US2207220A - Series-parallel centrifugal pump - Google Patents

Description

'July 9, 1940. A. HOLLANDER SERIES -ARALLEL CENTRFUGAL PUMP Filed April 26,. 1938 6 sheets-sheet 1 BYV NVENTOR A ToRNE July 9, 1940. A. HOLLANDER 2,207,220

" SERIES-PARALLEL CENTRIFUGAL PUMP l Filed April 26, 1938 6 sheets-sheet 2 v INVENTIOR BY w'@ www A TT ORNE Y July 9, v1940.

A. HOLLANDER SERIES-PARALLEL CENTRIFUGALlPUMP Filed April 26, 1938 6 Sheets-Sheet 5 locaw Hollander NVENTOR A TTOR/VEY .A. HOLLANDER l 2,207,220

SERIES-.PARALLEL CENTRIFUGAL PUMP July 9, 1940.

Filed April 26', 1938 e sheetssheet 4 adar Hollane y INVENTOR BY X2 '@Ww A TTORNE Y July 9, 1940- A. HoLLANDx-:R 2,27,220

lSERIESPARALLEL CENTRIFUGAL PUMP Filed April 26, 1938 s sheetssheet s lczdar Hbllander [1v VENTOR BY-` J Q MMM/L v."ITTORVE`Y 6 Sheets-Sheet I6 /N VENTO/e A TTORNE y Alan/ar /foilander July `9, l940 A. HOLLANDER SERIES-PARALLEL CENTRIFUGAL PUMP FiledvApril 26, 1938 Ill l rl A Patented July 9, 1.940

UNITED STATESk Plinn-:NTA IA-Flori maaar Hollander, Los Angeles, cant.;` assigner o Byron Jackson Co.,lluntington Park, ('falii'., a corporation of Delaware y Application April 26, 1938, Serial No. 204,347

s claims." (ci. 10s-10e) j This invention relates to improvements in multistage,. two-shaft centrifugal pumps of the type wherein the stages are arranged ingroups which may be connected togethereither in series or in parallel. This type of pump is particularly adapted for use as a fire pump, being compact and light in weight and capable of delivering either a large volume of liquid at. low pressure or a small volume 'at high pressure.

Fire pumps `are frequently 4required to operate against a relatively high suction lift, which causes cavitation if the'iirst stage impellers rotate too fast. This defect can be overcome, without .decreasing the pump capacity, by rotating the suction impellers at lower speed than the higher -stage impellers. By mounting the mst stage impeller of each group on a low speed shaft and the remaining impellers on a high speed -shaft,.

the capacity'of the pumpmay be materially increased while maintaining the diameter, and therefore the weight, within allowable limits.

In series-parallel, two-shaft pumps a 'crossover valve is employed to connect the discharge from the last stage of one group either to the dischargeheader, when operating the groups in parallel, orto the inlet o f the first stage of the other group, when operating 'the groups in series. In' prior .pumps the location of the crossao. over valve has-been more orl less haphazard, no *specialv consideration having been given to its Y location;` Y A- A principal object of this invention is to so arrangethe various stages that thev cross-over valve is located atamore vconvenient point, particularly from a standpoint of econimy of manufacture" andease of assembly and repair.

plane Vof the shafts, and a cross-over valve having'its axis in-the parting plane.

A still-furtherobject-is to provide an improved arrangement Aof the stages 'of a pump of the aforementioned type, whereby a more compact and lighter weight pump is made possible.

AiOther objects and advantages wili be apparent fr om the following description, taken in conjunc tion with the accompanying drawings, wherein:

Fig. 1 is aplan view of a pump constructedin accordance with this invention;

Fig. 2 is a side elevation of the pump shown in Fig. 1; I

3 is an end elevation of the pump, as viewed from the left of Fig. 1; Y Fig. 4 is a horizontal sectional view taken in A A further object is to provide a series-parallel, two-shaft pump having a casing split in they pair of third- stage impellers 25 and 26. ler i9 discharges through passage 2l into the inlii) the plane of the shafts, as indicated by sectiony line 4 4 of Fig'.`2; 3. .l l Fig. 5 is avertical sectional view taken in the` axial plane of the high-speed shaft, as indicated by line 5-5 of Fig. 4; 5 Fig. 6 is a vertical sectional view taken in the axial plane of the low-speed shaft, as indicated by lined-6 of Fig. 4;

Fig. 'Z-is a transverse section 1-1 of Fig. 4:

Fig. 8 is a transverse section takenon line 8-8 of Fig. 4;'and

F1g..9 is a .transverse taken on line section taken on lineA Referring t'o thetdrawings, the pump casing l5 is shown as comprising an upper section I and a lower section 2, having a parting plane extending through the axes of the impeller shafts 2 and 4. Cast integral with the upper casingsection are a discharge manifold 5 and a double suction 20 manifold 6. As shown in Fig. 1, the suction manifold is .formed with two duid passages 1 and l. the passage` I being provided with an inwardly opening check valve l0 at each end. l

Suction passage 8 communicates with the suc- 25 tion inlet l2 of the first stage impeller I2 of one group, and the suction passage 1 communicates with the suction inlet I4' of the rst stage impeller l5 ofthe other group. The impellers I3 A and I5 are mounted on the low-speed shaft I, 80 and, as shown in Fig. 4, are of larger suction .area and lower specific -speed than the impellers mounted on shaft 3. VAs shown in Fig. 9,1m--

peller I3dis'charges through its volute AI'I into the inlet I8 of impeller I9. The' impeller II similarly 85' 'discharges through its volute 29 into the inlet 2l 'of impeller 22. `The impellers I9 and 22 mounted on the high speed shaft 2.

By arranging the first stage impellers I2 and Il Y face-to-face with their inlets between the im- 40v pellers, and the second-stage impellers I9 and 22 back-to-back, the inlets of the latter are disposed in the same transverse planes as the im' .peller cavities of the former, resulting in a very compact arrangement. 'I'he second-stage im- 'pellers are preferably cast integral, as shown in Fig. 4.

Also mounted on the high speed shaft l is a @Dellet 28 of Aimpeller 25, and impeller 22 discharges through passage 29 into the inlet 30 of impeller 26. AThe impellers and 26are arranged backto-back and, like the impellers I9 and 22, are cast integral.- The impeller 2li` discharges direct-55 ly into the discharge header 'l through 32 (Fig. 7).

A two-way cross-over valve Il is provided for selectively connecting the discharge ofA impeller 25 with the discharge header li or the inlet Il of impeller I5. 'I'he valve is of the rotary type. with an axial inlet 25 in constant 'communication with the impeller cavity of impeller 25 through passage l1 (Fig. 8), and a lateral discharge port I8 selectively connectible with a passage 25 (Fig. 7) leading to the discharge header 5, or toa cross-over passage 4I leading to the inlet header l.

'I'he valve 35 is journaled in the casing sections I and2 with its axis lying in the parting plane of the sections and coaxial `with the low speed shaft 4. A valve stem 45 projects from one end v of the valve through a removable end plate l5,

and has an operating handle I1 keyed thereto. When the valve is rotated to the position indicated in Figs. 6 and "I, the impeller 25 discharges directly into the discharge header 5, and when rotatedto the position indicated in Figs. 4 and 8 the impeller 25 discharges into the inlet of impeller I5. Y

Adjustable packing glands Il are provided to seal the'junctures ofthe shafts l and I andthe pumpcasing. Apacking gland II isalsoprovided around the valve stem 45; The driving connec-` tions -for the shafts have not been shown inasmuch as any desired form of, driving-means may be provided, so long as the shafts are driven at the proper relative speeds.

The mode of operation of the pump is as follows: If a large volume of liquid at relatively low pressure'is desired, the cross-over valve is positloned as shown in Figs. 6 and 1, to connect the discharge of impeller 25 with the discharge header 5. 'l'.he impellers are then divided into two groups of three impellerseach,. operating in parallel. Liquid is drawn into mst-stage impeller Irfrom suction passage I and is discharged into theinlet I8 of impeller Il. Thelatterdischarges into the inlet 28 of impeller 25, which in turn discharges into .the discharge header through the cross-over valve 35. The impellers l5, 22, and 25 of theother group are similarly connected in series between the suction inlet 'I and the discharge header l.

To provide a relatively small volume oi' liquid at high pressure, .the valve ll is turned to the position shown in Figs. 4 and 8, to connect'the discharge oi the third-stage impeller 25 of'one group with the inlet of the mst-stage impeller I5 of `the other group. 'Ihe two groups are thus connected in series to form a six-stage pump, the

, impeller l5, 22, andl constituting the fourth,

fifth, and sixth stages', respectively. At this time the check valves Il in the suction header swing to closed position. i

The advantages of the stage arrangement and the location of the cross-.over valve should be apparent from the foregoing description. B y locatingthe valve withitsaxisin'the parting plane of the pump casing sections and in axial align-f Yl The stage arrangement affords a very' compact and light weight pump. All connecting passages betweenthe headers 5 and 5 and the initial and final stage impellers are of minimum length, since the header 5 is disposed directly over the inlets of the first-stage impellers and the header 5 is directly above the discharge of impeller 2G and the outlet. port of the cross-over valve. The cross connections between impellers I3 and I5,A and I5 and 22, respectively, are also of minimum length. The decrease in weight resulting from the reduction in the length of the various connecting passages is a very decided advantage in fire pumps, for obvious reasons. It also effects a material reduction in the manufacturing cost.

By employing parallel shafts and dividing the impellers between the shafts the available lateral space on a fire truck is utilized to funest capacity. As shown in Fig. 9, there is ample space between the side frames of the truckV chassis for two parallel sets of impellers, and by utilizing this space to the full extent a large number of stages may be provided without unduly increasing the length of the p'ump. e

The casting of the pump casing sections is greatly simplified by the arrangement shown, particularly with reference to the location of the cross-overs from one shaft to the other. The

cross-overs from impellers Il and l5'to impellers I5 and 22 are entirely in the lower half of the pump casing, while the/suction and discharge headers or nozzles andthe cross-over from impeller 25 to the valve 5I arelocated in the uppe half. v

While I have shown for purpose of illustration a pump embodying six stages connectible in series or in two parallel groups of three stages each; it will be understood that the invention is equally applicable to a pump having a different number of stages.

I claim;

1. In `fe}1seriesparallel mu'uistage centrifugal pump, means, a pair of spaced impeller shafts, a pair of suction impellers on one shaft, a 'pair of second-stage impellers on the other shaft and having their inlets substantially in planes including the impeller cavities of the suction impellers, the discharge from the suction impellers being connected respectively to the in- ,.lets of the second-stage impellers, a pair of thirdstage impellers on said other shaft. the discharge Afrom the second stage impellers being connected respectively to the inlets of the third-stage impellers, thereby forming a pair o.' three-stage groups of impellers, a cross-over from the thirdstage impeller of one group to the suction impeller of the other group for connecting said groups in seres, and ,a cross-over valve for -controlling said cross-over, said valve being disposed substantially in axial alignment with said suction impeller shaft and opposite said third-stage impellers. 2. A pump as defined in claim 1, in which said casing means comprises sections faces lying in a plane including the axes of said shafts, said valve being disposed with its axis in said plane.

3. In a series-parallel multistage centrifugal pump, casing means, a pair of spaced impeller shafts journaled t erein, one of said/shafts terminating within d casing a substantial distance from the end thereof, a plurality of groups of impellers on said shafts, the impellers of each f r' group being connected in series, a cross-over from the final-stage impeller of one group to the vrst stage impeller of another group for connecting said groups in series, and valve means in said casing for controlling said cross-over, said valve means being disposed in axial alignment with said one shaft between the end of said shaft and the adjacent end of said casing. v

4. A pump as dened in claim 3, in which -said valve means comprises a cylindrical bore in said casing coaxial with said one shaft, and a valve body rotatably mounted in said bore. A

5. A pump as dei-'med in claim 3, in which said valve means comprises acylindrical bore in -said casing between the end of said one shaft and the adjacent end of said casing, a valve body rotatably mounted in said bore, and a valve stem on said body projecting through said casing in coaxial relation to said one shaft. p

6. In a series-parallel multistage centrifugal pump, a pump casing, a. low-speed shaft and a high-speed shaft journaled in said casing, a pair of 4suction impellers of relatively large suction area secured to said low-speed shaft, a plurality of impellers of relatively small suction area secured to said high-speed shaft, said impellers being connected'in two parallel groups with the impellers in each group connectedin series, a cross-over from the final stage impeller of one groupto the suction impeller of the other group,

and valve means in said casing for controlling said cross-over, said valve means being vdisposed in axial alignment with said low-speed shaft.

'7. In a multistage centrifugal pump, a pump casing, spaced impeller shafts journaled in said casing, a pair of suction impellers ,on one shaft, a pair of final-stage impellers on the other shaft and offset axially with respect to said suction impellers, a cross-over connecting one of said.

final-stage impellers with one of said suction impellers, a cross-over valve controlling said crossover, said valve being disposed in axial alignment with said suction impellers and laterally opposite said final-stage impellers, a pair of suction.

nozzles extending across said casing in a direction transverse to the axes of.said shafts and in :superimposed relation to the suction eyes of said valve and communicating directly therewith in one position of said valve.

8. A portable re pump particularly adapted to be mounted on a' fire truck, comprising'a casing, a pair of parallel impeller shafts journaled in said casing and adapted to be disposed longitudinally of said fire truck, one of said shafts being of greater length than the other and determining theA longitudinal dimension of said casing, said other shaft terminating within said' casing a substantial distance from one end thereof, a plurality of impellers on each of said shafts, said longer shaft having a greater number of impellers than said other shaft and at least one of the impellers on said longer shaftbeing disposed axially beyondthe inner end of said other shaft, cross-overs in said casing connecting said impellers in a plurality of series groups, a cross-over valve in one cross-over adapted to selectively connect said groups in series or in parallel, said valve being mounted in said casing in axial alignment with the shorter of said shafts and axially beyond the inner end thereof, said valve having a stem projecting through the adjacent end of said casing in coaxial relation to said shorter shaft, the combined length of the shorter shaft, valve. and valve stem being substantially'equal to the length of said longer shaft,

- -whereby the overall length of the operating parts of said pump is divided substantially equally between the two shaft axes and the overall length of the pump is thereby reduced to a minimum.

9. In a series-parallel multistage centrifugal pump, a casing, a pair of impeller shafts journaled in said casing on spaced axes,-one of said shafts terminating within said casing a substantial distance from the end thereof, a plurality of groups of impellers on said shafts, the impellers of each group being connected in series and the final stage impellers of each 'group being mounted over in said casingconnecting the final-stage impeller of one group with the suction impeller of another group, and a valve for controlling said cross-over, said valve being mounted in said casing in axial alignment with said one shaft and axially beyond the inner end thereof and laterally opposite the final-stage impellers mounted on said other shaft. v

ALADAR HOLLANDER.

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