METHODS AND APPARATUS FOR MAKING PYTHON

Abstract: There is disclosed a method of making a python (11) by covering a bundle of tubes with a foam sheath (12), comprising the steps of expanding the cross-section of the foam sheath (12), passing the bundle of tubes through the sheath and collapsing the sheath on to the bundle of tubes, in which, for the expansion, the sheath is placed in an evacuable pipe (14) and sealed thereto at its ends.

Description: METHODS AND APPARATUS FOR MAKING PYTHON This invention relates to methods and apparatus for making python, which is to say foam sheath insulated tube bundles which carry beverages and coolant water from cellar to bar in hotels and inns. The application of the foam sheath to the tube bundle has evolved in recent times from the manual application of short (two metre) lengths using lubricant such as talc at point of installation through the application of lengthwise split foam with subsequent glue and wrap operations to the method disclosed in GB 2 214 262, which is the method currently in use to provide top-quality python up to 600 m in length. Other methods are also in use but they are by comparison extremely slow and inefficient, and, given, the limitations of space in most factory situations, can only produce relatively short lengths of python. The method of GB 2 214 262 involves the use of elongate lidded boxes in which the foam is laid. Foam sheath is conveniently available in 25 m lengths and this is nominally the length of each box. Whilst the method works quickly and efficiently, problems have been encountered with the sealing of the lids. The present invention solves that problem but also gives rise to other advantages. The invention comprises a method of making a python by covering a bundle of tubes with a foam sheath, comprising the steps of expanding the cross-section of the foam sheath, passing the bundle of tubes through the sheath and collapsing the sheath on to the bundle of tubes, in which, for the expansion, the sheath is placed in an evacuable pipe and sealed thereto at its ends. The pipe may have a perforate liner. A plurality of pipes may be arranged side by side, each loaded with foam sheath, and the bundle of tubes passed sinuously through the pipes to cover a single length of tube bundle with a series of lengths of sheath. The bundle of tubes may first be passed through all the loaded pipes, then the endmost sheath collapsed on to the bundle of tubes and released to slide through its pipe and the bundle moved through the remaining pipes to butt the leading end of the collapsed sheath against the trailing end of the next adjacent length of sheath which is then collapsed and this process may be repeated until all the lengths of sheath are abutted and collapsed. The method is essentially similar to the method described in GB 2 214 262, except for the fact that the foam sheath has to be fed through 25 m of tubes rather than being laid in an open 25 m box. This has never before been done in the context of making pythons. In variants of the method of GB 2 214 262 which involve purely overpressure internally of the foam sheath to expand it for passage therethrough of the tube bundle no containment for the sheath has been provided or proposed, the empty sheath merely being supported in open rainwater guttering. The advantage of easily being able to hold lengths of sheath expanded during the butting operation, which enables multiple lengths of sheath to be butted up readily, is not available to those techniques that depend upon a sealing effect between the leading edge of a pipe bundle and the interior of the sheath to maintain expansion pressure in the sheath. The bundle of tubes may be passed between consecutive pipes by a guide, which may define a curved path of such radius as will comfortably accommodate the flexibility of the bundle of tubes when encased in the sheath and lying in a plane containing the consecutive pipes. The guide may comprise a wheel, which may be a free-wheel. A particular advantage of the use of pipes rather than the lidded boxes of GB 2 214 262 is that they may more readily be arranged, viewed end-on, in two dimensional array, this reducing the floor space required for the production of python and generally improving the ease with which the apparatus can be operated because the various attention-requiring parts are compactly arranged and within easy reach, improving response-to-problem-time and reducing operator fatigue. The pipes and guides may be so arranged that the bundle of tubes experiences no or substantially no twist on passing through the pipes. The angle through which the bundle of tubes twists passing between adjacent pipes may be equal to or less than 45 °. Twist in the bundle of tubes causes migration of tubes relative to each other and introduces kinks and bends which make it difficult to install. The invention also comprises apparatus for making a python by covering a bundle of tubes with a foam sheath, comprising an evacuable pipe in which the sheath can be placed and seal means to seal the sheath thereto at its ends. The pipe may have a perforate liner, and may indeed have a plurality of liners of different diameters to accommodate different sizes of python. The python industry recognises a range of quasi-standard python configurations involving different numbers of beverage lines and coolant lines involving a range of sizes of foam sheath. The perforate liners are sized so as to accommodate the sheath for easy threading through the pipe when in its normal, unexpanded state, and holds it straight and steady on evacuation of the pipe to expand the sheath into contact with the liner. The liners may be nested within the pipe. The liner (or the innermost liner) may be held at each end of the pipe by a spigot fitting in the liner and sealingly secured by a flange to a flange on the end of the pipe. The apparatus may also comprise ferrule means adapted to seal the ends of the sheath to the ends of the pipe, which may comprise split conical ferrules. The apparatus may also comprise a pig attachable to the leading end of the bundle of tubes for guiding its passage through the foam sheath, and hauling means for hauling the tube bundle through the foam sheath. Embodiments of apparatus and methods for making python according to the invention will now be described with reference to the accompanying drawings, in which:- Figure 1 is an axial cross-section through a pipe showing python in the course of manufacture; Figure 2 is a side elevation of two pipes showing a guide for the passage of python between them; and Figure 3 is an end-on view of a two-dimensional array of pipes. The drawings illustrate methods and apparatus for making python, which comprises a bundle of beverage often with coolant tubes inside an insulating forma sheath. Python 11 is particularly illustrated in axial section in Figure 1, the sheath 12 being held expanded by an external vacuum prior to collapsing when the vacuum is released on to the bundle of tubes 13 which are pre-wrapped in cling film - the wrapping and the assembly through a loom and associated hauling gear are all prior art technology and need not be further explained here. The bundle 13 of tubes is covered with the foam sheath 12 by expanding the sheath pneumatically and hauling the bundle 13 through the expanded sheath 12. To this end the sheath 12, which is supplied in 25 m lengths in various inner diameters and wall thicknesses such as 42 mm inner diameter x 13 mm wall thickness, is first loaded into the evacuable pipe 14 which is itself a little short of 25 m long. The pipe 14 has endwise flanges 15 and vacuum connections 16. Liners 17 of perforate material such as mesh or apertured metal or plastic pipe are held in place by ends of the innermost liner 17a being on spigots 18a of end caps 18 sealingly secured to the flanges 15 by bolts 19. Of course, only one liner 17 need be used, but a range of sizes of liner is provided to correspond with the outer diameter of the sheath being used. Leaving the larger liners in place and nesting them gives support to the innermost liner and incidentally solves a storage problem. The innermost liner 17a is somewhat larger in diameter than the sheath 12 which can thus easily be pulled through the pipe 14. Conveniently, a 30 m flexible rod e.g. of plastics material is passed through the pipe 14 with a rope attached. The rope is simply tied or clamped on the one end of the 25 m length of sheath and pulled through so that the sheath is now within the liner 17a with each end projecting a little. Split conical ferrules 21 are inserted sealingly to compress the sheath ends against the outer apertures of the spigots 18a of the end caps 18. The pipe 14 can now be evacuated, which causes the sheath 12 to expand into contact with the liner 17. The plastic rod aforementioned can now be passed through the pipe 14 again, this time through the sheath 12 to draw a rope 22 therethrough. To the rope 22 is attached a pig 23 which is clamped to the end of the bundle 13 of tubes. The pig 23 and hence the bundle 13 can now be hauled through the 25 m of sheath 12. At the far end of the pipe 14, where the bundle 13 emerges, it can be taken round a guide 24 and hauled through a second pipe 14 (2) (Figure 2). The guide 24 is currently a free wheel arranged in the same plane as the axes of the two pipes 14, 14 (2). The pipe 14 (2) will have been prepared with its own sheath 12 and evacuated in the same way as the first pipe 14. Further pipes 14 (3), 14 (4) etc can be added so that the tube bundle 13 can be threaded through a plurality of sheaths. Pythons 100 m in length are quite normal in the trade, and the requirement goes up to 600 m. Twelve pipes are needed to make a 300 m python from 25 m long sheaths. Figure 3 shows how multiple pipes (six only being shown for clarity's sake) can be arranged in two-dimensional array, viewed end-on. It is desirable not to put any significant degree of twist into the tube bundle which would cause relative migration of the tubes in the bundle 13 and result in a kink or bend which could hamper on-site installation. It is desirable that no more than 45° of twist is introduced between adjacent pipes, it being remembered that this degree of twist is accommodated over the 25 m length and that the total twist inserted will always be arranged to be equal to zero or nearly zero.

Claims: CLAIMS 1. A method of making a python by covering a bundle of tubes with a foam sheath, comprising the steps of expanding the cross-section of the foam sheath, passing the bundle of tubes through the sheath and collapsing the sheath on to the bundle of tubes, in which, for the expansion, the sheath is placed in an evacuable pipe and sealed thereto at its ends. 2. A method according to claim 1, in which the pipe has a perforate liner. 3. A method according to claim 1 or claim 2, in which a plurality of pipes such evacuable is arranged side by side, each loaded with foam sheath, and the bundle of tubes passed sinuously through the pipes to cover a single length of tube bundle with a series of lengths of sheath. 4. A method according to claim 3, in which the bundle of tubes is first passed through all the loaded pipes, then the endmost sheath is collapsed on to the bundle of tubes and released to slide through its pipe and the bundle moved through the remaining pipes to butt the leading end of the collapsed sheath against the trailing end of the next adjacent length of sheath which is then collapsed and this process repeated until all the lengths of sheath are abutted and collapsed. 5. A method according to claim 3 or claim 4, in which the bundle of tubes is transferred between two consecutive evacuable pipes by a guide. 6. A method according to claim 5, in which the guide defines a curved path of such radius as will comfortably accommodate the flexibility of the bundle of tubes when encased in the sheath and lying in a plane containing the consecutive pipes. 7. A method according to claim 5 or claim 6, in which the guide comprises a wheel. 8. A method according to claim 6 or claim 7, in which the pipes, viewed end- on, are arranged in two-dimensional array. 9. A method according to claim 8, in which the pipes and guides are so arranged that the bundle of tube experiences no or substantially no total twist after passing through the pipes. 10. A method according to claim 9, in which the angle through which the bundle of tubes twists passing between adjacent pipes is equal to or less than 45°. 11. Apparatus for making a python by covering a bundle of tubes with a foam sheath, comprising an evacuable pipe in which the sheath can be placed and seal means to seal the sheath thereto at its ends. 12. Apparatus according to claim 11, in which the pipe has a perforate liner. 13. Apparatus according to claim 12 in which the pipe has a plurality of liners of different diameters to accommodate different sizes of python. 14. Apparatus according to claim 13, in which the liners are nested in the pipe. 15. Apparatus according to any one of claims 12 to 14, in which the liner is held at each end of the pipe by a spigot fitting in the liner and sealingly secured by a flange to a flange on the end of the pipe. 16. Apparatus according to any one of claims 11 to 15, comprising ferrule means adapted to seal the ends of the sheath to the ends of the pipe. 17. Apparatus according to claim 16, in which the ferrule means comprise split conical ferrules. 18. Apparatus according to any one of claims 11 to 17, comprising a pig attachable to the leading end of the bundle of tubes for guiding its passage through the foam sheath. 19. Apparatus according to any one of claims 1 1 to 18, comprising hauling means for hauling the tube bundle through the foam sheath.

Inventors: BROWN COLIN, BROWN, COLIN
Applicants: BROWN COLIN, BROWN, COLIN
Application year: 1998
Main classification: B29C63
IPC codes: B29C63