30 would remain closed, since all of the electrical parts of the installation will be ineffective. To permit operation in such case, the valve |39 inthe bypass is ope'n and both the centrifugal pump and vacuum pump are 'operated by the emergency engines. The float valve |35 will Vnow prevent, 4as before, any rise of liquid above the level tending to unseat its valve member from the vent |31.` Any accumulated air is drawn off through the valve |39. Continuous operation of the vacuum pump must, of course, take place.

In Figures 7 and 8 there is shown an alternative arrangement involving a centrifugal pump with its axis vertical particularly adapted for marine installations. In this case, the pump, indicated at |80, is driven by the motor |18, and its suction bell, in this case arranged uppermost, takes liquid through the intake connection 82, the liquid being discharged from the pump through the outlet connection |84 inwhich is interposed in conventional fashion a combination check and stop valve |86. The Avacuum pump in may be condriven continuously by the motor |18. It is connected through the passage |90, in which is interposed the valve |94 controlled by the solenoid |98, to the upper end of a standpipe |98. The lower end of this lstandpipe at 200 communicates with a pipe 20| which, at 2,02, is connected into the intake passage |82.` Electrodes 204 and 206 are located as indicated in the standpipe |98 and correspond to the electrodes 10 and 12' of Figure 4, with the exception, however, that they control only the valve'l94 corresponding to 28 of Figure 4, and have no control over the motor |18. Above the'electrode 206 the standpipe |98 is connected through pipe 208 to the tube 2|0 passinginto the suction bell of the pump and extending closely adjacent its shaft 2 |2.

The centrifugal pump in this case must be of a type which can run for'extended periods in dry condition.` Since high efficiency is not particu-- ing, which, when the By reason of the ejector 5 larly necessary in pumps for marine installations, the runner clearances may be larger than in the `case of land pumps, and the pumps may run indefinitely while dry without damage. If closer clearances are present, however, it may be desirable to lead from the water line `2|4|` which normally supplies water through 2 I6 to the packing gland of the pump some additional ilow through pipes 2|8 and passages 222 to the wearing rings 224 'serving for their temporary coolpump is operating to pump water, is effected by the water being handled.

In the vacuum linethere is preferably pro- -vided a relief valve |92 which will open this |18 is started and the valve |94 is open, due toV energization of its solenoid |96. Accordingly, a vacuum is drawn from the standpipe and the liquid to be pumped rises in the intake connections and the pump and through connection 20| in the standpipe |98 until the upper electrode 206 is submerged, whereupon the valve |94 closes, and shortly thereafter the relief valve |92 opens. action at the end of the tube 2|0 approaching the shaft 2|2 a difference in pressure is produced as in the other modifications, causing a further rise of liquid in the standpipe |98 and then flow of liquid therefrom through connection -208 to the suction chamber of the pump. Thus continuous removal of air which may accumulate in the standpipe through the intake connections in the passage 20| occurs. If any abnormal amount of air accumulates in the suction bell of the pump so that the tube 2|ll which is in its upper portion is uncovered, the ejector-action will cease and this air will flow yinto the upper portion of the standpipe |98.

soon as the tube2l0 is again submerged, howremoving from the standpipe the air which has owed therein. If the liquid level falls below the level of the electrode 204, the valve |94 will be opened and the vacuum pump will again act to draw a vacuum in the standpipe to reprime the system.

'I'he systems so far described are adapted for operation only with alternating current if the Bender-Warrick type of relay is to be used, since a current introduced in the secondary thereof is responsible for its operation. It may be noted that it is not generally permissible to provide electrodes for operating purposes which are connected directly to a'power supply, since accidental grounding might very well occur. 'I'he Bender- Warrick type of relay, on the other hand, provides a thoroughly safe arrangement, since the secondary is of such high resistance that even complete short eircuiting of it will not result in any abnormally high current flow. Furthermore, the voltages induced in this secondary are suf- .ciently high to overcome the relatively great resistances of waters matter.

While alternating current is available on -many ships, there are others on which only direct current is available, and for proper operation of the priming system in such cases, there must be provided a switching arrangement which is illustrated in the modification of .Figures 9,10 and 11 in conjunction with other features of the ar-` rangement. Y

containing little mineral trolled.

In these figures there is indicated at 230 a motor arranged to drive the centrifugal pump 232. This motor may be automatically controlled, as in the previous modication, or manually con- A suction manifold, indicated at 234, may .be selectively connected, for example, to various bilges and the line running therefrom to the centrifugal pump 232 contains the combination stop and check valve 236 of conventional type. Discharge takes place through a similar valve indicated at 238.

Communicating with the intake connection at 240 isa standpipe 242, extending from which is the vacuum line 252 controlled by the solenoid controlled check valve 250. The vacuum producing-device used in this instance may be either automatically controlled or manually controlled when the pump is operated. In either case, as will be evident hereafter. the valve 250 controls automatically the priming operation.

A connection indicated at 244, similar to the connection 208 of the modification of Figure 7, furnishes communication between the upper portion of thestandpipe 242 and the suction bell of the centrifugal pump, extending therein closely adjacent the shaft.

In the present case, instead of using electrodes,

there extend into the pipe shells 246 and 248 in which are located, respectively, lower and upper floats 264 and 258. These oats control, through interposition of an expandible bellows arrangement, switches 262 and 260, which should be of snap type to secure rapid'making, and breaking of contact. Such switches are well known per se, and need not be specifically described. Above the uppermost float 258 is an arrangement of bailles 254 and 256, designed to prevent the splashing of water into the vacuum connection when the arrangement is used in marine service.

to the oat 258 and does not reopen until the liquid level drops below oat 264, giving rise to the same general type of operation as heretofore described with reference to the electrode arrangements.

As soon as the pump is primed, a suction is produced in the connection 244, as in the previous4 modications, and by reason of the ejector action which then takes place, the liquid level is raised to the level of the connection between pipe 244 and the standpipe 242. Air accumulations are removed, asin the case of the previous modication.

It will be evident that the modifications specifically referred to herein as for marine use may be used in land installations, in which case the bafes become unnecessary. It may also be pointed out that the modification in Figures 9, 10 and 11 is applicable to alternating current operation as well as direct current operation.

It will be evident that various changes in details of the invention may be made within the scope of the appended claims.

What I claim and desire to protect by Letters Patent is:

1. In combination, a centrifugal pump; means providing a chamber connected to the intake passage of the centrifugal pump for accumulation of gas contained in the liquid being pumped;

means for evacuating said chamber to raise liquid therein to a level above the intake passage to thereby prime the pump: means connected to said chamberand subjected to an ejector action of liquid within the intake passage and being pumped to maintain a partial vacuum vin said chamber, said last means comprising'a tube opening closely adjacent the shaft of said pump and subjected to the ejector action of liquid adjacent 'said shaft; an electrode within said chamber The switches 258 and 264.are connected in circuit as indicated in Figure 11. A relay coilv 210 is adapted to close contacts through armatures 212 and 214. When the latter is closed it serves to energize theA solenoid 268 controlling the valve 250 to hold this valve open. The oat switches 256 and 264 are arranged to open when liquid` rises to rtheir level. v

The operation of this arrangement is quite similar to that of the'arrangement of Figure 7. When the liquid level is below the float switch 264, the circuit is closed at 260 and 262 through the solenoid 216, and also through the action of the relay armature 212, which, it will be noted, is in parallel with 262. AccordinglyVV the solenoid 268 is energized and the valve `25|) held open to permit the withdrawal of air.

When in the priming operation the liquid rises to the level of the float 264, switch 262 is opened, butwithout effecting any result,since the circuit is closed in parallel with this switch at 212. When the level rises to the float 258, the switch 260 is opened. deenergizing the coil 210 and thus permitting it to drop the conductors 21.2 and 214, deenergizing the solenoid 268, whereupon valve 250 closes under theaction of its controlling spring. l

When the liquid level drops, there will first occur closure of switch 260, but this will have no effect, since the switch 262 remains open and the conductor 212 is already in open position.

jacent said shaft; and means comprising a sole# below the top thereof; and means operating when liquid reaches said electrode to close communication between the chamber and'said evacuating means, whereby the means subjected to said ejector action serves alone to maintain the partial vacuum in said chamber. 1

2. In combination, a centrifugal pump;'means providing a chamber connected to the intake passage of the centrifugal pump for accumulation of gas contained in the liquid being pumped; means for evacuating said chamber to raise liqvuid therein to a level above the intake passage to thereby prime the pump; means connected to said chamber and subjected to an ejector action of liquid within the intake passage and being' pumped to maintain a partial vacuum in said chamber, said last means comprising a tube opening closely adjacent the shaft of said pump.

and subjected to the ejector action of liquid adnoid controlled valve effective to close communication between the chamber and said evacuating means when liquid in the chamber reaches a predetermined level below the level of connection with the chamber of the means subjected to said ejectoraction of liquid.

3. Incombination, a centrifugal pump; means providing a chamber connected to` the intake passage of the centrifugal pump for accumula- As soon as the float 264, however, is uncovered, v

switch 262 closes, whereupon the relay 216 is energized and the valve 250. is opened. T'hus` the valve 250 does not close until the liquid level rises tion of gas contained in theliquid being pumped; means connected to said chamber for evacuating it to raise liquid therein to a level above the intake passage to thereby prime the pump; means connected to said chamber and subjected to an ejector actio'n,of4liquid within the intake passage and being pumped to maintain a partial vacuum means to prevent splashing of liquid to thelast' Vnamed point of connection.

4. In combination, a centrifugal pump; means providing a chamber connected to the intake passage of the centrifugal pump for accumulation of gas contained in the liquid being pumped; means connected to said chamber for evacuating it to raise liquid therein to a level above the intake passage to thereby prime the pump; means connected vto said chamber and subjected to an ejector action of liquid Within the intake passage and being pumped to maintain a partial vacuum in said chamber, said last means comprising a tube opening closely adjacent the shaft of said pump and subjected to the ejector action of liquid adjacent said shaft; and means eiIective to close communication between the chamber and said evacuating means when liquid in the chamber reaches a predetermined level below the level of connection with the chamber of the means subjected to said ejector action `of liquid; and baiies within the chamber located above the level of connection with the chamber of the means subjected to said ejector action of liquid and below the connection with the chamber of' said evacuating meanstoprevent splashing of` liquid to the last named point of connection.

5. In combination, a centrifugal pump; means providing a chamber connected to the intake passage of the centrifugal pump for accumulation of gas contained in the liquid being pumped; means connected to the upper portion of said chamber for evacuating said chamber to raise `liquid therein to a level above the intake passage to thereby prime the pump; means for limiting the average level to which liquid will rise in said chamber during operation of the pump; and baille means located above said average level and below the level of connection with the chamber of the means for evacuating said chamber to prevent splashing of liquid to the last named level.

6. In combination, a centrifugal pump; means providing a chamber connected Vto the intake passage of the centrifugal pump for accumula.,

tion of gas contained in the liquid beingV pumped;

means for evacuating said chamber to raise liquid and subjected to the ejector action of liquid adjacent said shaft; and electrically controlled means effective to close communication between the chamber and said evacuating means when liquid in the chamber reaches a predetermined level below the level of connection with the chamber of themeans subjected to said ejector action of liquid. l

7. Incombination, a centrifugal pump; means providing a Achamber connected to the intake passage of the centrifugal pump for accumulation of gas contained in the liquid being pumped; means for evacuating said chamber to raise liquid therein to a level above the intake passage to thereby prime the pump; means limiting the level to which liquid may rise in said chamber under the action of said evacuating means; and means effective following a predetermined delay after the liquid level` drops to a predetermined level lower than the aforementioned level to stop the operation of said centrifugal pump.

8. In combination, a plurality of centrifugal pumps; means providing a plurality of chambers, one for each pump, connected to the intake passages of the centrifugal pumps for accumulation of gas contained in the liquid being pumped; common means for evacuating all of said chambers to raise liquid in each to a level above the intake passage of the corresponding pump to thereby prime the pump; means connected to each chamber and subjected to an ejector action of `liquid within its own intake passage and being pumped to maintain a partial vacuum in each chamber; and means individual to the chambers effective to close communication between any chamber and said evacuating means when liquid in said chamber reaches a predetermined level below the level of connection with said chamber of its means subjected to said ejector action of liquid.

9. In combination, a centrifugal pump; means providing a chamber connected to the intake passage of the centrifugal pump for accumulation of gas contained in the liquid being pumped; means connected to said chamber for evacuating it to raise liquid therein to a level above the intake passage thereby to prime the pump; means connected to said chamber and subjected to an ejector action of liquid within the intake passage and being pumped tomaintain a partial vacuum therein to a level above the intake passage to thereby prime the pump; means connected to said chamber and subjected to an ejector action of liquid Within the intake passage and being pumped to maintain a partial vacuum in said' chamber, said last means comprisingt a tube openingv closely adjacent the shaft of said pump connection with the chamber of the rst mentioned evacuating means, said last means comprising a tube opening closely adjacent the shaft of said pump'and subjected to the ejector action of liquid adjacent said shaft; and electrically controlled means effective to close communication between the chamber` and the first mentioned evacuating means when liquid in the chamber reaches a predetermined level below the level of connection with the chamber of the ilrst mentioned evacuating means.

FRANK s. BROADHURST.

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