Note: Descriptions are shown in the official language in which they were submitted.
CA 02329493 2001-O1-09
1
METHOD AND SYSTEM FOR CREATING AND MAINTAINING A FROZEN
SURFACE
This application is a division of Canadian patent application File No.
2,216,341 filed September 24, 1997.
Field of the Invention
This invention relates to a method of manufacturing a tube. This invention
also relates to a system for creating and maintaining a frozen surface, for
example, for
recreational exhibitions and athletic competitions at an ice skating rink. In
particular,
this invention relates to a system for efficiently conveying a coolant through
a medium
to be frozen. This invention also relates to a system that lends itself to
facilitate
installation and maintenance.
Background of the Invention
The earliest ice skating rinks were frozen ponds or lakes. Such ice sport
venues had the sizeable limitation that their existence was entirely dependent
upon the
temperature of the environment. For a long time, the dependency upon naturally-
formed ice restricted the enjoyment of ice sports in most countries to a
limited seasonal
period.
In the late nineteenth century, indoor ice skating rinks were designed to
provide venues on which ice sports could be enjoyed in most countries year
round.
These early indoor ice skating rinks used a system of steel or iron pipes to
carry an
artificially-cooled refrigerant, such as calcium chloride brine, under a tank
of water to
create a frozen surface capable of being skated upon. The steel. or iron pipes
were
embedded in concrete or sand beneath the tank and had an inner diameter of 1
to 1-1/2
inches with 4 inches between the centers.
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While capable of providing a frozen surface which could be skated upon indoors
year-round, the steel or iron pipe construction had its drawbacks. Perhaps,
one of the greatest
limitations on the steel or iron constructions was the surface area that these
systems provided for
heat exchange with the medium to be frozen, also known as the dynamic surface
area. In the steel
S or iron constructions, as structurally and dimensionally described above,
the dynamic surface area
was substantially less than the area of the skating surface available for heat
exchange with the
environment. The dynamic surface area of the steel or iron constructions is
estimated to be at
most 82% of the skating surface area.
More recently, ice skating rink systems have been constructed using smaller
diameter plastic tubing, such as those systems described in U.S. Patent Nos.
3,751,935;
3,893,507; and 3,910,059. In operation, a main supply pipe, o: header, feeds
into a plurality of
supply subheaders, each of which in turn is attached to the proximal ends of a
plurality of coolant
tubes. The plurality of coolant tubes can be fastened at their distal ends to
one end of a plurality
of U-shaped connectors, which in turn are fastened to a second plurality of
coolant tubes. The
1 S second plurality of coolant tubes is attached at their proximal ends to a
plurality of return
subheaders, which in turn feed into a main return header. The inner diameter
of the coolant tubes
used in these plastic constructions generally varies from 1/4 to 1/2 inches.
By using a smaller
center spacing between smaller tubes, these plastic systems may provide a
larger dynamic surface
area than the steel or iron constructions.
However, the dynamic surface area is only one factor influencing the overall
efficiency of a system designed to create and maintain a frozen surface. As
important to the
e~ciency of the system as the dynamic surface area is the ability of the
coolant to flow through
the system without significant pressure loss or flow interruption. As a
consequence, even though
the plastic systems may have improved the dynamic surface area over the iron
and steel
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constructions, the efficiency of these plastic systems is often significantly
compromised in practice
by unsatisfactory coolant flow characteristics at various points in the
system.
For example, as shown in Figs. 1 and 2 herein, one common area for flow
restriction to occur is at the transfer point between a subheader 30 and a
coolant tube 32. In the
conventional construction shown in Figs. 1 and 2, the subheader 30 has an
opening 34, through
which is disposed a connection fitting 36. The connection fitting 36 is
soldered into place with
the proximate end of the fitting 36 occluding as much as 25 percent of the
interior cross-sectional
area ofthe subheader 30. This occlusion can cause a layer 38 of coolant to
build up against the
fitting 36, and seriously degrade the flow characteristics of the coolant in
the area adjoining the
I 0 transfer point.
Moreover, at the distal end of the tube 32, where the tube 32 attaches to a U-
shaped connector 40, the conventional methods of construction can cause
additional flow
restriction problems. One flow restriction problem commonly occurring in
conventional
constructions is illustrated in Figs. 3 and 4. The U-shaped connector 40 shown
is fabricated by
15 bending a copper tube having an internal diameter similar to that of the
coolant tube 32. By using
this method of fabrication, the resulting inner diameter at a bight 42 of the
U-shaped connector
40 may be reduced to approximately half the diameter of the criginal copper
tube. The dramatic
decrease in the inner diameter of the U-shaped connector 40 at the bight 42
has a proportionally
dramatic effect on the fluid flow throughout the system.
20 Additionally, loss of flow pressure can result from the present methods of
system
construction used to join the coolant tubes 32 with the U-shaped connectors
40. The coolant
tubes 32 are fastened directly to the U-shaped connectors 40 by means of glue
and a circular
clamp or an eyelet, as shown in Figs. 3 and 4. As a consequence, the tubes 32
have a tendency
to leak, or even pop off of the U-shaped connector 40, spilling coolant
directly into the medium
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to be frozen and underlying foundational material and decreasing the pressure
and flow rate at
which the coolant is being transported throughout the system.
Furthermore, these plastic systems are often constructed using a type of
plastic
coolant tube having unfavorable performance characteristics. Commonly,
polyethylene or
polypropylene tubing is used for the coolant tubes in plastic ice skating rink
systems. During
manufacture, the polyethylene or polypropylene tubing is usually extruded, and
then passed
through a standard length (10-14 foot) cooling tank before being machine-
coiled on to spools for
delivery. As a consequence of this method of fabrication, the polyethylene or
polypropylene
tubing thermally sets with a curved, rather than a straight, structure in the
memory of the plastic.
l0 Therefore, when the tubing is uncoiled to be used in the plastic
construction illustrated in the
patents mentioned above, the tubing does not naturally lay straight and flat,
but takes on a
serpentine structure in at least one plane.
As a further consequence, when these polyethylene or polypropylene ice rink
systems are installed, the coolant tubing will commonly force its way under
pressure to the skating
1 ~ surface, and protn~de from the surface of the ice, providing a substantial
obstacle and hazard for
persons, for example skaters, using the frozen surface. It is therefore
necessary to resubmerge
the tubing under the surface of the ice through a method known as "burning
in". The tubing is
"burned" into the surface of the ice by melting the surrounding ice, and then
holding the tube in
place under pressure until the ice reforms around the problematic section of
tubing. Because of
20 the pressure of the coolant running through the tubing, as well as the
thermally-set disposition of
the tubing to return to the serpentine structure, it may be necessary to
repeat the "burning in"
process a number of times each season to maintain a skating surface free from
obstructions and
to prevent damage to the tubing.
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However, polyethylene and polypropylene tubing is sensitive to repeated
bending.
Repeated bending of the polyethylene or polypropylene tubing has been known to
cause
permanent damage to the tubing, and can result in the cracking or rupture of
the tubing with a
concomitant loss of coolant pressure in the system.
5 Summary of the Invention
According to an aspect of the present invention, a method of manufacturing a
tube
includes the steps of preparing a composition using ethylene vinyl acetate,
extruding the
composition to form a tube, and cooling the tube with the tube in a
substantially straight
configuration so that the tube is substantially set in a substantially
straight configuration.
According to another aspect of the present invention, a system for creating a
frozen surface on a medium includes a mechanism for exchanging thermal energy
between a
medium and a coolant, a mechanism for removing thermal energy from a coolant,
and a
mechanism for transporting a coolant between the mechanism for exchanging
thermal energy
between a medium and a coolant and the mechanism for removing thermal energy
from a coolant.
The mechanism for transporting a coolant includes first and second pipes and a
mechanism for
releasable connecting the first pipe to the second pipe so as to prevent the
first pipe from moving
axially relative to the second pipe in a first operational state, and to allow
the first pipe to be
moved axially relative to the second pipe in a second operational state.
According to a further aspect of the present invention, a system for creating
and
maintaining a frozen surface on a medium includes a mechanism for exchanging
thermal energy
between a medium and a coolant, the mechanism for exchanging thermal energy
between a
medium and a coolant having a substantially uniform cross-sectional area for
passing a coolant
therethrough. The system also includes a mechanism for removing thermal energy
from a coolant.
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The system further includes a mechanism for transporting a coolant between the
mechanism for
exchanging thermal energy between a medium and a coolant and the mechanism for
removing
thermal energy from a coolant. The mechanism for transporting a coolant is
connected to the
mechanism for exchanging thermal energy between a medium and a coolant so that
substantially
all of a coolant flowing from the mechanism for transporting a coolant to the
mechanism for
exchanging thermal energy between a medium and a coolant flows directly from
the mechanism
for transporting a coolant into the mechanism for exchanging thermal energy
between a medium
and a coolant.
Brief Description of the Drawings
Figs. 1 is a partial cross-sectional view of a portion of a prior art
subheader
showing in detail the transfer point between the subheader and a coolant tube;
Fig. 2 is a partial cross-sectional view of the transfer point between the
subheader
and the coolant tube taken about line 2-2 in Fig. 1;
Fig. 3 is a partial cross-sectional view of a prior art U-shaped connector
showing
in detail the connection of the U-shaped connector and a coolant tube;
Fig. 4 is a partial cross-sectional view of the connection of the U-shaped
connector
and the coolant tube taken about line 4-4 in Fig. 3;
Fig. 5 is an overall plan view of an ice skating rink including an embodiment
of the
present invention for creating and maintaining a frozen surface;
Fig. 6 is an enlarged, partial cross-sectional view of an insulation blanket
or layer
which is useful for insulating below the system shown in Fig. 5;
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Fig. 7 is an enlarged plan view showing in detail an embodiment of a panel for
use
in the embodiment shown in Fig. 5, and the interconnection of the panel with
supply and return
headers;
Fig. 8 is an enlarged plan view showing in detail another embodiment of a
panel
for use in the embodiment shown in Fig. S in particular at the curved ends of
the ice skating rink,
and the interconnection of the panel with supply and return headers;
Fig. 9 is an overall plan view of an ice skating rink including another
embodiment
the present invention for creating and maintaining a frozen surface with the
spacers and spacing
bars removed;
Fig. 10 is an enlarged plan view of an embodiment of a spline-connector used
to
connect two adjoining pipes in the header in the embodiment shown in Fig. 5,
the spline-connector
including a releasably attachable female coupling connected to a flexible hose
element;
Fig. 11 is an enlarged plan view of another embodiment of a spline-connector
for
use in the embodiment shown in Fig. 5, the spline-connector including a
releasably attachable
I ~ coupling connected to a fixed coupling attached directly to the spline-
connector;
Fig. 12 is an enlarged plan view of still another embodiment of a spline-
connector
for use in the embodiment shown in Fig. 5, the spline-connector including a
valve connected
between a releasably attachable coupling and a fixed coupling attached
directly to the spline-
connector;
Fig. 13 is an enlarged, partial cross-sectional view of a flexible hose used
to
connect a spline-connector with either a supply or a return subheader;
Fig. 14 is an enlarged, partial cross-sectional view of any of the embodiments
of
a spline-connector shown in Figs. 10, I l, and 12 showing in detail a first
and a second locking
mechanism used to prevent relative movement between the spline-connector and a
header pipe;
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Fig. 15 is a partial cross-sectional view of an embodiment of the present
invention
showing in detail a transfer point at the intersection of a subheader with a
coolant tube;
Fig. 16 is a partial cross-sectional view of the transfer point at the
intersection of
the subheader and the coolant tube taken about the line 16-16 in Fig. 15;
Fig. 17 is a cross-sectional view of an embodiment of the present invention
showing in detail a U-shaped connector;
Fig. 18 is a cross-sectional view of the U-shaped connector taken about line
18-18
in Fig. 17;
Fig. 19 is a partial cross-sectional view of the U-shaped connector of Figs.
17 and
18, showing in detail the interconnection of the U-shaped connector and a
coolant tube; and
Fig. 20 is a cross-sectional view of the U-shaped connector and the coolant
tube
taken about the line 20-20 in Fig. 19.
Description of the Preferred Embodiments
In general terms, the system of the present invention creates and maintains a
frozen
surface, such as ice, by removing thermal energy from a liquid medium, such as
water, and
exhausting the thermal energy at a location remote to the medium to be frozen.
Specifically with
reference to Fig. S, pressurized, chilled coolant passes through a plurality
of tubes spaced within
a tank or container 46 holding the medium to be frozen. As the coolant passes
through the
plurality of tubes, thermal energy is transferred from the medium to the
coolant through the walls
of the tubes. The coolant then passes from the tubes to a pump 54, and from
the pump 54 to a
refrigeration unit 70. The refrigeration unit 70 extracts the thermal energy
from the coolant and
returns the chilled coolant to the collection tank 68, whereupon the cycle is
repeated.
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According to an embodiment of the present invention, a system 44 for creating
and
maintaining a frozen surface is shown in Fig. 5. The system 44 in Fig. 5 is
shown fitted in a tank
or rink 46. The rink system 44 includes a main supply header 48, a main return
header 50, and
a plurality of panels 52. Unlike the constructions discussed above, the panels
52 used in the
embodiments of the present invention discussed herein are placed within the
medium to be frozen,
rather than being embedded in or placed underneath inches of sand or concrete
beneath the rink
46, although such a configuration is possible using the present invention. As
a consequence of
the direct thermal energy exchange relationship between the coolant in the
panels 52 and the
medium to be frozen, the efficiency of the system 44 is improved as a whole as
it is unnecessary
to first cool the floor of the tank 46 prior to cooling the medium to be
frozen.
To preserve the advantages of this direct thermal energy exchange relationship
by
preventing thermal energy from entering the tank from surface below the tank
46, an insulation
layer or blanket 53, as shown in Fig. 6, is placed beneath the panels 52. The
insulation layer 53
is fabricated in a sandwich constriction in which two layers of bubble
packaging material 53a are
laid face to face such that the bubbles of one layer fit within the dimples of
the other layer. The
two layers 53a are then covered on the externally facing surfaces 53b, 53c
with a layer 53d of foil
on the surface 53b, and a layer 53e of foil, or polyethylene, on the surface
53c. During
installation, the layer 53d is placed against the surface below the tank 46,
while the layer 53e faces
and is covered by the medium to be frozen.
A pump 54 is connected at an outlet 56 to the main supply header 48 via the
refrigeration system 70 and the collection tank 68, and forces a coolant, for
example, a mixture
of either ethylene glycol or propylene gylcol and water, into the main supply
header 48 under
pressure. Under most conditions, the coolant is, for example, a mixture of
either ethylene glycol
or propylene glycol and water in a ratio of 45:55. If the system 44 is
intended for use in a
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environment where the temperature of the surrounding environment is less than -
20 degrees F,
the coolant is, for example, a mixture of either ethylene glycol or propylene
glycol and water in
a ratio of 55:45. The coolant passes from the main supply header 48 and into
the individual
panels 52.
5 Each panel 52, generally indicated in Fig. S and shown in greater detail in
Figs. 7
and 8, is four feet wide and 100 feet long, and includes a supply subheader
58, a return subheader
60, first and second plurality of tubes 62, 64, and a plurality of U-shaped
connectors 66. The
pressurized coolant flows from the main header 48 into the supply subheader
58, which feeds into
the first plurality of tubes 62. As the coolant flows through the medium,
thermal energy is
10 transferred from the medium to the coolant through the walls of the tubes
62. The coolant then
passes through the plurality of U-shaped connectors 66 and into the second
plurality of tubes 64.
As the coolant flows through the medium for a second time, additional thermal
energy is
transferred from the medium to the coolant.
The coolant feeds from the plurality of tubes 64 to the return subheaders 60,
which
are connected to the return header 50. The coolant is transported along the
return header SO to
the pump 54, from which the coolant returns to the refrigeration system 70.
The refrigeration
system 70 extracts the thermal energy from the coolant, and exhausts the
thermal energy to the
environment. The chilled coolant is then returned to the collection tank 68,
for example a 15
gallon tank, to be re-introduced into the main header 48.
Alternatively, the system 44 may be configured to accommodate placement of the
refi-igeration system 70 and pump 54 at the center of the rink 46. As shown in
Fig. 9, with like
numbers used for like elements, a central supply header 72 is connected
through the refrigeration
system 70 and a collection tank 68 to the pump 54, branching off at a first T-
joint 74 to form two
main supply headers 48, one for each half of the rink 46. The supply headers
48 each feed into
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a plurality of subheaders 58, which in turn feed into a plurality of panels 52
in a direct thermal
energy transfer relationship with the medium to be frozen. The coolant returns
to the refrigeration
system 70 via a system of return subheaders 60 and return headers 50. The
return headers 50
are connected at a second T joint 76 to form a main return header 78, which
feeds directly into
the pump 54.
Because the system 44 can be assembled to accommodate rinks of different
widths
and lengths by adding additional panels 52, the requirements for the pump size
and the pressure
and flow rate of coolant (expressed as gallons per unit of time) will
necessarily differ according
to the exact dimensions of the assembled system 44. The coolant has an inlet
temperature (as
measured at the inlet of the supply header 48) of 18-20 degrees F, and an
outlet temperature (as
measured at the inlet of the pump 54) of 20-24 degrees F. It has been found
experimentally that
to provide a uniform thermal energy transfer, or thermal energy extraction,
from the medium to
be frozen, the velocity of the coolant in the system 44 should be at least 1
foot/second.
In an embodiment of the present invention, wherein the rink system 44 may be
1 S assembled and disassembled, for example at the end of a seasonal period or
after an athletic
competition or exhibition, the supply header 48 and the return header 50 are
made from lengths
of pipe 80, for example, enhanced PVC pipe (type 1, grade 1, 2000 psi
hydrostatic stress material,
in accordance with ASTMD1784) with an inner diameter of between 2 to 6 inches,
for example
4 inches, joined together at spaced intervals by connectors 82, 84, also
fabricated from enhanced
PVC schedule 80 pipe. The lengths of pipe 80 are joined together at four foot
inten~als to
coincide with the four foot width of the panels 52.
The connector 82, as shown in Figs. 10, 11 and 12, is used in the main supply
header 48 and the first section of the mam return header 50 upstream to the U-
shaped joint 86 in
the system 44 shown in Fig. 5, and U-shaped joints 88 and 90 in the system 44
shown in Fig. 9.
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The connector 82 is also designed to connect the main supply header 48 and the
main return
header 50 to the supply subheaders 58 and the return subheaders 60.
The connector 82 may include a pipe section 92, a flexible hose 94, a fixed
coupling 96 and either a male or female coupling 98. An opening 100 is
machined in the pipe
section 92 at half the distance from the ends. The opening 100 is then tapped
to accept the
threads of the fixed coupling 96. The pipe section 92 and the fixed coupling
96 are screwed
together until the pipe section 92 and the fixed coupling 96 mate securely.
A first, proximate end of the flexible hose 94, which has an inner diameter of
one
inch and is manufactured as shown in Fig. 13 with a helical steel spring 102
embedded within the
wall of the hose 94, is then placed over a portion of the distal end of the
fixed coupling 96 and
secured using a circular clamp, for example, a stainless steel clamp. The
second, distal end of the
flexible hose 94 is then placed over a portion of the proximate end of the
attachable coupling 98
and secured using a circular clamp, also a stainless steel clamp. The
attachable coupling 98 allows
the connector 82 to be connected to a mating male or female coupling 99
attached at the ends of
the subheaders 58, 60.
Alternatively, the attachable coupling 98 is attached directly to the fixed
coupling
96 of the supply header 48, while a mating male or female coupling 99 is
attached via a flexible
hose 94 to the supply subheader 58 and return subheader 60 corresponding to
the giver, panel 52,
as shown in Fig. 8. The mating couplings 99 are alternated between the supply
and return
subheaders 58, 60 for a given panel 52, i.e., each of the supply subheaders 58
may have a male
coupling 99, while the return subheaders 60 may have a female coupling 99. In
this fashion, when
the system 44 is to be disassembled to be transported or stored, the coolant
in the panel 52 can
be isolated in the panel 52 by attaching the male coupling 99 of the supply
subheader 58 to the
female coupling 99 of the return subheader 60.
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111=1.00002
Moreover, the panels 52 may be isolated in operation as well as in storage by
disposing a valve 104, for example, a brass or stainless steel ball valve,
between the fixed coupling
96 and the attachable coupling 98 on the spline-connector 82, as shown in
Figs. 7 and 12. By
connecting the valves 104 to the supply and return header connectors 82, the
coolant in a panel
52 may be isolated by closing the valves 104.
By way of example only, isolation of the panel 52 could be advantageous should
one of the coolant tubes 62, 64 of a panel 52 rupture. Isolation could prevent
loss of the coolant
into the medium to be frozen and the underlying foundational material, prevent
loss of pressure
throughout the system 44, and otherwise allow the repair of the panel 52 with
the ruptured tube
62 or 64 to be performed while maintaining the frozen surface on the portions
of the rr~edium
unaf-F~cted by the loss of coolant flew through the isolated panel 52.
Additionally, again by way of example only, isolation of the panels 52 could
be
advantageous during the freezing of the medium. Specifically, the panels 52
could be isolated so
that the medi:am is frozen in stages, panel by panel, until all of the medium
in the rink 46 is frozen
Such a staged process could be especially advantageous when attempting to
freeze a medium
when the temperature of the surrounding environment is substantially greater
than the temperature
at which the medium will freeze.
Fig. 14 shows the locking mechanisms used in any of the embodiments of the
connectors 82 shown in Figs. 10, 11 and 12. Particularly, each end of the
connector 82 is
machined to include a shoulder 110, an interior o-ring groove 112 and an
interior spline groove
114. Similarly, e<~ch end ofthe pipe 80 is machined to have an exterior spline
groove 116, which
corresponds axially with the interior spline groove 114 of the connector 82
when the end 118 of
the pipe 80 abuts the shoulder 110 of the connector 82
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In operation, an O-ring 108 is first placed in the interior O-ring groove 112.
The
pipe 80 is then placed into the connector 82 until the end 118 abuts the
shoulder 110. The o-ring
108 and the exterior surface of the pipe 80 thus forms a first sealing and
locking mechanism 12G
preventing relative movement of the pipe 80 and the connector 82 in the axial
direction. A second
locking mechanism 122 is formed when the spline 106 is placed through a hole
124, the hole 124
being connected through the wall of the connector 82 to the interior spline
groove 114. The
spline 106 fills the channel formed by the corresponding interior and exterior
spline grooves 114,
I 16, also preventing the relative movement of the pipe 8U and the connector
82 in the aria:
direction.
1 ~~ A further embodiment of the spline-connector, designated 84 in Figs. S,
7, 8, and
9, is used to couple the pipes 80 used in the second section of the main
return header S0. Because
the connectors 84 are not intended to be connected to the return subheaders
60, the connectors
84 are not manufactured with the opening 100 into which the fixed coupling 96
can be screwed.
The connectors 84, like the connectors 82, however, do feature both the first
and second locking
1 S mechanisms 120, 122.
As shown in Figs. 7 and 8, the panel S2 is defined by of the supply subheader
S8,
the return subheader 60, the first and second plurality of tubes 62,, 64 and
the plurality of U-
shaped sections 66. As further illustrated in Figs. 1 S and 16, the supply and
return subl:eaders
62, 64, fabricated from copper pipe, are machined with plurality of operungs
126. A barbed
20 saddle fitting 128, for example a copper fitting, is soldered over each
opening 126, using a silver
based solder. Use of the saddle fitting 128 is advantageous in that there is
limited obstruction of
the fluid flowing from the subheader S8, 60 into the tubes 62, 64 and the
subheaders .58, 60 have
a substantially uniform cross-sectional area. One end of one of the tubes 62,
64 is fitted over the
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barbed end 130 of saddle fitting I28 and fastened with a circular clamp. The
use of barbed ends
allows a secure attachment between the tubes 62, 64 and the subheader 58, 60
to be formed.
The tubes 62, 64 are made with a 1/2 inch inner diameter from a composition
prepared using ethylene vinyl acetate (EVA), for example, from a composition
prepared using
18% by weight of EVA combined with 82°ro by weight of polyethylene. The
percentage of EVA
may vary from between 15-25% by weight, while the polyethylene may vary from
between 75-
85% by weight. During manufacture, the composition is extruded to form the
tubes and is passed
through a cooling tank at a rate of 1 foot per second. Unlike the conventional
methods for
mmufacturing the polyethylene or polypropylene tubing described above, the
EVA/polyethylene
In tubes are passed through a cooling tank or tanks for a distance of between
25 and 36 feet with
the tubes in a si~bstantiaily straight configuration. The tubes may be cooled
by spraying the tubes
with water in the cooling tank or tacks, or by passing the tubes through a
water bath maintained
in the cooling ra,k or tanks. It is thought that the time spent by the tubes
in the cooling tank or
tanks allows the EVA/polyethylene tubes to thermally-set in a substantially
straight configuration.
;5 The extruded, cooled product, having a final inner diameter of 1/2 inch, is
then hand-coiled with
the e~c~ctive diameter of the coil being no less than 2.5 feet, and placed
into a gaylord container
for shipping. The tubes are fabricated in lengths of between 515 to 520 feet.
ThP tubes 62, 64 are joined in pairs, the proximate end of the tube 62
attached to
the supply subheader 58 and the proximate end of the tube 64 to the return
subheader 60.
'.l.t) Similarly, the distal ends of the pair of tubes 62. 64 are connected to
one of the ends of the
plurality of U-shaped connectors 66.
As illustrated in Figs. 17 and 18, each U-shaped connector 66 has a U-shaped
section 132 and a pair of barbed fittings 134. The U-shaped section 132 and
the barbed fittings
134 are made of copper. The distal ends i 36 of the barbed fittings 134 are
placed inside of ends
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t 6 ;PATENT
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I38 of the U-shaped section 132 and soldered in place using a silver based
solder. As shown in
Figs. 19 and 20, one of the distal ends of tubes 62, 64 is then placed over
each of the barbed,
proximate ends 140 of the barbed fitting 134, and fastened into place using a
circular clamp 139,
The U-shaped section 132 is of a constant inner diameter, for example, of
nearly
equal diameter to the tubes 62, 64 arid thus provides a substantially
continuous and substantially
uniform cross-sectional area through which the coolant medium can pass.
Furtheumore, the
barbed ends 140 of the fitting 134 provide for a secure attachment sae to
attach the ends of the
tubes 62, 64 to the U-shaped connector 66.
A uniform spacing between the cznters of the tubs 62, 64 is achieved in part
by
3 Cr welding a bar 142, for example, a brass bar of hexagonal or rectangular
cross-section, to the U-
shaped bend in each of the U-shaped connectors 66 that rr~a?~e up the panel
52. r~s shown in Figs.
7 and 8, the bar 142 can be straight or curved to keep the proper spacing
between tubes 62, 64
even in the rounded corners of the ice r-inic 46. In addition, spacers 144,
for example, made of
polyethylene, are placed at intervals along the tubes 62, 64 to maintain the
spacing between the
tubes 62, 64 and the spacing between the tubes 62, 64 and the surface over
which the system 44
is installed. The spacing between the centers of the tubes 62, 64 is between 1
and 1-1/2 inches,
while the spacing between the spacers 144 is approximately 14 inc);es.
The spacers 144 may either be removable or nor;-removable. If the spacers 144
are non-removable, i.e. enclose the entire circumference of the tubes 62, 64,
then it is preferable
%0 to place the tubes 62, 64 through the spacers 144 before attaching the
tubes 62, 64 to the barbed
saddle fittings 128 of the supply and return subheaders 58, 60. If flue
spacers are removable, i.e.
may be snapped around the tubes 62, 64, the spacers may be attached to the
tubes 62, 64 after
the tubes 62, 64 are connected to the respective supply and return subhezders
58, 60.
CA 02329493 2001-O1-09
1'7 >u'ATENT
11 I4.CCCu2
Still other aspects, objects, and advantages of the present invention can be
obtained
from a study of the specification, the drawings, and the appended claims.
