Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
21 7329q
LEAK-PROOF VENTING SYSTEM
FIELD OF THE INVENTION
The present invention relates to flue sections and to an
airtight venting system made by connecting in line such flue
sections.
10 DESCRIPTION OF THE PRIOR ART
As is known, wood, oil and gas burning appliances, stoves
or fireplaces are commonly used for heating houses and
buildings during the cold months of the year, or for cooking.
Vapours such as smoke and gases are given off from combustion
of these materials. The vapours escape through a flue or a
venting system connected to the appliance and leading to the
roof and to the exterior of the house or building equipped
with the appliance.
The flue or venting system usually comprises a plurality
of flue sections of a given length which are connected to each
other in line to form a duct or a chimney. Most of the time,
such system comprises two sets of flue sections, viz. a set
of inner flue sections directly connected to the flue of the
appliance, stove or fireplace and acting as the chimney per
se, and a second set of outer flue sections surrounding the
fi-rst set and acting as a thermal shield.
Stringent safety regulations require that the connections
between the flue sections of a least one of the two sets, viz.
the inner or the outer one, be air-tight, especially when the
appliance, stove or fireplace is supplied with gas, so that
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the leak loss be lower than 25 cubic feet per three hours
under an air pressure of 25 Pa.
To comply with these regulations, the sections are sealed
with a duct tape or they are fitted tightly together. Bayonet
type connections have been known in this field for more than
90 years as evidenced by US patents Nos.796,084; 1,217,805;
1,281,307 and 3,233,927. However, none of these patents
discloses or suggests to use an O-ring to make a tight seal.
In any event, sealing of one of the sets, most commonly
the outer set, increases the amount of time and material
required to complete the installation of the venting system.
When the sections are fitted tightly together without any tape
or seal, they may loosen up after a while, thereby causing the
flue to leak gases.
OBJECT A~D SU~ RY OF T~ lNV~:~TION
The object of the present invention is to provide an
improved flue section of very simple yet efficient structure,
which can be connected in line to similar flue sections in
such a manner as to form an airtight venting system or chimney
which is simple to install.
,
More particularly, the invention provides a flue section
having a pair of opposite ends of circular cross-section. One
of the ends, hereinafter called the "male end", is shaped and
sized to fit into the other end, hereinafter called the
"female end", of a similar flue section. Both ends have inner
and outer surfaces. The male end comprises at least two L-
shaped grooves, a peripheral outwardly-opening recess and an
O-ring.
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The L-shaped grooves are located on the outer surface of
the male end. Each L-shaped groove has a first and a second
arm. The grooves are positioned in such a manner to have the
first arm opening at the male end of the flue section while
the second arm extends toward the female end of the flue
section at a fixed angle.
The recess is positioned at a distance "H" from the
second arm of the L-shaped grooves. The 0-ring is mounted in
the recess and is protruding outwardly.
The female end comprises at least two inwardly-projecting
keys and a peripheral inwardly-projecting boss.
The keys are sized and shaped to engage the L-shaped
grooves of the male end of another flue section in order to
lock the male end into the female end by insertion and
twisting of the male and female end together, thereby forming
a "bayonet" type connection.
The boss is positioned at the distance "H" from the keys
in such a manner to be aligned and pressed against the 0-ring
of the other flue section and thus to make a tight seal when
the male end of the other flue section is fitted into the
female end of the flue section.
Preferably, the male end of the flue section has a given
length and comprises a flange limiting its insertion within
the female end of another similar flue section. Accordingly,
beyond this given length, the diameter of the flue section is
increased to be equal to the diameter of the female end.
Consequently, the female end cannot be fitted further than the
distance of the male end, after which both diameters of the
flue sections are equal.
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Another object of the present invention is to provide an
airtight venting system.
More particularly, the invention provides an airtight
venting system comprising a plurality of flue sections
connected in line to each other.
The flue section of the present invention provides an
airtight and leak proof venting system exceeding many times
the standard leakage requirements, thereby ensuring that the
appliances perform to its expected level. Furthermore, the
flue sections of the present invention are easy to connect to
each other.
B}2TF~ DESC~2TPTION OF THE D~AWINGS
The present invention will be more easily understood upon
reading of the following non-restrictive description of a
preferred embodiment thereof, made with reference to the
accompanying drawings in which:
- FIGURE 1 is a perspective view of a flue section
according to the invention;
- FIGURE 2 is an enlarged perspective view of a male and
a female end of two flue sections similar to the one
illustrated in Fig. 1, the ends of the two flue sections being
shown aligned in position to be connected to each other;
- FIGURE 3 is a partial longitudinal cross-section view
of two flue sections according to the invention connected to
each other; and
- FIGURE 4 is a schematic view of the assembly used to
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test the air tightness of the venting system according to the
invention.
For the purpose of simplicity, the same numeral
references have been used throughout the description and
drawings to identify the same structural elements.
D~SCRIPTION OF A ~K~RED E~R~nT~ENT OF THE
lNV ~ TION
Figure 1 shows a flue section (1) according to the
invention. As is shown, the flue section (1) has a male end
(3) and a female end (5), both forming a pair of opposite ends
-of circular cross-section. Each of the male and female ends
(3,5) has an inner surface (21) and an outer surface (23).
Figure 2 shows in detail the male end (3) of the flue
section (1) and the female end (5') of a similar flue section
(1'). The male end (3) comprises four L-shaped grooves (11)
on the outer surface (23) of the flue section (1). Each L-
shaped groove (11) has a first and a second arm (13,15). The
L-shaped grooves (11) are positioned in such a manner to have
the first arm (13) opening at the male end (3) of the flue
section (1) while the second arm (15) extends toward the
opposite female end of the flue section (1) at a fixed angle.
The male end (3) is shaped and sized to fit into the female
end (5') of the other flue section (1').
As is shown in Fig. 3, the male end (3) further comprises
a peripheral outwardly-opening recess (7) positioned at a
distance "H" from the second arm (15) of the L-shaped grooves
(11) and an 0-ring (9) mounted in the recess (7) and
protruding outwardly.
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The female end (S') of the flue section (1') comprises
a plurality of inwardly-projecting keys (19'), only two of
which are visible on the perspective view of figure 2. The
keys (19') are preferably four in number and are sized and
shaped to engage the L-shaped grooves (11) of the male end (3)
of another flue section (1) in order to lock the male end (3)
into the female end (5') by insertion and twisting of the male
and female end (3,5') together, thereby forming a "bayonet"
type connection.
As is shown in Fig. 3, the female end (5') of the flue
section (1') further comprises a peripheral inwardly-
projecting boss (17') positioned at the distance "H" from the
keys (19') in such a manner to be aligned and pressed against
the 0-ring (9) of the other flue section (1) and thus to make
a tight seal when the male (3) of the other flue section (1)
is fitted into the female end (5') of the flue section (1').
As is shown in Fig. 2, the male end (3) of the flue
section (1) preferably has a length "L" and a flange (33)
limiting its insertion within the female end (5') of the other
flue section (1'). Accordingly, beyond this length "L", the
diameter of the flue section (1) is increased to be equal to
the diameter of the female end (5'). Consequently, the female
end (5') cannot be fitted further than that length "L" of the
male end (3) after which both diameters of the flue sections
(1,1') are equal.
A diagram of the assembly of the venting system (25) used
for testing the performances of the present invention is shown
in Fig. 4. The venting system (25) comprises flue sections
(1) connected to each other and incorporating a 90~ bend ~27).
The system (25) is connected, for the purpose of the test, to
a flow meter (33) measuring the volume of gas passing through
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a section of the venting system (25) and a water column (31)
to measure the gas pressure inside the system.
Tests have been performed to determine the volume of gas
leaking off the entire system (25) and at the level of each
connections (35). The venting system (25) according to the
invention should have a leak loss of less than 6 cubic feet
per 3 hours, and preferably of less than 2, with an air
pressure of 0,1 inch measured on the water column (or 25 Pa)
on the longest configuration installation possible of the
system (25). In fact, the leak loss measured was 1.83 cu. ft.
per 3 hours, therefor 13 times less than the leak allotted by
the CGA standard. More particularly, at each joint
connection, the system should have a maximum leak loss of 1
cubic feet per 3 hours and preferably 0,4. In fact, the leak
loss measured at each joint connection was 0.26 cu. ft. per
3 hours which is exceptional.
Of course, the above description of the invention could
be extended to any variation that any person in the art would
or could think of.
