US2653546A - Self-priming pump - Google Patents

Description

Sept. 29, 1953 A. s. MARLow, JR

SELF-PRIMING PUMP Filed NOV- 5, 1949 W Re Ti ms. ND u Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE 2,653,546 sELF-PimvnNG rUMP Alfred S. Marlow,`Jr., Ridgewood, N. J. Application November 3, 1949, serial No. 125,302

z claims. (ci. 16a- 113) The present invention relates to improvements in liquid pumps, and in particular to pumps classified by their mode of construction and operation as diffuser centrifugal pumps.

Characteristic of centrifugal pumps is the requirement for priming. This is generally considered to be the inherent Weakness of a standard centrifugal pump, although to some degree known centrifugal pumps are constructed to perform a partial priming function, either by a system of recirculation priming or by diffuser priming, in which case the pump is considered to be a selfpriming centrifugal pump. In recirculation priming, a connection is made between the suction side of the pump and a pump reservoir on the discharge side providing a passage for recirculating priming liquid. Thus, when air enters the suction side of the pump, depriving it of its normal operating prime, a suitable by-pass control valve is actuated either manually or automatically to provide recirculation within the pump or the system so that pumping action may be sustained. Diffuser priming, on the other hand, is distinguished from recirculation priming by reason of the fact that the priming fluid from the pump reservoir does not return all the way to the suction side of the pump, but rather returns only to the circumferential portion of the impeller where it is admixed with air and ejected through diffuser passageways. As this action continues, all air is eventually removed and the pumping function returns to normal.

There are important advantages in the use of the diffuser principle of priming as compared with recirculation priming, particularly in that auxiliary valve mechanisms are not necessary Which, in recirculation priming pumps, are subject to mechanical failure. Once set in operation and given an initial prime, the diffuser type centrifugal pump will continue to operate when entrained air or gas is admitted to the pump on the suction side. The diffuser priming centrifugal pump, in fact, requires no more moving parts than are required with a standard non-priming centrifugal pump.

Requisite conditions for fluid flow to give efcient discharge and those for effective diffuser priming are directly opposite. Diffuser priming effectiveness is promoted by the existence of conditions which result in a large degree of turbulence at the impeller which, of course, are intolerable conditions for efficient discharge. With turbulence of the priming liquid, greater quantities of air or gas may be entrained with the priming liquid and transported to discharge or to a Ventilating separator in series with the pump. At the same time, however, balance must be preserved whereby the diffuser construction does not create undue friction losses during pumping.

It is the principal object of the present invention to provide a diffuser priming centrifugal pump having a novel and efficient diffuser for both priming and pumping.

A further object of my invention is to provide a diffuser type centrifugal pump capable of dayin and day-out pumping service in an efficient manner.

A further object of my invention is to provide a diffuser type centrifugal pump vvherein the diffuser element is of novel design, arranged to increase priming turbulence atthe circumference of the impeller and yet to retain a relatively non-turbulent flow during pumping. f

These and other objects and advantages of my invention, which will be understood during a consideration of the following detailed description of a preferred physical embodiment, are attained, in part, with a closed diffuser associated with a closed centrifugal impeller, the diffuser passages being so constructed that alternate passages are of the same size and shape while adjacent passages are of dissimilar size and shape. Likewise, the separation distance of the diffuser element at the entrance to the `diffuser passage from the periphery of the impeller for alternate diffuser passages are alike while for adjacent diffuser passages the separation distance is dissimilar.' Thus, a maximum amount of turbulence results and, at the same time, the volute construction of the passages is maintained so that friction loss will be small consistent With the necessary transposition from velocity to pressure in the fluid.

The invention Will best be understood by consderation of thedetailed specification which follows, taken in conjunction with the drawings in which,

Figure lis a vertical cross-section view ofr a diffuser centrifugal pump employing the principles of my invention, and f' Figure 2 is a cross-sectional View through the pump of Figure 1 taken along lines 2 2.

Referring to the drawings, the centrifugal pump of my invention may include a pump casing or housing I0 which encloses an impeller 'Il fixed to the end of a pump shaft l2 extending through the packing lantern I3 and trunnioned in the outside bearing bracket i4, the lantern i3 forming an hermetically sealed closure member against the side of housing IIJ. Intake for the pump is taken at the suction entrance l on the left hand side, the flow of fluid being directed thence past the suction check valve IB to the closed entrance of a diffuser element l1, through which it is directed via aperture I8 to the central portion of impeller Il.

Centrifugal force, which is derived as the impeller rotates by contact of the fluid against the impellei; vanes ittends to throw ythe liquid outwardly from this 'impeller through the diffuser passages 2U and the priming holes 20', the latter of which are arranged somewhat according to the A. C. Stratton Patent 2,281,175. Diiusenpassages 20 are generally constructed in vlt to transform the flow from high ivelocity at low pressure to lower velocity andhigher pressure,

consistent with the requirement -fo' which pump is built, and to maintain low frictionlosses.- At exit from the diluser passages 20 and from primingholesJU, the'li uid `flows through the 'Dllmp easing l0 ahdinto Vtledischarge""utlet '21, theme 'pest me {cne'ek valve 22 interne :discharge linen. It wll'lbenot'ea that, 'in the' instance of the pump' illustrated, easing lo is sumei'ently large to forni asubstantial reservoir for "a 'supply for priming nula', altllio'ligliv it is te be u'rluersteod that any other suitable reservoir may be used willen', ri'or example, may' be' entirely separate f romthe pumping hous'ng. Further 'possibilities lnel'uue thjesupplementsry usee'f e fleet operl'd Ventilating air separator in series with 'the pllip ifi `adeoruallee uur une devices or eopending application, Serial Number 10,752, ld Iie'blxaryf25, 1'94'8', which vid 'tHe pumping 0f eindigas'lilteaelsedsystr 2i ieri lie 'sulisteifu'allytfigeet to tile fpph'eralfpofrjtidn ofthe 'i'rnielle'r and radiate thei'fn [with fward vv'oll'it'e 'efi'rvature.y At the sii'e "time, 'the sidefwalls dfpassaes'b are :agees e gaat. the ,the u serves to slow down the velocity of the -fluii 'during pumping Y'with ra minimum of "fricvt'ie'r'l'ia'nd eddyilg. v t v i 'of interesse, alternate diffuser' 'passages '2n 'of the 'saine "s`i`ze 'and 'shape 'while' adjacent besseres e'r'e bfjlfsslinilr size 'and entre As :shown ih Fig'r'e v2, 'there :are an feven AYtotal numbei* Vof passages, every alternate 'passage being Aa smaller ps'sg' and, likewise, 'every yalternate pess'ge is appl-"oiiir'ately `twice the s'iz'e of the sfallr `pasas.,ags.` I have fo'nd tlii's'two-to-'one a'tio `4to 'be 'desibleas a ygeneral rule although iaiitie'ns 'may f course be 'resorted to dependlng upon the-proportions of the pump, -thegu`ality '91. li'siulii, endlth Speed. .0f Ppretien- It will also be noted that yalternatei vanes'Zt' have the Isame ,slight operating clearance with respect to the peripheryof the impeller, while adjacent zvelues have dissimilar clearance, resulting in inter-communicati'onV betweengadjacent diiuser passages., the purpose of which will be herein- `after-understood. i 5

`Prillning -or port "holes 20' 'are' arranged approxllmatcl'y 'midway of th'e 'diffuser passages '20 and enter Vfrom the passage yinto the reserve liquid space withlncasing i0, -in accordance with the aforementioned patent to A. C. Stratton Number 2,281,175 issued April 28, 1942 for Priming Means for Self-Priming Pumps. As illustrated, port holes are -disposed only in the larger dilfuser passages serving to enhance the priming action, but they may also be provided in the smaller diffuser passages if conditions warrant. Further, the ports may be doubled or otherwise used in multiple depending upon the priming effect desired and upon the shape, size, and disposition of the diffuser passages and the valles.

In operation, assuming that the suction line is airbound and that a supply of liquid exists the pump reservoir, the reserve or priming fluid will tendhto flow toward the impeller in the diffuser passages until it strikes the rotating im- Vpelle'r to 'be thrown outwardly. I conceive that,

since the optimum conditions for fluid flow from the illp'eller dictate the adoption of volute curvesv for the diffuser vanes, counter-flowtoward the impeller from the passages defined by volute shaped varies will result in the greatest degree -of disturbance at the impeller to assist priming. At the Sametime, this disturbing effect lis multiplied by establishing interference from one passage to the next adjacent passage which I produce by the application of dissimilar pas- "sage widths and prescribed 'intercolnmunication 'between passages at the impeller periphery. yAs priming of the pump progresses, a more uniform 'condition of flow replaces the turbulence of Ythe rst stages of priming in the diffuser and flow becomes bi-directional with -a iluid and air a'dmiXture moving outwardly while a more dense priming 'fluid moves inwardly. By proportioning the lsize of the alternate passageways, 'the location of priming holes, and the separation 'of alternate diffuser varies for a particular pump 4and for'a particular set of pumping conditions, thisbi-directional flow may be effectively regulated to arrive at the most desirable priming cycle. VInherentlyy the volume characteristics of inilow land outflow in priming will diner, and 'while a two to one ratio has been referred to, Ythe s'i'ze of the alternate passages may be modlled if desiredy for improved overall priming effectiveness. Further priming will then rid the pump entirely of air and the pump will again reach a stage of continuous outflow from all of nthe "diffuser passages. Thus, during pumping, rthe Ido'r'iditicl'n's 'for 'fluid flow remain substantially 'according to good engineering principles while during priming the added splashing and eddying at the impeller periphery results in Van increased Vtendency to pick up and pump air Afrolfthe suction side of the pump and carryit todisch'arg'e.

s 4l'le'rii'lb'efo're noted, I have chosen a ratio of two-'to-one for the widths of adjacent passageswhile it is contemplated that other ratios may prove e'q'ually or V'more efficient for some pumpingconditions.H I further consider'that it may be desirable to produce'repetitite groups of vthree or more inter-communicating diffuserepassage 'patterns around the periphery of the-im- Apeller in pumps of large size, the important con- :understood that other styles of construction may vbe utilizedand that various ymodifications vand refinements may be resorted to, and that no limitations are intended other than as defined in the subjoined claims.

Having thus described my invention I claim:

1. In a self-priming fluid pump, in combination, a pump housing including a reservoir for a supply of reserve fluid, a suction inlet and a dis-charge outlet in the pump housing, a centrifugal impeller arranged for axial rotation within the housing to exert driving forces for advancing liquid from the suction inlet through the reservoir to the discharge outlet, said impeller having its center of rotation in communication with said suction inlet, and a diffuser xed intermediate of the periphery of the impeller and the reserve iiuid reservoir and containing a series of co-extensively radiating flow passages separated from each other by the use of curved vanes, alternate vanes being equally spaced from the periphery of the impeller but consecutive vanes being unequally spaced from the periphery of the impeller, and alternate passages being provided with ports for direct communication from the impeller to the pump reservoir.

2. In a self-priming fluid pump, in combination, a pump housing including a reservoir for a supply of reserve iluid, a suction inlet and a discharge outlet in the pump housing, a centrifugal impeller arranged for axial rotation Within the housing to exert driving forces for advancing liquid from the suction inlet through the reservoir to the discharge outlet, said impeller having its center of rotation in communication with said suction inlet, and a diffuser fixed intermediate of the periphery of the impeller and the reserve iluid reservoir and containing a series of cci-extensively radiating flow passages separated from each other by the use of curved vanes, the diffuser iow passages being alternately of equal size and alternately provided with ports for direct communication between the impeller and the pump reservoir, but consecutively of different size, the vanes being alternately equally spaced, but consecutively unequally spaced from the periphery of the impeller.

ALFRED S. MARLOW, JR.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,281,175 yStratton Apr. 28, 1942 2,292,529 LaBour Aug. 11, 1942 2,450,143 Howard et al Sept. 28, 1948 2,461,925 Rupp Feb. 15, 1949 FOREIGN PATENTS Number Country Date 440,679 Germany Feb. 11, 1927

Images