GB2178001A - Dispensing arrangements for liquids and pastes - Google Patents

Abstract

An arrangement for dispensing liquids, eg carbonated beverages, or pastes comprises a container 10 made by a stretch-blow-moulding process from a plastics material which is flexible but substantially non-stretchable, preferably biaxially orientated polyethylene terephthalate, and a device which operates or is operable to apply a force to the container to eject the liquid or paste therefrom and/or to minimize head space in the container as liquid is dispensed. This force is applied to the container over substantially less than the area of the container projected in a plane at right angles to the direction of application of the force. The force may be applied by a caliper spring 13 operating to press together two rectangular frames 12 disposed on opposite sides of the frame, the container having dispensing valve 11 in its neck. Alternatively a large container with tube for dispensing to a remote tap is interposed between ribbed plates of a screw press having pressure sensors which activate a motor whenever applied pressure falls below a predetermined value (Figure 2). The container may be spherical and held between a hemispherical cradle and a hemispherical, electrically, hydraulically or pneumatically driven, piston (Figures 4A-4C). The dispensing valve 11 in the neck of the container preferably has a tubular section projecting into the container with a screw threaded member engaging within this section to form a spiral capillary exit passage for controlling the release of gas during dispensing. A dip tube, which gathers as a coil at the bottom of the container as the container collapses, may be attached to the dispensing outlet (Figure 5). <IMAGE>

Description

SPECIFICATION Dispensing arrangements for liquids and pastes This invention relates two dispensing arrangements for liquids and pastes and has a particularly useful but not exclusive application in relation to arrangements for dispensing carbonated beverages, including beer, sparkling wines and soft drinks on draught or domestically.

Draught beverages without carbonation, orwith carbonation upto about 1.2 volumes, are nowcommonly distributed in flexible containers in a size range from about2 litres upwards. Examples are bag-in-box wines, beer in Polypins, and milk in Pergals. Theflexi- ble envelopes are designed to collapse as the liquids are dispensed so that it is unnecessary to admitair, or other gas such as carbon dioxide, to replace the liquid.

Carbonation causes escalating problems with these containers as the level of carbonation required increases. Thus: (i) Carbon dioxide is lost by diffusion through the containerwalls.

(ii) The carbonation pressuretendsto burstthe container, especially if it is left in a car in hot weather or is otherwise exposed to high atmospherictempernatures.

(iii) As liquid is dispensed from the container the remaining liquid tends to de-gas (losing carbonation) ratherthan allow the container to collapse.

The problems can only be controlled at relatively high cost, by increasing container thickness, using rigid outer containers, applying pistons and/or other means.

It has now been found that these problems can be solved using certain types of polymeric container, and in particular biaxially-orientated polyethylene terephthalate (PET) containers made buy a stretchblow-moulding process. Such containers, fitted with suitable closures ortaps, are robust enough fordistri- bution purposes and are in rapidly-increasing use (mainly in 1.5 litres and 2 litres sizes) as bottles for soft drinks and beers. This robustness is achieved despite their being Iightinweight,mostofthebottlewall- thickness being between 0.2 mm and 0.5 mm. The bottles are flexible, in the sense of being deformable, but they have excellent properties of shape retention.

When flexible polymeric containers of most types for example, polyethylene - are subjected to external forces applied to part of their surface the internal pressure does not rise according to simple hydrosta tic calculation. Clearly the applied pressure is dissi- pated by elastic expansion ofthe bag. Howeverwhen the types of polymeric bottle referred to in the preceding paragraph are subjected to external forces ap plied to part oftheir surface it has been found that the internal pressure rises much more nearly in accordance with what would be expected from hydrostatic calculation.

According to the present invention there is provided a dispensing arrangementfora liquid or paste comprising a plasticscontainerforthe iiquid orpas- tethe side walls of which are flexible such that the container is capable of being substantiallytotallycollapsed but the walls of the container being substantially non-stretchable, said container being disposed in a devicewhereby a mechanicalforce can beap- plied externallyto the container over lessthan thefull sectional area of the container considered in the plane normal to the direction of application ofthe force to dispense the liquid from the container.

These dispensing arrangements may be provided at the point of sale of beverages on draught, or may be provided in the form ofadisposablepackagefor the eventual consumer. The size of the arrangement is limited only by manufacturing capability and con venience of handling when the container isfull.

The arrangement provides a high degree of protection against product loss or deterioration, or environmental contamination, during both distribution and dispensing.

Some embodiments ofthe invention will now be described by way of example with reference to the accompanying diagrammatic drawings inwhich: Figures lA and iB show a first embodiment of the invention in elevation and plan respectively, Figures2 and 3 respectively illustrate two further embodiments ofthe invention, Figures 4A, 4B and 4C illustrate the stages of opera tionofanarrangementsimilarto Figure 3 butdispensing liquid upward instead of downward, FigureS illustrates a modification for upward dis- pensing ofthe liquid, and Figure 6 illustrates another optional feature of the arrangements.

Referring first to Figures 1A and 1 B, a container 10 is made by a stretch-blow-moulding process from biaxially-orientated PET so as to have flexible walls which are substantially unstretched underthe internal pressures generated by carbonated beer or other carbonated liquids. The neck of the container is fitted with a valve 11 enabling the contents to be dispensed.

At opposite sides respectively ofthe container are two rectangular rigid planarframe members 12 con- structed from metal or moulded from stiff plastics material and each comprising two parallel channelsection side portions 12a interconnected bythree transverse channel-section portions 1 2b. A caliper spring 13 having a central aperture into which the neck ofthe containerfits has two arms 14 which rest againstthe centres of the middle transverse portions 126 of the two members 12 so asto urgethetwo members towards each other. Thus when the valve 11 is opened, the force exacted on the container by the members 12 expels the liquid from the container, and prevents decarbonation of the liquid remaining in the container by maintaining an adequate internal pressure in the container.This effect is contributed to by the fact that by reason of members 12 the said force is applied to only a small proportion of the surface area of the container. By selection ofthe strength ofthe caliper spring, the force can also be made sufficient to expel liquid out of the container and through the dispensing pipes and taps of conventional dispensing systems. The container progres sively collapses asthe liquid is dispensed, until only a minimal quantity remains and has eitherto be poured out or discarded with the squashed container.

Where the arrangement is solid in size and capacity suitable for domestic use, the illustrated arrangement may be enclosed in a box leaving only the neck and valve ofthe container exposed.

Figure 2 is an essentially fixed embodiment ofthe invention for installation in cellars, store-rooms, cabinets etc. Here a larger bottle 20 made in the same way as the container of Figures 1A and 1 B is mounted in a cradle and frame 21 at an angle which allows itto be self-draining. It is connected by a tube 22 to a remote tap for draught dispensing ofthe liquid. A contoured or heavily ribbed plate 23 is pressed against the bottle by a screw-press 25 powered by an electric motor. Interposed between the screw-press and the plate are two pressure sensors 24, both wired into the motor circuit. The first sensor activates the motor whenever the applied pressure falls below a predetermined value suitableforthe liquid and dispense system, and switches offthe motor when that value is reached.The second sensor closes down the motor circuit if there is a sudden fall in pressure as would be caused by sudden leakageora burst in the system. The plate 23 is designed to ensure thatthe force is applied to the bottle over substantially less than its projected area.

Figure 3 is an alternative embodiment to that in Figure 2. Here a spherical bottle 26 blow-moulded from PET is inverted in a hemispherical cradle 27 which has a hole in the bottom forthe outlet tu be of the bottle. Force to expel liquid from the bottle is applied by a rigid, hemispherical piston 28 of slightly smaller diameterthan that ofthe cradle. The piston is driven electrically, as above, or by hydraulic or pneumatic means 29. In suitable installations hydraulic pressure may be obtained from the publicwater supply.

In general, the collapse of a container is facilitated if a substantial part of one side of the container can then be made to collapse from an originallyconvexshape into a concave shape inside another part. Conical walls facilitate this type of collapse. Spherical con- tainers such asthe "Beer Sphere" are also suitable, as depicted in Figure 3.

Figures4A,4B and 4C illustrate the stages ofdefor- mation of a modified arrangement in which there is a vertical cylindrical hole 29through the centre of the piston 28 which accommodates the neck ofthe container and the connector fitted to it for dispensing of the liquid. In the earlier stages of deformation only the rim of thins hole makes contact with the container as shown in Fig u res 4A and 4B; the ring of contact coincides (in the case of a stretch-blow-moulded PET container) with a hard zone 30 of incompletelystretched polymerwhich surrounds the neck of the container.

The lower surface ofthe piston is hemispherical and ofapproximatelythe same curvature as the container. It is however preferably less than a hemisphere, which allows itto penetrate into the cradle whilestill leaving asmall clearanceforthewallsofthe collapsed container as shown in Figure 4C. Sincethe used container is bowl-shaped it can be stacked in a compact manner with others two await collection, e.g.

for recycling of the PET.

The arrangements of Figures 3 and 4 can be employed with the container inverted or inclined at an angle to the vertical. However, the upright position as depicted appears to offer several advantages, including (a) ease of loading and coupling for liquid dispensing and (b) thefactthat any gas initially present in the container is purged before dispensing begins.

In certain situations, however, it may be desirable notto vent gas from the container. Then a flexible dip tube 31 may be attached to the normal dispensing outlet, as depicted in Figure5.Asthecontainer26 collapses, this dip tube gathers as a coil atthe bottom.

This arrangement is also useful where cooled liquid is required and cooling is applied externallyfromthe cradle.

In some cases it has been found that the external force required is much less than that predicted from the equilibrium pressure of the dissolved gas inside.

This is because as liquid is withdrawn the remaining liquid remains supersaturated since the container is continuously collapsed by external force. Thus the minimum external force required is approximately the same astheforce required to collapse an empty container. If the supersaturated liquid remains undisturbed it only very slowly releases gas; equilibirum gas-pressure is approached gradually, over a long period.

It is possible to guard against even this possibility by means of a ratchet mechanism which has the effect of permitting movement ofthe device tending to collapse the container but preventing any movement permitting the container to expand.

A part of the consumer appeal of beers, sparkling wines and carbonated soft drinks is that they sparkle in the drinking container, i.e.theycontinuetorelease gas bubbles afterthey have been dispensed. This phenomenon occurs because they remain to some degree supersaturated after normal dispensing procedure; the supersaturation is slowly dissipated by nucleation of gas-bubble formation within the drinking container.

To maximisethe amount of gas availableforthis process it is desirableto minimisethe amountof gas released during the actual process of dispensing from the container. However,the abruptdrop of pressure that occurswhen a tap orvalve on oneofthesecon- tainers is opened causes highly tu rbulent flow which has a powerful effect in nucleating the release of gas.

Such an effect is well known to the designers of taps for use in bars, where the tap is remote from the container and connected to it by tubing. Selecting tubing of suitable properties and dimensions is essential to controlling the release of gas. It does so by ensuring that under flow conditions the pressure falls progressively rather than abruptly. It is common to use a length of capillary tubing forthis purpose.

This means of control is not available for those containers according to the invention where a tap or valve is connected directly to a containerofcarbon- ated liquid without tubing for connection purposes.

It is usual to find, however, that such taps and valves incorporate a shorttubularsection 32 projecting into the container as shown in Figure 6, th rough which section the beverages being dispensed passes.

Into this tubular section we insert a screw-threaded rod 33 as shown in Figure 6. The diameterofthe threaded rod 33 is equal to, or very slightly greater than that of interior of the tubular section so that it must be inserted by force and will not fall out subsequently. The threaded rod is not necessarily inserted to the full length of the tubular section. The screwthread ofthe rod in contactwiththesmooth interior surface ofthe section thus forms a spiral capillary path between the liquid in the containerthe tap or valve mechanism.

This capillary path plays the same role as capillary tubing in bar systems as mentioned above.

Different liquids, dispensing temperatures and levels of carbonation will require different capillary paths. These can be achieved by: (i) Different pitches of screw-thread (ii) Different depths of screw-thread (iii)Different diameters ofthe cavity/rod combination (iv) Different depth of insertion of the rod into the cavity.

The materials and mode of construction of the device should not themselves nucleate gas release, because of surface imperfections and/orthe induction ofturbulence. Thus, for example, the base of the screw-thread should ideally be rounded rather than narrow and deep; and a hydrophilic plastics surface will be advantageous in some circumstances.

Claims (12)

1. Adispensing arrangement for a liquid or paste comprising a plastics containerforthe liquid or paste thesidewallsofwhichareflexiblesuchthatthe container is capable of being substantiallytotallycollapsed butthewalls of which are flexible such thatthe container is capable of being substantiallytotallycollapsed butthewalls ofthe container being substan- tially non-stretchable, said container being disposed in a device whereby a mechanical force can be applied externallyto the container over less than thefull sectional area of the container considered in the plane normal tothe direction of application of the force to dispense the liquid from the container.

2. A dispensing arrangement as claimed in claim 1, wherein the container is equipped with a dispensing valve on the neck thereof.

3. A dispensing arrangement as claimed in claim 1 or claim 2, wherein said container is made from biaxially-orientated polyethyleneterephthalate by a stretch-blow-moulding process.

4. A dispensing arrangement as claimed in any one of claims 1 to 3,wherein said device comprises a pair of rigid elements disposed opposite sides respectively of the container and making contact with thecontainerthrough projections on the surfaces of said elements, and means urging said elementstowards each other.

5. A dispensing arrangement as claimed in any one of claims 1 to 3, wherein the container is of circu larcross-section and said device comprises a cradle element and a piston element which respectively pro- vide a semi-circular section cradlesupportforthe container and a piston face of semi-circular cross- section in contact with the container said piston face having a smaller radiusthan the supportface ofthe crease, and means for urging said elements together to expel the liquid content ofthe container.

6. Adispensingarrangementasclaimed in claim 5, wherein said container is spherical and the support face of the cradle element and said piston face are substantially hemi-spherical.

7. A dispensing arrangement as claimed in any one of claims 4to 6, wherein said means urging said elements together comprises springs or other resilient means.

8. Adispensing arrangement as claimed in claim 7, wherein said resilient means comprises a caliper spring straddling the neck of the container and urging said elements towards each other.

9. A dispensing arrangement as claimed in any one of claims 4to 6, wherein said means urging said elements together comprises a motor connected to move one of said elements towards the other.

10. A dispensing arrangement as claimed in any one of claims 1 to 9 when appendentto claim 2, wherein the valve member has a tubular section projecting into the container and wherein a member is engaged in saidtubularsection which membercooperates with the internal wall of said section to form a spiral capillary exit passage for liquid dispensed from the container which passage is upstream ofthe valve.

11. A dispensing arrangement as claimed in any one of claims 1 to 10, wherein said elements are interconnected by a ratchet mechanism which permitts them to move towards each other but prevents movement, or permits only limited movement, ofthe elements away from each other.

12. A dispensing arrangement substantially as hereinbefore described with reference to and as illustrated in Figures 1A and 1 B, or Figure 2 or Figure 3, or Figures 4A, 4B and 4C ofthe accompanying drawings.