HK1192772B - Reusable fitting for attaching a conduit to a port - Google Patents

Description

Reusable fitting for attaching a tube to a port

Cross Reference to Related Applications

This application claims earlier filed on 26.8.2011 entitled "Reusable Fitting for attaching a Conduit to a Port" U.S. provisional patent application serial No.61/527,638, filed on 26.8.2011 entitled "Chromatography Apparatus with Diffusion-Bonded coupling", U.S. provisional patent application serial No.61/527,639, filed on 26.8.2011 entitled "Liquid-Chromatography Apparatus with High Pressure seal" U.S. provisional patent application serial No.61/527,747, filed on 26.8.2011 entitled "Microfluidic Chromatography Apparatus for use in electrojetting Apparatus (61/527,648), and priority of U.S. provisional patent application serial No.61/621,852 entitled "Chromatography column assembly" filed on 9/4/2012, which is hereby incorporated by reference in its entirety.

Technical Field

The present invention generally relates to reusable fittings for attaching a tube to a port. More particularly, some embodiments of the invention relate to removable and replaceable fittings for use in high pressure fluid systems, such as High Performance Liquid Chromatography (HPLC) systems.

Background

Capillary HPLC systems typically require a steel ferrule to connect the capillary to a metal or plastic fluid port to provide a fluid-tight seal and substantially zero void volume between the capillary and tubing embedded within the port. In this connection, the capillary is held in a fitting having a steel ferrule and a compression nut. The compression nut presses against the collar so that the fitting grips the capillary tube and the capillary tube is thus pressed into direct contact with the inlet or outlet of the tubing embedded in the port. Once connected, the steel ferrule is permanently affixed to the capillary tube and therefore is only available for a particular port. If the fitting is moved to a different port, even small manufacturing tolerances typically result in void volume or interference, which can cause damage and/or improperly seat the steel ferrule. Furthermore, since the steel ferrule is permanently attached to the capillary, if a portion of the fitting is damaged during use, the entire fitting is discarded and a new fitting installed, as no portion of the fitting can be simply removed or replaced.

As known in the art, there are alternatives to non-removable, non-reusable and non-replaceable steel ferrules for use in HPLC systems, such as polytetrafluoroethylene ferrules and high performance polyetheretherketone fittings. However, the pressure of teflon ferrules is limited to under a few thousand pounds per square inch (psi), while high performance peek fittings have limited reusability because the peek seal cone may be damaged during extended use.

Disclosure of Invention

In one aspect, the invention features a reusable fitting for attaching a tube to a port. The reusable fitting includes a housing, a spring, a retainer, and a cap. The housing includes a ferrule portion at the proximal end of the housing. The spring is in physical communication with the housing. The retainer is disposed between the spring and the housing. The retainer has an opening for allowing entry of a distal portion of the conduit, and a retaining feature fixed to a proximal end of the conduit to limit axial movement of the conduit in a distal direction. The retainer defines an eccentric opening through which the retention feature of the conduit passes. The cap is in communication with the spring such that the spring urges against the retainer to urge the tubing in a proximal direction.

In another aspect, the invention features a liquid chromatography apparatus that includes a tube for conveying a fluid, a port in fluid communication with the tube, and a fitting for attaching the tube to the port. The fitting includes a housing having a ferrule portion at a proximal end of the housing and a spring in physical communication with the housing. The fitting also includes a retainer and a cap. The retainer is disposed between the spring and the housing. The retainer has an opening for allowing a distal portion of the conduit to enter and is in physical communication with a retaining feature fixed to a proximal end of the conduit to limit axial movement of the conduit in a distal direction. The retainer defines an eccentric opening through which the retention feature of the conduit passes. The cap is in physical communication with the spring to urge the spring against the retainer to urge the retainer against the tubing in the proximal direction.

In yet another aspect, the invention features a kit having components that can be assembled to form a reusable fitting for attaching a conduit to a port. The reusable fitting includes a housing having a ferrule portion at a proximal end of the housing. The reusable fitting also includes a spring in physical communication with the housing, and a retainer disposed between the spring and the housing, and a cap. The retainer has an opening for allowing a distal portion of the conduit to enter and is in physical communication with a retaining feature fixed to a proximal end of the conduit to limit axial movement of the conduit in a distal direction. The retainer defines an eccentric opening through which the retention feature of the conduit passes. The cap is in physical communication with the spring to urge the spring against the retainer to urge the retainer against the tubing in the proximal direction.

Drawings

The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like reference numerals indicate like elements and features in the various figures. For purposes of clarity, not every component may be labeled in every drawing. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 is a diagram of an embodiment of a reusable accessory according to the present invention.

Figure 2 is a cross-sectional view of an embodiment of a reusable fitting according to the present invention.

Fig. 3 is a cross-sectional view of a housing for the reusable fitting of fig. 2.

Fig. 4A is a cross-sectional side view of a holder for the reusable fitting of fig. 2.

Fig. 4B is an end view of the holder shown in fig. 4A.

FIG. 5 is a cross-sectional view of a cap for the reusable fitting of FIG. 2.

Fig. 6A is a cross-sectional view of a portion of an embodiment of a liquid chromatography device in a disengaged configuration in accordance with the invention.

Fig. 6B is a cross-sectional view of a coupling configuration for the portion of the liquid chromatography apparatus shown in fig. 6A.

Detailed Description

Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the teachings. Reference to a particular embodiment in the specification does not necessarily all refer to the same embodiment.

The present teachings will now be described in more detail with reference to exemplary embodiments thereof as shown in the accompanying drawings. While the present teachings are described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be recognized by those skilled in the art. Those skilled in the art with access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, which are within the scope of the present disclosure as described herein.

As used herein, the term "substantially" may be used to modify any quantitative representation that may permissibly vary without resulting in a change in the basic function to which it is related.

As used herein, the term "capillary" refers to a tube having an inner diameter of no more than about 300 μm. Depending on the context, the words "capillary" and "tubing" may be used interchangeably herein.

As used herein, the term "retention feature" refers to anything built or configured on a pipe that, when retained in a fitting, limits axial movement of the pipe.

In brief summary, the present invention relates to a fitting that includes, in part, a ferrule formed of polyetheretherketone or the like, and a retainer capable of locking and unlocking a conduit in the fitting. The fitting provides a fluid tight seal and substantially zero void volume at the junction of two fluid conduits at high pressure, which may exceed 20000psi in some embodiments. The fitting is removable, reusable, and replaceable, and allows a user to connect and reconnect the capillary to the fluid port without permanently bonding the ferrule to a particular capillary, and thus to a particular port. The fitting may be replaced if a portion or all of the fitting is damaged during use.

FIG. 1 is a schematic view of a reusable fitting 10 including a housing 12 having a ferrule portion 14, and a retainer 16. Ferrule portion 14 has a bore defining a channel for receiving tube 18, and ferrule portion 14 is configured to be received by a female receptacle of a metal or plastic port. The ferrule portion 14 is formed of, for example, polyetheretherketone or a polyetheretherketone-type polymer. Ferrule portion 14 may be integral with housing 12 as shown, or may be a separate component.

The tube 18 is held in the fitting 10 and is pressed into the receptacle to mate with the inlet or outlet of the tube embedded in the port. Compression may be achieved using any suitable force applied to the ferrule portion 14, such as a screw compression force, a spring force, a clamping force, or a combination of one or more of these forces, while allowing subsequent separation of the tubing 18 from the ferrule portion 14 without damaging the tubing 18. In other words, the ferrule portion 14 is not permanently attached to the tube due to compression.

As used herein, the term "retainer" means any object having structure that enables the pipe 18 to be locked to or unlocked from a fitting. The retainer 16 may be a part of the housing 12 or may be a separate component positioned inside or outside of the housing 12. The retainer 16 has an opening aligned with the passage defined by the ferrule portion 14 for receiving the tubing 18. The holder 16 includes one or more locking regions 20 or locking mechanisms. By way of example, the locking region 20 may engage one or more hooks, straps, notches, grooves, pins, flanges, or similar features. The locking region 20 may lock the tube 18 by coupling a retention feature 22 of the tube 18 into the locking region. Additionally, the structure 20 may unlock the tube 18 by allowing the retention feature 22 to bypass the obstruction imposed by the locking region 20. In various embodiments, the retention feature 22 associated with the tube 18 is a steel sheath disposed over a portion of the tube 18, a material coated on a surface of the tube 18, or anything constructed or shaped on the tube 18 that can interact with the locking region 20 to limit axial movement of the tube 18 within the fitting 10.

FIG. 2 is a cross-sectional view of one embodiment of a reusable fitting 30 according to the present invention. The fitting 30 includes a housing 32, a spring 34, a retainer 36, and a cap 38. The housing 32 is shown in isolation in fig. 3, and the housing 32 includes a collar portion 40 at a proximal end, and an inner surface 42 defining a chamber 43 at a distal end. The housing may have any suitable shape, for example, the illustrated housing 32 has a circular cross-section, but other polygonal cross-sectional shapes are possible. The housing 32 is made of any suitable material, such as a polymeric material or a metallic material. Although shown as a single piece housing 32, in some alternative embodiments, the housing comprises two or more components. In other embodiments, the ferrule portion 40 may be a separate component from the rest of the housing 32. Ferrule portion 40 is shown having a bore 44, bore 44 defining a passage for receiving a pipe. In some embodiments, the inner diameter of the bore 44 is no more than about 300 μm. The width (or diameter) of the chamber 43 is greater than the width (or diameter) of the bore 44. The ferrule portion 40 is configured in shape and size to be compatible with the female receptacle of the port such that the ferrule portion 40 can be tightened into the port. The ferrule portion 40 is formed of polyetheretherketone or similar materials, such as polyetheretherketone type polymers, but in other embodiments the ferrule portion 40 may be constructed of other materials, such as graphite or polyimide.

Referring to both fig. 2 and 3, the spring 34 is disposed in a chamber 43 of the housing 32. The retainer 36 is disposed inside the chamber 43 at the end closest to the ferrule portion 40. The housing 32 has a threaded inner surface 45 and a threaded outer surface 47 adjacent the collar portion 40, the threaded inner surface 45 engaging a threaded surface on the cap 38, the threaded outer surface 47 configured to attach to a port. The spring 34 is disposed in the chamber 43 between the retainer 36 and the cap 38. By way of example, the spring 34 may be a coil spring (as shown), a reed, a compressible resilient washer, a hollow cylinder formed from a compressible material, or the like, such that when the spring 34 is subjected to compression between the retainer 36 and the cap 38, a force is applied to hold the retainer 36 fixed in place within the chamber 43 of the housing 32. Thus, the retainer 36 urges the conduit 18 in a proximal direction (i.e., to the left in the figure).

In some preferred embodiments, the retention feature comprises a sleeve 46 disposed on a proximal portion of the tube 18. The sleeve 46 engages the structure of the retainer 36 to limit axial movement of the conduit 18 in the distal direction (i.e., to the right in the figure).

In one embodiment, the housing 32 does not include the ferrule portion 40 shown in FIG. 2. Instead, a replaceable cap is provided at the end of the proximal portion of the tube or cannula. By way of example, the cap may be made of a polyetheretherketone type polymer and be shaped to remain at the end of the pipe or sleeve. As the fitting is urged into the receptacle to couple the conduit to the port, the compression of the spring applies an axial force sufficient to provide a face seal at the end face of the conduit. In another alternative embodiment, a replaceable gasket is used in place of the cap to seal the end face of the tube to the port in the receptacle. The cap or gasket may be removed and optionally replaced with another cap or gasket when the fitting is reattached to the receptacle, or secured to a port in a different receptacle.

Fig. 4A is a cross-sectional side view of the retainer 36 for the reusable fitting 30 of fig. 2, and fig. 4B is an end view corresponding to the retainer 36 as viewed from the left-to-right direction of fig. 4A. The retainer 36 includes an inner surface 50 at one end to receive one end of the spring 34 and a notch 52 at the other end, the notch 52 being aligned with a passage in the ferrule portion of the housing for receiving tubing. The slot 52 includes a first inner surface 54 having a perimeter and a second inner surface 56 having a perimeter less than the perimeter of the first inner surface 54. The locking region is collectively defined by inner surfaces 54 and 56. The first inner surface 54 defines an opening sufficient to receive a sleeve (retaining feature) on a conduit, while the second inner surface 56 has a smaller circumference that cannot receive a sleeve but is still sufficient to allow a conduit to pass through.

The eccentric opening 58 defines an unlocking zone at one end of the slot 52. The eccentric opening 58 is a radial extension for both inner surfaces 54 and 56 that allows the proximal portion of tubing (including the cannula) to pass through the retainer 36 by bypassing the obstruction provided by the locking region defined by the second inner surface 56. As the conduit and sleeve move radially toward the center of the retainer 36 (i.e., toward the axis 57), axial movement in the distal direction is prevented once the sleeve encounters the narrow opening defined by the second inner surface 56.

The larger diameter opening at the end of the slot 52 furthest from the axis 57 allows a user to pass the retention feature 46 through the retainer 36 and then move the retention feature 46 and the pipe 18 back to position them along the axis 57, thereby locking the retention feature 46 and the pipe 18 to the fitting 30. The retention feature 46 and the tube 18 may then be disengageably removed from the fitting 30 in the distal direction without damaging them. The fitting 30 may be reused with another conduit in the same port, or may be used to couple a conduit to a different port. In other embodiments, other shapes and sizes of slots may be used to lock the retention feature 46 and the tube 18 to the fitting.

Fig. 5 shows a cross-sectional view of the cap 38 for the reusable fitting 30 of fig. 2. The cap 38 has a bore 58 and an inner surface 60 at its proximal end, the bore 58 being aligned with the passage defined by the ferrule portion 40 of the housing 32 of fig. 3, the inner surface 60 defining a cavity 62 for engaging the spring. The outer surface of the cap 38 includes threads 64 to engage complementary threads 45 in the chamber 43 of the housing 32 of fig. 3. Referring again to fig. 2, the cap 38 is tightened into the housing 32 by rotation, which urges the spring 34 against the retainer 36. The retainer 36 in turn pushes against the ferrule portion 40 to seal the fluid port.

In one embodiment of the invention, components of a reusable fitting (such as fitting 30 of FIG. 2) are provided as a kit. The components can be assembled to form a reusable fitting for attaching the conduit to the port.

Fig. 6A and 6B are cross-sectional views of a portion of a liquid chromatography device 70 in a disengaged configuration and a coupled configuration, respectively, according to one embodiment of the invention. The illustrated portion 70 includes a conduit 72 for conveying fluid, a port 74 for fluid communication with the conduit 74, and a fitting 76. For example, the tube 72 and fitting 76 may be similar to the tube 18 and fitting 30 shown in FIG. 2. The port 74 may be a fluid inlet port or a fluid outlet port, for example, an output port of a pump, an input port of a column, a sample injector port, a port of a valve, or a port of a T-splitter. For example, the port 74 may be made of metal or plastic. The fitting 76 includes a collar portion 78, the collar portion 78 having a shape and size compatible with a female receptacle 80 of the port 74 such that the collar portion 78 may be tightened into the port 74.

By way of non-limiting numerical example, the conduit 72 may have an inner diameter of less than or about 300 μm. A portion of the tube 72 is typically disposed within a sleeve 82, the sleeve 82 extending through the collar portion 78 of the fitting 76.

The threaded portion 84 of the fitting 76 mates with the threaded portion 86 of the female receptacle 80 of the port 74. When tightened into the port 74 by mating threads, the fitting 76 presses the conduit 72 forward and against the inlet/outlet of the conduit 88 embedded in the port 74. The tube 72 in turn pushes the retainer 90 back towards the cap 92. The device 70 provides a fluid tight seal and substantially zero void volume at the junction of the two conduits 72 and 88 and can withstand pressures that may exceed 20000 psi.

In some embodiments, the liquid chromatography apparatus is an HPLC system, for example, a version of ACQUITYUPLC ® systems or nano ACQUITYUPLC @ systems available from Waters Corporation of Milford, Mass.

Modifications, variations, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the teachings of the invention as claimed. For example, various embodiments include springs in the form of coils, with other configurations of springs being contemplated. For example, the spring may be any structure or mechanism having a spring constant or other elastic properties, such as a wave washer, an elastomeric material, or the like. The invention is therefore not limited to the preceding illustrative description.

Claims (21)

1. A reusable fitting for attaching a tube to a port, comprising:

a housing comprising a ferrule portion at a proximal end of the housing;

a spring in physical communication with the housing;

a retainer disposed between the spring and the housing, the retainer having an opening for allowing entry of a distal portion of a conduit, and a retaining feature fixed to a proximal end of the conduit to limit axial movement of the conduit in a distal direction, the retainer defining an eccentric opening through which the retaining feature of the conduit passes; and

a cap in communication with the spring to urge the spring against the retainer to urge the tubing in a proximal direction.

2. The fitting according to claim 1, wherein said collar portion has a first bore defining a passage for receiving a pipe.

3. The fitting according to claim 2, wherein a distal end of said housing defines a chamber having a width greater than said first bore of said ferrule portion.

4. The fitting according to claim 3, wherein at least a portion of said chamber is internally threaded.

5. The fitting according to claim 1, wherein said ferrule portion is formed of polyetheretherketone.

6. The fitting according to claim 1, wherein said housing is formed of a polymer or steel.

7. The fitting according to claim 1, wherein an outer surface of said housing is threaded for attachment to a port.

8. The fitting according to claim 1, wherein said retention feature comprises a sleeve disposed on a proximal portion of said conduit.

9. The fitting according to claim 8, wherein said sleeve is formed of steel.

10. The fitting according to claim 2, wherein said retainer has an inner surface at a distal end of said retainer for engaging said spring, and wherein said retainer has a notch at a proximal end of said retainer defined by two inner surfaces, a portion of said notch being aligned with said channel defined by said ferrule portion of said housing for receiving said conduit.

11. The fitting according to claim 10, wherein said two inner surfaces include a first inner surface having a perimeter and a second inner surface having a perimeter, said first inner surface having a perimeter that is greater than a perimeter of said second inner surface, wherein said first inner surface allows entry of a retention feature of said conduit and said second inner surface obstructs said conduit retention feature, thereby restricting axial movement of said conduit in a distal direction.

12. The fitting according to claim 10, wherein said slot at said retainer's proximal end further comprises an eccentric opening relative to said two inner surfaces, said eccentric opening being a radial extension, said eccentric opening allowing a retaining feature of said conduit to pass therethrough.

13. The fitting according to claim 2, wherein said cap has a second bore to receive said tube, and an inner surface defining a cavity to engage said spring, said second bore being aligned with said channel defined by said first bore of said collar portion of said housing.

14. The fitting according to claim 4, wherein a surface of said cap is threaded for engaging an internally threaded portion of said chamber to enable tightening of said cap to said housing.

15. A liquid chromatography apparatus comprising:

a conduit for conveying a fluid;

a port in fluid communication with the conduit; and

a fitting for attaching the conduit to the port, the fitting comprising:

a housing having a ferrule portion at a proximal end of the housing;

a spring in physical communication with the housing;

a retainer disposed between the spring and the housing, the retainer having an opening for allowing a distal portion of the conduit to enter and being in physical communication with a retaining feature fixed to a proximal end of the conduit to restrict axial movement of the conduit in a distal direction, the retainer defining an eccentric opening through which the retaining feature of the conduit passes; and

a cap in physical communication with the spring to urge the spring against the retainer to urge the retainer in a proximal direction against the tubing.

16. The liquid chromatography device of claim 15 wherein an outer surface of the housing is threaded for attachment to the port.

17. The liquid chromatography device of claim 15, wherein the collar portion is formed of polyetheretherketone.

18. The liquid chromatography device of claim 15 wherein the housing is formed of a polymer or steel.

19. The liquid chromatography device of claim 15 wherein the retention feature comprises a sleeve disposed on a proximal portion of the conduit.

20. The liquid chromatography device of claim 19 wherein the sleeve comprises steel.

21. A kit having components that can be assembled to form a reusable fitting for attaching a conduit to a port, the reusable fitting comprising:

a housing having a ferrule portion at a proximal end of the housing;

a spring in physical communication with the housing;

a retainer disposed between the spring and the housing, the retainer having an opening for allowing a distal portion of a conduit to enter and being in physical communication with a retaining feature fixed to a proximal end of the conduit to restrict axial movement of the conduit in a distal direction, the retainer defining an eccentric opening through which the retaining feature of the conduit passes; and

a cap in physical communication with the spring to urge the spring against the retainer to urge the retainer in a proximal direction against the tubing.