US3501176A - Connector assembly - Google Patents

Description

March 17, 1970 R. A. ARMS 3,501,176

CONNECTOR ASSEMBLY Filed April 11. 1968 INVENTOR Richard A.Arms

A-TIURNEYS jww w United States Patent 3,501,176 CONNECTOR ASSEMBLY Richard A. Arms, Kennett Square, Pa., assignor to Hewlett-Packard Company, Palo Alto, Calif., a corporation of California Filed Apr. 11, 1968, Ser. No. 720,712

Int. Cl. F161 37/14 US. Cl. 285-305 5 Claims ABSTRACT OF THE DISCLOSURE A connector assembly uses a continuous septum to effect a fluid seal. In one application, the conventional disc shaped septum in the injection port of a gas chromatograph is replaced by an elongated strip of septum material which is disposed transversely 'across the inlet of the injection port. A hypodermic needle or syringe may then be inserted through the elongated septum material and liquid or gas samples introduced therethrough. After each or several insertions of the needle, the elongated septum may be repositioned along its axis so as to present a new untouched portion of septum material to the needle. In another application, continuous strip-like septums are positioned at either end of a cavity to permit the interconnection of capillary sized tubes.

This invention relates to a connector assembly and, more particularly, to a connector assembly having particular advantages when used in the field of gas chromatography.

BACKGROUND OF THE INVENTION In the field of gas chromatography a small liquid samplc is introduced into and vaporized in the so called injection block of the gas chromatograph. The injection block is located at the inlet end of a separating column and is heated to cause flash vaporization of the sample when injected. The sample usually is injected by means of a syringe or hypodermic needle through a self-sealing material, referred to as a septum, which seals the interior of the injection block from the atmosphere. A carrier gas is swept across the backside of the septum and into the column to transport the vaporized sample through the column for separation and subsequent detection.

The syringe, which often is capable of dispensing the sample in microliter quantities, may be operated either manually or automatically. Regardless of whether the operation is manual or automatic, after the septum has been used one or more times, it can be contaminated with the sample so as to degrade the analytical results. Additionally, with usage, the septum tends to develop leaks, also resulting in degraded analytical results. Whether the problem be leaks or contamination, it must be replaced. Replacement is a time consuming process since the chromatograph usually must be cooled down so that the operator may replace the septum. Such operation requires anywhere from one-half up to as much as three hours after the chromatograph is shut down until it again can be brought up to temperature and operation resumed. This loss of time is appreciable and undesirable to say the least.

When working with fluids, it is often necessary to connect fluid carrying conduits together. For this purpose many diverse tubing connectors have been developed. Many of these are difficult to use, expensive and require a wrench or other tool to effect the coupling. The septum described above is but one type of connector assembly. It couples the syringe to the separating column of a gas chromatograph.

It is, therefore, an object of this invention to obviate 3,501,176 Patented Mar. 17, 1970 many of the disadvantages of the prior art connector assemblies.

Another object of this invention is to provide an im- BRIEF DESCRIPTION OF THE INVENTION The improved connector assembly of this invention includes a tubular member which defines a cavity having an axis and inlet and outlet openings. The tubular member is of sufficient size to receive capillary sized tubes such as the needle of a syringe through either or both of its inlet and outlet openings. A self-sealing elongated member is positioned in the inlet and/or outlet of the tubular member with the members axis intersecting that of the tubular member. The tube or tubes to be coupled are inserted through the elongated member. To renew the seal provided by the elongated member, it is drawn along its axis relative to the inlet and/or outlet.

In a preferred embodiment of this invention the connector assembly is adapted for use as the injection block of a gas chromatograph. When so adapted, the outlet opening of the tubular member has the inlet of a gas chromatograph column inserted therein. A self-sealing, elongated member has its longitudinal axis disposed in the inlet opening of the tubular member with its axis intersecting the axis of the cavity. In this manner, the elongated member is a substitute for the normal disc-like septum and is adapted to be punctured by a syringe for the introduction of a sample to be vaporized and swept through the separating column. If the elongated member develops a leak clue to successive punctures or becomes contaminated, the member is drawn across the inlet to expose a new portion to the syringe.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation as well as additional objects and advantages thereof will best be understood from the following description when read in connection with the accompanying drawings, in which:

FIGURE 1 is a cross-sectional view taken along lines 11 of FIG. 2 illustrating an injection block utilizing a continuous septum constructed in accordance with this invention;

FIGURE 2 is a. partial front elevation view of the front of a gas chromatograph showing the injection port and the elongated septum constructed in accordance with this invention;

FIGURE 3 is a front view of the driving mechanism having the driving knob removed for pulling the elongated septum illustrated in FIG. 2;

FIGURE 4 is a side view of the mechanism employed to draw the elongated septum through the injection port for its replacement;

FIGURE 5 is a cross-sectional view of a tubing connector assembly, adapted to interconnect two capillary size tubes, constructed in accordance with this invention; and

FIGURE 6 is a partial cross-sectional view of a rectangular elongated septum.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 there is shown a preferred embodiment of the invention. In this embodiment the connector assembly of this invention is substituted for the injection block of a conventional gas chromatograph. Such connector assembly includes a rectangular body member 10 which may be formed of stainless steel, aluminum or other suitable material. A bore 18 is formed in the body member to provide a cavity therein. One end 14 of the body member 10 (the lefthand end in the drawing) is counter bored at 12 and the other or inlet end 19 is flared as to facilitate the insertion of a syringe 16 into the cavity for the injection of a sample. Only the needle portion of the syringe 16 is illustrated. Immediately adjacent the inlet 19 to the cavity there is formed a radial bore or orifice 23 whose axis intersects the axis of the cavity to accommodate an elongated septum member 22 of self-sealing septum-like material. Typically, this may be formed of a silicon rubber or any other suitable material capable of accommodating a hypodermic needle or a capillary sized tubing such as employed on syringes.

. The elongated member 22, which may be termed a septum rope, is perhaps best seen in FIG. 2. There the front face portion 8 of a typical gas chromatograph is partially illustrated. Also seen in the illustration of FIG. 2 is the head-on view of the flared or conical inlet 19 which accommodates the syringe 16. The elongated member 22 is drawn through the .radial orifice 23 in the body member 10 by any suitable means. Typical of one such means is that illustrated in FIG. 2 which includes a knob 50 which may be rotated by hand. The knob 50 drives one of a pair of closely spaced but not engaged knurled or toothed gear wheels 52 and 54 which may be best seen in FIG. 3. The upper gear wheel 52 is turned directly by the knob 50 which drives a shaft 56 on which the gear wheel 52 is mounted. The elongated member 22 is passed between the gear wheels 52-54. The spacing between the wheels 52-54 is less than the diameter of the elongated member 22 so that when the upper gear wheel 52 is rotated the member 22 is drawn or pulled through the radial orifice 22 from the supply cartridge 58.

The supply cartridge 58 may be mounted on the front of the chromatograph panel 8 as by a clip (not shown) and may be a hollow cylindrical chamber in which the elongated member 22 is wound in a roll 59 and withdrawn through the inside of the roll through a hole 60 in the front cap 62 of the supply cartridge 58. Although the manual knob 50 is shown for the means of drawing the elongated member 22 through the radial orifice 23, it is to be understood that any other mechanical or electromechanical drive mechanism may be employed. For example, an electric motor actuated by a manual switch or automatic control circuitry may be used to drive the gear wheel 52. Alternatively a solenoid may be operated to rotate a ratchet which incrementally advances the elongated member 22 in accordance with electrical signals.

The electrical signals in turn, if desired, may be derived from a computer or other control mechanism which is related to the injections made.

The side walls of the injection block (FIG. 1) are kept relatively thin in order to facilitate maximum transfer between heating coils 26 which are coiled about the body member 10. The entire assembly including the heating coils 26 and the body member 10 are then preferably cast within a heat conductive metallic block which acts as a suitable heat sink. This reduces variations in temperature within the body member and facilitates the transfer of heat between the heating coil 26 and the body member 10. An opening 30 is provided in the side wall of the body member 10 at a point along the counterbore 12 to permit the introduction of a suitable carrier. The carrier gas may be supplied through a tube 31 which may be soldered in place.

The counterbore 12 is counter bored to provide a shoulder portion 34 in which a ferrule 36 or other suitable gasket material such as an O-ring may be seated. The ferrule 36 provides a seal about a tubular insert 38 which is positioned coaxially within the counterbore 12. The tubular insert 38 may be either the end of a separating column of a conventional gas chromatograph or may be the connecting tube of any fluid system. The tubular insert 38 or column, as the case may be, is held in place 4 by the male insert 40 which is adapted to engage the ferrule 36 to provide a fluid or gas type seal for the interior of the cavity 12. The column or insert 38 thus is in continuous communication to the remainder of the gas chromatograph or fluid system.

In this manner, a carrier gas introduced through the opening 30 flows along the outside of the tubular insert or column 38 into the area adjacent the elongated member 22 and then through the tubular insert or column 38 into the chromatograph system. This permits the backside of the strip septum or elongated member 22 to be completely flushed of all sample material by the carrier gas.

To inject a sample into the injection block for vaporization and entrainment in the carrier gas, one need merely insert the syringe 16 into the center of the flared mouth 19 through the portion of the septum 22 and directly into the vaporization chamber itself. It now the septum through which the syringe is inserted becomes contaminated or damaged through usage or develops a leak during usage, one need merely rotate the knob 50 to advance the septum 22 through the radial orifice 23. This presents an entirely new, unused portion of septum material for the next operation. Alternatively, the septum may be advanced after each and every injection such that the septum is punched only once in any one spot. This represents a decided advantage over conventional septums used in gas chromatographs. In each instance the instrument using a conventional septum must be cooled before the septum can be handled and properly replaced. This results in a shut down time of up to three hours in some instances. Furthermore, the simplicity of construction of this new strip-like septum greatly reduces the cost of constructing injection blocks.

To prevent leakage within the injection block cavity, the radial orifice 23 is formed to have a diameter less than that of the strip septum 22. In alternative embodiments the elongated member or the strip septum 22 need not be cylindrical in cross section but rather may be rectangular as seen in FIG. 6, oval, or for that matter, any other cross-sectional shape. In the event that a rectangular septum 22' is employed, it may be constructed to present a relatively small thickness to the incoming springe 16 such that it resembles in cross s ction a conventional septum. The radial opening 23' is rectangular.

An alternative embodiment of the invention is illustrated in FIG. 5 which depicts a connector assembly utilizing two strip septums 22 to seal a connector assembly. Essentially, the connector assembly of FIG. 5 includes a block 70, of suitable relatively rigid material such as stainless steel having a bore 72 through its length. The bore 72 is of sufiicient diameter just to accommodate capillary sized tubes 74 of stainless steel or other material. Preferably, thebore diameter should not great y exceed twice the diameter of the tubes 74 to minimize if capillary tubes 74 (preferably sharpened) are inserted into the bore 72 from either end such that they are just short of touching within the central cavity portion, a communicating gas link is formed. When the tubes are withdrawn, different or new tubes may again be inserted through the septum. As the septum becomes leaky, damaged, or contaminated in any way, one need merely draw the two strip septums 22 through the radial orifices 76 as described.

To facilitate the insertion of the capillary sized tubes 74, the central bore 72 in the cavity may be counter bored as at 80 at either end to provide an enlarged portion. Finally, to prevent the capillary sized tube 74 from being pulled out through the strip septum material 22, a crook 82 is formed in the tubes 74 closely adjacent their ends. The crooks 82 provide an offset portion in the tubes 74 through which locking pins 84 may be passed. Radial holes 86 are drilled through the counter bored regions 80 at either end of the block 70 so as to intersect the axis of the main bore 72. These locking pins 84 are inserted through the holes 86 to lock the tubes 74 in place and may be of stainless steel or other suitable metal.

In use, gas flowing from the left, in the drawing, through the tube 74, shown in phantom passes into the righthand tube 74 through the small space provided by the bore 72. Desirably, the diameter of the bore 72 should approximate, i.e,, slightly exceed, that of the tube outside diameter to reduce dead space. Tubes appreciably greater than capillary size cannot be used for the simple reason that they tend to damage the septum material and cause leaks.

While the radial bores 23 (FIG. 1), 76 (FIG. 5), and 23' (FIG. 6) have been described as having an axis which intersects the axis of the central bores 18 (-FIGS. 1 and 6) and 72 (FIG. 5) it is to be understoodfthat the angle of intersection 0 has the limits 0 0 90 The ninety degree or perpendicular intersection is preferred but other angles may be used as desired or circumstances of construction dictate.

There has thus been described a relatively simple, low cost connector assembly which may be used for removably connecting capillary sized tubes together and as the inlet end of the injection block of a gas analysis apparatus. Both devices use as the sealing mechanism a strip septum which may be continuously or incrementally drawn across the opening or openings of the cavity to be sealed. In this manner, the inner cavity is free from leaks and contamination and its replacement is easily accomplished.

While the invention has been disclosed herein in connection with certain embodiments and certain structural and procedural details, it is clear that changes, modifications, or equivalents can be used by those skilled in the art.

What is claimed is:

1. A sealed connector assembly for interconnecting two tubes comprising:

a member defining a cavity and having first and second bores defining corresponding first and second openings to said cavity, each of said bores being adapted to receive one of said tubes;

a third bore in said member having an axis intersecting the axis of said first bore,

a fourth bore in said member having an axis intersecting the axis of said second bore; and

first and second self-sealing elongated members, each having a longitudinal axis, and respectively disposed axially in said third and fourth bores, thereby to seal said cavity.

2. A connector assembly according to claim 1 which also includes:

means for securing said tubes against axial movement including separate pins adapted to be positioned in said first and second bores transversely to and on the axes of said bores and on the non-adjacent sides of said third and fourth bores,

said two tubes each having an olfset portion adapted to engage the coresponding one of said pins.

3. A connector assembly according to claim 1 which includes means for incrementally moving each of said elongated members along their respective longitudinal axes through their respective bores, thereby to replace the seals for said cavity.

4. A connector assembly according to claim 3 wherein the respective cross-sectional areas of said e ongated members exceed the respective cross-sectional areas of said third and fourth bores. I

5. A connector assembly according to claim 2 wherein the respective cross-sectional areas of said elongated members exceed the respective cross-sectional areas of said third and fourth bores.

References Cited UNITED STATES PATENTS 1,529,390 3/1925 Brown. 1,712,069 5/1929 Cressler. 128218.1 2,176,042 10/1939 Pittenger 1282l8.1 XR 2,271,720 2/1942 Smith 128218.1 3,177,870 4/1965 Salem et al. 128214.2 3,326,206 6/1967 Barr et a1. 128--2 3,374,660 3/ 1968 McKinney et al. 3,431,783 3/1969 Radgens.

LOUIS R. PRINCE, Primary Examiner H. C. POST, III, Assistant Examiner Us. 01. X.R. 73-422; 285-469, 404

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