US3765453A

US3765453A - Freeze-drying vacuum valve

Info

Publication number: US3765453A
Application number: US00302619A
Authority: US
Inventors: M Parkinson
Original assignee: DRITRON Inc
Current assignee: DRITRON Inc
Priority date: 1972-10-31
Filing date: 1972-10-31
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16

Abstract

An all resilient vacuum valve for coupling material to be dehydrated to a freeze dryer in which the valve includes an outer elastomer tubular member for interconnecting the material to the freeze dryer and a stem slidably mounted in the tubular member for opening and closing the valve. The tubular member at its juncture with the freeze dryer is provided with a precision undercut, so precise that it permits not only a convenient snap fit of the valve to the freeze dryer chamber but also prevents accidental removal of the valve from the chamber while at the same time permitting the valve to be stressed considerably in any direction without impairing the vacuum system.

Description

United States Patent 1 Parkinson FREEZE-DRYING VACUUM VALVE lnventor: Martin c. Parkinson, Nyack, NY.

[73] Assignee: Dritron, Incorporated, WestNyack,

[22] Filed: Oct. 31, 1972 [211 Appl. No.: 302,619

[52] US. Cl 137/625.-24, 137/589, 285/DIG. 22 [51] Int. Cl. F16k 11/07 [58] Field of Search l37/625.24, 556.6,

Primary Examiner-Henry T. Klinksiek Assistant Examiner-Robert .1. Miller Attorney-Leo C. Krazinski [57] ABSTRACT An all resilient vacuum valve for coupling material to be dehydrated to a freeze dryer in which the valve includes an outer elastomer tubular member for interconnecting the material to the freeze dryer and a stem slidably mounted in'the tubular member for opening and closing the valve. The tubular member at its juncture with the freeze dryer is provided with a precision undercut, so precise that it permits not only a convenient snap fit of the valve to the freeze dryer chamber but also prevents accidental removal of the valve from the chamber while at the same time permitting the valve to be stressed considerably in any direction without impairing the vacuum system.

10 Claims, 6 Drawing Figures FREEZE-DRYING VACUUM VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to valves and, more particularly, to valves for use in freeze-drying, whereby air and other vapors are evacuated from a product.

2. Description of the Prior Art In conventional manifold freeze-drying procedures, metal tubes (ports) are welded to openings in vacuum chambers or tubular manifolds. Once the proper'number of tubes (ports) have been welded to thevacuum chamber or tubular manifold, rubber valves of various types are fitted over the tubes, as is evident in U.S. Pat. No. 3,6l2,l of Oct. l2, l97l. In certain manifold freeze-dryer designs it is also necessary to weld a metal baffle plate behind each opening either to prevent ice blockage of the port, if the vapor condenser is very near the port opening, or to prevent crosscontamination of the product if ports are near and directly opposite each other, as may be the case in tubular manifold designs.

In conventional operation, a refrigerated condenser (mechanical freon refrigeration, or dry ice, or liquifled gases) is placed within the vacuum chamber and samples to be freeze-dried are placed in containers, such as serum bottles. The contents of the bottle is'pre-frozen by rotating the bottle in a dry-ice/solvent bath or other,

suitable means of freezing the product. The bottle is then connected to one of the rubber valves on the vacuum chamber or tubular manifold. Under the influence of the vacuum and the ambient room temperature, ice within the bottle sublimes directly from the frozen to the vapor state, by-passing the intermediary liquid phase. This drying is so gentle that when water is added to the dried product it reconstitutes to virtually the identical original product.

It has been found that, as currently fabricated, the large amount of intricate welding required at each port provides an excessive opportunity for vacuum leaks to occur. Also, corrosion may occur in a matter of a few years (and sometimes in a few months), particularly at the welded points. Also, vacuum leak detection is difficult often requiring return of the equipment to the manufacturer for repair or expensive factory trained field service representative repair.

SUMMARY OF THE INVENTION Accordingly, an object of the invention is 'to provide such apparatus for freeze-drying material which overcomes the disadvantages and difficulties heretofore encountered.

Another object is to eliminate all welds and merely cut holes in the vacuum chamber or tubular manifold, whereby the excellent corrosion resistance of the steel remains the same.

Another object is to provide apparatus that is substantially leak proof.

Another object is to provide an improved valve for coupling the material to be freeze-dried to the perfo-' rated vacuum chamber or tubular manifold.

A further object is to accomplish the foregoing ina simple and practical manner.

Other and further objects will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawing, forming a part of the specification, wherein:

FIG. 1 is a side elevational view ofa vacuum valve attached to a freeze dryer manifold in operative use, in

accordance with the present invention.

FIG. 2 is an end elevational view of the valve in the direction of the arrow 2 in FIG. 1.

FIG. 3 is a longitudinal sectional view of the valve taken along line 3-3 of FIG. 2 illustrating the details of the valve while in the inoperative position.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 1 showing the stem and main valve sleeve openings within the freeze dryer chamber in registration.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 1 showing the stem and tubular member openings in registration.

FIG. 6 is a sectional view taken along line 66 of FIG. 1 with the stem rotated from that shown in FIG. 3 and with the vent hole and venting slot in registration.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 m6 of the drawing, there is shown a vacuum valve 10 removably attached to a freeze-dryer vacuum chamber or tubular manifold 11 and carrying a bottle 12 containing a product to be freeze-dried. As seen in FIG. 3, the valve 19 consists of two parts, an outer sleeve 13 and an inner tubular stem 14. Preferably, the sleeve 13 is-made of silicone rubber so as to clearly see open and closed positions of the valve and the stem 14 is made of polypropylene for its unbreakable long life. The durometer of sleeve 13 is preferably between 35 50, Shore A, although softer and harder rubber durometers may be used.

The sleeve 13 has a transverse vent opening 16 adjacent its inner end and at its innermost end larger opposed transverse openings 17 for disposition within the chamber 11. The sleeve 13 is open at one end and has its other end 18 tapered with a closed end wall 19 or baffle within the chamber 11, and between the

openings

16 and 17 is shown a shoulder 20 in abutting engagement with a manifold wall 21 of the chamber 11. At the inner side of the shoulder 20 is provided a precision undercut or groove 22, which will be covered in greater detail hereinafter. Adjacent the outer end of the sleeve 13 is integrally formed at an angle a second open-ended sleeve or tubular member 23 having a bore 24 in communication with a bore 26 of the sleeve 13. The open end of the sleeve 23 is adapted to carry the bottle 12 or other container to be evacuated.

The stem 14 is shown formed with a head 27, preferably of square shapewith concave sides 28 for easein manipulation, a tubular shank portion 29 and a solid shank portion 31 interconnecting the head 27 and tubular shank portion 29. The tubular shank portion 29 is provided with a transverse inlet opening 32 adjacent the solid shank portion 31 for registration of the

bores

24 and 26 when the valve 10 is in its operative or open position, that is, when the stem 14 is pushed into the outer sleeve 13, as shown in FIG. 1. The innermost end of the stem 14 is shown with opposed openings 33, preferably open ended slots; the diameter of the stem 14 from its inner end for a distance of about one-half inch has a reduced portion 34, where the stem enters the vacuum chamber 11, and the stem 14 is also provided along its peripheral surface with a longitudinal slot 36 which interconnects the vent opening 16 with the bore 24 for bleeding air into the bottle 12 when the stem 14 is rotated l80 from that shown in FIG. 3.

Returning now again to the precision undercut 22, which meshes with the manifold wall 21, as seen in FIG. 3, and which permits a convenient snap fit of the valve 10 to chamber 11, it also prevents accidental removal of the valve and permits the valve to be stressed or flexed to an extreme degree in any direction without impairment of system vacuum. Since the dimensions of the undercut 22 are critical, it is best to give examples illustrating the same, (-a) one with a 25 inch OD. and (b) another with a 4 inch O.D. stem. In the case of the k inch stem, the dimensions of the outer sleeve 13 are 1 inch O.D. X b inch ID. and the opening in the chamber 11 is three-fourths inch. A 0.18 inch deep by 0.015 -0'.0l8 inch wide undercut 22 in the outer sleeve 13 with its tapered end portion 18 permits convenient coupling to the chamber manifold wall 21, as is evident in FIG. 3. When the stem 14 is then inserted into the sleeve 13, the bulbous portion 37, which was displaced inwardly when the sleeve 13 was inserted in the manifold wall 21, is expanded outwardly to form a high vacuum tight seal.

In the case of the inch stem, a simple increase of one-fourth inch in all sizes is merely required, that is, 1 inch diameter opening in the chamber wall and l% inch O.D. X inch ID. of the sleeve 13, but with the same dimensions of undercut, that is, 0.18 inch deep by 0.015 0.018 inch wide. A high vacuum tight seal is provided thereby. It is believed that the same proportion can be used for a stem A inch CD. as well as for a stem 1% inch O.D.

To operate satisfactorily close tolerance must be maintained, particularly for the precision undercut 22. The depth of the undercut should not vary more than :t 0.40 inch within the framework of the other valve dimensions. The valve must maintain a high vacuum tight seal, yet the stem 14 must rotate easily and the valve must be capable of bending to a severe degree when a heavy bottle 12 or container is connected to the vapor inlet tube 23. Too little undercut will prevent turning the stem 14 and too much undercut will cause the valve 10 to leak when flexed.

Another important dimension of the valve is the reduced portion 34 at the inner end of the stem 14. In the previous examples given where stem 14, OD. dimensions are given as one-half inch, this refers to approximately a 7% inch length at the end of the stem 14. The remaining CD. of stem 14 is slightly larger in all cases, typically +0.030 inch, that is, 0.530 inch and 0.780 inch for 1% inch and 54 inch O.D. stems, respectively. The reason for the two dimensions for each stem 14 0D. is as follows:

As this reduced portion 34 of about one-half inch in length enters the chamber 11, it expands the rubber bulbous portion 37, thereby loosening the close fit of the stem 14 and tubular shank portion 29 outwards toward the rubber vapor inlet tube 23. When flask 12 is connected to this tube, air would leak through vent hole 16 and channel its way through to the vapor inlet opening 32 in the 'stem 14 if the stem 14 had the same O.D. along its entire length.

In operation, the outer sleeve 13 of the valve 10 with its tapered end portion 18 is readily inserted into an opening of the freeze-dryer manifold 21 and snapped into position by virtue of the precision undercut 22. In FIG. 3 note the bulbous portions 37 brought about by the compression of the manifold 21 on the sleeve and that the stem 14 is in the withdrawn position. Also, the inner face of the shoulder 20 bears against the manifold wall 21 and thus prevents further insertion of the valve sleeve 13. The stem 14 is rotated 180 from that shown in FIG. 3, that is, with inlet opening 32 at the top and the longitudinal slot 36 at the bottom, and then pushed through the bore 26 of the sleeve until the head 27 rests against the open end of the sleeve 13, as shown in FIG. 1. The valve is now in the closed or inoperative position and the vacuum system can be placed in operation. The bottle 12 may now be inserted into tubular member 23, see FIG. 6. The stem 14 is then rotated 180 to register inlet openings 32 with the bore 24 and bore 26 of the sleeve, whereupon evacuation of the bottle takes place.

During evacuation it is to be noted that there is a high velocity of water molecules flowing from the bottle 12, which molecules strike the end wall 19. The end wall functions as a baffle to force the molecules out through opposed holes 17. There is a slight increase in pressure at each of these two openings 17 causing the molecules to take a momentary directional path parallel to tbe openings and then, almost immediately, the molecules take on a purely random path tothe surface of the condenser, inner pot (not shown) to which they adhere, that is, freeze and are no longer in the system. Thus, the baffle design insures a more random and more uniform condensing of the water vapor and thereby takes maximum advantage of the available condenser surface.

This baffle, therefore, greatly increases the single run ice condensing capacity of the condenser in manifold freeze-dryer designs which place the condenser immediately' adjacent to the port opening.

Another advantage of baffle 19 occurs in tubular manifold freeze-dryer designs in which the port openings are directly opposite each other and at a relatively short distance (2 inch or 3 inches) from each other. Some portion of the solid material to be dried often escapes during freeze-drying and in the absence of a baffle may find direct access to another container. Prevention of cross-contamination is particularly important when drying different bacterial cultures at the same time on the same manifold.

Upon completion of evacuation the stem 14 is rotated the inlet opening is closed and the vent opening 16 is in registry with the longitudinal slot 36, which in turn is in communication with the bore 24 of the tubular member 23. Accordingly, the bottle 12 is vented gradually after which the bottle may be removed and another bottle substituted and the cycle repeated.

From the foregoing description it will be seen that the present invention provides an improved vacuum valve for freeze-dryers wherein by the use of clear silicone rubber for the sleeve open, closed and vent positions are directly observed.

As various changes may be made in the form, construction, and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matters are to be interpreted as illustrative and not in any limiting sense.

What is claimed is:

1. A vacuum valve for connecting a container to be evacuated to a freeze dryer chamber, having an opening in a manifold wall thereof comprising, in combination, a first elastomer tubular member having an open end and a closed end with at least one opening, a second elastomer tubular member integral with said first tubular member intermediate said ends and extending at an angle from said first tubular member, said second tubular member being in communication with said first tubular member at their juncture and open at its free end for air tight support of said container, said first tubular member being adapted to have its closed end inserted through said chamber opening into said chamber and a portion of said first tubular member adjacent said closed end being seated upon said manifold wall at said chamber opening, a stem slidably and rotatably mounted in said first tubular member having an opening for opening and closing said valve, and means including a shoulder and undercut portion adjacent said closed end of said first tubular member for precision securement of said valve to said chamber.

2. A vacuum valve according to claim 1, wherein said undercut portion consists of a circumferential groove of predetermined width and depth on said first tubular member between said shoulder and said closed end.

3. A vacuum valve according to claim 2, wherein said predetermined width and depth of said undercut portion are 0.18 inch deep by 0.015 0.018 inch wide for a k or 34 inch diameter stem.

4. A vacuum valve according to claim 3, wherein the depth of the undercut should not vary more than i 0.040 inch.

5. A vacuum valve according to claim 2, wherein an innermost end of said stem has a reduced diameter of about one-half inch along its linear length.

6. A vacuum valve according to claim 2, wherein said first tubular member is of clear silicon rubberf 7. A vacuum valve according to claim 2, wherein said stem opening is adapted for communication with said first and second tubular members when said valve is in an open condition and out of communication when said stem is rotated to place said valve in a closed position.

8. A vacuum valve according to claim 7, wherein said first tubular member has a vent opening and said stem has a longitudinal slot along its peripheral length for communication with said vent opening and said second tubular member for venting said container.

9. A vacuum valve according to claim 8, wherein said closed end of said first tubular member has a pair of opposed openings and said closed end acts as a'baffle to direct fluid flow'from said container through said opposed openings in said first tubular member into said chamber.

10. A vacuum valve in accordance with claim 9, wherein said stem has opposed openings at its innermost end for communication with said opposed openings in said first tubular member when said valve is in an open condition.

Claims

3. A vacuum valve according to claim 2, wherein said predetermined width and depth of said undercut portion are 0.18 inch deep by 0.015 - 0.018 inch wide for a 1/2 or 3/4 inch diameter stem.

4. A vacuum valve according to claim 3, wherein the depth of the undercut should not vary more than + or - 0.040 inch.

6. A vacuum valve according to claim 2, wherein said first tubular member is of clear silicon rubber.

7. A vacuum valve according to claim 2, wherein said stem opening is adapted for communication with said first and second tubular members when said valve is in an open condition and out of communication when said stem is rotated to place said valve in a closed position.

9. A vacuum valve according to claim 8, wherein said closed end of said first tubular member has a pair of opposed openings and said closed end acts as a baffle to direct fluid flow from said container through said opposed openings in said first tubular member into said chamber.