US3089423A

US3089423A - Corrosive resistant pump

Info

Publication number: US3089423A
Application number: US71548A
Authority: US
Inventors: Samuel H S Raub; Edwin S Malkin; William J Alton
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1960-11-25
Filing date: 1960-11-25
Publication date: 1963-05-14
Anticipated expiration: 1980-05-14

Description

y 14, 1953 s. H. s. RAUB El'AL 3,089,423

CORROSIVE RESISTANT PUMP Filed Nov. 25, 1960 2 Sheets-Sheet 1 INVENTORS SAMUEL H. S. RAUB EDWIN S. MALKIN WILLIAM J. ALTON A T TORNEV May 14, 1963 s. H. s. RAUB ETAL CORROSIVE RESISTANT PUMP 2 Sheets-Sheet 2 Filed Nov. 25, 1960 INVENTORS SAMUEL H. 5. RAUB EDWIN S. MALKIN Wll.

LIAM J. LJZQN w! ATTORNEY United States Patent 3,089,423 CORROSIVE RESISTANT PUMP Samuel H. S. Raub, Bay Village, Ohio, Edwin S. Mallqn,

Wilton, Conn., and William J. Alton, Cleveland, Ohio,

assignors to Union Carbide Corporation, a corporation of New York Filed Nov. 25, 1960, Ser. No. 71,548 Claims. (Cl. 103-87) This invention relates to corrosive resistant centrifugal pumps composed, for example, of impervious graphite for use specifically with corrosive liquids, and more particularly it concerns improvements in pumps of this character.

A corrosive resistant centrifugal pump which has enjoyed great success for transporting corrosive liquids in the chemical industry is disclosed and claimed in United States Patent No. 2,858,768, issued to W. M. Gaylord, in, et al. on November 4, 1958. Difficulty, however, has been encountered with a pump of this type owing principally to the over-zealousness of the customer to perform proper maintenance upon the pump. For example, the customer when making an inspection of the pump commonly may find a slight amount of leakage resulting from normal wear of the rubbing parts of the seal assembly. It has been the customers practice to tighten all the adjustments provided for the seal assembly mainly because the construction of the assembly is such that it is difiicult to know through which of its parts leakage has occurred. This practice has at times brought undue pressure to bear upon the parts of the seal assembly which interferes with their proper function, if not eventually causing their fracture, they being composed of impervious graphite, for example. Another difiiculty has been that of preventing liquid leakage from coming into contact with metal parts of the pump and corroding them, and of properly cooling the rubbing parts of the seal assembly in order to prevent abnormal wear during operation of the pump.

It is therefore the principal object of the invention to simplify and improve upon the construction of the seal assembly for pumps of the above referred type.

A more specific object is to provide for greater facility on the part of the customer to detect even the slightest leakage from the pump and through what parts of the assembly leakage has occurred and also to provide for more convenient adjustments for the customer to make in order to eliminate leakage, even while the pump is still operating.

Another object is to provide for entrapment of leakage which may occur within the seal assembly and for carrying such leakage away without contact with metal parts of the pump.

Still another object is to provide for flushing of the seal assembly with a coolant in order to prolong the wear life of rubbing parts of the assembly.

Yet another object is to provide for fewer metal parts to be used within the seal assembly than heretofore employed.

These objects are attained by the invention which comprises an improved seal assembly for a corrosive resistant centrifugal pump of the above referred type. The seal assembly is composed of a corrosive resistant material, for example, impervious graphite, and comprises a rotary seal ring secured to a shaft sleeve provided onto the shaft which drives the pump and a stationary seal ring mounted within the volute cover of the pump, the rotary and stationary seal rings providing therebetween a primary seal, and a non-rotating seal ring adaptor secured to the stationary seal ring by an adjustable metal follower plate. The adaptor provides an annular chamber for entrapping leakage through the primary seal and also provides secondary seal for the pump operable through rotation of the "ice shaft. Drainage means are provided to the seal ring adaptor together with means for a coolant.

1n the drawings:

FIG. 1 is a perspective view of a corrosive resistant centrifugal pump embodying the invention;

FIG. 2 is a vertical elevation partially in section of the pump shown in FIG. 1;

FIG. 3 is an enlarged detail of a portion of FIG. 2;

FIG. 4 is an enlarged perspective view of a part only of the shaft sleeve shown in FIG. 2;

FIG. 5 is a perspective view of the follower plate for mounting of the seal ring adaptor shown in FIG. 2; and

FIG. 6 is a perspective view of a rubber compression ring employed in conjunction with the follower plate shown in FIG. 5.

Referring to the drawings, there is shown a corrosive resistant centrifugal pump of the type referred to above but embodying the principles of the invention. As there shown, the pump comprises a volute casing V and cover C both of impervious graphite, for example, which are supported by a unitary metal casting, preferably iron, comprising a motor engaging flange B, a volute supporting flange F, and struts H therebetween, forming a hollow open sided barrel shaped casting. The motor engaging flange B is bolted to the frame of a motor M mounted on a foundation N. The volute casing V and cover C are bolted between the'flange F and a metal cover flange T. A discharge flange G is bolted to the top of flanges F and T, and a suction nozzle Z is bolted to the cover flange T. The flange F and cover flange T have cast holes for bolts 12, and both have T slots 20 receiving standard square head bolts for the discharge flange G. The cover flange T has similar slots 22, for mounting the suction nozzle Z.

The motor M has a motor shaft D on which is sleeved an impeller shaft S of stainless steel. The impeller shaft S passes through registered central apertures in the flange F and volute cove-r C and has secured thereto an impervious.

graphite impeller I which rotates inside the volute casing V. Thus, it will be seen that the pump is of a type which fastens to the frame of the motor and uses the bearings of the motor, it having none of its own.

The motor shaft D is hollow and is. mounted in motor bearings 2-4 in the motor frame, and the impeller shaft S has a close tolerance slip flt over an extension provided on the motor shaft, seating on and keyed to milled shoulders 26. A drawbolt 28 having its head outside of the motor passes through the hollow motor shaft D and is screwed into threads 30* within the bored end of the impeller shaft S, thus providing for easy removal of the impeller and its shaft. to the impeller shaft S in any conventional fashion, for example, by threading it on.

In accordance with the invention, the pump is provided with a seal assembly liquid-tightly secured within the volute cover C as shown in FIGS. 2 and 3. As shown, a shaft sleeve 34 of impervious graphite is provided-onto the impeller shaft S and separates the shaft from the seal assembly. The shaft sleeve 34 has an enlarged diameter end provided with threads onto which is secured the impeller I, as at 36. A rotary seal ring 38 of impervious graphite similarly is secured onto the shaft sleeve 34 behind the impeller I and is of a diameter slightly less than the registered aperture in the volute cover C so as to rotate freely therein.

The rotary seal ring 38 rotates against a stationary seal ring 40 also composed of impervious graphite, the rubbing interfaces of which provide a primary seal for the pump. The stationary seal ring 40 is partly secured within the volute cover C by a gland nut 42 threaded into the cover, as at 44. A packing box 46 composed, for example, of

corrosive resistant plastic gaskets, is compressed by the I The impeller I may be mounted,

3 gland nut 42 and prevents against leakage between the stationary seal ring 46 and volute cover C.

Mounted behind the stationary seal ring 40 is an impervious graphite non-rotating seal ring adaptor 50. The adaptor 50 has an inside diameter larger than the diameter of the shaft sleeve 34 and defines an annular chamber 52 for entrapping leakage. At its outer end, the adaptor 50 has a reduced diameter neck providing a close tolerance but free rotating fit with the shaft sleeve 34- which passes through it. The adaptor 50 is keyed to the stationary seal ring 40 through pins 54 and fitted over the neck of the adaptor 50 is a metal follower plate 56 secured to the metal flange F by bolts, shown in broken lines in the drawing. The follower plate 56 prevents rotation of both the stationary seal ring 40 and adaptor 50 and secures them tightly within the volute cover C. A rubber compression ring 58 dampens vibration of the follower plate 56 and reduces stress upon the adaptor 50.

The shaft sleeve 34 at its outer end has spiral grooves 60 whose helix is directed opposite to rotation of the sleeve with the impeller shaft S as shown in FIG. 4. The spiral grooves 60 in conjunction with the close tolerance but free rotating fit of the shaft sleeve 34 within the neck of the adaptor 50 actually provide a pumping action which in effect is a secondary seal for the pump. A preferred contour for the spiral grooves 60, as best shown in FIG. 3, consists of a rounded bottom V shaped groove in which the side of the groove nearest the impeller is the longer.

Drainage means 70 are provided to the adaptor 50 and serve to carry off leakage from Within the chamber 52 without contact with metal parts of the pump. Inlet means 72 may also be provided for flushing the chamber 52 with a coolant, for example, water, in order to prevent Wear of the rubbing surfaces of both the rotary and stationary seal rings 38 and 40.

The collection of liquid drainage through drainage means 70 is an indication to the customer operating the pump that tightening of the seal assembly is needed. This can be quite simply achieved by tightening down upon the bolts which secure the metal follower plate 56 to the flange F. Similarly, leakage through the packing box 46, in dicated by the presence of leakage on the outside surfaces of the seal assembly, can be eliminated by tightening of the gland nut 42. To carry away from the plate F such leakage as may occur past the packing box 46, the cover C is provided with a drip lip 76. For a similar purpose, the adaptor 50 is also provided with a drip lip 78 at its outer end. Thus, it will be appreciated that a customer operating the pump has greater facility for observing leakage from the pump upon periodic inspection and for determining the several sources from which it may occur, and is also provided with more convenient adjustments for eliminating leakage, even while the pump is still operating.

It will, of course, be understood that various adaptations and modifications of the pump herein described may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. In a corrosive resistant pump including a hollow metal casing having a volute support flange and a motor engaging flange, a volute casing and cover of a corrosive resistant material mounted to said volute support flange, a motor mounted to said motor engaging flange and an impeller within said volute casing secured to a shaft driven by said motor; the improvement which comprises a seal assembly of a corrosive resistant material comprising, in combination, a shaft sleeve provided onto said shaft and rotatable therewith, said shaft sleeve having spiral groove means provided thereon at an end remote from said impeller, a rotary seal ring secured to said shaft sleeve and a stationary seal ring mounted within said cover, said rotary and stationary seal rings providing therebetween a primary seal for said pump, a seal ring adaptor positioned to said stationary seal ring, said adaptor being of a dimension larger than said shaft sleeve and providing therewith an annular chamber for entrapment of leakage through said primary seal, said spiral groove means on said shaft sleeve cooperating through a close but free running fit with said adaptor to define a secondary seal for said pump operable through rotation of said shaft, and means for preventing rotation of both said stationary seal ring and said adaptor and for securing them within said volute cover.

2. A corrosive resistant pump as defined by claim 1 in which said adaptor is provided with drainage means.

3. A corrosive resistant pump as defined by claim 1 in which said adaptor is provided with inlet means for a coolant.

4. A corrosive resistant pump as defined by claim 1 in which said corrosive resistant material is impervious graphite.

5. A corrosive resistant pump as defined by claim 1 in which said means for preventing rotation of said stationary seal ring and said adaptor comprises a metal follower plate secured to said metal casting.

6. A corrosive resistant pump comprising, in combination, a hollow metal casting having a volute support flange and a motor engaging flange, a volute casing and cover of a corrosive resistant material, a metal cover flange, said volute casing and cover being mounted between said cover and support flange, a motor mounted to said motor engaging flange and having a motor drive shaft, an impeller shaft driven by said motor drive shaft, a shaft sleeve of a corrosive resistant material provided onto said impeller shaft and rotatable therewith, an impeller secured to one end of said shaft sleeve within said volute casing, said shaft sleeve having spiral groove means provided thereon at an end remote from said 7 impeller, the helix of said spiral groove means being directed opposite to rotation of said impeller shaft, a rotary seal ring secured to said shaft sleeve and a stationary seal ring mounted to said cover, said rotary and stationary seal rings being composed of a corrosive resistant material and providing therebetween a primary seal for said pump, a seal ring adaptor of a corrosive resistant material keyed to said stationary seal ring, said adaptor being of a dimension larger than said shaft sleeve and providing therewith an annular chamber for entrapment of leak age though said primary seal, said spiral groove means on said shaft sleeve cooperating through a close but free running fit with said adaptor to define a secondary seal for said pump operable through rotation of said impeller shaft, a metal follower plate mounted to said adaptor and secured to said metal casting for preventing rotation of both said stationary seal ring and said adaptor, and drainage means provided to said adaptor for carrying leakage out of said chamber without contact with metal parts of said pump.

7. A corrosive resistant pump as defined by claim 6 in which said adapter is provided with inlet means for a coolant.

8. A corrosive resistant pump as defined by claim 6 in which said follower plate is insulated from said adaptor by a rubber compression member.

9. A corrosive resistant pump as defined by claim 6 in which said stationary seal ring is sealed against leakage within said volute cover by a packing box and in which said packing box is secured within said volute cover by a gland nut.

10. A corrosive resistant pump as defined by claim 6 in which said corrosive resistant material is impervious graphite.

References Cited in the file of this patent UNITED STATES PATENTS