EP0033790B1 - Apparatus for feeding a liquid to an applicator - Google Patents

Abstract

An apparatus for feeding a liquid to an applicator especially a paint applicator (8) is particularly easy to use and to clean. The apparatus includes a vessel (1) and a pressurizing assembly (9) supported on the vessel (1) and including a housing for receiving a capsule of liquefied or pressurized gas and pressure reducing means. Liquid (16) to be applied is expelled from the vessel (1) through a feed conduit (3) to the applicator. In the preferred form of the apparatus, the vessel (1) receives a container (2) in which the liquid to be fed is initially supplied.

Description

• This invention relates to apparatus for feeding a liquid to an applicator, and in particular, to apparatus primarily intended for painting.
• For many years it has been common practice to apply a liquid to a surface using a brush, the brush first being dipped in a reservoir of the liquid and then wiped over the surface to be coated. For relatively large surface areas, rollers rather than brushes are used, the roller also being dipped in a reservoir of the liquid and then rolled across the surface to be coated. As an alternative to the use of a brush or roller, a pad has, in more recent times, sometimes been used: again, the pad is dipped in a reservoir of the liquid and then wiped across the surface to be coated.
• The mode of application described above is unduly time consuming because of the necessity to dip the applicator (brush, roller or pad), in the liquid at frequent intervals in order to replenish the supply of liquid on the applicator. This is a particular problem when the user is standing on a ladder or a pair of steps which is frequently the case, for example when painting a ceiling. To mitigate this problem it has been proposed in the case of rollers to increase the liquid capacity of the roller by providing it with its own small liquid reservoir; this attempted solution, however, considerably increases the weight of the roller making it very tiring to use.
• From time to time throughout this century it has been proposed to provide the liquid applicator with a connection via a length of tube to a reservoir of liquid and to feed the liquid from the reservoir to the applicator by pressure generated by a pump. This arrangement has the considerable advantage over the conventional arrangements described above that a user does not continually have to replenish the liquid on the applicator nor does the applicator have to be excessively heavy. These proposed pressurized arrangements have not, however, proved satisfactory. If the reservoir of liquid and its associated pump is placed on the ground during application of the liquid then a long length of tubing is required between the reservoir and the applicator and this can impede the user. If, on the other hand, the reservoir and pump are carried by the user then this impedes the user during painting and is tiring as a result of the weight of the reservoir and pump assembly.
• It is known to dispense a liquid from a vessel using a small capsule of pressurized gas. For example, soda syphons have been available for some years operating on this principle. National Can Corporation have disclosed a paint apparatus in which a vessel of paint is pressure fed by pressurized gas from a capsule to a roller; in operation the vessel is rested on the ground and a long length of tubing connected between the vesel and the roller to allow a user to paint a surface, holding a the roller alone. An illustration of this proposed apparatus appeared on pages 30A and 31 A of the Journal of Paint Technology Vol. 40, No. 521, June 1968. Liquid vessels pressurized by capsules of gas are also described in United States Patents Nos. 3 352 457 and 3 558 010 assigned to National Can Corporation.
• The specification of United States patent No. 3,558,010 discloses an apparatus for dispensing liquid in which a dispensing assembly including a gas or like fluid-containing cartridge and a regulator unit is attached to a vessel and liquid dispensed from the vessel through a tube to an applicator.
• The painting apparatus proposed by National Can Corporation still suffers various drawbacks. The use of a long length of tubing can impede the user as already mentioned and also this apparatus, as well as the pressurized arrangements already described, is difficult to clean and messy to use. If the painting apparatus includes its own pressure vessel for containing the paint, the paint must first be poured into this vessel and then, after painting, any paint left in the vessel must be poured out and the vessel, in addition to all the rest of the apparatus, must be cleaned. The time saved during painting with the apparatus may thus be consumed in extra time spent preparing the apparatus for use and cleaning the apparatus after use.
• To some extent, the cleaning operation can be reduced by supplying the paint in its own pressure vessel to which the pressurizing arrangement is then directly attached, since this avoids the need to clean the vessel after use. However, in this case the vessel containing the paint must be specially constructed both to be sure of withstanding the pressure contained in the vessel during use and to receive the pressurizing arrangement. This greatly increases the cost of the paint vessel over a conventional paint can.
• It is an object of the invention to provide an apparatus for feeding liquid under pressure, that mitigates at least some of the disadvantages described above.
• According to the invention there is provided an apparatus for feeding liquid under pressure, the apparatus including:
• a vessel,
• a pressurizing assembly including a housing for receiving a capsule of liquified or pressurized gas and pressure reducing means,
• a first path extending from the high pressure side of the pressure reducing means for communicating with the outlet of a capsule inserted, in use, in the housing,
• a second fluid path extending from the low pressure side of the pressure reducing means into the vessel,
• a hand-held applicator for coating a surface with liquid, and
• a feed conduit, including a flexible, tube extending between the vessel and the applicator, for transferring liquid to the applicator,
• characterized in that a liquid container is received, in use, within the vessel, the second fluid path extends into the container and the feed conduit extends into the container for transferring liquid from the container to the applicator.
• The use of a small capsule of liquified or pressurized gas to provide the pressure in the container provides an extremely compact, lightweight and convenient pressurizing arrangement.
• The provision of a container within the vessel is an important feature of the present invention. The liquid to be fed to an applicator can be sold in the container which since it is, in use, disposed in the outer vessel, does not have to be sure of withstanding pressure and can be of simple construction. After the liquid has been fed from the container, the latter can be thrown away and the vessel does not have to be cleaned.
• Preferably the top of the container is substantially closed; the feed conduit may pass through the top of the vessel and the top of the container to a location adjacent the bottom of the container; the portion of the top of the container through which the feed conduit passes may be in the form of a diaphragm, the diaphragm closing over the junction between the container wall and the feed conduit. This inhibits liquid spilling from the container into the vessel.
• A small hole may be provided in the top of the container to allow gas to flow between the container and the vessel to equalize the pressure therein. Alternatively a slit may be provided in the top of the container.
• The container may also include a closure member which can be secured over the diaphragm when the container is not in use to seal the container. This preserves the liquid in the container when it is not in use and prevents spillage.
• The pressure reducing means may include a valve member mounted in a passage providing communication between 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 position, 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 reducing means.
• The bias force of the spring acting on the piston or diaphragm may be adjustable, whereby the pressure of gas required to move the piston or diaphragm away from said one position to another position is adjustable.
• In use, a capsule of liquified or pressurized gas is located in the housing. The gas may be carbon dioxide or nitrous oxide or any gas which does not have too substantial a deleterious effect on the liquids with which it will come into contact.
• The vessel may comprise a body part and a lid.
• The lid may be mounted on the body part of the vessel such that if excess pressure develops between the lid and the body part the vessel is vented between the lid and the body part.
• The pressurizing assembly may be mounted on the lid.
• The vessel may be arranged to be carried by a user without using his hands. In this case the user has both hands free to operate the applicator or perform any other function.
• A handle may be mounted on the vessel. The handle may be of inverted rectangular 'U' shape.
• A clip may be provided on the vessel for attaching the vessel to a belt, to enable a user to suspend the vessel from his waist.
• A pressure relief valve may be mounted in a wall of the vessel. The pressure relief valve may be mounted on the lid of the vessel. An actuating arrangement may be provided for actuating the pressure relief valve each time the apparatus is assembled for use. Such an arrangement safeguards against the possibility of the pressure relief valve becoming stuck.
• Manually operable means may be provided for venting the pressurized gas in the vessel to return the pressure in the vessel to atmospheric pressure. The venting means may be provided by the pressure reducing means. Alternatively the venting means may be provided by some other arrangement, for example by the pressure relief valve.
• The applicator may, for example, be a pad, a roller or a brush. The length of tube is preferably between one and two metres long. The tube must be long enough to allow a user full range of movement of the applicator but excessive length is undesirable as it may impede the user, increases the pressure required to feed the liquid and adds to the length of tube to be cleaned. In a particular example of the invention the tube is one and a quarter metres long. The applicator is preferably provided with a valve for controlling the flow of liquid along the tube.
• By way of example, an apparatus for feeding a liquid to an applicator will now be described with reference to the accompanying drawings, in which:
• Figure 1 is a side view of the apparatus,
• Figure 2 is a sectional side view of part of the apparatus;
• Figure 2A is a side view of a closure member associated with a component shown in Figure 2,
• Figure 3 is a sectional side view of another part of the apparatus,
• Figure 4 is a sectional side view of a switch included in the apparatus,
• Figure 5 is a sectional side view of a small part of the apparatus illustrating a modification which may be made to the apparatus of Figure 2,
• Figure 6 is a sectional side view of another small part of the apparatus illustrating another modification which may be made to the apparatus of Figure 2, and
• Figure 7 is a sectional side view of a pressure indicator which may be incorporated in the apparatus.
• Figure 1 shows a vessel 1 of circular cross-section having a body 4 and alid 5 in which is received acontainer 2 containingpaint 16. The vessel 1 andcontainer 2 are made of a plastics material. A feed conduit for the paint is provided by a pipe 3 extending from the centre of thelid 5 of the vessel, towards the bottom of the container. Thecontainer 2 has a well 6 formed in its base and the pipe 3 extends into this well. A flexible tube 7 which is one and a quarter metres long is attached to the end of the pipe 3 and leads to a paint pad 8.
• A pressurizingassembly 9 including a capsule of liquified gas and a reduction valve (not shown in Figure 1) is mounted eccentrically on thelid 5 and pressurizes the vessel 1 and the inside and outside of thecontainer 2. Also mounted on thelid 5 is a safety valve (not shown in Figure 1) and ahandle 10 which has two upright limbs extending from the diametrically opposite parts of the periphery of thelid 5 and an integral cross-member connecting the tops of the upright limbs. Thus, thehandle 10 is of inverted rectangular 'U' shape.
• Referring now to Figure 2, which shows the upper portion of the vessel 1 and thecontainer 2 but does not show the pressurizingassembly 9, thelid 5 is screwed onto the body 4 of the vessel and an '0'ring 60 seals the junction between these parts. Thelid 5 has an aperture in which is received a safety valve 11 in the form of a pressure relief valve. The safety valve 11 comprises agrommet 12 and avalve member 13 received in thegrommet 12. In its normal unoperated position shown in Figure 2 the valve member seals the aperture in thelid 5.
• The top of thecontainer 2 is defined by alid 170 permanently fitted to thecontainer 2 and defining a diaphragm 14 which has a central aperture through which the pipe 3 extends as a close fit and asmall hole 15 which ensures equalisation of pressure between the inside and outside of the container but which is not sufficiently large to allow paint to pass through the hole except at a very slow rate. The diaphragm 14 is inset from the top of the container defining a recess above the diaphragm which receives a sealing plug 80 (Figure 2A) when thecontainer 2 is not in use to seal the container. While the part 14 is referred to as a "diaphragm", it should be understood that this part may be of rigid construction.
• Thelid 5 has a central cylindrical recess within which the tube 7 is secured to the pipe 3. To assemble the apparatus the end of the tube 7 is passed through thelid 5 and fitted over the pipe 3. The tube 7 is then pulled back through thelid 5 drawing the end of the pipe 3 into the recess. The assembly of the pipe 3 and tube 7 are a tight fit in the recess and seal the junction of the tube 7 and thelid 5.
• Referring now to Figure 3 which shows the pressurizingassembly 9, the assembly has abody 18 including a screw threadedboss 19 which passses through an aperture in thelid 5 of the vessel 1 and to which a nut is secured to retain theassembly 9 on thelid 5. One ormore pegs 89 on the base of thebody 18 engage in corresponding recesses (not shown) in the top of thelid 5 and locate theassembly 9 on thelid 5. Theassembly 9 includes ahousing 20 for receiving acapsule 24 of liquid carbon dioxide. A capsule piercing member 21 including apiercer 42 is received in thebody 18 and an '0'ring 23 seals the interface of the piercing member 21 and thebody 18. The end of the piercing member 21 adjacent thehousing 20 has a bore sized to receive the neck of thecapsule 24 and an '0' ring 45 is seated in the bore to seal the interface of the capsule neck and the bore. To insert acapsule 24 into theassembly 9 thehousing 20 is first unscrewed. Thecapsule 24 is then placed in thehousing 20 and thehousing 20 brought into position to be screwed onto thebody 18. At this stage, the neck of thecapsule 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 thehousing 29 is now screwed onto thebody 18, the housing drives the capsule onto thepiercer 42 and the capsule is pierced allowing gas to flow along a fluid path from the capsule through the piercing member 21 into achamber 25 defined by the piercing member 21 and avalve housing 22 which is screwed onto the piercing member and whose interface with the piercing member is sealed by an '0'ring 46. Thechamber 25 is the high pressure chamber of an adjustable pressure reducing valve assembly which will now be described.
• Thevalve housing 22 slidably receives avalve member 26 which has aclosure disc 27 at one end which is in thechamber 25 and ahead 28 at the other end. Theclosure disc 27 abuts a seat formed on thehousing 22 and is resiliently biased by aweak spring 34 against the seat. The right hand end (as seen in Figure 3) of thebody 18 has abore 30 in which apiston 29 is slidingly received, an '0'ring 41 being provided around thepiston 29 to seal the interface of thepiston 29 and thebore 30. Thebore 30 is closed by acap assembly 31 screwed onto the exterior of thebody 18. Thepiston 29 is inwardly biased by acompression spring 32 extending between the piston and thecap assembly 31. In the position shown in Figure 3 thehead 28 of thevalve member 26 abuts thepiston 29. Achamber 33 is defined between thevalve housing 22 and thepiston 29; this chamber communicates with aduct 44 which extends through theboss 19 of thebody 18 and thus provides a fluid path between the vessel 1 and thechamber 33.
• Thecap assembly 31 consists of an operatingmember 81 screw-threaded on thebody 18, an adjustingmember 82 screwed into an axial passage of themember 81 so that the relative axial position of themembers 81 and 82 can be adjusted by screwing themember 82 into themember 81, and aclosure member 83 which fits over the outer end of the axial passage in themember 81 and which conceals the adjustingmember 82 and also locks the adjustingmember 82 to the operatingmember 81. Thespring 32 extends between thepiston 29 and the adjustingmember 82, and the maximum separation of thepiston 29 and the adjustingmember 82 is limited by the engagement of ananchor 84 extending from thepiston 29 with the adjustingmember 82.
• Before insertion of thecapsule 24, with the pressure in the vessel 1 atmospheric and with the valve set to provide a finite gauge pressure in the vessel 1, the pressure inchamber 33 is atmospheric so that the piston abuts the end face of thebore 30 and thevalve member 26 is pressed against the action of thespring 34 to an open position in which theclosure disc 27 is spaced from the seat on thevalve housing 22. Upon insertion of thecapsule 24, pressurized gas passes through thechamber 25 and thechamber 33 into the vessel 1. As the pressure in thechamber 33 then increases to above atmospheric thepiston 29 is pressed outwards against the bias of thespring 32 to a position in which the force of the pressure over the face of the piston substantially equals the force of the spring 32 (there is also a force applied to the piston by thespring 34 but this is so small as to be insignificant). The pressure continues to increase until the piston reaches the position shown in Figure 3 at which stage theclosure disc 27 abuts the valve seat of thevalve housing 22 and the flow of gas from the capsule stops.
• When the pressure in the vessel 1 drops, for example as a result of paint being fed from thecontainer 2, the force exerted by thespring 32 on thepiston 29 will overcome the force of the gas pressure and thevalve member 26 will be pressed into the open position. Thus thepiston 29 andspring 32 regulate the pressure in the vessel 1. During normal operation the operatingmember 81 is in the position shown in Figure 3. The pressure which this produces in the vessel 1 is dependant upon the axial position of the adjustingmember 82 and this position is set in the factory to produce the desired pressure and theclosure member 83 then positioned over the end of the adjusting member. For example, screwing the adjustingmember 82 towards thepiston 29 increases the compression of thespring 32 and therefore increases the pressure at which thevalve member 26 is moved into the closed position. In order to set the position to which a user screws the operatingmember 81, aflange 35 is provided around the periphery of themember 81 and this flange engages aprojection 36 on thelid 5 of the vessel 1 when themember 81 is screwed to the pressurized position.
• Anotherprojection 37 is provided on thelid 5 and engagement of theflange 35 with thisprojection 37 limits the outward movement of themember 81 and prevents the cap assembly being removed after the pressurizingassembly 9 is mounted on thelid 5.
• In the event of thevalve member 26 becoming stuck in the open position, the pressure on thepiston 29 gradually increases and the piston is moved outwards against the bias of thespring 32. Thebore 30 however is grooved at 38 so that once the piston reaches the ends of the grooves compressed gas can pass around the side of the piston and out to atmosphere through another groove provided along the screw threads of themember 81 and thebody 18. As an alternative to providing the groove, themember 81 may be apertured.
• When the operatingmember 81 is unscrewed so that theflange 35 abuts theprojection 37, thehead 84 extending from thepiston 29 is compelled, by engagement with the adjustingmember 82, to move outwardly. Thus even if the piston is inclined to stick once themember 81 is unscrewed, thepiston 29 will be in its outward venting position.
• In the event of both thevalve member 26 and thepiston 29 becoming stuck there is still thesafety valve member 13 in the top of the vessel 1 to stop excess pressure developing. Still another safety arrangement (not shown) may be provided by deliberately weakening a portion of the vessel 1 so that this portion of the vessel bursts in a controlled manner when the pressure exceeds a predetermined level; alternatively the vessel body 4 may be formed such that upon excess pressure developing, it distorts destroying the seal between the vessel body 4 and thelid 5.
• Referring again to Figure 1, the paint pad 8 is in some respects similar to a conventional pad in that it has an outer layer ofmaterial 46 supported on afoam backing layer 47 which has a closed cell structure so that it does not absorb the paint; the foam backing layer is in turn attached to ametal backing plate 48. Unlike conventional paint pads, however, the metal backing plate has a central aperture at which the flexible tube 7 terminates and thefoam backing layer 47 contains a series of passages extending outwardly from the central aperture and terminating within thelayer 46 at a plurality of locations distributed over the pad.
• The flexible tube 7 passes through thehandle 49 of the paint pad 8 and an on/off switch orvalve 50 and a regulatingscrew 51 are provided on thehandle 49.
• The on/offswitch 50 is shown in Figure 4 and comprises aswitch member 52 pivotally mounted intermediate its ends on thehandle 49. One end of theswitch member 52 presses via asmall plate 53 on the tube 7 and the other end is used to operate the switch. In the position shown in Figure 4 the switch is in the "off" position and the tube 7 is squeezed flat. If a user now pivots theswitch member 52 anticlockwise (as seen in Figure 4), themember 52 passes through a dead centre position and then allows the tube 7 to return through its own resilience to a circular cross-section. Theplate 53 reduces the frictional force opposing movement of the tube 7 and reduces wear on the tube.
• The rate of flow of paint through the tube 7 can be controlled by the regulatingscrew 51. Screwing in thescrew 51 restricts the internal cross-sectional area of the tube 7 by flattening the tube. In the innermost position of thescrew 51 the tube may be completely closed.
• The operation of the apparatus shown in Figures 1 to 4 will now be described.
• Paint is supplied to a user in thecontainer 2 with theplug 80 sealing over the diaphragm 14. The user removes theplug 80 and places thecontainer 2 in the vessel 1 and screws thelid 5 onto the vessel 1 at the same time inserting the pipe 3 which is secured to thelid 5 into the central aperture in the diaphragm 14. The user then ensures that theswitch 50 on the paint pad is in the "off" position and inserts acapsule 24 into theassembly 9 as already described. The vessel 1 may be carried in the hand by thehandle 10 but preferably thehandle 10 is suspended from a belt passed around the waist of the user since this is less tiring and also leaves the user with a free hand. Thehandle 10 may be provided with a clip (not shown) for attaching the vessel 1 to a belt. The vessel 1 is pressurized by screwing in thecap assembly 31.
• The user adjusts the rate of flow of paint with the regulating screw orregulator 51 and is then able to paint without interruption. Theswitch 50 enables the user to start and stop painting at will.
• In the particular example described thecontainer 2 has a capacity of one litre which is sufficient to paint about twelve square metres of a surface and the capsule holds four litres of gas (at atmospheric pressure). The pressure in the vessel 1 is normally regulated to be in the range of between ten and twenty pounds per square inch above atmosphere while the pressure in the capsule is of the order of 700 to 900 pounds per square inch.
• One capsule contains more than sufficient gas to discharge all the paint from a container.
• In order to recharge the vessel 1 with a new paint container thecap assembly 31 is unscrewed to the limit of its movement; this causes thevalve member 26 to close (if it is not already closed) and compressed gas in the vessel 1 moves thepiston 29 outwards and escapes to atmosphere around the edge of the piston. Even if thepiston 29 tends to stick it is positively pulled outwards by engagement of thehead 84 with the adjustingmember 82. Thelid 5 can then be unscrewed, since the vessel 1 must be at ambient pressure, the pipe 3 withdrawn from thecontainer 2, the container removed from the vessel 1, and a new container inserted as described above. As the pipe 3 is withdrawn through the diaphragm 14, paint on the outside of the pipe is wiped off the pipe.
• It is helpful for the user to have some indication that the vessel 1 is pressurized and for this purpose a pressure indicator as shown in Figure 7 may be provided. The indicator is mounted on thevessel lid 5 which is formed with an inwardly extendingcircular rib 152 over which a flexible diaphragm 1 53 is fitted. The upper face of thediaphragm 153 carries aprojection 154 which is accommodated in a hole in thelid 5. When the vessel is not pressurized the diaphragm 1 53 is not flexed and the top of theprojection 154 is below the upper surface of thelid 5. Upon pressurization of the vessel, however, thediaphragm 153 flexes and theprojection 154 protrudes from thelid 5; theprojection 154 is preferably in a colour contrasting with thelid 5 so that it can be easily seen.
• After use the apparatus is cleaned. Only the pipe 3, tube 7 and paint pad 8, however, require to be cleaned since the other parts of the apparatus do not come into contact with the paint. Even if the vessel 1 is inadvertently knocked over during use, the diaphragm 14 retains the paint in thecontainer 2 so that the vessel 1 does not need cleaning. Since both theswitch 50 andregulator 51 act externally on the tube 7 they do not become contaminated with paint. The paint pad 8 is dismantleable to facilitate cleaning.
• The '0' ring seals are made of a material which is not affected by the fluid to which they are exposed in use.
• Conveniently the vessel 1, the flexible tube 7, theassembly 9, thehandle 10, and the paint pad 8 are made of plastics materials. For water based paint thecontainer 2 is preferably made of a plastics material but, since plastics materials are attacked by solvent based paints (for example gloss paints) over an extended period of time, thecontainer 2 is preferably made of metal if it is to contain solvent based paints. Thecontainer 2 may be made in various other forms. For example the container may be made of cardboard with a metal foil liner.
• It may be desirable to provide means to prevent the insertion in the vessel of an unsuitable container, that is one containing a paint of inferior grade or a grade different to the paint which the apparatus is primarily intended to feed. Such means may, for example, take the form of one or more interengaging ribs and grooves or other formations on the external surface of the container and the inner surface of the vessel, or of suitably shaping the interior contour of the vessel to inhibit the insertion therein of a container which has other than a matching shape.
• If desired a multiplicity of balls may be provided on the surface of thepaint 16, the balls each being of a diameter slightly bigger than the internal diameter of the pipe 3 and having a density very slightly lower than that of the paint so that they float with nearly all of the ball below the paint surface. A sufficient number of balls are provided such that there are two layers of balls across the entire surface of the paint. As the level of paint in thecontainer 2 drops to a low level the lower layer of balls approach the bottom of the pipe 3; finally when the paint level is almost down to the level of the bottom of the pipe 3 the lower layer of balls reach the level of the bottom of the pipe 3 and one of the balls becomes located over the end of the pipe 3 preventing further flow of liquid. This automatic interruption of the paint flow when thecontainer 2 is almost empty ensures that gas does not enter the pipe 3; if gas were allowed to enter the pipe 3 this could result in sputtering of the paint from the pad 8.
• In the drawings the pressure vessel 1 is shown with square corners and straight sides. In accordance with well known design procedure for such vessels, however, the corners are preferably rounded off and the sides bowed outwardly.
• After use of apparatus described above, the apparatus may be cleaned by pumping a solvent, which in the case of water based paints may be water, through the apparatus using the pressure of the capsule of carbon dioxide.
• In the illustrated apparatus a paint pad is attached to the free end of the tube 7. However, a paint brush or roller may alternatively be attached, these devices having an on/off switch and a regulator similar to the paint pad. When using a brush, the flow of paint may be required to be somewhat slower and this can be achieved by appropriate adjustment of the regulator on the brush handle. If desired the applicator may be of a modular construction consisting of a handle incorporating the on/off switch and the regulator and a pluraltiy of heads including at least one pad, roller and brush which can be attached to the handle. The on/off switch and the regulator may be combined into a single control if desired. For the sake of simplicity the regulator may be omitted.
• A shoulder strap may be attached to the vessel 1 to allow a user to carry the vessel over his shoulder or any other arrangement may be provided to enable a user to carry the vessel.
• Thelid 5 may be clamped onto the body 4 of the vessel 1 by a plurality of toggle clamps, instead of screwing the lid onto the body. This has the advantage that the '0' ring or diaphragm is not subjected to a rubbing action upon tightening of thelid 5. Furthermore the toggle clamps can be spring biased into their closed position in such a way that if the pressure in the vessel exceeds a predetermined level at least one of the toggle clamps is forced open and thelid 5 lifts off the vessel body 4.
• A particular example of a lifting lid assembly is shown in Figure 5. In this figure, thevessel body 104 is shown with a liftinglid 105, an 'O'ring seal 106 being provided between portions of thewalls 104 and 105 which with the vessel 1 unpressurized are overlapping. Thelid 105 is retained on thebody 104 by aring clamp 107 screwed onto thebody 104 and a number ofsprings 108 are provided around the periphery of thelid 105 between thelid 105 and thering clamp 107. In the position shown in Figure 5, the vessel is unpressured, thelid 105 rests on top of thebody 104 and thesprings 108 are substantially unstressed.
• As the vessel 1 is pressurized thelid 105 lifts off thebody 104 and thesprings 108 become stressed. Under normal operating pressure portions of thewalls 104 and 105 continue to overlap and the '0'ring 106 seals the interface therebetween. Upon excess pressure developing, however, thesprings 108 are further compressed and thelid 105 is lifted clear of the '0'ring 106 venting the vessel.
• In the arrangement shown in Figure 2 the diaphragm 14 has ahole 15 which ensures equalisation of pressure between the opposite sides of the diaphragm. In place of the aperture, a slit may be provided in the diaphragm, extending for example radially from the central aperture in the diaphragm.
• Alternatively it may be possible to omit both the pin hole and the slit and rely on the diaphragm flexing in the region of its central aperture to allow the passage of gas between the diaphragm 14 and the pipe 3.
• The diaphragm 14 may, if desired, initially be without the central aperture. In this case the pipe 3 is provided with a pointed end and is sufficiently stiff to puncture the diaphragm when it is first pressed through the diaphragm. It may be advantageous to neck the pipe where it engages the diaphragm. This may be advantageous if an anti-sputter arrangement of a kind which will now be described is employed in the apparatus shown in Figure 2. The anti-sputter arrangement consists of providing a compression spring under thecontainer 2 so that as thecontainer 2 empties of paint it becomes lighter and is lifted up relative to the vessel 1, and, when thecontainer 2 is virtually empty of paint, the end of the pipe 3 bears against the bottom of thecontainer 2 sealing over the pipe 3. If desired a resilient member for example a closed cell foam may be provided on the bottom of thecontainer 2 under the pipe 3 to ensure that a good seal is obtained between the pipe and the container.
• Necking the pipe 3 where it passes through the diaphragm ensures that there is very little resistance to relative motion of thecontainer 2 and the pipe 3 and also allows free flow of gas into the container. When the pipe 3 is withdrawn from thecontainer 2 after use the lower unnecked portion of the pipe is wiped clean as it passes through the diaphragm.
• In the pressure reducing valve assembly shown in Figure 3 apiston 29 is used. As an alternative a diaphragm connected to the wall of thebore 30 and spring biased in the same manner as thepiston 29 could be used. In this case it may not be possible for gas pressure to be vented through thecap 31. An alternative way of venting the gas may be to open the safety valve. Thespring 34 which biases thevalve member 26 into its closed position may be omitted since gas pressure from thecapsule 24 can be used to perform this biasing function.
• - - Thehousing 20 of the pressure reducingvalve assembly 9 may be provided with external radially projecting fins to facilitate screwing and unscrewing of thehousing 20. Also thecapsule 24 may be located in thehousing 20 in such a way that when the housing is unscrewed thecapsule 24 is automatically withdrawn from thepiercer 42 and comes away with the housing from which it is then removed.
• The safety valve assembly may be modified in such a way that every time thelid 5 is secured to the vessel body 4 the safety valve is tested. An arrangement of this kind is shown in Figure 8. In this arrangement the safety valve assembly consists of ahousing 110 in which avalve member 111 carrying aclosure member 112 is mounted. Aspring 113 biases theclosure member 112 onto a spherical seat formed at the bottom of thehousing 110. Upon excess pressure developing theclosure member 112 is lifted off its seat venting the vessel. The interface of thevessel body 114 and screw-onlid 115 is around the outside of the body and is sealed by an '0' ring. On one portion of the top of the vessel body 114 a ramp shapedcam surface 116 is provided. Alever 117 is pivotally mounted on thelid 115 at one end and has acam follower 118 on the other engaging the top of thevessel body 114. Intermediate the ends of thelever 117, the lever touches or is spaced just underneath the lower end of thevalve member 111. As thelid 115 is screwed onto thebody 114, thelever 117 engages thecam surface 116 once in each revolution of the lid and this engagement raises thelever 117 lifting thevalve member 111 into its vented position. When the lid is fully screwed on, thecam surface 116 is arranged to be spaced circumferentially from thecam follower 118 so that the safety valve assembly is closed.
• Although the apparatus has been described with reference to the application of paint, it can be used to apply other liquids to a surface. For example it can be used to apply preservative to a wooden surface or for washing surfaces. The apparatus can also be used to feed liquids to other kinds of applicators, for example to a spray head. With a spray head, the apparauts can be used as a garden spray apparatus.

Claims (17)

1. An apparatus for feeding liquid under pressure, the apparatus including:

a vessel (1),

a pressurizing assembly (9) including a housing (20) for receiving a capsule (24) of liquified or pressurized gas and pressure reducing means (26, 29, 32),

a first fluid path extending from the high pressure side of the pressure reducing means (26, 29, 32) for communicating with the outlet of a capsule (24) inserted, in use, in the housing (20),

a second fluid path extending from the low pressure side of the pressure reducing means (26, 29, 32) into the vessel (1),

a hand-held applicator (8) for coating a surface with liquid, and

a feed conduit (3, 7), including a flexible tube (7) extending between the vessel (1) and the applicator (8), for transferring liquid to the applicator,

characterized in that a liquid container (2) is received, in use, within the vessel (1), the second fluid path extends into the container and the feed conduit (3, 7) extends into the container for transferring liquid from the container to the applicator (8).

2. An apparatus according to claim 1, further characterized in that the top (170) of the container (2) is substantially closed.

3. An apparatus according to claim 2 further characterized in that the feed conduit (3, 7) passes through the top (5) of the vessel (1) and the top (170) of the container (2) to a location adjacent the bottom of the container.

4. An apparatus according to claim 3 further characterized in that the bottom of the container (2) has a well (6) formed therein, and wherein the end of the feed conduit (3, 7) is within the well.

5. An apparatus according to claim 3 or 4 further characterized in that the portion of the top (170) of the container (2) through which the feed conduit (3, 7) passes is in the form of a diaphragm (14), the diaphragm closing over the junction between the container wall and the feed conduit.

6. An apparatus according to claim 5 further characterized in that a small hole or slit (15) is provided in the diaphragm (14) defining a part of the second fluid path.

7. An apparatus according to claim 5 or 6 further characterized in that the container (2) includes a closure member (80) which can be secured over the diaphragm when the container (2) is not in use to seal the container (2).

8. An apparatus according to any preceding claim further characterized in that means to prevent the insertion in the vessel of an unsuited container are provided.

9. An apparatus according to any preceding claim further characterized in that the pressure reducing means (26, 29, 32) includes a valve member (26) mounted in a passage providing communication between the first fluid path and the second fluid path, the valve member (26) 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 used, into the first position, and a piston or diaphragm (29) co-operable with the valve member and movable away from one position in which the valve member (26) is held in the second position by the piston or diaphragm (29) to another position in which the valve member assumes its first position, the piston or diaphragm being biased to said one position by a spring (32) and being biased away from said one position to another position by the pressure of gas on the low pressure side of the pressure reducing means.

10. An apparatus according to claim 9 further characterized in that the bias force of the spring (32) acting on the piston or diaphragm (29) is adjustable, whereby the pressure of gas required to move the piston or diaphragm away from said one position to another position is adjustable.

11. An apparatus according to any preceding claim further characterized in that the tube (7) is between one and two metres long.

12. An apparatus according to any preceding claim further characterized in that the feed conduit (3, 7) comprises a relatively rigid pipe (3) in the vessel and a flexible tube (7) extending between the pipe (3) and the applicator (8), one end of the tube (7) being fitted over one end of the pipe (3) and the junction of the tube and the pipe being a tight fit in an internal recess of the vessel, the tube passing through a bore extending between the recess and the exterior of the vessel.

13. An apparatus according to any preceding claim further characterized in that the vessel (1) includes a body part (4) and a lid (5).

14. An apparatus according to claim 13 further characterized in that the pressurizing assembly (9) is mounted on the lid (5).

15. An apparatus according to any preceding claim further characterized in that the vessel (1) is arranged to be carried by a user without using his hands.

16. An apparatus according to claim 15 further characterized in that a clip is provided on the vessel for attaching the vessel to a belt.

17. An apparatus according to any preceding claim further characterized in that a pressure relief valve (11) is mounted in a wall of the vessel (1).

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