WO2002013722A1

WO2002013722A1 - Needle nib insert

Info

Publication number: WO2002013722A1
Application number: PCT/NZ2001/000151
Authority: WO
Inventors: John Robert Main; Peter James Murphy
Original assignee: Prima Technologies Limited
Priority date: 2000-08-11
Filing date: 2001-07-26
Publication date: 2002-02-21
Also published as: AU2001284553A1

Abstract

A dispenser which includes a nib insert (11) of metal or other suitable material so that it might withstand stresses exerted thereon by a needle (15) into which it taper engages under the control of a screw cap. The nib insert is preferably engaged within a ferrule with an external thread (8) on which the cap or collar (13) for the needle screw engages.

Description

NEEDLE NIB INSERT

TECHNICAL BACKGROUND

The present invention relates to dispensing apparatus. BACKGROUND ART

Many forms of dispensing apparatus exist where, using a plunger in a barrel, liquid can be drawn into the barrel under the action of the plunger to then be expressed from the barrel out of an appropriate outlet under the action of the plunger. Such appropriate outlets can take a variety of different configurations. The present invention is directed to such an outlet assembly of a kind preferably with a needle outlet e.g. for inj ection of medicaments into domestic or farm animals. DISCLOSURE OF THE INVENTION

The present invention is therefore directed to such assemblies and to related means and methods. In one aspect the present invention consists in a dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) using a chamber of variable volume (e.g. varied in volume by a plunger or piston) wherein there is provided an assembly providing said chamber adapted to be capable of firstly drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, to express the liquid in the chamber out through an outlet, said apparatus being characterised in that a metal "nib insert" having a liquid passageway therethrough is engaged in a fluid tight manner about said outlet, and a needle structure or other outlet member (e.g. catheter, etc) [hereafter referred to as "needle structure"] is mounted to receive liquid via said liquid passageway,

Preferably said nib insert includes a one way valve adapted to prevent drawback into said variable volume chamber.

Preferably said nib insert includes a tapered end adapted to be received internally of the needle structure. Preferably said needle structure is in the form of an injection needle having one enlarged end with an outstanding feature (or number thereof) to facilitate its retention relative to said nib insert (preferably by a collar screw engageable to said assembly. Preferably said collar includes recesses into which the tapered end of said nib insert firming holds the outstand feature(s) of the needle structure.

In a further aspect the present invention consists in a nib insert of a kind previously as defined, said insert being or including a metal member having a passageway therethrough, the needle end about said passageway being frusto-conically tapered over at least a region thereof, and there being a thread provided about said member away from said needle end thereof.

Preferably said nib insert has held within said metal member by a valve seat a biassed valving element whereby there is one way valve into said passageway from the non needle end. In another aspect the present invention consists in a dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) using a chamber of variable volume (e.g. varied in volume by a plunger or piston) wherein there is provided an assembly providing said chamber adapted to be capable of firstly drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, to express the liquid in the chamber out through an outlet, said apparatus being characterised in that a "nib insert" having a liquid passageway therethrough is engaged in a fluid tight manner about said outlet, and a needle structure or other outlet member (e.g. catheter, etc) [hereafter referred to as "needle structure"] is mounted to receive liquid via said liquid passageway,

Preferably said nib insert is of a metal (eg; stainless steel, plated brass, etc.) and/or a plastics material such as a polycarbonate an acetyl or a polysulphone plastic.

Preferably said nib insert includes a one way valve adapted to prevent drawback into said variable volume chamber. Preferably said nib insert includes a tapered end adapted to be received internally of the needle structure.

Preferably said nib insert is "snap lock" engageable in a skirt surrounding the outlet or defusing the outlet (e.g. such as shown in some of the embodiments hereafter described).

Preferably said needle structure is in the form of an injection needle having one enlarged end with an outstanding feature (or number thereof) (e.g. a flange end) to facilitate its retention relative to said nib insert (preferably by a collar screw engageable to said assembly. Preferably said collar includes recesses into which the tapered end of said nib insert firming holds the outstand feature(s) of the needle structure.

In a further aspect the present invention consists in a nib insert of a kind previously as defined, said insert being or including a member having a passageway therethrough, the needle end about said passageway being frusto-conically tapered over at least a region thereof, and there being provided snap locking members or a shoulder or a projection or projections away from said needle end thereof.

Preferably said nib insert is held within said member by a valve seat and/or a biassed valving element whereby there is a one way valve into said passageway from the non needle end.

As used herein the term "snap lock" feature a component or an interaction or the like refers (in one range of embodiments) to a moulded or machined component of one member providing a retainment feature capable by interaction directly with the complementary member (e.g. using flexible shoulder, flange or the like defining members) of locking in against easy disengagement and (in another type of embodiment) to a feature that lends itself for such interengagement reliant upon an interposed annular or part annular member such as an O-ring or circlip respectively. In that later form preferably a said snap lock feature et al refers to an O-ring or circlip locating feature.

In another aspect the present invention consists in a dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) using a chamber of variable volume (e.g. varied in volume by a plunger or piston) capable of firstly drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, to express the liquid in the chamber out through an outlet, said apparatus being characterised in that about said outlet from said variable volume chamber is defined both an external and an internal thread, a threaded member (hereafter defined "nib insert") having a passageway therethrough is screw engaged or engageable into said internal thread, and a cap with an internal thread and a passageway is screw engaged to said external thread about said nib insert, and

(optionally) a needle structure or other outlet member (e.g. catheter, etc) [hereafter referred to as "needle structure"] is retained or retainable at least in part within said passageway through said cap and is or can be held in such retained engagement with said cap by part of said nib insert.

Preferably said nib insert includes a one way valve adapted to prevent drawback into said variable volume chamber. Preferably said nib insert is of a metal (eg; stainless steel, plated brass, etc.) and/or a plastic such as a polycarbonate, acetyl or polysulphone plastic.

Preferably said nib insert includes a tapered end adapted to be received internally of the needle structure in the passageway of said cap.

Preferably said needle structure is in the form of an injection needle having one enlarged end with an outstanding feature (or number thereof) (e.g. a flanged end) for engagement into with said cap e.g. an annular rib.

Preferably said cap includes recesses into which the tapered end of said nib assembly firming holds the outstand feature(s) of the needle structure.

In a further aspect the present invention consists in a nib insert of a kind previously as defined, said insert being or including a member having a passageway therethrough, the needle end about said passageway being frusto-conically tapered over at least a region thereof, and there being provided about said member away from said needle end thereof, a region of external threading (preferably adapted to allow its engagement with a said internal thread of a suitable dispenser), and preferably having held within said member (preferably by a valve seat) a biassed valving element whereby there is a one way valve into said passageway from the non needle end.

In another aspect the invention is a nib assembly as previously defined substantially as hereinafter described with reference to any of the accompanying drawings.

In another aspect the present invention consists in a dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) using a chamber of variable volume (e.g. varied in volume by a plunger or piston) capable of firstly drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, to express the liquid in the chamber out through an outlet, the apparatus being characterised in that about said outlet from said variable volume chamber is defined an external thread and part of a snap locking means is defined inwardly thereof, a complementary snap locking nib insert having a passageway therethrough is snap lock engaged with said part of a snap locking means, and a cap with an internal thread and a passageway is screw engaged or engageable to said external thread about said outlet, and a needle structure or other outlet member (e.g. catheter, etc) [hereafter referred to as

"needle structure"] in use is retained or retainable by said cap on part of said nib insert, liquid being expressible in such condition from said chamber via the outlet, the nib insert and the needle structure.

Preferably said nib insert is of a metal (eg; stainless steel, plated brass, etc.) and/or plastics material such as a polycarbonate, acetyl or polysulphone plastic.

Preferably said nib insert includes a tapered end adapted to be received internally of the needle structure in the passageway of said cap. Preferably said needle structure is in the form of an injection needle having one enlarged end with an outstanding feature (or number thereof) (e.g. a flanged end) for engagement into with said cap e.g. an annular rib.

Preferably said cap includes recesses into which the tapered end of said nib assembly firming holds the outstand feature(s) of the needle structure. In a further aspect the present invention consists in a nib insert of a kind previously as defined, said insert being or including a member having a passageway therethrough, the needle end about said passageway being frusto-conically tapered over at least a region thereof, and there being provided about said member away from said needle end thereof, a snap lock feature (preferably adapted to allow its engagement with a complementary snap lock feature of a suitable dispenser), and preferably having held within said member (preferably by a valve seat) a biassed valving element whereby there is a one way valve into said passageway from the non needle end.

In still a further aspect the present invention consists in dispensing apparatus of a kind substantially as hereinafter described with reference to any one or more of the accompanying drawings. h still a further aspect the present invention consists in an outlet assembly for injection apparatus substantially as hereinafter described with reference to any one or more of the accompanying drawings.

In still a further aspect the present invention consists in a method of injection or liquid dispensing when performed substantially as herein described with reference to any one or more of the accompanying drawings.

In still a further aspect the present invention consists in a dispenser of a kind substantially as herein described having an infeed for liquid from a direction substantially as hereinafter depicted and having an outlet assembly substantially of a kind as herein described or herein previously defined, preferably with reference to the accompanying drawings.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

The invention consists in the foregoing and also envisages constructions of which the following gives examples. DETAILED DESCRIPTION OF THE INVENTION

One preferred form of the present invention will now be described with reference to the accompanying drawings in which;

Figure 1 is a side elevation view of a preferred dispenser in accordance with the present invention in its configuration with the handles apart, thereby having the variable volume chamber in its enlarged condition, the piston being moveable to the left under operation by an operator, i.e. by squeezing the handles against a bias, there being an intake for liquid from a reservoir (not shown) into such chamber and the ability to express the same out of the outlet assembly shown and circled,

Figure 2 is an enlargement of the arrangement within the encircled region of Figure

1,

Figure 3 is a perspective view of the apparatus of Figure 1 but with the cap and needle structure removed and with the nib assembly exploded away from the remainder,

Figure 4 sho s a sectional view depicting a prior art nib that is moulded as an integral part of the chamber for attachment via the screw thread to needle structure, the plastic nib being susceptible to fracturing at the point denoted as "A" where high concentrations of stress occur during use,

Figure 5 shows a nib that accords with the present invention, the nib being of a resilient metallic material (e.g. stainless steel or brass) and separable from the plastic chamber via a screw thread or similar,

Figure 6 shows an alternative arrangement to that shown in Figure 5 where the nib is again manufactured from a metallic material or a polycarbonate, an acetyl or a polysulphone plastic but instead of being screw threadably engaged with the plastic chamber the nib is pressed into the chamber or alternatively the chamber is moulded around the nib during manufacture or alternatively the nib is glued into the chamber.

Figure 7 is an exploded view of part of a dispenser in accordance with the present invention having a nib insert, having an outstanding pair of protuberances each adapted to slide into a receiving snap lock feature internally of the threaded skirt about the outlet, such outstanding members preferably being wedged or ramped on one side to allow such insertion and not so ramped on the "shoulder" side to ensure retention,

Figure 8 is a plan view of the nib insert shown in Figure 7,

Figure 9 is the side elevation of the nib insert of Figures 7 and 8,

Figure 10 is a cross section showing a nib insert of an assembly as shown in Figure 7 in its engaged condition (no nib being shown for clarity), Figure 10A is an enlargement of the encircled region of Figure 10,

Figure 11 is an exploded view of an alternative of Figure 7 where the nib insert has four retaining protuberances,

Figures 12 through 14A correspond to Figure 11 in the same way as Figures 8 through 10a correspond to Figure 7, Figure 15 shows yet a further embodiment where in this exploded view a continuous peripheral flange is provided capable of being snap lock engaged in a complementary feature,

Figure 16 is a plan view of the nib insert of Figure 15,

Figure 17 is a side elevation of the nib insert of Figure 16,

Figure 18, in a similar manner to that of Figures 10 and 14, shows the assembly of Figure 15 in section in its assembled condition with Figure 18A showing an enlarged view of the encircled region of Figure 18, Figure 19 is an exploded view of still a further embodiment, this time where the nib insert includes a peripheral groove adapted to locate a circlip as shown (or in the alternative an O-ring) which once fitted will provide the appropriate snap lock feature,

Figure 20 is a plan view of the nib insert of Figure 19, Figure 21 is a side elevation of the nib insert of Figure 20,

Figure 22 is a section of the assembly of the components of Figure 19,

Figure 22 A is the enlargement of the encircled region of Figure 22,

Figure 23 is a side elevational view of an arrangement where the cap when distended to the condition as shown in Figure 23A by appropriate screw thread rotation is capable of receiving laterally of the passageway axis an appropriate needle, such a needle having been shown laterally positioned in Figure 23B and thereafter upon appropriate rotation of the cap to the condition of Figure 23C can then have the nib insert lodged therewithin to provide the fluid tight communication from the nib outlet to the needle structure and at the same time by being lodged within the needle preventing lateral displacement of the needle from the cap, and Figure 24 is a cross section of a preferred clip fit engagement of a preferred stainless steel needle nib insert clip fit retained within a moulded ferrule of the outlet to the variable volume chamber which has the capability of performing in conjunction with a cap or collar in any of the ways previously shown.

In the preferred form of the present invention there is a variable volume chamber 1 (preferably cylindrical in form) to receive slidingly there within a plunger or piston 2. It includes an intake 3 from a needle or other member 4 adapted to penetrate into a supply reservoir for the liquid to be drawn into the chamber 1.

Once liquid is drawn into the chamber 1 it can be expressed therefrom out of the outlet 5 by moving the piston or plunger 2 to the left from the condition shown in Figure 1 by squeezing together the two handle components 6a and 6b against the bias of the spring 7. Such arrangements are well known in the art.

Disposed about the outlet 5 is both an external thread 8 and an internal thread 9. It is into the internal thread 9 that the external thread 10 of a nib insert 11 can be screw engaged in the manner shown in Figures 1 and 2. It is onto the external thread 8 that an internal thread 12 of a cap 13 engages.

A needle structure 14 includes a needle region 15 capable of being inserted into a catheter or through the skin of an animal whilst its enlarged end region 16 includes an outstanding annular rib 17 adapted to be received in a corresponding location groove in a passageway out through the cap 13. This enlarged end region 16 and its outstanding feature 17 is held in such engagement after assembly by reliance upon the tapered end region 18 of the nib insert 11. This tapered end region is preferably frustoconical thereby providing a wedging effect on the enlarged end 16 against the cap 13 passage walls and of course to hold the retention upstand 17 in place.

Persons skilled in the art will appreciate how if desired components 11 and 14 can be made of an appropriate metal material, e.g. stainless steel.

Persons additionally will see how the nib insert 10 within the region 19 thereof can locate a ball spring and valve seat so as to provide a non return valve feature within the nib insert thus meaning that, in use, retraction of the piston 2 back to the condition as shown in Figure 1 is unlikely to draw materials out of an animal into which an injection has just been made. It also has the effect of closing the chamber 1 so that the withdrawal of the piston 2 to the condition as shown in Figure 1 will have a better liquid draw in effect via the member 4. It is believed that with the provision of such a strong metal nib insert in nested relationship within the needle structure the overall strength of the end is enhanced notwithstanding it may be desirable to include many of the components in a material other than an appropriate metal. For example, the cap 13 can be of a suitable plastics material as can of course that member or region (preferably part of a moulding) providing the internal and external threads 9 and 8 respectively.

A problem with the type of nib depicted in Figure 4 is fracturing due to excessive pressure loading and bending moment as the fluid is dispensed from the apparatus. This pressure can be high enough to fracture the nib at the point denoted by "A" thereby rendering the dispensing apparatus useless. In Figure 5 the nib insert 20 is manufactured from a resilient metallic material such as stainless steel or brass (preferably plated) or even, for example, aluminium that has a superior fracture toughness to that of the nib of Figure 4 (moulded from a plastics material). The nib of Figure 5 is also replaceable affording the dispensing apparatus improved versatility over the arrangement shown in Figure 4. As shown in Figure 5 the nib insert 20 has a male screw thread 21 which engages and mates with the thread 22 of the chamber, the chamber also being threaded to receive the needle structure as before as in the arrangement of Figure 4. In Figure 6 the screw portion of the nib has been removed allowing the nib to be inserted into the chamber by some pressing action, the resulting engagement providing a tight fit so that during operation the nib is prevented from coming lose. The present invention also envisages alternatives where the surface finish of the nib includes some retention features such as annular ribs or even a knurled finish, such features providing enhanced retention once the nib is installed. Alternatively, the chamber might be moulded around the nib during an injection moulding procedure. In another alternative form, before the nib is inserted into the chamber, the screw portion of the nib that has been removed has had glue applied to its surface and/or alternatively the inside of the chamber has had glue applied. In Figures 7 through 22 A a variety of different retention types are described for the nib insert which are not reliant upon internal threading of the skirt about the outlet.

For example a snap lock feature reliant upon a pair of protuberances 23 provides the engagement in an appropriate snap lock feature 24.

A similar arrangement occurs with the embodiment of Figures 11 through 14 A but this time there are four such protuberances.

The arrangement of Figure 15 is different in that a continuous ramped or the like deformable flange 25 provides the snap lock feature of the nib insert and that is received as shown in Figure 18A by a corresponding snap lock feature 26.

The embodiment of Figures 19 through 22A preferably utilises a circlip 27 (although in an alternative it could be an O-ring) adapted to be received in the snap lock feature (being the annular groove or circlip or O-ring seat 28). As shown in Figure 22A there are complementary parts 28 and 29 to provide the requisite snap locking with the circlip interposed therebetween.

Persons skilled in the art will appreciate how, with each of the embodiments described with reference to Figures 7 tlirough 22A preferably each nib insert is preferably of metal or other durable material and preferably each has a tapered region as previously described for wedge location internally of an appropriate nib.

Figure 23 A through 23 C shows a means of needle engagement and association with the apparatus to some extent similar to that disclosed in Simcro Tech Limited New Zealand Patent Specification 260359 the full content of which is hereby here included by way of reference. Figure 24 shows a preferred form of stainless steel needle nib insert capable by virtue of its angled ridge of being clip fit received within the moulded plastics ferrule of the outlet which has a complementary clip fit feature (an annular groove) and which has an external thread for the engagement as previously described with an appropriate cap or collar. In this arrangement the cap 30 can if desired be of the form disclosed in the aforementioned Simcro Tech Limited New Zealand Patent Specification or any other alternative form which will allow lateral association of a needle 31 therewith and subsequent insertion of the needle insert 32 within the flanged and enlarged end 33 thereof. Between the conditions shown in Figures 23 A through 23 C any appropriate form for the cap needle insert and needle can be utilised which has a like effect.

Claims

CLAIMS:

1. A dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) reliant on a dispenser assembly providing a chamber of variable volume adapted to be capable of drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, of expressing the liquid in the chamber out through an outlet, said apparatus being characterised in that a metal nib insert having a liquid passageway therethrough is engaged in a fluid tight manner about said outlet, and a needle structure or other outlet member (e.g. catheter, etc) [hereafter referred to as

"needle structure"] is mounted at least in part about and on said nib insert to receive liquid via said liquid passageway thereof from said outlet.

2. A dispenser of claim 1 wherein said nib insert is an assembly which includes or is associated with a one way valve adapted to prevent drawback into said variable volume chamber via said outlet.

3. A dispenser of claim 1 or 2 wherein said nib insert includes a tapered end adapted to be received internally of the needle structure.

4. A dispenser of claim 3 wherein said needle structure receives the tapered end internally of a collar retainable end region of the needle structure.

5. A dispenser of claim 4 wherein a collar screw engageable to said dispenser assembly about the nib insert retains the needle structure by its collar retainable end region relative to and/or on said nib insert.

6. A dispenser of claim 5 wherein said collar can receive the needle structure by at least its retainable end and can engage the thus received needle structure operatively on the nib insert by moving the collar as it is screwed tight.

7. A dispenser of claim 5 or 6 wherein said collar can locate an enlarged retainable end of the needle structure for axial movement under the action of the collar as it is screw rotated relative to the dispenser assembly thereby to provide a fluid tight connection between said nib insert and the needle structure, and vice versa.

8. A dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) reliant on a dispenser assembly providing a chamber of variable volume adapted to be capable of drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, of expressing the liquid in the chamber out through an outlet, said apparatus being characterised in that a nib insert having a liquid passageway therethrough is engaged in a fluid tight manner about said outlet, and a needle structure is mounted at least in part about and on said nib insert to receive liquid via said liquid passageway,

9. A dispenser of claim 8 wherein said nib insert is from said outlet of a plastics material.

10. A dispenser of claim 9 wherein said plastics material is an acetyl or polysulphone plastic.

11. A dispenser of claim 8 or 9 wherein said nib insert includes or is associated with a one way valve adapted to prevent drawback into said variable volume chamber via said outlet.

12. A dispenser of claim 11 wherein said nib insert includes a tapered end adapted to be ^• received internally of the needle structure.

13. A dispenser of claim 3 wherein said needle structure receives the tapered end internally of a collar retainable end region of the needle structure.

14. A dispenser of claim 4 wherein a collar screw engageable to said dispenser assembly about the nib insert retains the needle structure by its collar retainable end region relative to and/or on said nib insert.

15. A dispenser of claim 5 wherein said collar can receive the needle structure by at least its retainable end and can engage the thus received needle structure operatively on the nib insert by moving the collar as it is screwed tight.

16. A dispenser of claim 8 herein said nib insert is "snap lock" engageable in a skirt surrounding the outlet or defining the outlet.

17. A nib insert of a kind and suitable for a dispenser as claimed in any one of claims 1 to

16, said insert being or including a member having a passageway therethrough, the needle end about said passageway being frusto-conically tapered over at least a region thereof, and there being a thread provided about said member away from said needle end thereof.

18. A nib insert of claim 17 at least primarily of metal.

19. A nib insert of claim 18 or 19 wherein it has held therewithin by a valve seat a biassed valving element whereby there is one way valve into said passageway from the non needle end.

20. A dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or apure liquid compound) using a chamber of variable volume (ie;. varied in volume by a plunger or piston) capable of firstly drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced to express the liquid in the chamber out through an outlet, the apparatus being characterised in that about said outlet from said variable volume chamber is defined both an external and an internal thread, a threaded nib insert having a passageway therethrough is screw engaged into said internal thread, and a cap with an internal thread and a passageway is screw engaged to said external thread of said outlet about said nib insert, and

21. A dispenser of claim 20 wherein said nib insert includes a one way valve adapted to prevent drawback into said variable volume chamber.

22. A dispenser of claim 20 or 21 wherein said nib insert is of a metal.

23. A dispenser of claim 20, 21 or 22 wherein said nib insert includes a tapered end adapted to be received internally of the needle structure.

24. A dispenser of claim 23 wherein said needle structure is in the form of an injection needle having one enlarged end for engagement into and/or with said cap.

25. A dispenser of claim 24 wherein said enlarged end includes a peripheral flange.

26. A dispenser as claimed in claim 25 wherein said peripheral flange is capable of being engaged laterally of said cap when said cap is at least largely unscrewed from said external thread of said outlet and thereafter can be axially moved under the screw tightening of said cap so as to have the tapered end of said nib insert in a fluid tight manner received within the said at least one enlarged end of said injection needle.

27. A dispenser of a kind capable of expressing a liquid (whether a solution, suspension, emulsion, suspo emulsion or a pure liquid compound) using a chamber of variable volume (e.g. varied in volume by a plunger or piston) capable of firstly drawing in a liquid feed via a liquid inlet, as the volume of that chamber is enlarged, and thereafter, as the volume of that chamber is reduced, to express the liquid in the chamber out through an outlet, the apparatus being characterised in that about said outlet from said variable volume chamber is defined an external thread and part of a snap locking means is defined inwardly thereof, a complementary snap locking nib insert having a passageway therethrough is snap lock engaged with said part of a snap locking means, and a cap with an internal thread and a passageway is screw engaged or engageable to said external thread about said outlet, and a needle structure or other outlet member (e.g. catheter, etc) [hereafter referred to as

28. A dispenser of claim 27 wherein said nib insert is part of an assembly which includes a one way valve adapted to prevent drawback into said variable volume chamber.

29. A dispenser of claim 27 wherein said nib insert is of a metal.

30. A dispenser of claim 27 wherein said nib insert is of a plastics material.

31. A dispenser of claim 27, 28, 29 and 30 wherein said nib insert includes a tapered end adapted to be received internally of the needle structure.

32. A dispenser of any one of claims 27 to 31 wherein said needle structure is in the form of an injection needle having one enlarged end for engagement into and/or with said cap.

33. A dispenser of claim 32 wherein said enlarged end includes a peripheral flange.

34. A dispenser as claimed in claim 33 wherein said peripheral flange is capable of being engaged laterally of said cap when said cap is at least largely unscrewed from said external thread of said outlet and thereafter can be axially moved under the screw tightening of said cap so as to have the tapered end of said nib insert in a fluid tight manner received within the said at least one enlarged end of said injection needle.

35. Dispensing apparatus of a kind substantially as hereinafter described with reference to any one or more of the accompanying drawings.

36. Dispensing apparatus having an outlet, nib insert and needle retention cap substantially has herein described with reference to any one or more of the accompanying drawings.