Note: Descriptions are shown in the official language in which they were submitted.
CANADA
TITLE: FIRE-RATED VENTILATION DUCT AND IMPROVEMENTS THEREIN
FIELD OF THE INVENTION
[0001] The present invention relates to duct systems and more
particularly, to a fire-
rated ventilation duct system.
BACKGROUND OF THE INVENTION
[0002] Various regulatory regimes require that buildings be designed
and
constructed to provide safe means of egress to enable the occupants to safely
exit the
building in case of fire. Typically, this involves constructing floors and
walls in a building
which are fire-rated and designed to prevent fire from spreading from one
area,
compartment, or floor, to another. To ensure the designated egress routes such
as
stairways are passable, fresh air is supplied to egress routes, so they are
maintained
under positive pressure, and contaminated air is exhausted from fire
compartments.
Such an arrangement is designed to prevent the contaminated air from migrating
from
the engaged fire compartment to the egress routes and/or other sections of the
building.
[0003] In addition to ventilating the egress routes in a building, new
buildings may
be designed to utilize the fire rated ventilation ducts for the handling of
other types of
non-hazardous exhaust that pass through the interior sections and fire
separations in
the building before being exhausted outdoors. For instance, commercial kitchen
dishwasher exhaust and swimming pool exhaust are two examples of exhaust
systems
that contain high moisture and mildly corrosive elements that benefit from the
elimination of required fire dampers, and the associated costs for the
inspection and
maintenance of the fire dampers, in these types of duct systems.
[0004] To protect these ducts so they can continue to function when
exposed to
fire, building codes typically require a shaft type construction that is
configured to
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enclose the duct and the duct supports. Shaft type construction typically
requires
multiple layers of gypsum board to be installed to metal framing members. Such
installations typically require considerable space around the duct to
accommodate the
multiple layers of gypsum board. In addition, to the requirements for
installation, there
are limitations on the maximum span which limits the enclosable duct size, and
the
resultant fire ratings are typically limited to a 2-hour fire rating when
enclosing
horizontal ducts.
[0005] In
the art, there are also known fire-rated wrap systems that utilize ceramic
insulation. Such systems typically involve wrapping installed ventilation
systems
fabricated from sheet metal with one or two layers of ceramic insulation
blankets that
are enclosed in a foil scrim outer layer. Most systems require the end of each
insulation
wrap to be overlapped by the next wrap section along the duct's length and
sealed with
foil backed tape in order to create a seal. Typically, the end of each wrap
around the
duct typically overlaps the starting end of the wrap so there are no butt
seams in the
system, with the ends once again sealed with foil backed tape. Stainless steel
bands
are then wrapped and clamped around the outer insulation layer to hold the
insulation
in place during a fire.
[0006]
While the outer foil scrim layer construction can be effective to provide the
required fire resistance rating, the foil scrim layer is easily susceptible to
physical
damage. As a result, local regulatory regimes and/or building codes require
that the
"wrapped" systems also be encased or enclosed with an outer sheet metal casing
to
prevent damage to the foil scrim layer to thereby avoid reducing the fire-
rating or fire
resistance rating of the system.
[0007] It
will be appreciated that "wrap type" fire-rated duct systems suffer from a
number of drawbacks including:
(1) the need for coordination of multiple trades, and possible return
visits by
some early scheduled trades, to properly install the various components
comprising a complete system. This substantially increases the wrap
system's installed cost and can also result in project delays.
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(2) the inability to ensure all aspects of the system have been correctly
installed per the manufacturer's and listing requirements due to the
multiple insulation layers required and the additional outer sheet metal
enclosure. Improper installation could result in a system offering little or
no fire protection.
(3) the increased outer dimension and/or weight of the completed system
due to the thickness of the insulation wrap material and the multiple
required overlaps at the insulation blanket seams.
(4) the difficulty in installing and supporting the outer sheet metal
casing
around the insulated duct system due to the multiple overlaps required in
the insulation wrap system which gives rise to uneven surfaces that must
be enclosed.
[0008] In
the art, there are also known fire-rated duct systems that utilize rigid fire-
resistant insulating boards as cladding to make the duct systems fire
resistant. Similar
to ceramic insulation wrap systems, the fire-resistant insulating boards are
installed
after the duct (sheet metal) systems are first installed. Each system and
board
manufacturer typically have its own specific installation requirements.
Typically, the
installation of the board systems involves the placement of spacers, cut from
the same
board material as the outer enclosure, around the duct so that the fire-
resistant
enclosure boards can clear the duct's traverse duct connectors. Installation
of the
enclosure boards often involves applying mastic to the edges of abutting
boards in
order to provide a seal between the boards. This is followed by nailing,
stapling or
otherwise banding the boards together along their longitudinal edges to
prevent them
from separating in a fire. Some known systems also require additional boards
to be
installed over the transverse joints in the system to prevent the passage of
heat though
those joints.
[0009] It
will be appreciated that known "board type" fire-rated duct system also
suffer from a number of drawbacks including:
(1) the need for multiple trade coordination to install the finished
system
which similar to the insulation wrap systems can result in project delays
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(2) the insulating boards are susceptible to damage from physical impact
during installation and/or after installation
(3) certain types, or brands, of insulating boards are not moisture
resistant
and therefore need to be replaced overtime, particularly if exposed to
water or to high levels of moisture for any extended period of time.
[00010] Accordingly, there remains a need for improvements in the art.
BRIEF SUMMARY OF THE INVENTION
[00011] The present invention is directed to a fire-rated ventilation duct
system and
improvements therein.
[00012] According to an embodiment, the present invention comprises a fire-
rated
ventilation duct section comprising: an inner liner configured as conduit for
air
movement, said inner liner comprising a metallic material and having a first
end and a
second end, and said first end including a first connection section, and said
second
end including a second connection section; an outer casing configured for
encasing
said inner liner, said outer casing comprising a metallic material having a
fire-rating,
said outer casing having a first end and a second end, and said first end
including a first
duct connection section configured for joining one end of a second fire-rated
ventilation
duct, and said second end including a second duct connection section
configured for
joining one end of a third fire-rated ventilation duct; an insulation layer
configured to
provide a thermal insulation layer between said inner liner and said outer
casing, and
said first connection section of said inner liner further comprising a first
liner spacer and
said second connection section of said inner liner further comprising a second
liner
spacer, said first and said second liner spacers being configured to define a
cavity for
receiving and positioning said insulation layer between an outer surface of
said inner
liner and an inner surface of said outer casing; said first duct connection
section of said
outer casing being configured to attach to at least a portion of said first
connection
section of said inner liner, and said second duct connection section of said
outer casing
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being configured to attach to at least a portion of said second connection
section of
said inner liner to form a sealed duct section.
1000131 According to another embodiment, the present invention comprises a
fire-
rated ventilation duct assembly comprising: a first duct module, said first
duct module
including, an inner liner configured as conduit for air movement, said inner
liner
comprising a metallic material and having a first end and a second end, and
said first
end including a first connection section, and said second end including a
second
connection section; an outer casing configured for encasing said inner liner,
said outer
casing comprising a metallic material having a fire-rating, said outer casing
having a
first end and a second end, and said first end including a first duct
connection section
and said second end including a second duct connection section, an insulation
layer
configured to provide a thermal insulation layer between said inner liner and
said outer
casing, and said first connection section of said inner liner further
comprising a first liner
spacer and said second connection section of said inner liner further
comprising a
second liner spacer, said first and said second liner spacers being configured
to define
a cavity for receiving and positioning said insulation layer between an outer
surface of
said inner liner and an inner surface of said outer casing; said first duct
connection
section of said outer casing being configured to attach to at least a portion
of said first
connection section of said inner liner, and said second duct connection
section of said
outer casing being configured to attach to at least a portion of said second
connection
section of said inner liner to form a sealed duct section; and a second duct
module,
said second duct module including, an inner liner configured as conduit for
air
movement, said inner liner comprising a metallic material and having a first
end and a
second end, and said first end including a first connection section, and said
second
end including a second connection section; an outer casing configured for
encasing
said inner liner, said outer casing comprising a metallic material having a
fire-rating,
said outer casing having a first end and a second end, and said first end
including a first
duct connection section and said second end including a second duct connection
section, an insulation layer configured to provide a thermal insulation layer
between
said inner liner and said outer casing, and said first connection section of
said inner
liner further comprising a first liner spacer and said second connection
section of said
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inner liner further comprising a second liner spacer, said first and said
second liner
spacers being configured to define a cavity for receiving and positioning said
insulation
layer between an outer surface of said inner liner and an inner surface of
said outer
casing; said first duct connection section of said outer casing being
configured to
attach to at least a portion of said first connection section of said inner
liner, and said
second duct connection section of said outer casing being configured to attach
to at
least a portion of said second connection section of said inner liner to form
a sealed
duct section; and said second duct connection section of said first duct
module being
configured for joining the first duct connection section of said second duct
module, so
that said first duct module and said second duct module are coupled together
to form
said fire-rated ventilation duct assembly.
1000141 According to another embodiment, the present invention comprises a
fire-
rated duct section comprising: an inner liner configured as conduit for air
movement,
said inner liner comprising a metallic material and having a first end and a
second end,
and said first end including a first spacer section, and said second end
including a
second spacer section; an outer casing configured for encasing said inner
liner, said
outer casing comprising a metallic material, said outer casing having a first
end and a
second end, and said first end including a first duct connection section
configured for
joining one end of a second fire-rated ventilation duct, and said second end
including a
second duct connection section configured for joining one end of a third fire-
rated
ventilation duct; an insulation layer configured to provide a thermal
insulation layer
between said inner liner and said outer casing, and said first and said second
spacer
sections being configured to define a cavity for receiving and positioning
said insulation
layer between an outer surface of said inner liner and an inner surface of
said outer
casing; and said first duct connection section of said outer casing being
configured to
attach to at least a portion of said first spacer section of said inner liner,
and said
second duct connection section of said outer casing being configured to attach
to at
least a portion of said second spacer section of said inner liner to form a
sealed duct
section.
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1000151 According to another embodiment, the present invention comprises a
fire-
rated duct assembly comprising: a first duct module, said first duct module
including,
an inner liner configured as a conduit for air movement, said inner liner
comprising a
metallic material having a specified fire-rating, and having a first end and a
second end,
and said first end including a first connection section, and said second end
including a
second connection section; an outer casing configured for encasing said inner
liner,
said outer casing comprising a metallic material having a fire-rating
specification, said
outer casing having a first end and a second end, and said first end including
a first
duct connection section and said second end including a second duct connection
section, said first duct connection section of said outer casing being
configured to
attach to at least a portion of said first connection section of said inner
liner, and said
second duct connection section of said outer casing being configured to attach
to at
least a portion of said second connection section of said inner liner to form
a sealed
duct section; said outer casing comprising a first duct connector at said
first end, and a
second duct connector at said second end, said first duct connector comprising
a
formed section having a J profile, and said second duct connector comprising a
formed
section having a J profile; and a second duct module, said second duct module
including, an inner liner configured as a conduit for air movement, said inner
liner
comprising a metallic material having a specified fire-rating, and having a
first end and a
second end, and said first end including a first connection section, and said
second
end including a second connection section; an outer casing configured for
encasing
said inner liner, said outer casing comprising a metallic material having a
specified fire-
rating, said outer casing having a first end and a second end, and said first
end
including a first duct connection section and said second end including a
second duct
connection section, said first duct connection section of said outer casing
being
configured to attach to at least a portion of said first connection section of
said inner
liner, and said second duct connection section of said outer casing being
configured to
attach to at least a portion of said second connection section of said inner
liner to form
a sealed duct section; said outer casing comprising a first duct connector at
said first
end, and a second duct connector at said second end, said first duct connector
comprising a formed section having a J profile, and said second duct connector
comprising a formed section having a J profile; and said first duct connector
of said first
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duct module being configured for coupling to said second duct connector of
said
second duct module, so that said first duct module and said second duct module
are
connected together to form said fire-rated ventilation duct assembly.
[00016] Other aspects and features of the present invention will become
apparent to
those ordinarily skilled in the art upon review of the following description
of
embodiments of the invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[00017] Reference will now be made to the accompanying drawings which show, by
way of example, embodiments of the present invention, and in which:
[00018] Fig. 1 shows in diagrammatic form a fire-rated duct system comprising
a
straight rectangular duct section according to an embodiment of the present
invention;
[00019] Fig. 2 shows an exploded view of the rectangular duct section
of Fig. 1;
[00020] Fig. 3 shows a longitudinal sectional view of the rectangular
duct section of
Fig. 1 taken along the line A-A;
[00021] Fig. 4A shows an inner liner spacer comprising a roll
formed/broken "J"
profile according to an embodiment of the present invention;
[00022] Fig. 4B shows an inner liner spacer comprising a roll formed/broken
"L"
profile according to an embodiment of the present invention;
[00023] Fig. 4C shows an inner liner spacer comprising a slip on "J"
profile
according to an embodiment of the present invention;
[00024] Fig. 4D shows an inner liner spacer comprising a slip on "L"
profile
according to an embodiment of the present invention;
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1000251 Fig. 5A shows an outer casing connector comprising roll formed/broken
casing connector according to an embodiment of the present invention;
[00026] Fig. 5B shows an outer casing connector comprising roll formed/broken
casing connector according to another embodiment of the present invention;
[00027] Fig. 5C shows an outer casing connector comprising a slip on casing
connector according to an embodiment of the present invention;
[00028] Fig. 5D shows an outer casing connector comprising a slip on casing
connector according to another embodiment of the present invention;
[00029] Fig. 6 shows a cross-sectional view of the rectangular duct
section of Fig. 1
taken along the line B-B;
[00030] Fig. 7 shows in diagrammatic form a fire-rated duct system comprising
first
and second adjoining duct sections;
[00031] Fig. 8 shows a longitudinal sectional view of the rectangular
duct sections of
Fig. 7 assembled together and taken along the line C-C;
[00032] Fig. 9A shows an outer casing connector comprising a reinforced roll
formed/broken casing connector according to another embodiment of the present
invention;
[00033] Fig. 9B shows an outer casing connector comprising a reinforced roll
formed/broken casing connector according to another embodiment of the present
invention;
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[00034] Fig. 9C shows an outer casing connector comprising a reinforced roll
formed
casing connector according to another embodiment of the present invention; and
[00035] Fig. 9D shows an outer casing connector comprising a reinforced roll
formed
connector according to another embodiment of the present invention.
[00036] Like reference numerals indicate like or corresponding elements or
components in the drawings.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[00037] Reference is made to Fig. 1, which shows in diagrammatic form a fire-
rated
ventilation duct system according to an embodiment of the present invention.
The fire-
rated ventilation duct system comprises a rectangular duct section or module
indicated
generally by reference 100. A duct system is formed by adjoining or connecting
together rectangular duct sections or modules 100, for example, as indicated
by
reference 800 and described in more detail below and with reference to Fig. 8.
It is to
be appreciated that while the duct sections are described with a rectangular
configuration, according to other embodiments, the duct sections may equally
comprise square, oval, circular and other cross-sectional configurations.
[00038] Reference is made to Fig. 2, which shows an exploded or expanded view
of
the rectangular duct section 100 of Fig. 1, as indicated generally by
reference 200.
According to an embodiment, the rectangular duct section 200 comprises an
inner duct
or inner duct liner indicated by reference 210, and an outer casing indicated
generally
by reference 220. According to an exemplary implementation, the inner duct
liner 210
comprises a plurality of panels or sections 211, for example, four panels as
indicated
individually by references 211a, 211b, 211c and 211d as shown in Fig. 2, and
also
described in more detail below. According to an exemplary implementation, the
outer
casing 220 comprises a plurality of panels or sections 222, for example, four
panels as
indicated individually by references 222a, 222b, 222c and 222d as shown in
Fig. 2, and
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also described in more detail below. As also shown in Fig. 2, the duct section
200
comprises an insulating layer indicated generally by reference 230. According
to an
exemplary implementation, the insulating layer 230 comprises panels formed
from a
non-combustible insulating material and indicated individually by references
230a,
230b, 230c and 230d in Fig. 2.
1000391 According to an exemplary embodiment, the inner duct 210 is fabricated
from a metal or metallic sheet, such as, galvanized steel, aluminized steel,
stainless
steel, or aluminum, or other types sheet metals, as required by the
ventilation system's
intended application. The inner duct or duct liner 210 may be formed or
fabricated with
a number of cross-sectional shapes or profiles, for instance, square,
rectangular,
circular or oval. According to an exemplary implementation, the inner duct
liner sections
or tubes 210 can be formed from flat metal sheets or from continuous metal
coils. In
typical installations and applications, rectangular shaped or oval shaped
tubes are
generally utilized as they are easier to fit into the crowded or confined
ceiling spaces
typical in the buildings being constructed today.
[00040] The wall thickness of the inner duct liner 210 will vary and/or be
dependent
on the metal used to fabricate the inner liner, the specific metal type, the
dimensions of
the ducts and/or duct spans, and/or operating pressure of the duct system. In
accordance with industry practice, the metal thickness should, at a minimum,
meet the
requirements of applicable industry standards or regulations, such as for
example, the
ASH RAE or SMACNA HVAC standards.
[00041] According to an exemplary implementation, the inner duct liner 210 may
be
fabricated in square, rectangular, circular or oval configurations in a
similar manner
according to a process comprising the following steps or operations:
- forming one piece of flat metal into a tube of the desired shape;
- forming two or more pieces of flat metal into "L" shaped sections and
joining
their longitudinal edges to form a square or a rectangular tube;
- forming one piece of flat metal into a "U" shape them capping the "U"
with a
separate flat piece forming a square or rectangular tube;
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- forming two pieces of flat metal into "U" shapes, with square or curved
corners,
then joining them to form a square, rectangular, or oval tube;
- utilizing four or more separate flat pieces, forming them if required,
and then
joining them to form a tube; or,
- utilizing a continuous strip of metal from a coil that is spirally wound
on a
machine to form a continuous round tube that then form into the desired duct
cross section, typically an oval section though squares and rectangles
sections
are possible.
[00042] As shown in Fig. 2, the inner duct liner 210 includes at one end,
liner spacer
sections 212, indicated individually by references 212a, 212b, 212c and 212d,
and liner
spacer sections 214, indicated individually by references 214a, 214b, 214c and
214d, at
the other end of the inner liner 210. The liner spacer sections 212, 214 are
configured to
provide a mechanism for connecting or attaching the inner duct liner 210 to
the outer
casing 220 comprising the outer casing panels 222, as depicted in Fig. 3 for
example.
The liner spacer sections 212, 214 are also configured to provide a mechanism
for
sealing the joint between adjacent duct sections 100 together to form a sealed
fire-
rated duct assembly, for example, depicted and indicated by reference 800 in
Fig. 8, as
described in more detail below. As will also be described in more detail
below, a rigid
connection is formed between the inner duct liner 210 and the outer casing
220, which
further provides structural integrity for maintaining the seal of each fire-
rated duct
section 100 and an assembled system comprising multiple fire-rated duct
sections 100
joined together.
[00043] As shown in Fig. 2, the outer casing 220 includes at one end
connectors
connector sections 224, i.e. "outer casing connector sections 224", indicated
individually by references 224a, 224b, 224c and 224d, and at the other end
includes
connectors or connector sections 226, i.e. "outer casing connector sections
226",
indicated individually by references 226a, 226b, 226c (and 226d). The outer
casing
connector sections 224, 226 are configured to provide a mechanism for
connecting or
attaching the outer casing 220 to the inner duct liner 210, as depicted in
Fig. 3 for
example. The outer casing connectors 224, 226 are also configured to provide a
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mechanism for connecting or attaching adjacent duct sections 100 together to
form a
sealed fire-rated duct assembly, for example, depicted and indicated by
reference 800
in Fig. 8, as described in more detail below.
[00044] According to another aspect and as shown in Figs. 2 and 3, the liner
spacer
sections 212 are configured to create a channel or space with the outer casing
panels
222 for receiving and mounting the non-combustible material (e.g. a board or
layer) 230.
As also shown in Fig. 3, the duct liner section 100 may include an optional
internal
support or reinforcement post or member as indicated by reference 213. The
support
post or member 213 provides additional structural rigidity to the duct section
100, for
instance, to prevent deflection of the inner duct liner 210, particularly in
large duct
installations or application.
[00045] Reference is next made to Figs. 4A to 4D, which shows embodiments of
liner spacer sections for attaching the inner duct liner 210 to the outer
casing 220
according to the present invention.
[00046] As shown in Fig. 4A and according to one embodiment, the liner spacer
section comprises a liner spacer section with a broken J profile 410, which is
formed on
each transverse edge of the inner duct liner panel or section 211. The broken
"J" profile
is indicated generally by reference 412. The liner spacer sections are
configured to
provide an attachment point to the outer casing, to function as a spacer
between the
inner duct liner 210 and the outer casing 220 (for the insulating layer),
and/or providing
a sealing surface for joining or coupling duct sections together, as described
in more
detail below. According to an exemplary implementation, the liner spacer
section 410 is
roll formed from sheet metal as an integral component or element at each end
of the
inner duct liner 210. As shown, the liner spacer section 410 includes a
mounting or
attachment surface indicated by reference 414. The mounting surface 414
provides an
attachment point or surface for affixing or otherwise attaching the liner
spacer section
410 to an adjacent surface on the connector section 226 of the outer casing
220, as
shown in Fig. 2. The inner liner duct 210 is attached or connected to the
outer casing
220 utilizing mechanical fasteners, for example, as shown in Fig. 3 and
indicated by
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reference 221. Other fastening techniques may be used as will be understood by
those
skilled in the art.
[00047] Reference is next made to Fig. 4B which shows a liner spacer section
with a
broken "L" profile according to another embodiment of the present invention,
and
indicated by reference 420. The broken "L" profile is indicated generally by
reference
422. According to an exemplary implementation, the liner spacer section 420 is
roll
formed from sheet metal as an integral component or element at each transverse
end
or edge of the inner duct panels 211 in the inner duct liner 210. As shown,
the liner
spacer section 420 includes a mounting or attachment surface indicated by
reference
424. The mounting surface 424 provides an attachment point or surface for
affixing or
otherwise attaching the liner spacer section 420 to an adjacent surface on the
connector section 226 of the outer casing 220, for example, using mechanical
fasteners
as described above for Fig. 3.
[00048] Reference is made to Fig. 4C which shows a liner spacer section
comprising
a slip-on member or component with "J" profile according to another embodiment
of
the present invention, and indicated by reference 430. The broken "J" profile
is
indicated generally by reference 432. According to an exemplary
implementation, the
slip-on liner spacer section 430 is formed from sheet metal as a separate
component or
element which is connected, i.e. slipped on/over the transverse end or edge
434 of the
inner duct panels 211 in the inner duct liner 210. The slip-on liner spacer
section 430 is
formed with an attachment surface indicated by reference 436 to fasten or
otherwise
secure the outer casing panel 226 to the liner spacer section 430 and the
inner duct
liner 210. As shown in Fig. 4C, the slip-on liner space section 430 may also
include a
pocket or cavity 438 for receiving an adhesive or sealant which is applied to
further
secure and/or seal the slip-on liner spacer section 430 to the edge and/or
surface of the
inner duct panel 211.
[00049] Reference is made to Fig. 4D which shows a liner spacer section
comprising
a slip-on member or component with "L" profile according to another embodiment
of
the present invention, and indicated by reference 440. The broken "L" profile
is
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indicated generally by reference 442. According to an exemplary
implementation, the
slip-on "L" profile liner spacer section 440 is formed from sheet metal as a
separate
component or element which is connected, i.e. slipped on/over the transverse
end or
edge 444 of the inner duct panels 211 in the inner duct liner 210. The slip-on
liner
spacer section 440 is formed with an attachment surface indicated by reference
446 to
fasten or otherwise secure the outer casing panel 226 to the liner spacer
section 440
and the inner duct liner 210. As shown in Fig. 4D, the slip-on liner space
section 440
may also include a pocket or cavity 448 for receiving an adhesive or sealant
which is
applied to further secure and/or seal the slip-on liner spacer section 440 to
the edge
and/or surface of the inner duct panel 211.
[00050] It will be appreciated that the sealant pockets 438 (and 448) provide
an
effective mechanism to seal the slip-on liner spacer sections 430 to the inner
duct
panels 211 and provide a sealed or airtight inner duct liner 210.
[00051] According to another aspect, the slip-on liner spacer sections 430,
440 to
provide the capability to 'field modify' duct sections or modules 100. For
instance, the
inner duct liner 210 can be cut in the field, the slip-on liner spacer
sections 430
reinstalled and the inner duct liner 210 connected to the outer casing 220.
According to
another aspect, the slip-on liner spacer sections can be configured to act as
corner
fillers to cover the portion of insulation that is exposed and provide a duct
connection
sealing surface where the insulation would be exposed at the corners of square
and
rectangular profile ducts, i.e. between the inner duct liner 210 and the outer
casing 220.
[00052] It
will be appreciated that the liner spacer sections 410, 420 formed as an
integral component of the transverse edges of the inner duct panel 211
increases the
structural integrity, i.e. stiffness, of the inner duct liner 210. However,
for circular or oval
duct profiles, the slip-on liner spacer sections 430, 440 may be preferred due
to
additional considerations for forming raised profiles on curved liner
sections, as will be
apparent to those skilled in the art.
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[00053] According to another aspect and as shown in Fig. 6, the liner spacer
sections 212, 214 are formed as a continuous member or section along the
respective
transverse edges of the inner duct liner panel 211. This configuration
provides
increased stiffness (as describe above) and in addition provides a near
continuous
sealing surface for connecting adjacent duct sections or modules 100 together
to form
a fire-rated duct assembly 800 as shown in Fig. 8.
[00054] According to another aspect, the liner spacer sections 212, 214 may
formed
or fabricated with partially segmented and/or perforated configuration. The
partially
segmented and/or perforated liner spacers may be fabricated by removing or
modifying
some or all of the liner spacer's profile at required locations by notching,
punching,
drilling, slitting, or utilizing other metal fabrication techniques, as will
be understood by
those skilled in the art. Advantageously, partially segmented and/or
perforated liner
spacer sections provide weight savings while still maintaining the structural
stiffness for
the inner duct liner 210 and attachment points or surfaces for the connecting
to the
outer casing 220. In addition, the liner spacer sections 212, 214 having
partially
segmented and/or perforated provide a less-effective thermal bridge between
the inner
duct liner 210 and the outer casing 220 thereby reducing the amount of heat
transferred
between the inner duct liner 210 and the outer casing 220.
[00055] The inner duct liner 210 (Fig. 2) is formed by joining the
respective
longitudinal edges 213, indicated individually by references 213a, 213b, 213c
and 213d
in Fig. 2, of the inner duct panel(s) 212 together to form a single inner duct
liner or
conduit 210. According to an exemplary implementation, a mechanical mating
joint or
lock is formed on the opposing longitudinal edges of the inner duct panel(s)
212 or strip
that are to be joined together. Instead of, or in addition to, mechanical
locks, welding
techniques, e.g. continuous longitudinal weld seams or spirally wound weld
seams,
may be utilized to fabricate the inner duct liner 210. Such fabrication
techniques are
suitable for automated and/or largescale fabrication.
[00056] For mechanical joint fabrication, the longitudinal joint
between adjacent
panels or sheets 211 may comprise snap, acme, or Pittsburgh type mechanical
lock for
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inner duct liners 210 comprising 16ga or lighter metal. If a snap type
mechanical lock is
used, which is typically limited to 20ga metal, the assembled joint may
require
reinforcement with the use of rivets, screws, tack welding, dimpling, or other
mechanical fastening methods to lock the components of the male-female joint
together to prevent the male leg of the joint from lifting out of the female
pocket due to
system design pressure or other loads on the inner duct liner 210.
[00057]
For inner duct liners comprising 16ga or heavier metals, welded longitudinal
seams or spirally wound seams may be preferable over mechanical joint or lock
mechanisms due to practical limitations of forming or rolling the heavier
gauge metallic
sheets. As will be understood by those skilled in the art, suitable welding
techniques
include continuous welded seams, lapped resistance welded seams, or stitch
welding
lap seams with sealing between the stitch welds. For heavier or thicker gauge
panels,
other mechanical joints, such as pocket locks or mechanically fastened laps
seams, or
welded joints may be utilized.
[00058] According to another embodiment, the inner duct liner 210 includes one
or
more internal stiffeners indicated generally by reference 213 as shown in
Figs. 3 and 6.
The internal stiffeners 213 may comprise a hollow rod or post and are attached
or
installed between opposing inner duct liner panels, for example, at a midway
point
between the inner duct liner panels 211a and 211c as shown in Figs. 3 and 6.
The
internal stiffeners 213 are configured to resist positive and/or negative
loads, and can
be standardized over a range of inner duct liners 210. By including the
internal stiffeners
lighter gauge metallic sheets or materials may be used for the inner duct
liner 210. Duct
standards, such as SMACNA and ASHRAE HVAC, provide guidance of selection of
gauge for inner duct liner panels 211 and also guidance on the minimum
acceptable
size and spacing requirements for the internal stiffeners. For applications
comprising
higher pressures and/or wider or longer duct sections, additional internal
stiffeners 213
along the width of the inner duct liner 210, and/or along the longitudinal
span of the
duct assembly may be utilized, for example, as shown in Fig. 8 and indicated
by
references 213a, 213b. According to another aspect, the internal stiffener(s)
213 are
only connected or attached to the inner duct liner 210 in order avoid creating
a thermal
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bridge allowing heat to transfer directly between the inner duct liner 210 and
the outer
casing 220.
[00059] According to an exemplary implementation, the insulation layers, e.g.
non-
combustible boards, blanket or batts, 230 are installed, e.g. attached or
affixed, to the
respective sides of the inner duct panels 211, as depicted in Fig. 2 and also
shown in
more detail in Fig. 6. According to another exemplary implementation, the
insulation
layers 230 are attached or affixed to the inside surfaces of the outer casing
panels 222
as shown in Fig. 2.
[00060] For an inner duct liner 210 having with a curved surface, e.g.
a circular or
oval cross-section, the insulation layer 230 will typically comprise a blanket
or batt type
insulation in order to facilitate attachment or installation to the outer
surface(s) of the
inner duct liner 210. According to another implementation, the insulation
layer 230 may
comprise a non-combustible board which meets the fire resistance requirements
or
specifications (e.g. thickness and/or fire-resistance rating) and is also
flexible or
bendable to conform to the curved surface(s) of the inner duct liner 210.
According to
another aspect, the insulation board(s) can be formed to match the curved
profile of the
inner duct liner 210 according to the oval or circular profile and attached
directly to the
outer surface. The non-combustible insulation layer 230 may also be
temporarily held in
place during the assembly of the inner duct liner 210 and the outer casing 220
with the
use of weld or stick pins, adhesives, tapes, or friction fitted between the
inner duct liner
210 and the inner liner spacer sections 212.
[00061] As described above, the inner duct liner 210 can be fabricated
utilizing rolled
or brake formed techniques. It will be appreciated that when roll formed
mechanical
locks are used to connect the pieces or sections of the inner duct liner 210
into a tube,
the insulation layer 230 may be exposed at the corners of the inner duct liner
210 and
the outer casing 220 due to the notching required to form profiles along each
edge of
the inner duct liner panel 211. It will be further appreciated that the
exposed insulation
material makes it difficult to seal the inner duct liner 210 of one duct
section module to
the inner duct liner 210 of an adjacent duct section module in the field
without _
CA 3076978 2020-03-25
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additional treatment or coverage. According to an exemplary implementation,
the
exposed insulation edges are factory or field coated with a high modulus
mastic that
seals the insulation surface and bonds the insulation and seal material to the
edges
and/or surfaces of the liner spacer sections 212. For lower density insulation
layers 230,
or for insulation materials without sufficient inherent strength to provide a
sealed
surface, corner sections 610 (indicated individually by references 610a, 610b,
610c and
610d in Fig. 6) are attached to the inside face of the vertical leg of the
inner liner spacer
sections 212, as shown in Fig. 6. The corner sections 610 can be attached
utilizing
clinching, spot welding, or tack welding, or bonding, in addition to other
techniques as
will be understood by those skilled in the art. For non-metallic material(s),
the corner
sections 610 can be attached using mastic, or other suitable adhesives, for
bonding the
sections 610 in place, as will also be within the understanding of those
skilled in the art.
[00062] As described with reference to Fig. 2, the outer casing 220 according
to an
embodiment comprises outer casing panels 222, indicated individually by
references
222a, 222b, 222c and 222d for a 4-side configuration, fabricated from
galvanized steel,
or other high temperature sheet metal, for instance, aluminized sheet metal or
stainless
steel. As described above the outer casing 220 typically has the same cross-
sectional
shape or profile as the inner duct liner 210. For a rectangular configuration,
the outer
casing panels 222 are joined or connected along the respective longitudinal
edges 223,
indicated individually by references, 223a-b and 223b-a, 223b-c and 223c-b,
223c-d
and 223d-c, and 223d-a and 223a-d, in Fig. 2. The inner spacer sections 212
are
configured to offset or create a gap or space between the inner duct liner 210
and the
outer casing 220, which is substantially equal to, or slightly less, than the
thickness of
the insulation layer 230 required to achieve the desired or required fire-
resistance
rating. If the insulation layer 230 utilized comprises a blanket or batt type
insulation
material, then the insulation layer 230 is slightly compressed once the outer
casing 220
is installed in order to prevent the insulation from sagging and possibly
gapping at the
insulation seams resulting in a reduced fire resistance of the duct assembly.
1000631 As described above, the outer casing 220 comprises the outer panels
222
for a rectangular profile or cross-section. The thickness of the metal used to
fabricate
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the outer casing panels 222 will vary by the type of sheet metal used, the
size of the
duct being fabricated, the operating pressure for the duct system and/or the
required
fire-resistance rating. At a minimum the metal thickness of the outer casing
panels 222
should meet ASHRAE or SMACNA HVAC guidelines.
1000641 The outer casing 220 is fabricated in a manner similar to the inner
duct liner
210, for instance, as described above. However, the thickness of outer casing
panels
222 and/or the connection techniques or mechanisms will vary, for instance,
based on
the size of the outer casing 220 and/or the difference in size or dimensions
between the
inner duct liner 210 and the outer casing 220. According to an exemplary
implementation, the outer casing 220 may be fabricated in square, rectangular,
circular
or oval configurations according to a process comprising the following steps
or
operations:
- forming one piece of flat metal into a tube of the desired shape;
- forming two or more pieces of flat metal into "L" shaped sections and
joining
their longitudinal edges to form a square or rectangular tube;
- forming one piece of flat metal into a "U" shape them capping the "U"
with a
separate flat piece forming a square or rectangular tube;
- forming two pieces of flat metal into "U" shapes, with square or curved
corners,
them joining them to form a square, rectangular, or oval tube;
- using four or more separate flat pieces, forming them if required, and
then
joining them to form a tube; and
- using a continuous strip of metal that is spirally wound on a machine to
form a
continuous round tube that is cut to the required length and form into the
desired cross-section comprising an oval profile and/or a square or
rectangular
profile. should meet ASHRAE or SMACNA HVAC guidelines.
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[00065] The section connectors 224, 226 for the outer casing panels 222 are
formed
along the opposing transverse ends as shown in Fig. 2. The outer casing
section
connectors 224, 226 are fabricated utilizing a roll or brake forming process,
or as a
separate slip-on connector that is attached to the unfinished end or edge of
the
respective outer casing panel 224 or 226. The outer section connectors 224,
226 are
configured to provide a mechanism for joining individual duct sections 200 and
201
together into a continuous conduit at the installation site as shown in Fig. 8
and
described in more detail below.
[00066] Reference is made to Fig. 5A to 5D, which shows embodiments of outer
casing section connectors 224, 226 for the outer casing 220, e.g. the outer
casing
panels 222, for attaching the inner duct liner 210 to the outer casing 220
according to
the present invention.
[00067] As shown in Fig. 5A and according to one embodiment, the outer casing
section connector 226 (224) comprises a spacer or a section with a broken J
profile
510, which is formed on each transverse edge of the outer casing panel or
section 222.
The broken "J" profile is indicated generally by reference 512. The outer
casing section
connectors are configured to provide an attachment point or surface for
attaching the
liner spacer section 214. According to an exemplary implementation, the outer
casing
section connector 226 is roll formed from sheet metal as an integral component
or
element at each end of the outer casing panel 222. As shown, the outer casing
section
connector 510 includes a mounting or attachment surface indicated by reference
514.
The mounting surface 514 provides an attachment point or surface for affixing
or
otherwise attaching the outer casing section connector 510 to an adjacent
surface on
the liner spacer section 214 of the inner duct liner 210, as shown in Fig. 2.
The inner
liner duct 210 is attached or connected to the outer casing 220 utilizing
mechanical
fasteners, for example, as shown in Fig. 3 and indicated by reference 221.
Other
fastening techniques may be used as will be understood by those skilled in the
art.
[00068] According to an exemplary implementation, the outer casing section
connector 226 (224) is roll-formed from the sheet metal piece as an integral
component
CA 3076978 2020-03-25
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at each end of the outer casing panel 222 with the outer edge or leg-end of
the J profile
having an internal or external return formed on the outer edge. It will be
appreciated
that this configuration is similar to the connection profiles under SMACNA T-
24, T-25a
and/or T25b industry standard.
[00069] Reference is next made to Fig. 5B which shows the outer casing section
connector 510 according to another embodiment of the present invention
configured
with a mounting or attachment surface 524 for affixing or otherwise attaching
the liner
spacer section 420 to the outer casing 220, for example, using mechanical
fasteners as
described above for Fig. 3.
[00070] Reference is made to Fig. 5C which shows an outer casing section
connector comprising a slip-on casing connector according to another
embodiment of
the present invention, and indicated by reference 530. According to an
exemplary
implementation, the slip-on outer spacer section 530 is formed from sheet
metal as a
separate component or element which is connected, i.e. slipped on/over the
transverse
end or edge 534 of the outer casing panels 222 of the outer casing 220. The
slip-on
liner spacer section 530 is formed with an attachment surface indicated by
reference
536 to fasten or otherwise secure the liner spacer section 214 of the inner
duct liner
210. As shown in Fig. 5C, the slip-on casing connector 530 may also include a
pocket
or cavity 538 for receiving an adhesive which is applied to further secure the
slip-on
casing connector 530 to the edge and/or surface of the outer casing panel 222.
[00071] Reference is made to Fig. 5D which shows the outer casing section
connector 540 according to another embodiment of the present invention
configured
with a mounting or attachment surface 546 for affixing or otherwise attaching
the liner
spacer section 420 to the outer casing 220, for example, using mechanical
fasteners as
described above for Fig. 3.
[00072] As shown in Figs. 5C and 5D, the slip-on casing connectors 530 (540)
can
be formed with sealant pockets 538 according to another embodiment. The
sealant
pockets 538 are configured to 'grab' the edge of outer casing panel 222.
According to
CA 3076978 2020-03-25
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another aspect, the sealant pockets 538 can be filled with a sealant indicated
by
reference 539 to provide a sealed air-tight connection. This alleviates the
need to
manually seal the perimeter edges of the slip-on casing connectors 530 in
order to
provide an air-tight duct assembly.
[00073] Reference is next made to Figs. 9A to 9D, which shows embodiments of a
reinforced casing section connector (224, 226) for the outer casing 220. The
casing
section connectors, i.e. duct connectors, are configured to connect adjacent
duct
modules or sections together to form a duct assembly as described in more
detail
herein.
[00074] As shown in Fig. 9A and according to one embodiment, the outer casing
section connector 226 (224) comprises a section with a broken J profile 910,
which is
formed on each transverse edge of the outer casing panel or section 222. The
broken
"J" profile is indicated generally by reference 912 with an external (e.g. on
the external
face or surface) reinforcing return or hem formed on the outer most horizontal
portion of
the "J" profile and indicated by reference 914. According to an exemplary
implementation, the outer casing section connector 226 is roll formed from
sheet metal
as an integral component or element at each end of the outer casing panel 222.
[00075] As shown in Fig. 9B and according to another embodiment, the outer
casing
section connector 226 (224) comprises a section with a broken J profile 920,
which is
formed on each transverse edge of the outer casing panel or section 222. The
broken
"J" profile is indicated generally by reference 922 with an internal (e.g. on
the internal
face or surface) reinforcing return or hem formed on the outer most horizontal
portion of
the "J" profile as indicated by reference 924. It will be appreciated that an
internal
reinforcement is advantageous for the casing section connector as it
eliminates the
exposed sharp edge of the sheet metal, while also providing the additional
reinforcement required. According to an exemplary implementation, the outer
casing
section connector 226 (224) is roll formed from sheet metal as an integral
component or
element at each end of the outer casing panel 222.
CA 3076978 2020-03-25
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[00076] According to another embodiment and as shown in Fig. 9C, the outer
casing
section connector 226 (224) comprises a section with an improved roll formed
"J"
profile indicated by reference 930, which is formed on each transverse edge of
the
outer casing panel or section 222. The improved "J" profile is indicated
generally by
reference 932 with an internal reinforcing return or hem formed on the outer
most
horizontal portion of the "J" profile indicated by reference 934. The internal
return 934 is
formed to create a recess or groove 936 on the interior face of the most
exterior face of
the casing connector which is configured to function as a pocket or retention
edge, for
instance, to locate and maintain the outer edge of the corner connectors (620)
tight to
the vertical legs of the casing connector. As shown in Fig. 9C, a bead or
bulge indicated
by reference 937 may also be formed in the outer casing section. The bead 937
is
configured to locate and/or maintain the lower edge of the corner connectors
(e.g. the
corner connectors 620 in Fig. 6) close or tight to the vertical sections or
"legs" of the
outer casing section connector 224 or 226.
[00077] As shown in Fig. 9D and according to another embodiment, the outer
casing
section connector 226 (224) comprises a section with an improved roll formed
"J"
profile indicated generally by reference 940, which is formed on each
transverse edge
of the outer casing panel or section 222. The improved "J" profile is
indicated generally
by reference 942 and comprises an external reinforcing return or hem formed on
the
outer most horizontal portion of the "J" profile as indicated by reference
944. The
external return 944 is formed to create a recess or groove 946 on the interior
face of the
exterior face of the casing section connector 226. The recess or groove 946 is
configured to function as a pocket or retention edge, for instance, to
maintain the outer
edge of the corner connectors (e.g. the corner connectors 620 in Fig. 6) close
or "tight"
to the vertical legs of the outer casing section connector. As also shown in
Fig. 9D, a
groove or recess indicated by reference 948 may be formed in the outer casing
section
connector 226, adjacent to the vertical section of the outer casing section
226. As
shown, the groove or recess protrudes from the outer face of the connector 226
and is
configured to locate and/or maintain the lower edge of the corner connectors
(e.g. the
corner connectors 620 in Fig. 6) close or tight to the vertical sections or
"legs" of the
CA 3076978 2020-03-25
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outer casing section connector 224 or 226. The outer casing connectors 224,
226 are
connected or affixed to the inner duct liner 210 in a manner similar to those
described
above.
[00078] According to another aspect, the slip-on casing connectors 530 provide
the
capability to 'field modify' a duct section. The field modification may
comprise, for
instance, cutting the outer casing panels 222 and then re-installing the slip-
on
connectors 530 and re-attaching the liner spacer connectors 212, 214 to
reconnect the
inner duct liner 210. According to another aspect the slip-on connectors 530
are
configured to provide additional structural rigidity or integrity, and can
reduce the need
or the number of internal stiffeners, and/or allow for smaller outer liner
section
connectors 530, 212 or 214, for a given size duct and/or duct operating
pressure.
[00079] As shown in Fig. 2, the outer casing panels 222 comprise longitudinal
edges
223, indicated individually by references 223a-b, 223b-a, 223b-c, 223c-b, 223c-
d,
223d-c and 223d-a, which are joined or connected together to form the outer
casing
210 as an enclosure around the inner duct liner 210. According to an exemplary
implementation, the outer casing panels 222 are joined together utilizing a
mechanical
lock mechanism, such as a mating type joint or lock (e.g. comprising male and
female
sections or components), which is formed on the opposing longitudinal edges of
the
outer casing panel 222, as will be understood by those skilled in the art. In
addition, to
mechanical lock mechanisms, the outer casing panels 222 can be joined or
attached
together using welding techniques, for instance, longitudinal or spirally
wound seams.
According to another aspect, the longitudinal joints and mechanical locks can
be
strengthened by including fasteners connecting the male and female sections of
the
mechanical lock or by stitch welds along the exterior edges along the length
of joint.
1000801
Once the outer casing 220 is assembled around the inner duct liner 210
and the insulation boards 230, the section connectors 212, 214 and 224, 226
(or if
being utilized, the slip-on connectors are first installed), the section
connectors are
finished. For a rectangular or a square profile, the section connectors are
finished with
corner connectors 620, indicated individually by references 620a, 620b, 620c
and 620d,
CA 3076978 2020-03-25
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in Figs. 6 and 7. The corner connectors 620 are configured to provide
additional
structural integrity and also keep the cross-section profile of the duct
module 200 at
least substantially square. According to an exemplary implementation, the
corner
connectors 620 are configured to snap into place between a groove in the
casing face
and the return edge of the upper flange of the joint.
[00081] To complete the fire-rate duct assembly, the liner spacer connectors
212,
214 are connected to the outer casing section connectors 224, 226. The inner
duct liner
210 and the outer casing 220 are aligned on one end to ensure an even sealing
surface
exists when being installed on site. Once aligned, the outer casing section
connectors
224, 226 are attached to the respective liner spacer connectors 212, 214,
utilizing
screws, rivets, mechanical clinching, or adhesive bonding. For duct sections
or
modules 100 that will not be modified in the field, the outer casing section
connectors
224, 226 and the liner spacer connectors 212, 214 are joined or attached
together, as
described above.
[00082] Reference is next made to Fig. 7, which shows a fire-rated duct
assembly
700 according to an embodiment of the present invention and comprising a first
duct
section or module 200 and a second duct section or module 201. As shown in
Fig. 7, a
fire-resistant sealant or gasket 702 is applied to the face or surface of the
liner spacer
connectors 212, 214 on the second duct module 201 to further seal to prevent
leaks in
the duct assembly 700 during normal operation and when exposed to fire. The
fire-
resistant sealant may comprise either a mastic, or a tape like, gasket, and is
applied
prior to joining the duct sections 200 and 201 together. The second duct
section 201 is
positioned towards the first duct section 200 to align the holes in the
respective corner
connectors 620 on the first 200 and the second 201 duct sections or modules,
as
shown in Fig. 7. To secure the duct sections 200 and 201 together, a corner
bolt 710 is
inserted through each corner connector 620 pair and tightened with a nut 712
as shown
in Fig. 7 and further in Fig. 8.
[00083] To further strengthen (and seal) or prevent the connectors from
potentially
separating under high heat conditions, the joint or joining surfaces of
adjacent duct
CA 3076978 2020-03-25
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sections 200 and 201 are strengthened or enhanced with additional retention
mechanisms as shown in Fig. 8 and indicated by reference 810. The retention
mechanisms indicated by reference 810, indicated individually by references
810a,
810b (for the top and bottom connection edges of the outer duct sections)
comprise a
retention clip, for instance, a roll formed retention clip. The roll forming
process creates
a spring like bias in the clip favouring the clip in a semi-closed or
retracted state which
snaps over the top edges of the respective section connectors of the adjacent
duct
sections or modules 200 and 201 (Figs. 7 and 8). According to an exemplary
installation, the retention clips 810 are approximately 6" in length and
installed on
approximately 12" centers along the span. To further secure the retention
clips 810, the
clips 810 are crimped tight in at least two locations per clip to ensure the
clips 810
locked onto the section connectors of the respective outer casing panels and
cannot
expand and fall off when exposed to the high temperatures of a fire. The
second
retention mechanism indicated by reference 820 comprises installing additional
fasteners through the section connectors 224, 226, for instance, comprising
self-
drilling/self-tapping screws 822 screwed through the adjacent section
connectors.
1000841
For duct sections or modules having a circular or oval profile, the assembly
process is modified and comprises the following steps. A fire resistant
sealant or gasket
is applied to the face of the liner spacer connectors, comprising a sealant as
described
above. The first and second duct sections are drawn together to align the
outer casing
connectors. Clamps are attached at the centers of the top and bottom flat
sections as
well as at the centers of the curved portions of the section connectors to
temporarily
hold the adjacent duct sections or modules in place. Fasteners, for example,
self-
drilling/self-tapping screws 822 are installed through the adjacent section
connectors,
positioned approximately on center and on an approximately 6" to 8" spacing.
100085] The present invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. Certain
adaptations and
modifications of the invention will be obvious to those skilled in the art.
Therefore, the
presently discussed embodiments are considered to be illustrative and not
restrictive,
the scope of the invention being indicated by the appended claims rather than
the
CA 3076978 2020-03-25
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foregoing description, and all changes which come within the meaning and range
of
equivalency of the claims are therefore intended to be embraced therein.
CA 3076978 2020-03-25
