Centrifugal cleaner apparatus and canister type arrangements thereof

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for application to a tubular shell to form therewith a centrifugal separating chamber comprising a body for insertion in one end of the shell, a peripheral surface portion of said body being formed for a bearing fit with an inner wall surface portion of the shell, one end surface portion of said body being adapted to position inwardly of the shell to form one end of the separating chamber and the opposite end surface portion of said body being arranged thereby to face outwardly of the shell, said body being formed to provide therein means defining a flow path including a flow restricting inlet in said opposite end surface portion thereof arranged to open outwardly therefrom in a sense axially of said body, said inlet and the opening therefrom being offset from the central longitudinal axis of said body and located to lie within the limits of the shell to which said body is applied and arranged to be generally parallel to said longitudinal axis, said flow restricting inlet being continued inwardly of said body by means arranged to define a flow restricting passage forming part of said flow path, said passage having one end communicating with said inlet and the other end communicating with said one end surface portion of said body, the arrangement enabling an introduction of a slurry, the contents of which are to be separated, to said flow path, in a sense axially of said body, and said passage being constructed and arranged to direct slurry from said inlet to move about and axially of said body in a controlled fashion and in exit from said passage to move over said one end surface portion of said body.

2. Apparatus as in claim 1 wherein the cross-sectional area of said flow restricting passage is maintained essentially constant within the limits thereof, said peripheral surface portion of said body includes a generally cylindrical portion, said body has a central axially directed second passage and said one end surface portion of said body includes a tubular projection which forms an axial extension of said central passage and defines therewith an overflow nozzle in connection with said body.

3. Apparatus as in any one of claim 1 wherein said one end surface portion of said body is formed to provide a helically developed flow channel opening outwardly therefrom which forms a direct continuation of said flow restricting passage, said passage is narrow in width and relatively deep and the narrowness of said passage is continued by said flow channel.

4. Apparatus as in claim 1 wherein, in the application of said body to the shell, said inlet is defined by a recess which communicates with said flow restricting passage by way of a lateral opening therefrom adjacent the innermost or base portion thereof.

5. Apparatus as in claim 1 wherein said peripheral surface portion of said body formed for a bearing fit with an inner wall surface portion of the shell to which the body is applied has a generally cylindrical configuration and the portion of said flow path defined by said flow restricting passage is formed in the outer peripheral surface of said cylindrically configured body portion at a location intermediate its said end surface portions.

6. Apparatus as in claim 1 wherein, within the limits thereof, said flow restricting passage has a crosssectional area the depth to width ratio of which is approximately 3 to 1.

7. Apparatus as in claim 1 wherein said flow restricting passage is arcuate in its longitudinal extent, which is less than 360.degree., is narrow in its lateral extent and relatively deep and is continued by a flow channel formed about said one end surface portion of said body, which flow channel has a rapid reduction in its depth from the one end thereof connected to said passage to that end which extends to the surface which is outermost on said one end surface portion of said body.

8. Apparatus as in claim 1 wherein said flow restricting passage is arcuate in a longitudinal sense and in this sense has an arcuate extent of substantially 90.degree..

9. Apparatus as in claim 1 wherein said flow restricting passage is extended by a channel created by the form of said one end surface portion of said body which forms therewith a spirally developed path the arcuate extent of which is substantially 450.degree..

10. Apparatus as in claim 9 wherein the said path is narrow throughout its length and the major extent thereof opens from said one end surface portion of said body.

11. Apparatus providing a centrifugal cleaner as in claim 1 including a tubular shell in combination with said body wherein said body is slip fit in one end of said shell and an inner wall surface portion of said shell provides an outer side wall portion of said flow restricting passage and said inlet, and said inlet, passage and a channel in said body form a continuous flow path the major portion of which is open to and faces outwardly of said one end portion of said body.

12. Apparatus as in claim 11 wherein said body includes a central through passage providing an overflow nozzle for the separating chamber which it caps and an extended portion of said flow path is narrow and relatively deep in comparison to its width.

13. A centrifugal cleaner installation comprising means defining an infeed chamber and a rejects chamber mounted in a relatively fixed axially spaced relation by structural members which are spaced to provide free access to a space which they bound, one or more centrifugal cleaner units, means for an operative slip fit coupling of said one or more cleaner units to and between said means defining the infeed chamber and the rejects chamber, said cleaner unit including means defining a separating chamber having an overflow end and an overflow end, the overflow end of said separating chamber being communicated with said infeed chamber by way of means defining a restricted inlet to a flow path which exits to said separating chamber, said inlet being directed in generally the same sense as the longitudinal axis of said separating chamber, said inlet being arranged to open laterally to a spiral inflow passage forming part of said flow path, which is directed axially and inwardly to the overflow end of said chamber.

14. An installation as in claim 13 characterized in that said centrifugal cleaner unit includes means defining a cap for the overflow end of said separating chamber, said inlet and said inflow passage are formed in said cap, the cross-section of said spiral inflow passage is substantially constant from adjacent said inlet to the surface of said cap which is innermost, and rapidly and relatively uniformly diminishes as to its depth in the said innermost surface portion of said cap, which defines the limit of said chamber at the overflow end thereof.

15. An installation as in claim 13 including means defining a discharge passage from the underflow end of said separating chamber and means in connection with said rejects chamber defining an extension of said discharge passage to which said centrifugal cleaner is end abutted and freely fit in the slip fit coupling thereof between said infeed and said rejects chambers, by means of which said separating chamber is communicated with said rejects chamber.

16. An installation as in claim 13 wherein said structural members are vertically extending laterally spaced rigidifying members which define an open framework within which said one or more centrifugal cleaner units are positioned with free access thereto.

17. Apparatus as set forth in claim 16 wherein said open framework is vertically oriented to position said infeed chamber at the top and said rejects chamber at the bottom thereof, and means defining an infeed passage for material the constituents of which are to be separated and/or cleaned is positioned centrally of said frame and connected to discharge to said means defining said infeed chamber, there being a plurality of said centrifugal cleaner units similarly slip fit to and positioned between said means respectively defining said infeed chamber and said rejects chamber and similarly communicating their separating chambers with said infeed chamber and said rejects chamber and said means defining said infeed chamber is constructed and arranged to receive material from said infeed passage and disperse said material in a flow laterally thereof and includes means defining exit passages therefrom arranged for a respectively direct and coaxial connection with feed inlets of the applied cleaner units whereby to cause the material to move from said infeed chamber to each cleaner unit in a direct axial flow.

18. Apparatus for providing an installation of centrifugal cleaners comprising means defining an infeed chamber, means defining a rejects chamber, means mounting said chambers in an axially spaced relation, one or more centrifugal cleaner units mountable in the space between said chambers, said chamber mounting means being an open framework arranged to provide free access for a lateral insertion of said one or more centrifugal cleaner units for positioning thereof in axial alignment with openings to and from said chambers, each cleaner unit being comprised of a tubular shell having an overflow end and an underflow end and means capping its overflow end to form therein a separating chamber, a restricted axially oriented inlet being defined at the outermost portion of said capping means and arranged to align with one of said openings in said means defining said infeed chamber, to receive directly therefrom, in a coaxial flow, the material to be separated, a flow restricting passage formed to follow and form an extension of said inlet having a discharge end which opens to an innermost surface portion of said capping means, which defines one end of said separating chamber, in an arrangement providing that the material to be separated or cleaned is caused to move to and through the separating chamber in a vortex-like flow pattern, said flow restricting passage being substantially constant as to its cross-sectional area and thereby determining the effective separation of materials which pass therethrough in the movement thereof to and through said separating chamber.

19. Apparatus as in claim 18 wherein said means defining said infeed chamber and its connections with each centrifugal cleaner unit applied are constructed and arranged to provide for movement of material therein to each cleaner unit by passing the material across the opening from said infeed chamber with which the restricted inlet of the cleaner unit is aligned, whereby to introduce the material to said cleaner unit by way of a direct line axial flow thereof from the infeed chamber to the cleaner unit.

20. Apparatus as in claim 10 wherein said capping means includes an outermost surface portion which has a generally planar configuration constructed and arranged for the positioning thereof in a sealing abutment with a wall portion of said means defining said infeed chamber to cause said axial inlet to form a direct restricted extension of said one of said openings in said means defining said infeed chamber with which it aligns.

21. Apparatus as in claim 18 wherein said axially oriented inlet has a pocket-like configuration a wall portion of which has an opening laterally thereof to one end of said flow restricting passage and said passage is extended at its other end, which is exposed to said separating chamber, by a flow channel at the innermost surface of said capping means, the portion of said flow channel adjacent said other end of said passage being relatively deep and said flow channel being sharply sloped at its base to quickly reduce in depth so as to provide that the materials leaving said passage will have a smooth rapidly moving flow which is inherently maintained as the material passes to and through said separating chamber in an induced vortex type flow pattern.

22. Apparatus as in claim 18 wherein said capping means is a separable body which is adapted for a bearing slip fit in the overflow end of said tubular shell.

23. Apparatus as in claim 18 including slip fit coupling means for operatively connecting and mounting each said centrifugal cleaner unit by a slip fit application thereof of means embodied in connection with one of said means respectively defining said infeed and said rejects chambers, said coupling means being constructed and arranged to accommodate an axial movement of the centrifugal cleaner unit to facilitate both the installation thereof and removal thereof from an operative connection to both said chambers.

24. Apparatus as in claim 18 wherein said means defining said infeed chamber includes spaced relatively facing wall portions between which materials to be separated or cleaned are delivered, one of said facing wall portions includes said openings for respective alignment with an axial inlet of a capping means of an applied centrifugal cleaner unit, said capping means having means defining, therein and in connection therewith, an outlet from the separating chamber of the centrifugal cleaner unit of which it forms a part which extends through, bridges said spaced wall portions, is sealed from said infeed chamber and serves to channel from said separating chamber a predetermined portion of the materials which are separated in passage through said separating chamber, means defines a discharge chamber for said predetermined portion of said materials to the side of said means defining said infeed chamber remote from said centrifugal cleaner units a discharge passage from which is directed through at least a portion of means defining an infeed passage which is connected to deliver materials to said infeed chamber.

25. Apparatus as in claim 24 wherein said means defining said discharge passage has at least a portion thereof positioned concentric with and in spaced relation to a portion of said means defining said infeed passage.

26. Apparatus as in claim 18 wherein a slip fit coupling is provided between said means defining said infeed chamber and the capping means of said one or more centrifugal cleaners, facilitating the slip fit application of said cleaners in the first instance.

27. Apparatus for providing an installation of centrifugal cleaners comprising means defining an infeed chamber, means defining a rejects chamber, means mounting said chambers in an axially spaced relation, one or more centrifugal cleaner units mountable in the space between said chambers, said chamber mounting means being arranged to provide free access for a lateral insertion of said one or more centrifugal cleaner units for positioning thereof in axial alignment with openings to and from said chambers, each cleaner unit being comprised of a tubular shell having an overflow end and an underflow end and means capping its overflow end to form therein a separating chamber, means defining a restricted inlet oriented axially and directed inwardly of the outermost surface of said capping means, arranged to align with one of said openings in the means defining said infeed chamber, to receive directly therefrom, in a coaxial flow, the material to be separated, said capping means including in the body thereof a relatively short flow restricting passage forming a continuation of said inlet and having a discharge end which opens to the innermost surface of said capping means, which defines one end of said separating chamber, in an arrangement providing that the material to be separated or cleaned is caused to move to and through the separating chamber in a vortex-like flow pattern, the means defining said axially oriented inlet having an opening thereto defined by means forming an extension thereof telescopically related to means defining a tubular extension of said one opening in the said means defining said infeed chamber which aligns therewith, and said means defining said infeed chamber being arranged to deliver material to said axially oriented inlet by a flow of said materials in a direction which is over said one aligned opening and in a sense generally transverse thereto.

28. Apparatus for providing an installation of centrifugal cleaners comprising means defining an infeed chamber, means defining a rejects chamber, means mounting said chambers in an axially spaced relation, one or more centrifugal cleaner units mountable in the space between said chambers, said chamber mounting means being arranged to provide free access for a lateral insertion of said one or more centrifugal cleaner units for positioning thereof in axial alignment with openings to and from said chambers, each cleaner unit being comprised of a tubular shell having an overflow end and an underflow end and means capping its overflow end to form therein a separating chamber, said capping means including at the outermost end thereof an axial inlet arranged to align with one of said openings in said means defining said infeed chamber, to receive directly therefrom, in a coaxial flow, the material to be separated, said capping means including in the body thereof a relatively short flow restricting passage forming a continuation of said inlet and having a discharge end which opens to the innermost surface of said capping means, which defines one end of said separating chamber, in an arrangement providing that the material to be separated or cleaned is caused to move to and through the separating chamber in a vortex-like flow pattern, said means defining said infeed chamber including spaced relatively facing wall portions between which materials to be separated or cleaned and delivered, one of said facing wall portions including said openings for respective alignment with an axial inlet of a capping means of an applied centrifugal cleaner unit, said capping means having means defining, therein and in connection therewith, an outlet from the separating chamber of the centrifugal cleaner unit of which it forms a part which extends through, bridges said spaced wall portions, is sealed from said infeed chamber and serves to channel from said separating chamber a predetermined portion of the materials which are separated in passage through said separating chamber, said means defining an outlet in and in connection with said capping means including telescopically related pipe-like structures one of which projects through said infeed chamber and has a slip fit with another which defines the portion of said outlet in said capping means, and one of said facing wall portions including therein, adjacent said one pipe-like structure, one of said openings which align with the axial inlet in the related centrifugal cleaner unit in which is connected one end of a tube segment arranged to project and to slip fit with and form an extension of the means defining said axially oriented inlet, providing thereby that the said related centrifugal cleaner unit may be slip fit to couple the same with said one pipe-like structure and said tube segment and in a predetermined orientation with reference to said means defining said infeed chamber.

BACKGROUND OF THE INVENTION

This invention relates to improvements in centrifugal cleaners and/or separators and in canister type installations thereof which render such devices economical to fabricate, more efficient and satisfactory in use, adaptable to a wide variety of applications and unlikely to malfunction. Such devices have a wide variety of application not the least of which is their important application to the processing of pulp. In such applications their use is to separate and classify the contents of a pulp slurry into accepts and rejects so that the pulp fibers which are eventually utilized in a paper making, board making or similar process will be clean and well defined and retain optimal strength for the purpose intended.

While the art in question has been highly advanced, it has far from reached a peak. The structure and concepts involved are so simple that the solution of problems encountered in its developing use has proven to be exceedingly difficult, particularly as related to the needs evidenced in the development of associated production techniques in related fields. Basic to the needs and solution of problems evidenced in the use of heretofore known centrifugal cleaners has been the necessity of finding a way to increase their throughput while maintaining and preferably increasing their cleaning efficiency. A lower pressure drop with increased throughput has also been a primary goal of researchers. That a solution to such a problem would be important, particularly in pulp processing, has been well recognized for some time since inherent in the solution would be an ability to achieve better results in a single pass through a centrifugal cleaner. Under such conditions not only would the processing of pulp be expedited but a given processing installation, for a given application and output, would require a smaller number of cleaners, thereby minimizing capital investment, installation and maintenance requirements and costs.

It is to the solution of the foregoing problem that the present invention has been successfully directed.

In addition to the foregoing, other problems have been evidenced in the application of multiple centrifugal cleaners or separators in canister type installations. In such installations, the form and nature of the conventional construction of centrifugal cleaners and/or separators has made them difficult and time consuming to install, particularly in a manner to achieve a compact package. Not only has set up time for a canister type installation been excessive but the nature of the packages so provided have presented plumbing difficulties and high cost in their maintenance. Even more important, prior art canister type installations have not been readily adaptable to a change of application. Such problems are also solved by the present invention.

As far as the present inventors are aware, the following patents are those most pertinent to the present invention:

______________________________________ U.S. 3,724,674 Loison April 3, 1973 3,105,044 Troland Sept. 24, 1963 2,719,631 Vicard Oct. 4, 1955 1,990,943 Horne et al Feb. 12, 1935 2,956,679 W. Hoffmann Oct. 18, 1960 3,598,731 R.H. Frykhult et al Aug. 10, 1971 3,717,255 Rowland et al Feb. 20, 1973 3,335,860 J. Baxter,Jr. Aug.15, 1967 3,543,931 Edward L. Raestatter Dec. 1, 1970 Canada 677,785 Freeman et al Jan. 14, 1964 588,344 Freeman et al Dec. 8, 1959 Norway 103,815 Voith Feb. 22, 1964 ______________________________________

While the noted patents flirt, to some extent, with the noted problems, they do not afford either the particularly advantageous solutions or the construction for centrifugal separators and/or cleaners and canister type installations thereof as achieved by the present invention.

SUMMARY OF THE INVENTION

For convenience of disclosure, the phrase "centrifugal cleaner", as herein employed, refers to any and all devices having the nature of centrifugal type cleaners or separators.

One development of the present invention is a structural arrangement providing simple and highly improved "top inlet" centrifugal type cleaners featuring a unique head portion which may be readily interchanged in accordance with the changing needs of a particular installation or application. In accordance with the invention this head may be readily applied (in preferred embodiments without tools) to form an axial extension of one end of a conical or other configured shell which defines therewith a centrifugal separating chamber. The end of the head which positions outermost of the separating chamber has a feed inlet opening the direction of which is generally the same as that of the central axis of the head and the central longitudinal axis of the associated separating chamber. The inner end of the relatively short inlet passage defined by the feed inlet opening is merged with and opens laterally to a helically configured flow channel the base of which faces away from the head end which embodies the inlet opening and forms a guiding surface for inflowing material to move through the head to the associated separating chamber. At the end of this flow channel which connects with the inlet passage, the head is formed to produce therein a flow restricting passage of short longitudinal extent which forms a bridge between the inlet and the following portion of the flow channel which in accordance with the invention is exposed to and forms part of one end of the separating chamber which it caps. In the example illustrated the arcuate extent of the flow restricting passage is approximately 90.degree. and its depth to width ratio is maintained in the neighborhood of 3/1 for maximum performance while the exposed portion of the flow channel extends approximately 360.degree.. In the preferred embodiment illustrated the flow channel is relatively deep until the terminal portion thereof from which the inflowing material is discharged to the separating chamber. Thus, the invention head provides a "roof" surface for the separating chamber which has a spiraling channel-like configuration and the material to be separated is led through the head in an axial sense. This arrangement is in distinct contrast to the construction afforded in use of a conventionally provided tangential inlet to the body or head of a centrifugal cleaner. Moreover it provides distinct and unexpected advantages.

Input to the centrifugal cleaners of the invention may be achieved merely by flowing any fluid, liquid and/or solid composite, elements of which are to be separated, over and across one end of its inlet passage or an axial extension thereof. The arrangement is such that pressure or power necessary for throughput of a given amount of material to be separated is minimized and throughput per unit time may be significantly increased, if so required. The top inlet arrangement also permits, where desired, a larger inlet opening than is normally possible with the tangential inflow construction of prior art cleaners. The invention construction also minimizes energy losses and undesirable side effects on the contents of a flow directed to the shell attached to the head, within which shell, per se, the orbiting of the materials introduced is smoothly developed in a natural manner. It has been found that the cleaning or separating efficiency of a centrifugal cleaner embodying the invention concepts is significantly enhanced by the arrangement here provided.

Of particular importance in preferred embodiments of the invention cleaner is the narrow relatively deep channel which is provided for inflowing material. This permits a very quick movement of undesirable foreign material to the outside wall of the channel. In the embodiment illustrated the cross sectional area of the enclosed portion of the passage in the cleaner head is maintained constant, with a resultant reduction in pressure drop in the transition of the material from the round inlet portion of the opening through the head to the portion which has a rectangular cross section. The enclosure of the axially extending helically formed flow channel in the head as here provided eliminates the possibility of heavy material cycling at the top of the cleaner and causing the excessive wear which is a problem in conventional cleaners.

The use of a long narrow helical inlet in preferred embodiments permits the use of larger inlet and discharge openings due to the increased effectiveness of dirt removal which is enabled by the invention features. A result of this construction is an increase in the capacity of a cleaner of a given size.

Apart from the foregoing, the invention concepts enable a highly improved plug-in type centrifugal cleaner assembly which requires neither supply hoses nor clamps. This last minimizes the normally anticipated time, labor and cost in installing a canister type package of centrifugal cleaners. In a preferred embodiment, a canister type installation in accordance with the invention resembles a carrousel. In the arrangement illustrated the invention units are installed between two slurry carrying chambers to provide a clean, neat compact highly efficient package lending ease and simplicity in its setup, maintenance and use.

The preferred embodiments of the canister-type package per the present invention feature sloping dividers forming the base of the supply chamber. This provides for ease of cleaning as well as maintaining a velocity in the delivery of materials to the supply chamber which is sufficient to prevent solids from settling. The canister type package lends particular ease in reference to enabling the application of vacuum to both the accepts and rejects of the cleaner.

A primary object of the invention is to provide improvements in centrifugal cleaners and separators and canister type packages thereof rendering them simple to fabricate, more efficient and satisfactory in use, adaptable to a wide range of applications and unlikely to malfunction.

Another object of the invention is to provide centrifugal type cleaners having an increased throughput capacity and achieving a cleaning efficiency which is proportionately greater than that achieved by the centrifugal cleaners of the prior art which have a lesser throughput capacity.

A further object of the invention is to provide unique centrifugal type cleaners featuring an improved head construction having an inlet the opening to which may be fed by passing the material to be separated over and/or across said opening.

An additional object of the invention is to provide improvements in canister type installations of centrifugal cleaners or separators which may be assembled and serviced essentially without tools.

Another object of the invention is to provide centrifugal cleaners, elements and canister type packages thereof possessing the advantageous structural features, the inherent meritorious characteristics and the means and mode of use herein described.

With the above and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviously not necessarily the only form of embodiment of the invention,

FIG. 1 illustrates a canister type cleaner in accordance with the present invention embodied in a package having a carrousel form, the construction being generally diagrammatically illustrated in a vertical sectional view wherein parts are eliminated for clarity of disclosure;

FIG. 2 is a generally diagrammatic view showing a fragment of the top of the construction of FIG. 1, parts being partially eliminated for clarity of disclosure;

FIG. 3 is a fragmentary vertical section (relatively enlarged) of the head portion of a single cleaner, as embodied in the construction of FIG. 1;

FIG. 4 is a fragmentary sectional view (relatively enlarged) of a portion of a single cleaner taken on line 4--4 of FIG. 1;

FIG. 5 is a view similar to that of FIG. 4 showing a modification of the construction there illustrated;

FIG. 6 is a top view of the head of a preferred embodiment of a centrifugal cleaner in accordance with the invention, such as utilized in the installations of FIGS. 1 and 10;

FIG. 7 is a side elevation view of the head taken on line 7--7 of FIG. 6 with its housing removed;

FIG. 8 is a fragmentary view taken on line 8--8 of FIG. 6 showing the head in an installed position;

FIG. 9 is a bottom view of the head shown in FIGS. 6 and 7;

FIG. 10 is a view similar to FIG. 1 showing a modification of the package there illustrated; and

FIG. 11 is a fragmentary sectional view illustrating a further modification of a package per the present invention.

Like parts are indicated by similar characters of reference throughout the several views.

FIGS. 3 to 9 illustrate a basic element of preferred embodiments of centrifugal cleaners in accordance with the present invention, in the form of an easily applied and easily replaceable head 10. As seen in FIGS. 3 and 7, the head 10 caps and forms an axial extension of the head end of a shell 11 which defines therewith a centrifugal separating chamber 12. The shell 11 may have various tubular configurations but for the purposes of the present disclosure it is illustrated to have an upper or head end portion 13 which is cylindrically configured and a lower end 13' which is conically convergent to its projected extremity. The latter is truncated to define a rejects or discharge opening 14.

The head 10 is molded or cast of plastic or such other material as may be suitable for the intended application. The main body portion 15 thereof has a generally cylindrical outer configuration and includes a central axially directed passage 16 extended at one end by a relatively thin walled tubular projection 17 formed to resemble the entrance end of a bell type overflow nozzle. The opposite end of the passage 16 is axially extended by a tubular projection 19 paired and integrated, at one side thereof, with a second generally tubular projection 21 defining an entrance to a flow channel formed in and extended through the main body of the head 10. The base ends of the projections 19 and 21 merge with a planar surface 20 extending transversely of and defining one end of the body portion 15. The outer periphery of the surface 20 is radially extended by a circular flange 22 forming an external projection from the outer surface of the body portion 15.

In its application, the head 10 is inserted in the head end 13 of the shell 11, with the projection 17 as its leading end. The arrangement is such to provide that the body portion 15 nests interiorly of the shell with its outermost cylindrical surface portions bearing on the inner wall of the shell and its flange 22 extended over and seated in end abutted relation to a similar flange 11' rimming the opening to the head end of the shell. Suitable sealing means may be applied between the flanges 22 and 11', if such is deemed necessary, whereupon these flanges will be simply interconnected by the application of a clamping band 23. The band 23 is generally U-shaped in cross section and conventionally constructed and applied to encompass, contain and clamp together the abutted flanges 22 and 11'. Since the detail of the clamping band 23 is conventionally contrived and well known to those versed in the art, such detail is not further described.

The innermost end of the tubular projection 21 opens to a pocket or recess 24 directed inwardly of the body portion 15, the opening to which pocket is essentially in a transverse plane of the head which is occupied by the surface 20. The direction of the pocket 24 is in a sense parallel to and it is spaced radially outward from the central longitudinal axis of the head. The pocket 24, which is outwardly extended by the projection 21, defines a feed inlet to the flow channel formed in the body portion 15.

Adjacent its base 26, the peripheral wall of the pocket 24 has an opening 28 communicating its interior with the entrance end of the flow channel 30 in the body portion 15. The channel 30 is helically configured and is formed in and about the outer periphery of the body portion 15. In the orientation shown in the drawings, the base surface 32 of the channel 30 is uppermost and facing in the direction of that portion of the head incorporating the projection 17. The forming of the channel 30 produces on the exterior of the body portion 15 a wall structure 34 which provides an extension of the base of the pocket 24. The structure 34 extends outwardly, transversely of and in bridging relation to the channel 30, in an underlying generally spaced relation to the surface 32. The surface 32 is itself helically configured and is formed, in part, by the surface portion of the wall structure 34 which faces in the direction of the projection 17. The arcuate extent of the surface of the structure 34 which faces the surface 32 is relatively short and terminates about 90.degree. from that point at which it connects to the base 26 at the opening 28. The inner wall surface of the shell 11 provides an outer side wall for the channel 30 when the head 10 is inserted in the shell while its opposite and parallel side 31 is provided on the body portion 15 in a manner believed clear from the drawings. The arrangement described provides a restricted flow passage within the limits of the wall structure 34 which communicates at one end with the pocket 24 and at the other end with that portion of the flow channel in the head which is beyond the wall structure 34. Beyond the wall structure 34 the channel has an arcuate extent of approximately 360.degree.. This 360.degree. portion of the channel opens at its bottom from the discharge face 33 of the main body portion of the head 10 and the channel is thereby exposed to the interior of the separating chamber 12 when the shell 11 is capped by the head 10.

Considering that the head 10 has been inserted in the shell as shown in FIG. 3, channel 30 has a generally rectangular cross section and in accordance with the present invention the height or depth of the channel with respect to its width, in the restricted flow passage portion thereof which connects the pocket 24 with the exposed portion of the channel, is at a ratio of approximately 3 to 1. Within this restricted flow passage the cross sectional area of the channel is essentially constant, thereby avoiding a resultant reduction in pressure drop in