Conventionally, the sheath itself is wrapped in a protective layer of tape, as it is of a crumbly texture and can easily be damaged e. g. by abrasion. The tape is applied by wrapping it helically around the sheath.

The tape itself, however, is prone to"grinning", i. e. parting at its overlaps when the python negotiates a sharp bend and tape winding tension has to be carefully controlled to reduce the likelihood of grinning while at the same time not putting the tape under such a high tension that it compresses the foam sheath unduly, reducing its insulating efficiency.

The present invention provides python not subject to this problem, yet which can be produced at no greater cost, even, possibly, at less cost, than conventional, tape-wrapped python.

The invention comprises in one aspect a"python"comprising a bundle of tubes in a foam sleeve, characterised by a protective coating applied to the outer surface of the foam sleeve in liquid form and cured.

The coating may be applied as a dispersion and may for example comprise a polyurethane-a highly elastic coating is desirable which will not be prone to cracking and which accommodates flexure of the python. The coating may be a water based emulsion.

The coating may comprise a pigment, and may comprise a fire retardant.

The coating may be applied by spraying, dipping or brushing and at least two coats, preferably three, may be applied to build up the coating to a thickness of 100- 200 microns.

The wet coating may be cured by infra-red or ultra-violet radiation, or by convected heat.

As the python may be wound up on a reel, it may be desirable to apply an anti-blocking agent after curing, so that the adjacent turns do not stick together. The blocking agent may comprise talcum powder, a silicone release agent or a polyethylene sleeve.

In many pythons, in addition to beverage supply tubes, there are also coolant tubes. In multi-tube pythons, numerous different beverages are carried, and some of them may require to be delivered at different temperatures from others. In the bundle, it is arranged so far as possible that the tubes carrying beverages that need to be served chilled are placed in contact with a coolant tube. Flash heating or cooling is sometimes used at the bar delivery point to adjust the temperature.

A problem, however, is that pythons, in the run from cellar to bar, must usually negotiate bends, and bending a bundle of tubes usually involves relative displacement of tubes with possible"migration"of tubes from inside to outside of the bundle and vice versa. This can often separate a beverage supply tube from an associated coolant tube, leading to the beverage being delivered at the wrong temperature or to excessive flash heating or cooling requirements at the bar dispensing point.

The present invention, in another aspect, provides a solution to this problem.

The invention, in that other aspect, comprises a python incorporating a beverage supply tube and a coolant tube contained within a common boundary surface, one of which may be inside the other.

The tubes may be integrally extruded and may be connected by at least one web extending between the outside of the inner tube and the inside of the outer tube.

The tubes, however, may be separately extruded, the one being threaded inside the other. The inner tube may then be held out of contact with the other tube by web means between the two tubes. The web means may be extruded with one or the other or both of the tubes.

The python may be enclosed in an insulating, e. g. a foam sleeve and may consist of the inner and outer tube arrangement on its own or bundled together with other tubes, the bundle, being wrapped in film before application of an insulating sleeve.

The python may have a coolant tube and more than one beverage tube. The coolant tube may be central and surrounded by the beverage tubes.

The sleeve may be conventionally wrapped for protection or, of course, protected by a coating applied in liquid form and cured.

Embodiments of python according to the invention will now be described, together with methods for their manufacture, with reference to the accompanying drawings, in which: Figure 1 is a view of a python with parts cut away to reveal the structure; Figure 2 is a block diagram showing methods for making the python illustrated in Figure 1; Figure 3 is a view of one embodiment of a tube-in-tube design; Figure 4 is a view of another embodiment of a tube-in-tube design; Figure 5 is a view of a third embodiment of a tube-in-tube design; and Figure 6 is a view of a python incorporating a tube-in-tube design; Figure 7 is a view of a multiple tube-in-tube design; Figure 8 is a view of a python incorporating multiple tube-in-tube designs; and Figure 9 is a view of a python like that of Figure 8, but with a different bundling configuration of the tubes.

Figure 1 illustrates python comprising a bundle 11 of tubes 12 in a foam sleeve 13. The tubes 12 comprise beverage delivery tubes 12a and coolant tubes 12b, the bundle 11 being wrapped in a cling film 14, essentially containing the bundle 11 for application of the foam sleeve 13.

Conventionally, the foam sleeve 13, after application to the bundle 11, would be wrapped in a plastic tape, applied helically by a wrapping machine.

Python of this general type is described, together with methods for making the same, in EP 0 328 233 B and EP 0 560 464 B.

Instead, however, of the conventional helically wrapped protective tape, the foam sleeve 13 is, according to the invention coated with a protective coating 15 applied to its outer surface in liquid form and cured.

The coating is applied e. g. as a dispersion of polyurethane in a water base, and may also comprise a pigment, e. g. for colour-coding-python, while essentially capable of being made with any desired numbers and diameters of tubes 12 in the bundle 11, is often supplied in a range of standard formats, which could be readily identified by colour coding, and it becomes much easier to do this, with the invention, by stocking a range of pigments for incorporation into the coating rather than by stocking a range of coloured tape.

The coating may also comprise a fire retardant and any other beneficial additive as may be desired.

Figure 2 illustrates, in block form, methods for making a python as illustrated in Figure 1.

Box 21 indicates the python production process up to the application of the foam sleeve 13 to the tube bundle 11. This is essentially a discontinuous process in which python of any desired length, say 200 m or 300 m, is produced by feeding the tube bundle through a number of lengths of sheath held expanded by differential air pressure inside-to-outside.

Python passes from this production stage, box 21, to a coating stage, box 22, in which the water based polyurethane suspension is applied, by spraying, dipping- as by running the python through a bath-or brushing, and in which two or three coats may be applied to build up a desired thickness, usually 100 to 200 microns.

The wet python passes then to a curing stage, box 23 where it is cured by infra-red or ultra-violet radiation, or by air convection as will be appropriate for the coating polymer.

The cured polymer may be tacky, still, and box 24 indicates a stage in which an anti-blocking agent such as talcum powder or a water based silicone release agent or even a polyethylene sleeve is applied prior to the python being wound up in a drum at winding step 25.

Figures 3,4 and 5 illustrate a beverage supply tube 31 and coolant tube 32, the supply tube 31 being contained within a common boundary surface 32a inside the coolant tube 32, although, of course, the coolant could, if desired, flow in the inner, supply tube 31 if desired, the beverage flowing in the outer tube 32.

Figure 3 illustrates an embodiment in which the tubes 31 and 32 are integrally extruded, being connected by webs 33 extending between the inside of the outer tube 32 and the outside of the inner tube 31.

Figures 4 and 5 illustrate embodiments in which the tubes 31 and 32 are extruded separately, tube 31 being threaded inside tube 32. Web means 33 on the inner tube 31 (Figure 4) or on the outer tube 32 (Figure 5) keep the inner tube 31 spaced from the outer tube 32.

Figure 6 illustrates, in like fashion to Figure 1, a python including such a tube arrangement 31,32 as one of its bundle tubes.

Figure 3 also illustrates an arrangement in which the outer tube 32 can be regarded as enclosing three beverage tubes formed between the webs 33, and one coolant tube, namely the central tube 31. Such an arrangement can be enclosed within an insulating foam layer on its own or with other, similar or dissimilar tubes.

Figure 7 illustrates an arrangement in which a central coolant tube 71 with ribs 72 is inserted into an enveloping tube 73 together with three beverage tubes 74. The whole can then be enclosed in a foam sheet, not shown.

Figure 8 illustrates an arrangement in which a foam sleeve 81 surrounds a coolant tube 82 with three inserted arrangements like that of Figure 3.

Figure 9 illustrates an arrangement like that of Figure 8, but with the foam tube 81 surrounding the tube 82 and three inserted arrangements 83 in a different configuration- the axes of the tubes 82,83 are arranged in a square (seen in cross-section) which will clearly pack into a smaller cross-section (and need a smaller cross-section foam sleeve 81) than the embodiment of Figure 8 which, however, might have more even temperature distribution as between the beverage supply tubes. The tube 82 may of course be utilised for the supply of gas, and as pressure air from cellar to bar, but may also be used for the supply of cooled water which may return from the bar via the outer spaces in the tubes 82,83.