This invention relates to a dispenser for dispens¬ ing fluent substances, for example mastics _*

Previous dispensers for mastics have often been in the form of a gun, A cartridge of mastic is inserted into the barrel of the gun and a piston is driven forwards from the rear of the cartridge by a mechanical drive expelling the mastic from a nozzle at the front of the dispenser. The mechanical drive for the piston takes the form of a ratchet mechanism and a trigger which each time it is squeezed advances the piston a short distance along the cartridge. With viscous mastics heavy pressure must be applied to the trigger and this makes prolonged opera¬ tion of the gun very tiring for the operator. Also as a result of the intermittent _* movement of the piston the flow of mastic from the gun is also intermittent and this makes it difficult to apply the mastic evenly.

It has been proposed to replace the mechanical drive with a compressed air drive. In one proposed arrange¬ ment the compressed air is supplied from a compressor remote from the dispenser and connected thereto by an air line.

Such an arrangement is disadvantageous in that it is costly

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and the provision of a compressor and air line can obstruct the use of the dispenser and extend the time taken for doing any particular job. In another proposed arrangement the compressed air is contained in the dis- penser itself and this avoids the need for a compressor or air line. -However in order to accommodate a suffi¬ cient quantity of compressed air the dispenser must be made much larger than would be necessary with a remote supply of compressed air. Furthermore the pressure of the compressed air will fall rapidly with use so that unless provision is made to compensate for this fall in pressure, thereby adding to the expense of the dispenser, the per¬ formance of the dispenser will not be satisfactory.

. Furthermore, none of the proposed arrangements are able to dispense with equal efficiency a full range of mastics whose viscosity covers a very wide range.

It is an object of the invention to provide a dispenser for dispensing fluent substances that mitigates the disadvantages described above. According to the invention a dispenser for dis¬ pensing fluent substances includes an elongate barrel for receiving a cartridge of a fluent substance, a nozzle assembly for connection at a front end of the barrel and a pressurising assembly supported on the dispenser and including a housing for receiving a capsule of liquefied or pressurised gas, pressure adjusting.means, a first fluid path extending from one side of the pressure adjust¬ ing means for communicating with the outlet of a capsule inserted, in use, in the housing, and a second fluid path extending from the other side of the pressure adjusting means into the rear end of the barrel.

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a - The use of/capsule of pressurized gas in combina¬ tion with pressure adjusting means provides a compact lightweight and convenient pressurizing assembly which is able to dispe with good efficiency mastics of wide ranging viscosity.

The pressurising assembly may be mounted on the rear end of the barrel.

The rear end of the barrel may consist of an end cap closing the rear end of the barrel and defining the rear end wall of the barrel. The pressurising assembly may be mounted on the end. cap.

The end cap may be attached to the body of the barrel in such a way that, in the event of the pressure in the barrel exceeding a safe pressure, the end cap moves relative to the body of the barrel venting the excess pressure.

A pressure indicator may be mounted on the rear end of the barrel to indicate to a user whether or not the barrel is pressurised. The pressure adjusting means may include a valve member mounted in a passage providing communication be¬ tween the first fluid path and the second fluid path, the valve member being movable between a first position in which the passage is closed and a second position in which the passage is open the valve member being resiliently biased, in use, into the first position, and a piston or diaphragm co-operable with the valve member and movable away from one position in which the valve member is held in the second position by the piston or diaphragm to another position in which the valve member assumes its first posi¬ tion, the piston or diaphragm being biased to said one position by a spring and being biased away from said one

position to another position by the pressure of gas on the low pressure side of the pressure adjusting means.

The "bias orce of the spring acting on the piston or diaphragm may be adjustable to adjust the pressure of gas required to move the piston or diaphragm away fro said one position to another position.

In use, a capsule of liquefied or pressurised gas is located in the housing. The gas may be carbon dioxide or nitrous oxide or any gas which does not have a substan tial deleterious effect on the fluent substances with which it will come into contact.

A valve may be provided between the interior of the barrel and the outlet of the nozzle assembly or con¬ trolling the flow of fluent substance from the dispenser. This provides further control when dispensing the mastic. With both pressure adjusting means for adjusting the pres sure exerted on the mastic and a valve to control the flo of the mastic, the rate of dispensing of mastic can be controlled very well. The valve may be arranged so that it is actuated by rotation of the barrel relative to the nozzle; alternativ he valve may be arranged so that it is actuated by slidi movement of the barrel relative to the nozzle. It is advantageous for the nozzle to be kept stationary and the barrel moved in order to operate the valve since this en¬ ables movement of the nozzle to be more carefully control

The nozzle assembly may include a nozzle mounted in such a way that its orientation with respect to th other part of the assembly is adjustable. The nozzle may be eccentrically located on the front end of the barrel. A pressure relief valve may be mounted on the rear end of the barrel, or any other convenient part of the barrel.

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Manually operable means may be provided for vent¬ ing the pressurised gas in the barrel to return the pressure i the barrel to atmospheric pressure. The venting may be provided by the pressure adjusting means but alternatively the venting means may be provided by some other arrangement, for example by the pressure relief valve.

Before use, a cartridge of a fluent substance is inserted into the barrel. The cartridge may be provided with a piston at its rear end.

The cartridge and barrel may be arranged such that when the cartridge is located in the barrel the front end of the cartridge seals against the front end of the barrel; in this case the rear end of the barrel is sealed. Alternatively, the cartridge and barrel may be arranged such that when the cartridge is located in the barrel the rear end of the cartridge seals against the rear end of the barrel around the entry of the second fluid path into the barrel.

The nozzle assembly may be attached to the front end of the cartridge, projecting through an opening in the front end of the barrel.

The cartridge and the barrel may be arranged such that the cartridge can be fitted into the barrel in only one orientation and is held in that- position by inter- engagement of the cartridge and barrel.

A cartridge assembly may be inserted into the barrel, the cartridge assembly including a cartridge having an elongate chamber containing a fluent substance to be dis¬ pensed, a piston member slidably mounted at one end of the chamber for sliding movement along the chamber, the other end of the chamber being provided with means defining

an outlet for the fluent substance, and a valve control member adjacent the other end of the chamber to control opening and closing of the outlet.

The outlet defining means may comprise one or more apertures in the cartridge for example in an end wall thereof. Alternatively, the outlet defining means may comprise a portion of the chamber end wall which has been weakened and can be removed by a user to produce an aperture. In one position of the valve eontrol member an aperture of the member may be aligned with and directly adjacent the outlet defining means and in another posi¬ tion of the member the outlet defining means may be covered over by the member. Alternatively, the valve control member may carry a separate closure member haying an aperture, the aper¬ ture in the closure member being aligned with and direct adjacent the outlet defining means in one position of the valve control member and the outlet defining means being covered over in another position of the valve cont member.

The closure member may comprise the rear end of a nozzle.

The other end of the cartridge may be formed with a recessed end wall and the valve control member may be received within the recess. The valve control member may be push fitted into the recess.

Releasable holding means may be provided for hold¬ ing the valve control member in a fixed position relativ to the cartridge, when the cartridge is first manufactur The holding means may be breakable prior to use of the cartridge assembly to allow movement of the valve contro

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member relative to the cartridge _*

A nozzle may be fitted to the valve control member around the aperture. A male coupling part of the valve control member may engage a female coupling part of the nozzle•

The valve control member may be rotatably mounted on the cartridge.

The cartridge may be of circular cross-section. The valve control member may be mounted for rotation about the central longitudinal axis of the cartridge, the outlet defining means on the cartridge being eccentrically positioned.

The piston member may be provided with a bore there¬ through, the bore being blocked by the fluent substance. The piston member may be provided with a peripheral skirt extending towards said one end of the chamber. The outer surface of the skirt may be formed with one or more ribs extending around the periphery of the skirt.

The cartridge may be made of a plastics material, which may be translucent. At least the periphery of the piston member may be brightly coloured so that it can be more easily seen through the cartridge.

By way of example, a dispenser for dispensing fluent substances will now be described with reference to the accompanying drawings, in which:

Figure 1 is a partly sectional side view of a dis¬ penser including a cartridge assembly;

Figure 2 is a sectional side view of the front of the dispenser including the cartridge assembly; Figure 3 is sectional view of a pressure adjusting assembly which forms part of the dispenser of Figure 1 ;

Figure 4 is a perspective cut-away view illustrating

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the mounting of the pressure adjusting assembly on the body of the dispenser;

Figure 5 is a sectional view of part of a cartridge assembly prior to insertion into the dispenser; Figure 6 is a sectional side view of the front end of a modified.for of the dispenser shown in Figures 1 to 4;

Figure 7 is a front schematic view showing a modification to the dispenser of Figure 6; Figure 8 is a sectional side view similar to

Figure 6 showing another modification to the dispenser of Figure 6;

Figures 9A, 9B and 90 illustrate a modification which may be made to the part of the cartridge assembly shown in Figures 1 and 2;

Figure 10 is a side sectional view illustrating a modification which may be made to another part of the cartridge assembly;

Figure 11 shows a pressure indicator which may be incorporated in the dispenser; and

Figure 12 is a sectional side view of a pressure relief arrangement which may be incorporated in the dis¬ penser.

Figure 1 shows a dispenser having an elongate barrel of circular cross section, a pressurising assembly 2 and a nozzle and operating means 3» The pressurising assembly 2 is attached to a rear end cap 4 of the barrel, the end cap being screwed on to the tubular body part 1 of the barrel. A cartridge 5 is received in the barrel body 1 and has an elongate chamber containing a fluent substance to be dispensed, for example a mastic. At the rear end of the cartridge a piston member 47 is εlidably mounted in the cartridge 5 and, during use of the dispenser, the

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piston is acted upon on its rear side by pressurised gaβ supplied by the pressurising assembly 2. As the fluent substance is expelled from the dispenser the piston member 47 travels down the cartridge 5 and the level of fluent substance in the cartridge 5 (the walls of which are translucent or transparent) can be seen through a longitudinal slot 67 in the barrel body 1 ; the piston member 47 is preferably brightly coloured so that it can be easily seen. A seal 19 is sandwiched between the rear end of the cartridge 5 and the end cap 4 so that pressurised gas from the pressurising assembly 2 is confined to the space inside the rear end of the cartridge.

Figure 2 shows the nozzle end of the dispenser in more detail. Referring now to Figures 1 and 2, the cart- ridge 5 is made of a plastics material which is inert to the fluent substance and has a transverse front end wall 7 located within the cartridge close to one end thereof and having an eccentric aperture 8 of circular cross-sec¬ tion. The tubular wall 6 or the front end face of the cartridge 5 and the barrel body 1 are provided with inter- engageable parts (not shown in the drawings) which allow the cartridge to be fully inserted into the barrel body 1 in only one orientation of the cartridge relative to the barrel body. The end of the tubular wall 6 is formed with an inwardly protruding lip 9. A plastics valve control member 10 having an eccentric aperture 11 defined by a tubular wall 13 is housed between the lip 9 and the end wall 7 and is mounted for rotation about the longitudinal axis of the cartridge. The valve member 10 is snap fitted into the recess at the front of the cartridge between the wall 7 and the lip 9.

The apertures 8 and 11 are of the same size and shape and, ^' in one position of the valve member (shown in Figures 1 and 2), they are directly aligned. The end wall 7 of the cartridge 5 is formed with a resilient rim 12 around the aperture 8. This rim protrudes for- wardly of the rest of the end wall 7 and bears against the valve member 10 sealing the interface of the valve member and the end wall.

The cartridge 5 and valve control member 10 together define a cartridge assembly.

A front end cap 14 whose peripheral wall is define by a plurality of resilient fingers, is snap fitted on to the front of the barrel body 1 • The inside of the cap includes an integral lug 15 the end of which is received in a corresponding recessed boss 16 defined in the valve member 10.

A nozzle 17 is fitted over the tubular wall 13 n the end of the cartridge and extends through an aperture in the end cap 14. A flange 18 in the nozzle 17 is provided on the inner side of the end cap 14 and prevents the nozzle 17 being pulled off the cartridge.

Rotation of the barrel body 1 relative to the end cap 14 rotates the valve member 10 relative to the end wall 7 of the cartridge 5 so that the apertures 8 and 11 move from an aligned (open) position shown in the drawing to a non-aligned position; as the non-alignment of the apertures 8 and 11 increases so the valve progressively closes and once the apertures are completely out of align ment the valve is closed. Since the cartridge 5 can be inserted into the barrel body 1 in one orientation only, the position of the.end cap 14 relative to the barrel bod 1 in the fully open position of the valve is fixed so it

possible to provide markings on adjacent exterior surfaces of the barrel body 1 and the end cap 14 indicating the open and closed positions of the valve. If desired stop means (not shown in the drawings) may be provided on the barrel body 1 and the end cap 14 to limit the relative rotation of those parts to about 90 degrees. Alternatively or additionally stop means may be provided in the valve itself.

As already mentioned, the substance in the cartridge 5 is expelled, under the control of the valve just described by the piston member 47 driven by pressurised gas behind the piston member. The pressurised gas is supplied by the pressurising assembly 2 which is showa in Figure 3 and which will now be described. The assembly 2 includes a housing 20 for receiving a capsule 24 of liquid carbon dioxide. A capsule piercing member 21 including a piercer 42 is received in the body 18 and an '0* ring 23 seals the interface of the piercing member 21 and the body 18. The end of the piercing member 21 adjacent the housing 20 has a bore sized to receive the neck of the capsule 24 and an '0' ring 45 is seated in the bore to seal the interface of the capsule neck and the bore. To insert a capsule 24 into the assembly 9 the housing 20 is first unscrewed. The capsule 24 is then placed in the housing 20 and the housing 20 brought into position to be screwed on to the body 18. At this stage, the neck of the capsule 24 is in sealing engagement with the piercing member 21 but the capsule is to the left of the position shown in Figure 3 so that the capsule is not yet pierced. As the housing 20 is now screwed on to the body 18, the housing drives the capsule on to the piercer 42 and the capsule is pierced allowing gas to flow

along a fluid path from the capsule through the piercing member 21 into a chamber 25 defined by the piercing member 21 and a valve housing 22 which is screwed on to the piercing member and whose interface with the pierc- ing member is sealed by an JO* ring 46. The chamber 25 is the high pressure chamber of an adjustable pressure reducing valve assembly which will now be described. The valve housing 22 slidably receives a valve member 26 which has a closure disc 27 at one end which is in the chamber 25 and a head 28 at the other end. The closure disc 27 abuts a seat formed on the housing 22 and is resiliently biased by a weak spring 34 against the seat. The right hand end (as seen in Figure 3) of the body 18 has a bore 30 in which a piston 29 is εlidingly received, an '0* ring 41 being provided around the pisto 29 to seal the interface of the piston 29 and the bore 3 The bore 30 is closed by a cap 31 screwed on to the exterior of the body 18. The piston 29 is inwardly biase by a compression spring 32 extending between the piston and the cap 31 • In the position shown in Figure 3 the head 28 of the valve member 26 abuts the piston 29. A chamber 33 is defined between the valve housing 22 and the piston 29; this chamber communicates with a duct 44 which extends through the boss 19 of the body 18 and provides a fluid path between the barrel and the chamber Before insertion of the capsule 24, with the pres¬ sure acting on the piston member 47 atmospheric and with the valve set to provide a finite gauge pressure in the barrel, the pressure in chamber 33 is atmospheric, the piston 29 abuts the end face of the bore 30 and the valve member 26 is pressed against the action of the spring 34 to an open position in which the closure disc 27 is space from the seat on the valve housing 22, Upon insertion an piercing of the capsule 24, pressurised gas passes throug

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the chamber 25 and the chamber 33 into the barrel. As the pressure in the chamber 33 then increases to above atmospheric the piston 29 is pressed outwards against the bias of the spring 32 to a position in which the force of the pressure over the face of the piston sub¬ stantially equals the force of the spring (there is also a force applied to the piston by the valve member 26). The pressure continues to increase until the piston reaches the position shown in Figure 3 at which stage the closure disc 27 abuts the valve seat of the valve housing 22 and the flow of gas from the capsule stops. When the pressure acting on the piston member 47 drops, for example as a result of a .fluent substance be¬ ing expelled from the cartridge 5, the force exerted by the spring 32 on the piston 29 will overcome the force of the gas pressure and the valve member 26 will be pressed into the open position. Thus the piston 29 and spring 3 regulate the pressure acting on the piston 47. The com¬ pression of spring 32 can be adjusted by screwing the cap 31 towards or away from the piston 29. For example, screwing the cap 31 towards the piston 29 increases the compression of the spring 32 and therefore increases the pressure at which the valve member 26 is moved into the closed position. In the event of the valve member 26 becoming stuck in the open position, the pressure on the piston 29 gradually increases and the piston is moved outwards against the bias of the spring 32. The bore 30 however contains an axial slot 38 so that once the piston reaches the slot compressed gas can pass around the side of the piston and out to atmosphere through apertures in the cap 31« limit means (not shown) are provided to limit the inward and outward movement of the cap 31. The limit of the inward movement of the cap is chosen according to the

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maximum pressure which, is to be allowed in the barrel... Outward movement of the cap 31 is limited to prevent the cap 31 being removed.

The pressurising assembly 2 is mounted on the end

5 cap 4 by a form of bayonet fitting which will now be described with reference to Figures 3 and 4. The body 18 (of which all but the base part is cut away in Figure 4) of the pressurising assembly has a pair of integral clamping plates 68, 69 defining a base surface of the

10 pressurising assembly 2. A spigot 70 extends below the base surface of the pressurising assembly and, when the dispenser is assembled, projects into the cap 4 so that the duct 44 extends into the barrel.

The top of the cap 4 is formed with a pair of ,. ^' 1 clamps 71 , 72 which extend parallel to the upper surface of the cap 4, and a stop 73 _*

In order to fit the pressurising assembly 2 on to the end cap 4 _» the housing 20 is removed, the end cap is set to a zero pressure setting, the spigot 70 is inse

20 into the hole provided in the end cap 4 and the clamping plates 68, 69 are brought into engagement with the upper surface of the cap, the relative positions of the cap an the clamping plates being as shown in Figure 4. The pressurising assembly is hen rotated relative to the en

25 cap 4 in the direction of the arrow 75. This rotation introduces the clamping plates 68, 69 underneath the clamps 71 - 72. The clamping plates 68, 69 are formed wi raised ramp surfaces 76, 77 which increase the tightness of clamping as the clamping plates are progressively

30 introduced under the clamps. 'T* shaped notches are provided on the lower surfaces of the clamps 71 , 72 and . these engage the ramp surfaces 76, 77 once the clamping plates 68, 69 are fully introduced under the clamps. Th

stop 73 prevents further rotation of the pressurising assembly beyond this clamped position. An '0' ring 78 shown in Figure 3 _» is provided in a groove formed around the spigot 70 and seals the interface of the base of the pressurising assembly 2 and the end cap 4.

The clamping arrangement is such that the pressuris¬ ing assembly can be fitted on to the end cap only with the clamping plate 68 engaging the clamp 71 and the clamp¬ ing plate 69 engaging the clamp 72 and not vice versa. As the pressurising assembly 2 is clamped, the cap 31 o the assembly passes an upwardly extending lip 79 on the clamp 72. The lip 79 prevents the pressurising assembly being undamped from (or clamped onto) the end cap until the cap 31 has been unscrewed to a zero pressure setting and thereby relieved any gas pressure in the barrel: until the cap 31 is unscrewed to this position the lip 79 obstructs the cap 31 and prevents rotation of the pressuris¬ ing assembly relative to the cap 4.

A fluent substance to be dispensed is supplied to a user as an assembly comprising the cartridge 5 with the piston member 47 and the valve member 10. Prior to use the cartridge is as shown in Figure 5 with the aperture 8 in the end wall 7 of the cartridge sealed but *ith outlet defining means at the front end of the cartridge comprising a plastics disc 80 integrally formed with the end wall 7 with the peripheral portion of the disc adjoining the end wall 7 being relatively weak. A pull tag 81 is integrally formed with the peripheral portion of the disc 80 and the disc can be removed by pulling the tag 81. Pulling the tag 81 removesthe peripheral portion of the disc 80 and the disc either comes away with the peripheral portion or can be lifted out after removing the peripheral portion. The aperture 8 is left upon removal of the disc. A cap 82

is fitted over the end of the tubular wall 1 »

The use of the dispenser will now be described in greater detail assuming that a user is about to use a new cartridge assembly and that the end caps 4 and

5 14 are detached fro the barrel 1 with the pressurising assembly clamped to the end cap 4 but not charged with a capsule 24.

The user takes a cartridge assembly, removes the cap 82, pulls the tag 81 extracting the disc 80, and

10. inserts the cartridge assembly into the barrel 1 from the rear in the correct angular orientation; forward movemen of the cartridge assembly into the barrel is limited by radially inwardly directed lip at the front end of the barrel. The user then fits the nozzle 17 over the tubula

15 wall 1 in the end of the cartridge assembly snaps the end cap 14 on to the barrel body 1 over the nozzle 17 and rotates the barrel relative to the end cap 14 to close the rotary valve at the front of the cartridge assembly. Next the user screws the end cap 4 (with the

20 assembly 2 attached thereto) on to the barrel body and inserts a capsule 24 into the assembly 2 as already des¬ cribed. The pressure acting on the piston member 47 is adjusted by appropriate adjustment of the cap 31 accordin to the viscosity of the particular fluent substance bein

25 dispensed.

The user controls the rate of extrusion of the fluent substance during use by adjustement of the rotary valve at the front of the dispenser. For best results t user holds the end cap 4 and assembly 2 in one hand and

30 the end cap 14 in the other hand and rotates the end cap while holding the end cap 14 still, in order to adjust th rate of extrusion; this technique enables the user to exe cise close control over the movement of the nozzle 17. I

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the particular example described the pressure acting on the piston member 47 can be regulated within the range of zero to fifty pounds per square inch above atmosphere while the pressure in the capsule is of the order of 7Q0. to 900 pounds per square inch. One capsule contains more than sufficient gas to discharge all the fluent substance from a cartridge.

The pressure of the fluent substance on the end wall 7 flexes the end wall and in particular the resi- lient rim 12 into intimate contact with the valve member

10 thereby preventing leakage along the interface of these parts.

In order to recharge the dispenser with a new cartridge assembly, the cap 31 is unscrewed to the limit of its movement; this causes the valve member 26 to close (if it is not already closed) and compressed gas in the barrel moves the piston 29 outwards and escapes to atmos¬ phere around the edge of the piston. The end caps 4 and 14 are then removed, the nozzle 17 is removed from the cartridge assembly, the cartridge assembly is withdrawn and a new cartridge assembly inserted as described above.

After use, the cartridge assembly is removed and the cap 82 fitted over the tubular wall 13 _» in place of ., the nozzle 17 _» closing the cartridge 5« The nozzle 17 is then either cleaned or thrown away. No other parts of the dispenser should require cleaning. Once the cartridge is empty the complete cartridge assembly is thrown away. The valve on the cartridge assembly is used only to control the flow of the substance in that cartridge and is discarded with the latter. Thus the valve is exposed to limited use only and problems caused by wear of the valve are avoided.

Figure 6 shows an alternative arrangement of the front of the dispenser which will now be described. A

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cartridge 105, which can be of conventional construction, has a tubular wall 106 made of cardboard and lined with metal foil, a piston 1 7 and a metal end-wall 107 defin¬ ing a peripheral rim and having an externally εcrew- threaded neck--108. A nozzle assembly 103 is screwed onto the neck 108 and draws the cartridge 105 towards the front of the barrel so that the peripheral rim of the end wall 107 presses against a seal 109 in the front end of the barrel. The nozzle assembly 103 includes a body part 110, a two piece valve member 111 rotatably mounted on the body part 110, a resilient member 112, a nozzle 113 _> and a clamping ring 114. The body part 110 has a passageway 115 which extends from the neck 108 of the cartridge 105 where the passageway is of circular cross-section to an opening 116 on a forward face of the body part where the passageway has the cross-section of a segment of a circle (although other cross-sections may be used). The valve member 111 has a rearward face with an opening 117 which lias the same cross-section as the opening 116 and is aligned with the opening 116 in the open position of the valve shown in Figure 6. The part of the valve member 111 -surrounding the opening 117 has an inwardly projecting cir cular flange which engages the resilient member 112 pressi the interengaging faces of the body part 110 and the valve member 111 into intimate contact. Rotation of the barrel relative to the nozzle 113 moves the interengaging faces relative to one another from the position shown in Figure 6 to one where the openings 116 and 117 are out of fluid communication with one another. Stop means (not shown) are provided on the body part 110 and the valve member 111 to limit the relative rotation of these parts to about 90 degrees.

The nozzle 113 is detachably mounted on the member 111 by the clamping ring 114 screwed on to the member 111. This mode of attachment of the nozzle 113 allows the nozzle to be fixed to the body part 110 at any selected orientation of the nozzle relative to the body part.'

The substance in the cartridge 105 is expelled -under the control of the rotary valve just described by the piston 147 driven by pressurised gas supplied by the pre— ssurising assembly 2 as already described in respect of the dispenser shown in Figures 1 to 5»

The other parts of the dispenser ^' are generally the same, as those shown in Figures 1 and 3 with the exception that since the junction of the cartridge and the barrel is sealed at the front, the barrel is pressurised so that the slot 67 must be omitted or be covered by a translucent material and the seal 19 can be omitted but another seal must be provided between the end cap 4 and the barrel body 1. It is believed that the operation of the modified dispenser will be clear from the description above of the operation of the dispenser shown in Figures 1 to 5» The nozzle assembly 103 is screwed on to the cartridge 105 after the cartridge has been inserted into the barrel. After use, a screw cap is screwed over the neck 108 of the cartridge closing the cartridge and the nozzle assembly is dismantled and cleaned. In order to facilitate cleaning of the passageway 115 a special tool may be provided having a resilient head which can be passed through the passageway 115 to remove any fluent substance from the passageway. Although in the arrangement shown in Figure 6 a resilient member 112 is provided to bias the body part 110 against the valve member 111 this resilience may be provided inherently in either the body part 110 or the valve member

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111 and the member 112 omitted.

In order to improve the seal of the rotary Valve shown in Figure 6 when it is in the closed position, the abutting faces of the body part 1 0 and the valve member 111 which separate the openings 116 and 117 in the closed position of the valve may be shaped so that they engage with a wedging action when the valve is closed. Also, th cartridge 105 may be provided with an eccentrically posi— tipned neck 108 in which case the length of the body part 110 can be substantially reduced.

Figure 7 shows another form of rotary valve which ^' can be mounted on the front end of the barrel in place of the rotary valve shown in Figure 6. This modified rotary valve is positioned adjacent the neck 108 of the cartridg and includes a retaining member (not shown in Figure 7) which is screwed on to the neck 108 of the cartridge, a valve plate 51 pivotally mounted on the retaining member by a pivot 52, and an operating ring 53- The nozzle 13 attached to the valve plate 51 around an opening 54 in th valve plate. In the position shown in solid outline in

Figure 7, the valve is closed, the valve plate 51 coverin over a central passage 55 extending from the neck 108 of the cartridge. If however the operating ring 53 is rotat anti-clockwise the valve plate 51 is itself rotated anti- clockwise by engagement of a pin 56 on the operating ring in a slot 57 on the valve plate and the parts finally as¬ sume the position shown in dotted outline in Figure 7 in which the valve is open, the opening 54 and the passage 5 being aligned. Figure 8 shows another alternative valve arrangemen at the front end of the dispenser in which the rotary valve shown in Figure 6 is replaced by a slide valve. Th slide valve has a valve housing 60 which is screwed on to

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the neck 108 of the cartridge 105, and a valve closure member 61 connected via bars 62 to an actuating member 63• The interface of the actuating member 63 and the housing 60 is sealed by a pair of *0' rings 74 _* A nozzle 64 is screwed on to the actuating member 63 and retains the closure member 61 in position. A compression spring

64 biases the actuating member to its forward position (not shown) in which the closure member 61 seats on a seat¬ ing 65 formed on the valve housing. In the position shown in Figure 8 the actuating member 63 has been retracted against the bias of spring 64 by a user who grips lugs 66 extending outwardly from the actuating member 63; in this ^' position the closure member 61 is spaced from the seating

65 and the valve is open. It will be seen that the valve can easily be dismantled for cleaning.

Figures 9A, 9B and 90 illustrate a modified form of the rotary valve assembly shown in Figures 1 and 2. The valve member* 10 is replaced by a valve member 10A shown in plan in Figure 9A and in side section in Figure 9B. The end wall 7 of the cartridge is replaced by an end wall 7A having two eccentric apertures 8A and shown in Figure 90• In other respects the arrangement of the front of the dispenser and cartridge assembly is the same except that the end cap 14 has a central hole rather than an eccentric - hole to accommodate the nozzle. The valve member 10A has a central extension with a bore 11A which, at the left-hand side (as seen in Figure 9B), engages the end wall 7A, the bore opening out into a transverse slot. In one position of the valve member 10A relative to the end wall 7A (the open position of the valve), the slot is in registration with the apertures 8A. On rotating the valve member 10A from this position, however, the path of communication is progressively reduced and the valve closed.

A cartridge assembly incorporating a valve member 10A may be locatable in the dispenser in either of two orientations spaced 180° apart. With the valve member 10A, the open positions of the valve will occur in the same positions of the end cap 1 relative to the barrel body 1 in each of the two orientations of the cartridge assembly within the dispenser.

An advantage of the use of this form of rotary valv is that it enables the cartridge to be used in a dispense which has provision only for a central nozzle outlet. In the modification described with reference to Figures 9A, 9B and 90 the end wall 7A has two apertures 8A spaced 180° apart around the end wall 7 _» three (or mor apertures may alternatively be provided in the end wall 7 symmetrically positioned around the end wall and the valv member may be provided with three (or more) radially exte ing slots in place of the transverse slot in the valve member 10A. The three (or more) radially extending slots each communicate with the central bore 11A. With three (or more) symmetrically arranged apertures and slots, the cartridge assembly may be locatable in the dispenser in any of three (or more) orientations. The provision of mo apertures in the end wall 7A reduces the size of any individual aperture for a given total aperture area in th end wall 7A and less rotational movement of the valve member is required .to open and close the valve.

When more than one aperture is provided in the end wall of the cartridge assembly, it is not necessary for these apertures to be symmetrically positioned around the end wall provided the slots in the valve member are also arranged asymmetrically.

The valve members 10 and 10A may be held in the fro end of the cartridge 5 by a bayonet fitting rather than as a snap fit.

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In order to ensure that the fluent substance in the cartridge is not degraded between the time of manu¬ acture and first use by a user, the rotary valve is preferably closed at the time of manufacture. To ensure that the valve is not accidentally opened, holding means comprising a flexible tag may be attached to the valve member 10 or 10A and lie in a longitudinal groove in the side of the tubular wall 6 of the cartridge to prevent relative rotation of the valve member and the cartridge. 0 The distal end of the ta is accessible to a user and, before use, the user can flex the tag inwardly out of the groove freeing the valve member.

Figure 10 shows a particular form of piston member 47A which may be used in. place of the piston member 47 5 shown in the drawings. The piston member 47A is provided with a skirt 150 having a series of axially spaced annular ribs. In use the pressurised gas presses the skirt 150 against the wall of the cartridge and the ribs make inti¬ mate contact with the cartridge wall. Q The piston member 47A also has a central bore 151 _* It is thought that without such a bore when, during manu¬ facture, the piston member is inserted into the cartridge air is trapped between the piston member and the fluent substance; this air then passes out around the piston.member 5 and may carry some fluent substance with it; the fluent substance then becomes trapped between the piston member and the cartridge wall and sets, spoiling the seal between these parts. With the piston member 47A, the air passes out through the central bore 151 and, upon further inser- 0 tion of the piston member, the fluent substance also passes up the bore 151• In time the fluent susbstance in the bore 151 sets thereby sealing the bore 151. Alternatively the bore may be mechanically sealed after filling.

An indicator may be provided on the end cap 4 to indicate to a user whether or not there is pressurised gas in the barrel. A suitable form of indicator is shown in Figure 11. The end cap 4, is ormed with an inwardly extending circular rib 152 over which a flexible diaphragm 153 is fitted. The upper face of the diaphragm 153 carries a projection 154 which is accommodated in a hole in the end cap 4. When the barrel is not pressurise the diaphragm 153 is not flexed and the top of the pro ec tion 154 is flush with, or below, the upper surface of the end cap 4» Upon pressurisation of the barrel, howeve the diaphragm 153 flexes and the projection 154 protrudes from the end cap 4? the projection 154 is preferably in a colour contrasting with the end cap 4 so that it can be easily seen. A pressure of just a few pounds per square inch is sufficient to raise the projection 154 giving an indication that the barrel is pressurised.

A further pressure safety valve arrangement may be provided in the manner of fixing the end cap 4 to the barrel body 1. Such an arrangement is illustrated in

Figure 12 (in which the pressurising assembly is not show A seal 155 is provided between the end of the barrel body and the end cap 4. The end cap 4 has a peripheral wall 1 which is provided around its distal end with a plurality of inwardly projecting lugs 157. The end of the wall of the barrel body is provided with an outwardly extending flange 158 and a resilient member 159 is interposed betwe the flange 158 and the lugs 1 7. The parts are arranged such that while the pressure in the barrel remains within the working pressure range of the dispenser the seal 155 seals the junction of the cap to the barrel but when the pressure exceeds the working pressure range of the dispen

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the end cap 4 is ^" raised sufficiently, as a result of compression of the member 1 9 _» for pressurised gas to pass between the junction of the cap and.the barrel body. Longitudinal grooves are provided in the flange 158 and member 159 and the end cap 4 is fastened to the barrel body 1 by passing the lugs 1 7 through these grooves and then twisting the end cap 4 relative to the barrel body 1•

In the safety valve arrangement shown in Figure 12 the seal 155 is provided between the end cap and the

■JO barrel body, which is the correct location of the seal when the front end of the cartridge is sealed against the barrel as in the embodiments shown in Figures 6, 7 and 8. If the dispenser is of the form shown in Figures 1 to 5 then the seal 1 5 should be provided between the rear end

15 of the cartridge and the end cap but in other, respects the construction of the safety valve arrangement may be as shown in Figure 12.

As described, the end cap 4 is secured to the barrel body by a kind of bayonet fitting but it will be appreciated

20 that toggles or other fastening means could be employed. The resilient member 159 may be omitted if the resilience is provided inherently in the flange 158 or the end cap 4.

In addition or instead of the safety valve arrangement

25 shown in Figure 12, a pressure relief valve of the kind used on domestic pressure cookers may be provided on the end cap 4. This pressure relief valve may be arranged in such a way that every time the end cap 4 is secured to the barrel body 1 the valve is tested. Tet another safety

30 arrangement which may be incorporated is the deliberate weakening of a small area of the barrel body or end cap so that this area breaks in the event of excess pressure in the barrel.

The space between the cartridge and the barrel may

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be sealed at the rear as shown -in Figure 1 or at the front as shown in Figures 6 to 8 irrespective of the kind of valve used at the front of the dispenser. When sealing is at the rear, the end cap 4 may be arranged to seal on to the inner or outer face of the cartridge wall instead ^" of on to the end of the cartridge wall. Wher the cartridge is sealed at the front, as in Figure 6 for example, the dispenser is able to accommodate cartridges of different lengths. In the valve arrangement shown in Figure 2, the tubular wall 13 has an external screw-thread to receive the nozzle 17 and cap 82. Alternatively, the nozzle 17 and the cap 82 may be a press fit over the tubular wall 1 When the cap 82 and nozzle 17 are screwed onto the valve member it is preferable to provide stop means for limitin the rotation of the valve member relative to the cartridg since this facilitates screwing of the nozzle 17 or the cap 82 onto the valve member. The stop means may be arra such that at one limit of rotation of the valve member th valve is fully opened and at the other limit or rotation the valve is fully closed. Preferably the arrangement i such that screwing the nozzle onto the valve member rotat the valve member into the open position.

The projecting wall 13 on the valve member 10 may be dispensed with leaving the member 10 with a simple aperture into which the nozzle is fitted and the rear end of the nozzle may terminate flush with the rear of the valve member 10 so that the bore in the nozzle defines th aperture 11 • This enables the degree of rotation/extent of overlapping of apertures 8 and 11 characteristic to be changed simply by changing the size and/or shape of the internal cross-section of the nozzle. The nozzle may be force fit in the valve member 10 and pass freely through

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front end cap 14 or the nozzle may be a force fit in the front end cap and mere3_y be located in the valve member 10. In this case where the valve member 10 does not have a tubular wall 13 _» the cartridge may be closed after use by a resilient sealing plug press fitted into the aperture 11• -.

The outlet of the nozzle of the dispenser may be of any selected shape and area. Different shapes of nozzle are better for different jobs and it may therefore be desirable to provide several different nozzles with each dispenser. The same nozzle may also be used to dis¬ pense beads of different shapes; if the bead is laid behind the nozzle the shape of the bead is determined by the internal cross-section of the nozzle but if the bead is laid ahead of the nozzle the shape of the bead is determined by the external cross-section of the portion of the nozzle that passes over the bead immediately after it is laid. For example a nozzle of triangular internal cross-section can be used to dispense a bead of triangular cross-section if the bead is laid behind the nozzle and the same nozzle, if provided with a rectangular cut-out, can also be used to dispense a bead of rectangular cross-section, if the head is laid ahead of the nozzle and the rectangular cut¬ out is arranged to pass over the bead immediately after it is laid.

In the form of cartridge assembly shown in Figures 1, 2 and 5 the valve at the front of the assembly is a rotary valve but other forms of valve could be used. For example, the valve control member 10 might be mounted for sliding movement across the end wall of the cartridge.

It may not be necessary to manufacture the recessed front end wall 7 of the cartridge assembly as a closed wall

with a weakened portion. If the valve on the front of the cartridge assembly provides a sufficiently good seal and if the cap 82 provides a sufficiently good seal, the aperture 8 may be provided in the end wall 7 when it is

5 first manufactured. Another possibility would be to

-provide a separate metal foil closure sealing the apertur 8 prior to its first use.

The cartridge used in the dispenser may be made of plastics material or may be made of cardboard lined with

• _j O metal foil. The material from which the cartridge is made should be selected according to the fluent substance which it is to contain since it must be substantially inert to this substance.

While one particular method of securing the pressuri

-J5 ing assembly 2 to the end cap 4 has been described, many other methods may be employed. For example the body 18 of the assembly 2 could be provided with a screw-threaded boss extending through the end cap 4, a nut being provide on the other side of the end cap screwed on to the boss.

20 Alternatively, the end cap 4 could be provided with a 'T ¹ shaped slot, the pressurising assembly having a lug which could be inserted through the top of the 'T* and then sli down the 'T' to clamp the assembly 2 to the end cap 4«

In the pressure adjusting assembly shown in Figure

25 3 _» a piston 29 is used. As an.alternative a diaphragm connected to the wall of the bore 30 and spring biased in the same manner as the piston 29 could be used. In this case it may not be possible for excess gas pressure to be vented through the cap 31 • If a pressure relief valve is Q mounted on the end cap 4 an alternative way of venting the gas may be to open this pressure relief valve.

The dispensers described above are able to dispense a wide variety of fluent substances such as sealants and

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mastics with similar efficiency. The pressure adjusting means 2.enables the force on the piston 47 to be adjusted according to the viscosity of the substance to be dispensed and the valve at the front of the dis- penser enables a user to exercise close control over the rate of extrusion of the substance. Also it has been found that the method of gripping the dispenser with one hand at the back and one at the front makes it very easy even for an inexperienced user to produce Yexy good results when using the dispener, for example for puttying.

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