High-speed centrifugal filter assembly and method

• US 4,472,276 A
• Filed: 04/24/1981
• Issued: 09/18/1984
• Est. Priority Date: 07/24/1980
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Taylor, Dermot B.
• Primary Examiner(s): SPEAR JR, FRANK
• Application Number:
  US06/257,507
• Time in Patent Office: 1,243 Days
• Field of Search: 29/163.5 F, 29/457, 210/927, 210/448, 210/452, 210/350, 210/236, 210/479, 210/474, 210/476, 210/359, 210/361, 210/380 R, 210/382, 210/497.3, 210/493.1, 210/232, 233/2
• US Class Current: 210/236
• CPC Class Codes: B01D 2315/02 Rotation or turning
• CPC Class Codes: B01D 61/147 Microfiltration
• CPC Class Codes: B01D 63/16 Rotary, reciprocated or vibrated modules
• CPC Class Codes: B01D 65/08 Prevention of membrane fouling or of concentration polarisation
• CPC Class Codes: B04B 5/0421 pivotably mounted
• CPC Class Codes: B04B 7/16 Sieves or filters filters in general B01D; sieves in general B07B

Abstract

The filter assembly for swinging bucket type centrifuges includes a cylindrical filter body disposed within a filter body holder, both having hemispherical outer ends. The diameter of curvature of the filter body is smaller than the diameter of curvature of the holder allowing the contact surface between the holder and the body to be in the shape of a ring; centrifugal forces thus result in compression of the filter body thereby preventing cracking. The filter'"'"'s crenelated shape is provided through use of a plunger to apply force to the filter against the crenelated filter membrane forming member. The filter assembly also may have a chamber and a meniscus equalizing pore around the filter holder. The chamber and appropriately positioned pore prevent fluid from rising during centrifugation and contaminating the particulate. A method for installation includes providing a filter body with an open inner end and a rounded outer end, placing a filter plate in one recess therein and a filter membrane in the other recess therein and applying force to provide the membrane with a crenelated shape. Another method includes the additional step of positioning an insert within the body to form a fluid retaining cavity and a meniscus equalizing pore.

Claims

1. A filter assembly for use with high-speed centrifugation apparatus comprising:

a filter body adapted to be disposed within a filter holder in a centrifugal rotor, said filter body having an outer end of generally rounded configuration, with a radius of curvature greater than that of said filter holder and defining an interior chamber;

filter plate means disposed within said interior chamber, said filter plate means defining a plurality of fluid flow paths;

a filter forming member disposed within said interior chamber of said filter body and adjacent said filter plate means, said filter forming member having a crenelated periphery for contact with a filter membrane, to form said membrane to a crenelated configuration.

2. The invention as set forth in claim 1 wherein said multiplicity of crenelations in said filter forming member comprises a multiplicity of spherical sections adjoining one another and intersecting at substantially straight lines and having a substantially triangular cross-section with one leg of said triangle being arcuate.

3. The invention as set forth in claim 2 wherein said spherical sections are configured such that radii of the sphere of which said spherical sections comprise a portion substantially intersect the respective vertices of said triangle formed by said arcuate section of said triangular cross-section.

4. The invention as set forth in claim 1 further including a filter membrane disposed within said interior chamber of said filter body and in contact with said filter forming member.

5. The invention as set forth in claim 4 further including a filter membrane retaining member, said filter membrane retaining member being mountable upon said filter body to contact said filter membrane to hold the latter in place in said filter membrane forming member until surface tension of the liquid to be filtered is sufficient to hold said filter membrane in place.

6. The invention as set forth in claim 5 wherein said filter membrane retaining member defines a passage for accommodating a plunger member.

7. The invention as set forth in claim 5 further including a plunger guide member, said plunger guide member being mountable upon said filter body and defining a passageway to guide passage therethrough of a plunger member.

8. The invention as set forth in claim 5 further including a plunger member configured to be movable though said passageways in said plunger guide member to apply force to said filter membrane against said filter forming member for forming said filter membrane into a desired crenelated configuration.

9. The invention as set forth in claim 1 wherein said interior chamber of said filter body includes a chamber portion for receiving fluid passing through said filter plate means upon centrifugation.

10. The invention as set forth in claim 1 further including a filter membrane, having a crenelated configuration, disposed adjacent said filter plate means.

11. A high speed filter assembly for installation in a filter holder of a high speed centrifuge comprising:

a filter body defining a hollow interior and having an outer end fittable into said filter holder;

a filter insert member disposed within said hollow interior of said filter body and defining an interior chamber, said filter insert member having an outer end of generally rounded configuration, said filter insert member including means for contacting the inner walls of said filter body, said filter body and said filter insert forming an anti-capillarity chamber therebetween, said filter insert defining a meniscus equalizing pore connecting said interior chamber of said filter insert member and of said anti-capillarity chamber, said meniscus equalizing pore being positioned to equalize the level of fluid between said interior chamber of said filter insert member and said anti-capillarity chamber; and

filter plate means disposed in contact with said filter insert member and defining a plurality of perforations for passage therethrough of fluid.

12. The invention as set forth in claim 11 further including a filter membrane in contact with said filter plate member.

13. The invention as set forth in claim 12 wherein said filter membrane is configured to have a substantially flat, closed outer end and an open inner end and includes a peripheral wall in contact with the wall of said filter body.

14. The invention as set forth in claim 13 wherein said peripheral wall of said filter membrane is crenelated.

15. The invention as set forth in claim 12 wherein said anti-capillarity chamber is annular in form.

16. The invention as set forth in claim 15 further including a filter membrane positioning member mountable upon said filter body to hold said filter membrane in a selected position and further including a plunger guide member mountable upon said filter membrane retaining member and defining a passage therethrough for a plunger member, for guiding said plunger member.

17. The invention as set forth in claim 16 further including a plunger member movable though said passages in said filter membrane positioning member and said plunger guide member to thrust said filter membrane, when disposed upon said filter membrane positioning member, into said filter body, thereby forming said filter membrane into a desired crenelated configuration.

18. The invention as set forth in claim 11 wherein the filter body is composed of flexible material.

19. The invention as set forth in claim 11 wherein said filter holder of said centrifuge has a radius of curvature and wherein said filter insert member has a larger radius of curvature than said filter holder.

20. A method for providing a filter assembly for use in high-speed centrifugation wherein said filter assembly is placed within a filter holder rotatable at high rotational velocities comprising the steps of:

(a) providing a filter body having a hollow interior and fittable into said filter holder;

(b) positioning a filter insert member within said filter body to form a fluid retaining cavity and a meniscus equalizing pore connected thereto;

(c) disposing a filter plate member in contact with said filter insert member;

(d) disposing a filter membrane upon the open end of said filter body; and

(e) forcibly thrusting said filter membrane into said filter body against said filter plate member, whereby said filter membrane assumes a folded form whereby it has crenelated sides and a substantially flat bottom in contact with said filter plate member and said crenelated sides are in contact with the wall of the filter body.

21. The method as set forth in claim 20 wherein said filter body is of flexible material and further including the step of flexing the filter body portion in which the said formed membrane is disposed to set the folds in the membrane member.

22. The method as set forth in claim 20 wherein said thrusting of said membrane into said filter body and against said filter plate member is accomplished by use of a plunger member, said plunger member being thrust into said open end of said filter body to press said filter membrane member thereinto.

23. A filter assembly for high-speed centrifugation comprising:

a filter body having a peripheral wall, an outer end of generally hemispherical configuration, and an open inner end, said hemispherical outer end having a radius larger than that of a filter holder into which said filter body is placed for centrifugation, said filter body having a generally hollow interior and including a first interior shoulder extending from the wall of said filter body and including a second interior shoulder extending from the wall of said filter body and spaced from said first interior shoulder, the latter being closer to said hemispherical outer end of said filter body than the former, said filter body further including an interior side wall disposed between said first shoulder and said second shoulder to form a first recess, said second shoulder and the wall of said filter body forming a second recess, the diameter of said first shoulder being smaller than the diameter of said second shoulder, and the diameter of said first recess being smaller than the diameter of said second recess.

24. The invention as set forth in claim 23 further including a filter plate member disposed within said first recess, said filter plate member defining a plurality of perforations for passage therethrough of filtrate material and being supported by said first shoulder.

25. The invention as set forth in claim 24 further including a filter member disposed within said second recess, said filter member having a generally cup-shaped configuration and including a floor and a side wall, said filter member being in contact with said second shoulder and above said filter plate member, the side wall of said filter member being in contact with the wall of said filter body, the floor of said filter member having a diameter greater than that of said filter plate member.

26. The invention as set forth in claim 25 wherein the side wall of said filter member is laterally displaced from the periphery of the filter plate member.

27. The invention as set forth in claim 26 wherein said filter body defines a filtrate cavity outwardly of said first shoulder for reception therein of filtrate material passed thereinto through said perforations of said filter plate member from a liquid medium contained in said filter member, upon centrifugation.

28. The invention as set forth in claim 25 wherein the side wall of said filter member is crenelated.