US3732981A

US3732981A - Filtration column

Info

Publication number: US3732981A
Application number: US00068710A
Authority: US
Inventors: M Mendelsohn
Original assignee: Bio Rad Laboratories Inc
Current assignee: Bio Rad Laboratories Inc
Priority date: 1970-09-01
Filing date: 1970-09-01
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

A column for use in filtering a fluid wherein a tubular body adapted to contain a filter such as a resin material, has an upper open end for receiving the fluid to be filtered and a fluid passage extending to its lower end. Means is integral with the body for normally closing the lower end thereof. A line of weakness is disposed at the junction of the lower end of the body and the closing means and such lower end can be opened by grasping the closing means and moving it back and forth to cause fatigue of the material of the body and allow separation of the closing means therefrom, thereby leaving an opening at said lower end.

Description

United States Patent 1191 Mendelsohn 1 May 15, 1973 54] FILTRATION. COLUMN 3,509,879 5/1970 Bathish et al ..l28/272 2,750,068 6/1956 Platt, Jr ..22()/27 [75] Inventor 2 Dal) 829,178 8/1906 Stegmaier ..215/32 [73] Assignee: Bio-Rad Laboratories, Richmond, Primary Examiner-551mm Zahama Califv Assistant Examinerf gQalvetti A ttorney-Townsend & Townsend [22] F1led: Sept. 1, 1970 21 Appl. No.2 68,710 ABSTRACT A column for use in filtering a fluid wherein a tubular 52 us. (:1. ..210/94, 128/272, 210/282 body adapted to Contain a filter Such as a resin materi- 51 1m. (:1. ..B0ld 23/20 all has open end receiving the fluid be 58 Field 01 Search ..210/94 233 240 filtered and fluid Passage extending to its 21O/288, 128/272, 220/27, 213/32 Means is integral with the body for normally closing the lower end thereof. A line of weakness is disposed [56] References Cited at the junction of the lower end of the body and the closing means and such lower end can be opened by U D STATES PATENTS grasping the closing means and moving it back and forth to cause fatigue of the material of the body and 3,492,396 1/l970 Dalton et al. ..210/94 X allow separation of the closing means therefrom 3,392,834 7/l968 Chnstensen ..2l0/94 thereby leaving an p i g at i lower end 1,922,811 8/1933 Kabnick ..128/272 2 Claims, 5 Drawing Figures PATENTEU 3,732,981

INVENTOR B1 MONROE MENDELSOHN WWW ATTORNEYS FILTRATION COLUMN This invention relates to improvements in filtration columns and, more particularly, to such a column which can be opened in a manner to provide an opening having a predetermined cross-section.

Filtration columns used for analytical testing of different types of fluids, such as blood samples or the like, generally are formed of plastic material and are disposable since, in the ordinary course of the working day of a testing laboratory, many such columns are used. A large number of such columns are initially provided with the filter material so that they can be ready for use immediately. A typical test procedure is to direct a sample of blood through the filter material, usually a resin, to determine certain properties of the blood of which the sample forms a part.

In substantially all testing situations, it is important that the various columns of a group provide a substan-' tially uniform flow rate of the fluid samples which pass through the filters of the columns. Otherwise, the test results from the various columns will be difficult to interpret. This criterion depends ultimately upon the size of the fluid flow passage of each column. Thus, it is extremely desirable that each column have a fluid flow passage therethrough which is of uniform size and shape with respect to all other columns used for the same test purposes.

When the filter material is placed in the various columns prior to use, the material should be closed to the atmosphere to prevent deterioration or contamination of the material. Conventional columns have upper and lower cap members which close their upper and lower ends. These cap members are removed when it is desired to use a particular column. However, these cap members add to the problem of assembling the columns; thus, it is desirable to minimize the number of parts, if possible.

Columns of this type are generally formed from a suitable plastic, yieldable, material to minimize production costs and to permit mass production by a suitable molding technique. One of the ways that has been suggested to minimize the number of parts in the column is to have each column molded with a small projection closing the lower end of the column. Thus, a technician can snip the projection with scissors or other sharp instrument to open the lower end of the column. A significant disadvantage of this type of closure is that the opening produced at the lower end of the column is generally not uniform in size with the openings in other, identical columns. This is due to the fact that the cutting instrument may deform the lower end of the column, thus changing the shape of the lower opening, or in the alternative, small burrs or obstructions will form across the opening during the cutting operation and will limit the fluid flow through the column. Thus, the rate of flow will be different from that of other columns.

The present invention is directed to an improved filtration column for overcoming the problems of the conventional columns by providing a column having a closing means integral with the lower end thereof, which closing means can be manually grasped and moved back and forth until the material of the column fatigues to allow separation of the closing means. The column is provided with a line of weakness situated such that, when the closing means is separated from the column, the opening which results will be uniform in size with openings of other columns of like construction. This factor therefore assures that uniform flow rates will be achieved through the various columns to thereby give uniformity in test results of various samples directed through the columns.

The concepts of the present invention are achieved by utilizing a tip member which is of a size and a shape which can be easily grasped and moved back and forth to cause fatigue of the material at the line of weakness between the lower end of the column and the tip member itself. The line of weakness is provided so that the tip member can be cleanly separated from the main portion of the column to provide a lower opening which is free of any burrs or other obstructions which would restrict the fluid flow through the column. The column of this invention can also be utilized with a cap member for closing the open upper end of the column to thereby avoid any contact of the atmosphere with the filter material within the column itself.

The primary object of this invention is to provide an improved filtration column having a tubular body formed with its lower end closed and having means which can be manually separated from the body to define an opening which will be free of obstructions and which will be uniform in size with respect to openings of columns of substantially the same construction.

Another object of this invention is to provide a filtration column of the type described wherein the tubular body thereof is provided with a tip member integral with the lower end thereof adjacent to a line of weakness so that the tip member can be manually grasped and worked back and forth to cause fatigue of the material forming the body at the line of weakness to allow separation of the tip member from the body to form the lower opening thereof.

A further object of this invention is to provide a filtration column of the aforesaid character wherein the bore through the body extends partially into the tip member to thereby assure thatthe opening in the lower end of the body formed when the tip member is removed therefrom will be clear of obstructions and of a predetermined size notwithstanding the integral connection between the tip member and the body itself.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawing for an illustration of the invention.

In the drawing:

FIG. 1 is a perspective view of the filtration column of this invention with the cap member thereof separated therefrom and with the lower tip member thereon;

FIG. 2 is a vertical cross-section of the column;

FIG. 3 is an enlarged, fragmentary cross-sectional view of the column taken along line 3-3 of FIG. 2;

FIG. 4 is a side elevational view of the column with the cap member thereon and with the lower tip member removed therefrom; and

FIG. 5 is an enlarged, fragmentary cross-sectional view of the column taken along line 5-5 of FIG. 4.

The filtration column which is the subject of this invention is broadly denoted by the numeral 10 and includes a tubular main body 12 having an upper portion 14 and a lower portion 16. Portion 14 has a diameter greater than portion 16 as shown in FIGS. 1 and 2, portion 14 being generally cylindrical whereas portion 16 has a slight taper causing it to decrease slightly in diameter as the lower end thereof is approached.

The junction between

portions

14 and 16 defines a seat 18 for the lower end 20 of a cap member 22 which is adapted to be received within portion 14 for closing body 12. End 20 has a bottom wall 24 which closes the top of portion 16 when cap member 22 is inserted in body 12 as shown in dashed line in FIG. 4. Cap member 22 is itself tubular in construction and has an upper flange 26 provided with a groove 28 in the lower surface thereof for mating with an annular bead 30 on the upper end of portion 14. Bead 30 snaps into groove 28 inasmuch as flange 26 is resilient so as to yield outwardly when cap member 22 is urged into body 12 and when the flange engages bead 30. Cap member 22 has a top opening 32 surrounded by flange 26.

The lower end of portion 16 is closed by a tip member 34 which is generally rectangular in configuration and has a pair of opposed, flat faces 35. It is integral with portion 16 at a juncture 36 having a minimum cross-section. The juncture is defined by an annular line of weakness 38.

Portion 16 has a first internal bore 40 in the upper, major portion thereof and a second, internal bore 40a which communicates with bore 40 and which extends downwardly below line of weakness 38 and into the upper part of tip member 34, as shown in FIG. 3. Bore 40a is substantially uniform in cross-section.

Body 12 and tip member 34 are initially formed integral with each other. They are formed from a suitable material, such as plastic or the like, wherein they can be molded as a unit. Moreover, the tip member can be severed from the lower end of body 12 by moving the tip member back and forth until the material of body 12 is weakened sufficiently to cause it to fatigue to thereby allow a clean separation of tip member 34 from body 12. This separation occurs precisely at juncture 36 due to line of weakness 38. The separation of the tip member from portions 16 leaves the tip member with an open lower end 42 (FIG. with the opening being cleanly defined and having substantially the same cross-section as the lower bore part 40a. In this way, there will be no burrs or other obstructions across opening 42; thus, there will be no resistance to the flow of fluid downwardly through portion 16 such that uniform flow conditions will result.

In use, a suitable filter material, such as a resin or the 7 like, can be first inserted into bore 40 of portion 16, following which cap member 22 can be put into the place to close body 12. Bottom wall 24 will close the top of portion 16 and cause the filter material in bore 40 to be retained therein. Flange 26 will snap over bead 30 to hold the cap member 22 releasably connected to body 12. Column 10 can then be stored or moved to a,

point of use. v

When it is desired to utilize the filtration capabilities of the material in portion 16, cap member 22 is removed to allow a fluid to be directed into body 12 and toward and into and through the filter material in portion 16. Generally, before the fluid is directed into the body, the tip member 34 is separated from the lower end of portion 16 to provide a fluid flow path therethrough for a quantity of fluid directed into upper portion 14. Portion 14, therefore, serves as a reservoir which funnels the fluid into portion 16 and through the filter material therewithin.

The column of this invention is constructed so that a relatively large number of columns can be made using the same molding techniques and each column will give essentially the same fluid flow results inasmuch as the lower opening in each column will be substantially the same in cross section as the other openings of the other columns. Thus, tests conducted on various fluids, such as blood samples or the like will not produce spurious results due to irregular fluid flow rates through the various columns.

I claim:

1. A column comprising: a tubular body of a yieldable material having a pair of opposed ends, one of the ends being open, and a tip member having a pair of opposed, generally flat faces and being integral with the body for closing the opposite end thereof, such body having a line of weakness at the juncture of the body and said tip member, the length of the tip member being sufficient to permit it to be manually grasped and shifted back and forth relative to the body to cause the material at said line of weakness to fatigue and thereby permit separation of the tip member from the body so as to open said opposite end.

2. A column comprising: a tubular body of yieldable material having an upper portion and a lower portion, the upper portion having a diameter greater than the lower portion and the upper end of the upper portion being open; and a rectangular tip member integral with the body adjacent to the lower end of said lower portion for closing said lower end, said tip member having a pair of opposed, generally flat faces, there being a line of weakness at the junction between the lower portion and said faces of the tip member, the latter having a length sufficient to permit it to be grasped and manually moved back and forth to cause the material at such junction to fatigue at said line of weakness to thereby permit separation of said tip member from said lower portion and thereby open the lower end thereof.