Method of encasing bundles of tubes

A method of making a python in which a bundle of tubes is disposed coaxially within a close-fitting elongated sheath having a resiliently expandable inside diameter wherein the inside diameter is expandable by creating a pressure differential between the inside and the outside of the sheath to expand the sheath and inserting the tube bundle without substantial resistance from sliding contact with the expanded inside surface of the sheath, a pig being provided on the lead end of the bundle to assist passage through the sheath.

BACKGROUND OF THE INVENTION 
This invention relates to methods of making a python, that is to say a 
bundle of tubes encased in a foam sheath such as is used for the 
conveyance of beverages from cellar or cool store to a dispensing point 
such as a bar or soft drinks counter. 
Such bundles of tubes are required to be of surprisingly substantial 
length, and are used normally in lengths up to and exceeding 100 meters. 
The tube bundles are sheathed in a foam insulating material so as to 
maintain their low temperature up to the dispensing point, where they may 
need "flash" cooling or maybe heating immediately prior to dispensing in 
order to be served at the correct temperature. 
The tube bundles, of "food grade" plastics material for the conveyance of 
beverages and such additional "service", e.g. coolant tubes such as may be 
required, are assembled into a bundle and wrapped, usually in a cling-film 
material. The bundles are assembled to particular requirements, some at 
least being standard or substantially so by virtue of their being widely 
specified by brewery chains or like enterprises. 
As described in GB 2 166 833A, great difficulties are experienced in 
fitting the foam sheath onto the bundle of tubes. The practice of 
lubrication using talc is said there to be undesirable, but another 
problem is said to be that only short lengths of sheath can be pulled over 
the tube bundle, each length requiring to be accurately butted to its 
neighbor. The use of such short lengths is dictated clearly by the 
difficulty of using long lengths, and not, as suggested in GB 2 166 833A, 
because only short lengths, of a few meters, were available. 
In any event, the problem is solved, according to GB 2 166 833A, by first 
slitting the foam sheath along its length and introducing the bundle via 
the slit, which is then adhesively repaired. This solution has in fact 
been widely adopted. 
Difficulties occasionally arise in practice with this method, when the 
repaired slit constitutes a continuous line of impaired thermal resistance 
along which condensate can form in considerable quantity. The condensate 
then drips from the outer wrapping of the python and has obvious 
deletrious effects on the structure through which the python passes. 
SUMMARY OF THE INVENTION 
The invention provides a method of making a python in which a bundle of 
tubes is disposed substantially coaxially within a close-fitting elongated 
sheath having a resiliently expandable inside diameter. The method 
provides for pneumatically differentially pressurizing the inside of the 
sheath substantially throughout its length relative to the outside of the 
sheath with a greater relative pressure on the inside thereof thereby 
expanding the inside diameter of the sheath. The bundle of tubes is 
inserted longitudinally into the expanded sheath without substantial 
resistance from sliding contact with the expanded inside surface of the 
sheath. The differential pressure on the sheath is then relieved so that 
the inside diameter of the sheath contracts resiliently and closely around 
the bundle of tubes. 
In one form of the method an elongated length of the sheath is displaced 
laterally with respect to its axis into an elongated chamber through an 
elongated opening therein with opposite end portions of the sheath 
projecting from opposite ends of the elongated chamber. The inside 
diameter of the opposite end portions of the sheath projecting from the 
opposite ends of the elongated chamber are mechanically expanded. The 
opposite ends of the elongated chamber are pneumatically sealed around the 
respective projecting opposite end portions of the sheath. The elongated 
opening in the chamber through which the sheath entered is also 
pneumatically sealed. The chamber is pneumatically evacuated to expand the 
inside diameter of all of the sheath not already mechanically expanded at 
its end portions. The bundle of tubes is then inserted longitudinally into 
the expanded sheath by access through the sheath end portions projecting 
from the ends of the chamber. The vacuum within the chamber is then 
relieved so that the inside diameter of the sheath therewithin contracts 
resiliently around the bundle of tubes. The opposite end portions of the 
sheath are unsealed with respect to the opposite ends of the chamber and 
the opening in the chamber is also unsealed. The expanded inside diameter 
of the opposite end portions of the sheath is mechanically released so 
that they also contract resiliently around the bundle of tubes. Finally, 
the elongated length of sheath with the tube bundle therewithin is 
laterally displaced with respect to its axis out of the chamber through 
the opening. 
In another form of the method a forward portion of the sheath is 
pneumatically sealed. A streamlined pig is located on a lead end of the 
bundle of tubes. The pig and the lead end of the bundle of tubes are then 
inserted longitudinally into an entry end portion of the sheath opposite 
the forward portion thereof. That entry end portion of the sheath is then 
pneumatically sealed around the bundle of tubes without preventing 
longitudinal displacement of the bundle of tubes. The interior of the 
sheath is then pressurized to expand its inside diameter. The bundle of 
tubes is longitudinally displaced through the sheath from the entry end 
portion to the forward portion thereof by pulling or pushing without 
substantial resistance from sliding contact with the expanded inside 
surface of the sheath. The pressure on the inside of the sheath is then 
relieved so that the inside diameter of the sheath contracts resiliently 
and closely around the bundle of tubes.

BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 illustrates in cross-section a python as may be used for conveying 
beverages from a cellar or cold store to a bar in a public house, hotel, 
restaurant or like establishment. 
The python comprises a flexible bundle of tubes 11 which may be of various 
sizes and which are usually color and/or number coded. Larger tubes 10 may 
be used for circulating water or other coolant. 
The tubes 11 are wrapped in a bundle by for example a cling film wrapping 
12 and are encased in a soft, flexible and resilient foam sheath 13 which 
is in turn wrapped in a protective plastics material outer wrapping 14. 
The tubes 11 are of a food grade polymer material such as polyethylene. 
Such a python is known per se, but difficulty was experienced in threading 
the tube bundle through the sheath 13 and this could only be done in short 
lengths of a few meters and with the aid of talc as a lubricant. To solve 
that problem the tubular sheath 13 was first slit lengthwise and then 
opened out so it could be placed around the tube bundle. The slit was then 
repaired by adhesive prior to wrapping the now sheathed tube bundle in the 
protective wrap 14. This then gave rise to the further problem, however, 
that the insulation afforded by the repaired slit was inadequate and 
condensation would form along the length of the python at the position 
where the repaired slit underlay the protective wrap 14. The condensation 
would drip off and cause damage to woodwork and decoration in the property 
in which the python was installed. 
The present invention provides that pythons as illustrated in FIG. 1 can be 
made in long lengths--20 or 25 meters is a convenient length of sleeve and 
several sleeves may be applied at once to make a really long python, say 
100 meters long, which is standard, or even longer--with relatively few 
butt joints between sheath sections. In fact, the limitation is the 
available length of sheath material, but in practice, perhaps, it is just 
not convenient to work in lengths greater than 25 meters of sheath because 
of space limitations. 
The method is illustrated simply in FIG. 2, which shows the bundle of tubes 
11 wrapped in cling film 12 being introduced into a foam sheath 13 which 
has had its internal diameter expanded as illustrated by the arrows. Once 
the wrapped bundle is in place, the expansion force is relieved and the 
foam sheath reverts to its original internal diameter to closely surround 
and grip the bundle. The outer wrapping 14 of FIG. 1 can then be applied 
conventionally. 
While other expansion methods may be possible pneumatic expansion is 
certainly effective. 
FIG. 3 illustrates diagrammatically an assembly line for python in which 
the sheath's inner diameter is expanded pneumatically. 
A length of sheath material 13 is placed in a sealable chamber 15 in the 
form of a lidded box as seen more clearly, perhaps, in the cross sections 
of FIGS. 5A and 5B, the box comprising a base 16 and a lid 17 secured 
thereto by a piano hinge 18. A clasp fastening arrangement shown at 19 in 
FIGS. 5A and 5B holds the lid firmly closed onto the base, the rim being 
sealed as by rubber or like sealing beading 21. The box has end closures 
which have apertures to allow the sheath to protrude slightly from each 
end. 
In another arrangement illustrated in FIG. 5C, the lid 17 is lift-off 
rather than hinged and sits with feet 17a in wells 16a of the base 16 
which is in this case of a more profiled cross section to reduce the 
internal space from which air has to be evacuated. 
The box can conveniently be made in a length of 25 meters, to accommodate a 
similar length of sheath. 
At the right-hand inlet end of the box 15, the sheath protrudes over a 
funnel 22 which is split into two halves so that it can be applied and 
removed laterally without threading over an end of the sleeve, for reasons 
which will become clear later. The sheath end is clamped to the funnel 22 
e.g. by a hose grip type of clamp 23. 
The funnel 22 expands the end of the sheath and is pushed sealingly into 
the aperture 24 in the end enclosure 25 of the box 15. 
An alternative to the funnel is shown in FIG. 4B. A sheet metal spring 122 
is reduced in diameter by squeezing, and inserted into the free end of the 
sheath, then let go. The sheet metal spring expands, expanding with it the 
sheath. 
The other end of the sheath where it protrudes from the left hand end of 
the box 15 is also sealed, so that the box chamber 15 is adequately sealed 
all around. 
The idea, now, is that with the sheath 13 sealed in the sealed box 15, its 
internal diameter is pneumatically expanded. To this end, the box 15 is 
evacuated through a vacuum connection 26. Alternatively, or at the same 
time, an overpressure may be introduced to the interior of the sheath in a 
manner described hereinafter through a connection 27 at the left end of 
the box. 
The pressure air connection 27 can, before sealing off, be used to blow 
through the installed sheath 15 a butterfly-type carrier (not shown) for a 
hauling line 28 which will be attached to haul the bundle of tubes through 
the sheath. 
In any event, the differential pressure from inside to outside the sheath 
is such as will cause the wall of the sheath to compress and indeed to 
cause the internal diameter of the sheath 15 to expand by some 5 mm, to 
the condition illustrated in cross-section in FIG. 2. In this condition 
there is no substantial frictional resistance to the passage of the tube 
bundle through the sheath. 
The diameter of the funnel is chosen appropriately to the diameter of the 
sheath to ensure good sealing relationship. Different funnel 
configurations and sizes might be used in connection with the process 
described herein. 
The leading end of the tube bundle to be inserted in the sheath is attached 
to a pig 29 for guiding its passage thorugh the sheath. The pig 29 is 
hauled through the sheath by the hauling line or cable 28 which is on a 
winch situated at the end of the box 15. The cable 28 is attached to the 
end of the bundle of tubes 11 by two stepped locking inserts 32, better 
seen in FIGS. 6 and 7. A larger diameter such insert 32a is inserted into 
a larger tube and a smaller such insert 32b is inserted into a smaller 
tube 11. Hauling wire or cable 28 is introduced into a free end bore 33 of 
the insert, which is cut away so as to expose a lateral bore aperture 34 
through which the hauling wire or cable 28 can be pulled and, to secure 
the wire or cable, can be knotted. The two wires are quickly spliced to 
become one which passes through bore 29a in the nose of the pig 29. 
The pig 29 itself is a bullet shaped member having a rearwardly open cavity 
into which the leading end of the tube bundle fits. The pig 29 is thus 
slightly larger in diameter than the tube bundle, but not so big as to 
give rise to excessive frictional drag against the inner wall of the 
expanded sheath. 
With the hauling wire or cable 28 through the sheath, the leading end of 
the wrapped bundle of tubes 11 in the pig 29 and the pig in the funnel 22, 
the box 15 is evacuated to expand the inner wall of the sheath 13 and the 
pig is hauled through the sheath by a winch 35. 
As mentioned above, several cross-sectional sizes of tube bundles are often 
specified which fit into one of the standard range of sheaths. To 
accommodate the range, the apparatus includes a corresponding range of box 
15 inserts 36 comprising different diameter apertured or perforated tubes 
which in use closely surround the sheath 13 in the box. The inserts 36 
are, like the box 15 itself, hinged so as to open and close with the box 
15. The inserts 36 are supported and held in position when in the box 15 
on shaped blocks 37. In FIG. 5C nested inserts 36 are shown--the larger 
diameter inserts 36 are left in place, the smaller ones inserted inside 
them, which further reduces the free volume in the box and the pressure 
air or evacuation requirement. 
The apparatus illustrated in FIG. 3 can conveniently insert a wrapped 
bundle of tubes into a 20 or 25 meter length of sheath. For pythons longer 
than this the wrapped tube bundle is inserted serially into two or more, 
usually four, such lengths of sheath to make a python fifty or one hundred 
meters in length. This can be done as shown in FIG. 8 in which four 
similar evacuable boxes 81, 82, 83, 84 are set side-by-side. Lengths of, 
say, 25 meters of sheath 13 are placed in each box, each with a clamped 
funnel as described above. 
The winch 35 is placed at the end of one 84, of the boxes. Between each 
adjacent pair of boxes is a capstan 85 around which the hauling line 28 
can bend so that it can follow a serpentine path through the four boxes. 
With the hauling line 28 so threaded through all of the sheaths 13 in the 
boxes 81, 82, 83, 84 the pig 29 is attached to the leading end of the tube 
bundle as already described. The boxes are evacuated to expand the inner 
diameter of its sheath 13 and the pig 29 hauled through until the required 
length of tube bundle has traversed the funnel of box 81. This is 
indicated e.g. by a mark placed on the wrapped bundle as it is being 
supplied (assumedly for present purposes from a continuous supply). 
The sheath 13 of the box 81 will now be correctly positioned on the wrapped 
tube bundle and is now fixed in place by releasing the vacuum in box 81 so 
that the foam sheath resiles back to its original size which is adequate 
to grip the wrapped bundle and maintain its position on it. The funnel can 
now be removed. 
Because of the half turns around the capstans 85, however, the tube bundle 
still has not reached the exit end of the box 84. Hauling now continues 
until the leading edge of the sheath from box 81 abuts the tail end of the 
sheath of the box 82, the sheathed bundle now bending around the capstan 
85 between boxes 81 and 82. The funnel in the tail end of the box 82 at 
this stage prevents actual contact between the adjacent butt ends, but 
this can be removed (being split) once the vacuum is lifted from the box 
82 and the sheath therein returns to its original, unexpanded condition 
wherein it grips the tube bundle, as before. 
This process is repeated for the other two boxes 83, 84 until all of the 
sheaths are in abutting relationship when they may be adhesively secured 
together at their butt ends. 
The finished assembly is then wrapped in a protective cover in the normal 
way. 
The tube bundle is, as illustrated, assembled continuously with the 
sheathing thereof according to the invention. Individual tubes 11 are 
withdrawn from a creel or drum support arrangement 101 (FIGS. 3 and 8) 
through a collecting guide comb 102 and a bundle forming die 103 and from 
there pass to a cling-film wrapping machine 104 (of conventional type). 
The wrapped bundle is fed from there into the box 15 (or the first box 81, 
FIG. 8) by a caterpillar track-like belt feeder 105. 
Referring now to FIG. 10 means are somewhat schematically shown for 
pressurizing the interior of a sheath 110 to expand its inside diameter. 
An extended length of a sheath 110, perhaps 50 meters or more, is laid in a 
gutter-type support 111 or other similar support. A forward end of the 
sheath 110 is pneumatically sealed by a suitable tie-off or clamp 112. 
A pig 114 is provided on the lead end of the tube bundle 113 to smooth the 
passage of the cut end of the bundle 113 through the sheath 110. Without 
such streamlining the square-cut ends of the outer tubes of the bundle 113 
would tend to snag on the inside of the foam of the sheath 110. The 
construction of the pig 114 may be quite simple, as for example a wrapping 
of tape around the end of the bundle 113 to cover the sharp edges of the 
outer tubes. Alternatively the pig 114A could be a separate bullet-shaped 
part of plastic or metal suitably affixed to the end of the bundle, such 
as the pig 29. In any case the pig 114A is preferably of slightly larger 
diameter than the outside diameter of the bundle 113 as shown in FIG. 10. 
Not only does it guide the passage of the end of the bundle through the 
sheath but it may also serve as means for pneumatically sealing off the 
exposed tube ends. Also the pig 114 may itself form a pneumatic seal 
forward of the entry end portion of the bundle to supplement or even 
replace the clamp 112. 
A disc ring 115 is slipped over that lead end of the tube bundle 113 and 
the inside diameter of the ring 115 fits snugly enough about the tube 
bundle 113 to create a pneumatic seal but without preventing longitudinal 
displacement of the tube bundle 113 with respect to the ring 115. A collar 
116 is then loosely fitted about the lead end of the tube bundle 113 and 
by a flange 117 it is abutted against the ring 115. The collar 116 and 
ring 115 are then secured together by fastening means 118 so that a 
pneumatic seal is created between them. 
The pig 114 and the lead end of the tube bundle 113 are then forcibly 
inserted a short distance longitudinally into an entry end portion of the 
sheath 110 opposite the forward portion which is sealed by the clamp 112. 
The outside diameter of the collar 116 is sufficient to expand the end of 
the sheath 110, which is then wrapped about tightly by wire 119 or the 
like to create a seal between the collar and the tube bundle end. The 
inside diameter of the collar 116 is sufficiently large to create a 
clearance with respect to the tube bundle 113. By means of a suitable 
pressure line 120 extending through the collar 116 the interior of the 
sheath 110 is pressurized to expand its inside diameter slightly, creating 
a similar clearance about the pig 114 and the tube bundle 113. 
The tube bundle 113 is then pushed longitudinally into the expanded sheath 
110 from the entry end portion thereof to the forward portion thereof 
without substantial resistance from sliding contact with the expanded 
inside surface of the sheath 110. Pushing may be accomplished by drive 
rollers 121 and 122 or similar means. The pneumatic seal at the forward 
end of the sheath 110 may, if desired, be made at a sequence of points 
along the length of the sheath 110 as the lead end of the tube bundle 113 
advances so that the length of the sheath requiring expansion by 
pressurization is kept to a minimum. When the lead end of the tube bundle 
113 reaches the extreme forward end of the sheath 110 the pressure on the 
inside of the sheath is relieved so that its inside surface contracts into 
a close fit about the tube bundle. The short length of the sheath 110 
which remains after the clamp 112 is removed is simply cut off and 
discarded. The pig 114 covering the exposed ends of the tubes at the lead 
end 114 thereof is removed and the ring 115 and the collar 116 are slipped 
off the opposite end of the tube bundle 113. 
FIG. 11 somewhat schematically illustrates another form of inserting into a 
sheath 130 a tube bundle 131. As in the FIG. 10 embodiment a ring 132 and 
a collar 133 with a flange 134 are fitted about a lead end of the bundle 
of tubes and by a wrapping of wire 135 the end of the sheath 130 is 
secured to the outside of the collar 133. This creates a pneumatic seal at 
the entry end portion of the sheath 130 around the bundle of tubes 131 
without preventing longitudinal displacement of the bundle of tubes. A 
pressure line 136 is again provided. 
A pig 137 is affixed to a lead end of the tube bundle 131 and a haul liine 
138 is attached to the pig 137 and directed longitudinally through the 
sheath from its entry end portion to a forward end portion. At the forward 
end portion a ferrule 139 is inserted in the sheath 130 and with a 
wrapping of wire 140 around the end of the sheath a pneumatic seal is 
created between the inside of the sheath and a flange 141 on the ferrule 
139. The haul lilne 138 extends through a close-fitting hole in the center 
of the ferrule 139 in a pneumatic sealing relationship but without 
preventing longitudinal displacement of the haul line. 
The inside of the sheath is then pressurized through the pressure line 136 
to expand and create a slight clearance around the pig 137. The haul line 
is then pulled from the forward end portion of the expanded sheath and the 
bundle of tubes is thereby drawn through the length of the sheath 130 
without substantial resistance from sliding contact with the expanded 
inside surface of the sheath. The pressure on the inside of the sheath 130 
is then relieved so that its inside surface contracts into a close fit 
about the bundle of tubes. The pneumatic seals are removed at both ends, 
the pig is detached from the lead end of the tube bundle and the assembly 
of the collar 133 and ring 132 are removed. 
It is to be understood that none of the pneumatic seals in any of the 
foregoing embodiments need not be perfect. Some leakage of air can easily 
be tolerated so long as the means for pressurizing or suctioning can still 
create a pressure differential great enough to expand the inside diameter 
of the sheath to the slight degree needed to eliminate substantial 
resistance to movement of the tube bundle. 
Other modifications and variations of these embodiments will be apparent to 
those skilled in the art and may be made without departing from the scope 
of the present invention as defined in the following claims.