US2775350A - Filters - Google Patents

Description

H. A. JONES FILTERS Filed Dec. 28, 1953 Dec. 25, 1956 United States I Patent This invention is concerned with filters, more especially those known as Seitz filters such as are used inter alia for biological research and other laboratory work.

The smaller Seitz filter has found extensive use as a means of obtaining sterile solutions and it has recently been found very useful in the technique for the chromatography of sugars on charcoal. The conventional Seitz filter, however, is unnecessarily cumbersome. It is the main object of this invention to provide improved and simplified forms of Seitz filter, having fewer parts and giving a more even sealing pressure, which are relatively cheap to produce andin which the filter pads or the like may quickly be replaced. The invention also includes an improved method of filtration, using the new filters.

According to the invention av double-ended coupling memberis provided, adapted at its ends to be connected (as by screwing) the respective necks of two bottles or a likeicontainers, and having an internal flange, or apertured wall, and such coupling is adapted to be assembled onthe said containers, with one havinga Seitz pad or the like (with or without gauze) clamped between itself andlthe said flange or apertured wall and the other having-or not havingtas desired) "'a packing ring between itself and the flange or wall. In use, the substance to be filtered is placed in the container which is to have the Seitz pad or the like clampedag'ainst it, and after the'parts are secured together filtration is effected into the' oth er containen for example in. a centrifuge:

The improved method according to the invention com prises assembling the coupling member on to the receiver bottle, with the sealing ring in position if so required, placing a filter pad (and a gauze if necessary) in the open end of the coupling member, sterilising in an autoclave or the like, then attaching the other bottle (having the substance to be filtered) to the otherwise open end of the coupling and placing the whole unit in a centrifuge so that the receiver bottle swings outwards and the filtrate passes into it.

The coupling member may be of brass, heavily plated with say nickel and chromium, or may be of other suitable materials, and it will usually have a milled or knurled or other finger grip around the outside. Conveniently the coupling member is of the same external diameter as the body parts of the bottles, with a raised annular portion at the centre for gripping with the fingers.

In some forms the coupling member is of identical form at both ends, to receive two identical bottles, but in some cases one end may be adapted to receive a smaller or larger bottle than the other, or adaptors may be provided to enable a smaller or larger bottle to be coupled to the standard coupling member.

According to a further and preferred feature of the invention, in cases where the coupling member is provided with the said apertured wall, means is provided for guiding the filtrate away from the joint between the coupling member and the receiving bottle. In the more usual embodiments of this feature the small apertures in such wall are surrounded on the outlet side by a dea, 2,775,350 Patented Dem-25,

pending cylindrical wall or tube. -In another embodiment, such tube is .open at the top or entrance end and the apertures are in a closing wall at the bottom or outlet end of the tube, whereas in a third embodiment the said dividing wall is made concave or conical so as to extend into the outlet endof the coupling and so that the apertured portion is at a substantially lower level than the joint between the coupling member and the receiving bottle.

With these arrangements filtrate passing through the aperture in the dividing wall has no tendency or opportunity to. creep along the underside of that wall towards the bottle mouth, and thereby leakage is prevented.

The invention may be used with the so-called membrane filters, a non-rotatable washer or ring being provided between the membrane and the adjacent bottle, with or without an intermediate sealing ring of rubber or the like.

According to a preferred form of the invention the coupling is provided with an integral dividing portion formed to provide an outer annular portion for supportingelemen'ts and an annular portion extending therefrom towards one end of the coupling adapted for entrance into. the open end of a bottle and provided with apertures for directing liquid into said bottle.

Representative examples of the invention are illustrated in the accompanying drawing, wherein:

Fig. l is a part-sectional elevation of a filter assembly according to one form of the invention;

Fig. 2 is-a similar view of another and more preferred form of the invention; v

Fig. 3 is an exploded? view of the components of the assembly shown in Fig. 2;

Figs. 4-7 are sectional elevations of still other forms of coupling member; and j 8 is an exploded. view showing the components used with a membrane filter.

- Referring first to Fig. l, which showsa filter assembly having .two identical specimen bottles 1, 2, ,of ,known kind, with exteriorly screwedv months 1 2?, the coupling memberrisma one-piece integral unit of tubularforni,

having end portions 3,. 4, screw-threaded interiorlyjo receiverthe respective bottles, and having an inwardly.- projecting annular flange 5 at the centre of its length. The bottles are completely interchangeable. This flange 5 has a through bore 6 at the centre, and is recessed at 7 on each side, around the bore. A disc 8 of fine wire gauze is provided to lie in the uppermost recess 7, thereby covering the bore 6, and a Seitz pad 9 lies on top of the gauze and on the flange. The gauze 8 serves as a support for that part of the pad which lies over the orifice 6.

Externally, the coupling member is cylindrical, but at the centre it has a raised annular portion 10 which is milled or knurled, to serve as a finger grip and assist the screwing of the parts together tightly.

In use, the coupling member is screwed on to an empty specimen bottle 1, with a rubber ring 11 between the bottle and said flange 5 to form a seal. The gauze 8 and pad 9 are then placed in position in the open upper end of the coupling, and the assembly thus far effected is stood upright in an autoclave and sterilised. The coupling member of this sterile assembly is then screwed on to the other specimen bottle 2, containing the substance to be filtered, the pad 9 effecting a seal between that bottle and the said flange 5, and the completed assembly is then put into a centrifuge in such manner that the empty, sterile bottle 2 will swing outwards during centrifuging and receive the filtrate as it is forced through the pad 9.

Referring now to Figs. 2 and 3 the coupling member is an open ended tube as in Fig. 1, screwed interiorly at each end for connection to the bottles 1 and 2 but has integral dividing wall 12 centrally of its length. This wall 12 has a number of small through openings-13 near the centre and, on the outlet side, these are surrounded by a depending integral tube 14 which extends down almost'to the level of the bottom edge of the coupling.

The parts are'assembled and used in the same manner as in the'first example, except that the sealing ring 11 may be omitted. This is entirely optional. Also the gauze 8 may be omitted, though this is again optional. If a gauze is to be used, the top face of the wall 12 may be recessed to receive the gauze.

' In its preferred forms however, the invention comprises merely the parts shown in Fig. 3. The apertured wall 12 effectively supports the filter pad, and the depending flange or tube 14 prevents creep of the filtrate towards the outer wall of the coupling. There may be any desired number of through holes 13, and these may be of any suitable shape and in any desired arrangement.

Instead of the coupling member being a self-contained integral unit as shown, the wall 12 with attached flange 14 may be separately made and then secured in the outer tubular member, as by screwing and welding or brazing. However, the integral form is preferred as being more amenable to sterilisation.

In the modification shown in Fig. 4, the gauze 8 is omitted and the cavities in the two ends of the coupling member are separated by a wall 12 which has thesmall aperture 13 in it, but the depending flange 14 is omitted. In this case the sealing ring 11 (Fig. 1) would be necessary.

Fig. shows a variation of the arrangement shown in Figs. 2 and 3, in that the apertured dividing element is at the bottom end of the tube 14 instead of at the top. This allows the larger part of the filter pad being effective, over the whole cross section of tube 14. It may be necessary in this case to employ a gauze 8 as in Fig. 1.

A somewhat similar arrangement is shown in Fig. 6, where the dividing wall has a depression with conical sides, and with the apertures at its base. Here also the use of the gauze 8 may be desirable.

In order to avoid the use of the gauze and yet retain the maximum filter area, provision may be made for arching the filter pad to resist collapse. One such scheme is illustrated in Fig. 7, where the top face 15 of the annular supporting surface is inclined, and a packing ring 16 of triangular section is inserted between the pad nd the bottle 1. When the bottle is screwed home, the pad is retained in an arched form and therefore has an increased filtering area.

Referring finally to Fig. '8, there is a thin membrane filter disc 17, above which is a metal ring 18 having a tongue 18 to enter a slot 19 in the part 3. The top wall of the slot 19 may be inclined as shown to facilitate entry of the tongue 18 A sealing ring 20 of rubber fits around the upstanding flange 18* on the ring 18, to take the pressure of the bottle 1. By these means, the thin membrane filter can be'us'ed' without being distorted by the twist of the bottle in screwing the parts together.

In all forms, the coupling member may have external lugs or the like, or pivot pins, 'to engage corresponding parts in a centrifuge.

What I claim is:

A coupling construction for use in combination with a pair of specimen bottles and a filter comprising, a doubleended coupling having an outer peripheral wall and a partition extending transversely of the outer wall and being integral therewith at the midsection ofsaid coupling, the partition of said couplingbe'ing formed to have an outer annular portion and an'inner annular portion'concentrically thereof and having an'annular skirt depending axially therefrom toward one end of said coupling, the inner surface of the outer peripheral wall at opposite ends of said coupling being threaded for receiving the threaded open ends of the specimen bottles, the inner annular portion of the partition of said coupling being provided with openings for directing liquid within and through the confines of the inner annular portion of the partition.

References Cited in the file of this patent UNITED STATES PATENTS 1,052,391 Valerius et al. Feb. 4, 1913 1,140,758 Miller May 25, 1915 1,153,437 Miller Sept. 14, 1915 1,348,837 Allen Aug. 10, 1920 1,458,464 Byers June 12, 1923 2,110,237 Parsons Mar. 8, 1939 2,526,974 Schipanski Oct. 24, 1950 FOREIGN PATENTS 667,933 Great Britain Mar. 12, 1952 935,847 France Feb. 9, 1948

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