Note: Descriptions are shown in the official language in which they were submitted.
CA 02540992 2006-03-29
SHUTOFF VALVE ASSEMBLY FOR A VENT PIPE
TECHNICAL FIELD
The present invention relates to a shutoff valve assembly for a vent pipe of a
tank. In particular, the present invention relates to a shutoff valve assembly
for a
vent pipe that prevents leakage of fuel in the event the tank is tilted or
overturned.
BACKGROUND OF THE INVENTION
A typical fuel storage tank is provided, inter alia, with a fill pipe, a fuel
outlet,
and a vent pipe. The tank is filled through the fill pipe and fuel from the
tank is
delivered through a supply line connected to the fuel outlet. The vent pipe
provides a
means for the tank to breathe when fuel is withdrawn or added to the tank.
Venting
also provides pressure relief in case of overfill or rapid expansion or
gasification of
contents in the event of fire. A whistle may also be provided in the vent pipe
in order
to indicate fluid levels when filling the tank. The whistle provides a change
in an
audible signal when the fluid in the tank has reached a particular level. Vent
pipes
comprising a whistle are commonly referred to as whistling vents.
Fuel spills or leakage occurring from any of the aforementioned pipes or
outlets of a tank poses severe environmental and safety hazards. Typically,
the fill
pipe is covered with a removable cap fastened with a wing nut or the like
after a
filling operation. Automatic shutoff valves and valve protectors are employed
to
prevent fuel leakage from the fuel outlet in case the supply line is damaged
or the
tank is accidentally toppled or overturned. However, fuel may still spill or
leak
through the vent pipe or the whistling vents when a tank is toppled or
overturned.
Numerous devices have been provided in the past for preventing such spills or
leakages.
Canadian Patent Application No. 2,358,546 to Denby discloses a valve
incorporating a roll-over mechanism. A pendulous mass automatically urges, due
to
gravity, an o-ring towards, and ultimately against, a pressure surface when
the valve
is rotated as a result of displacing the tank from its normal upright
position.
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United States Patent No. 6,142,167 to Pettesch describes a vent valve
assembly capable of shutting off the valve during a rollover situation. A roll
over
valve is provided to open and close the fluid flow path between the vent valve
and
the tank interior. A rocker arm assembly rotatably mounted to a housing,
positions
the roll over valve in the open position when the tanker is upright and moves
the roll
over valve to the closed position when the tanker rolls more than a
predetermined
angle relative to the upright position.
United States Patent No. 1,942,630 to Woodbridge describes a vent plug. In
the normal upright position, a weighted valve member of the vent plug is out
of
contact with a valve seat permitting venting from the container. When the
container
is tilted, the weighted member rocks about a point of contact on a supporting
ledge
and closes a venting orifice by bringing the valve member into contact with
the valve
seat and thus prevents liquid from escaping the container.
United States Patent No. 4,846,208 to Hempel et al. discloses a closing
arrangement for a vent line of a tank. When a vehicle is in an inclined or
inverted
position, a mass part slides along guiding ribs and pulls a closing element
against an
outlet opening thus closing the vent line.
United States Patent No. 4,593,711 to Morris describes an overturn valve for
a tank to prevent leakage of fluid in the event the tank is accidentally
tilted or
overturned. The overturn valve is biased open by gravity in the normal upright
orientation of the valve assembly and is closed when the assembly is inclined
to
approximately 45 degrees from the normal upright orientation.
The shutoff assemblies described above contain numerous components, are
often difficult to assemble, and are expensive to manufacture. The components
of
the shutoff assemblies are typically exposed to adverse conditions that may
cause
them to malfunction. Therefore, there is a need for a shutoff valve assembly
that is
simple in construction and has fewer moving components.
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SUMMARY OF THE INVENTION
An object of the present invention is thus to provide an improved shutoff
valve
assembly for a vent pipe that addresses the limitations of the prior art.
The present invention accomplishes this by providing a valve having a bore
positioned along its longitudinal axis disposed in the vent pipe or the
whistling vent of
a tank. When the tank is in an upright position, the bore of the valve is
aligned with
the vent pipe opening to provide a continuous channel connecting the interior
of the
tank and the exterior thereof. In the event the tank is displaced from its
upright
position, the valve moves in response to gravity causing a misalignment of the
bore
of the valve and the vent pipe opening thereby cutting off the channel and
thus
preventing leakage of fuel.
According to an aspect of the present invention there is provided a shutoff
valve assembly for a vent pipe of a tank comprising a valve having a first
end, a
second end and an axial portion connecting the first and second ends; a
housing unit
for retaining the first end of the valve while the second end is free to
oscillate. The
valve has a bore extending substantially the length of the longitudinal axis
of the
valve, such that a channel is formed connecting the interior of the tank and
the
exterior thereof through the bore of the valve and the vent pipe when the tank
is in an
upright position and the channel is cutoff when the tank is displaced from the
upright
position.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the
following description in which reference is made to appended drawings wherein:
Fig.1 is a schematic view of a shutoff valve assembly for a vent pipe of a
tank
according to an embodiment of the present invention;
Fig. 2 (a) is a cross-section of a shutoff valve assembly for a vent pipe of a
tank
according to another embodiment of the present invention when the tank is in
an
upright position;
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Fig. 2 (b) is a cross-section of a shutoff valve assembly of Fig. 2(a) when
the tank is
displaced from an upright position; and,
Fig. 3 is a side elevation of a tank provided with a shutoff valve assembly
(shown in
ghosted view) for the vent pipe of Fig. 2(a).
DETAILED DESCRIPTION OF THE INVENTION
The shutoff valve assembly according to an embodiment of the present
invention is shown in detail in Figs. 1, 2(a), and 2(b). The housing 50
retains the first
end 80 of the valve 75 while the second end 85 thereof is free to oscillate.
The valve
75 has a bore 90 positioned substantially along its longitudinal axis. When
the tank
100 is in an upright position, the bore 90 of the valve 75 is aligned with the
vent pipe
30 to provide a continuous channel connecting the interior of the tank 100 and
the
exterior thereof as shown in Fig. 2(a). In the event the tank is displaced
from its
upright position, the second end 85 of the valve 75 moves in response to
gravity. As
shown in Fig 2(b), the displacement of the tank causes a misalignment of the
bore 90
of the valve 75 and the vent pipe 30 thereby cutting off the continuous
channel and
thus preventing leakage of fuel.
The valve 75 is shown to have a dumbbell-shape with spherical first 80 and
second 85 ends in Figs. 2(a) and 2(b). However, it is not restricted to this
shape
alone. Valves of other geometric designs with a bore therethrough may be
envisioned. However, the valve must provide a continuous channel connecting
the
interior of the tank with the exterior thereof, when the tank 100 is in an
upright
position and the channel must be cutoff by the misalignment, due to gravity,
of the
bore 90 and the vent pipe opening when the tank 100 is tilted or overturned.
The housing 50 is shown to have an upper chamber 55 and a lower chamber
60 in Figs. 2(a) and 2(b). The upper chamber 55 has a neck portion 65
dimensioned
to receive a stem portion 35 of the vent pipe 30. The lower chamber 60 has
flanges
70 that define the extremities of the oscillation of the valve 75 as shown in
Fig 2(b).
The housing 50 may be constructed in several other ways so long as the housing
50
retains one end 80 of the valve 75 in a pivotal manner and the second end 85
of the
valve 75 is free to oscillate. Additionally, a gasket or an o-ring may be
provided in
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between the neck portion 65 of the upper chamber 55 and the first end 80 of
the
valve 75. The inner surface of the housing 50 may be lubricated with suitable
lubricants such as grease, petroleum jelly, graphite etc., so as to facilitate
the
movement of the valve 75.
The valve 75 may have an opening (not shown) disposed thereon along the
length of the longitudinal axis. During the filling operation, should the oil
reach the
opening at the second end 85 and the operator does not stop the filling
immediately,
oil can leak out of the top of the valve. However, the opening which extends
to the
bore 90 may prevent any leak caused due to overfilling of the tank 100 by
creating a
back pressure. Typically, the opening may have a diameter of about 3 mm to
4mm.
The shutoff valve assembly of the present invention may be retro-fitted on an
existing tank 100 or may be manufactured in conjunction with a tank 100. The
lower
chamber 60 of the housing 50 can be mounted on a pre-existing opening for
receiving a vent pipe 30 in a tank 100. The first end 80 of the valve 75 is
retained in
the housing 50 such that the valve 75 is directed to the interior of the tank
100. The
stem portion 35 of the vent pipe 30 is then mounted into the neck portion 65
of the
upper chamber 55 as shown in Figs 2(a) and 2(b).
A vent whistle 40 is provided in the vent pipe 30 as illustrated in Figs. 2(a)
and 2(b). During filling of the tank 100, the vent whistle 40 provides a
change in an
audible signal when the fluid in the tank 100 has reached a particular level.
A tank 100 provided with a shutoff valve assembly according to an
embodiment of the present invention is shown in Fig. 3. As seen in Fig. 3, a
tank 100
has a fill pipe 5, fluid level gauge 25, and a vent pipe 30 on the top portion
thereof.
An outlet 15 is provided on the lower portion of the tank 100 and is connected
to a
supply line 20. The fill pipe 5 is closed with a removable cap 10 when not in
use.
The whistle 40 provided in the vent pipe 30 indicates the fuel level when the
tank 100
is being filled. A shutoff valve assembly comprising a housing 50 and a valve
75 is
disposed in the vent pipe 30 such that the valve 75 is exposed to the interior
of the
tank 100.
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A flexible metal hose may serve as the supply line 20. The advantage of
having a flexible metal hose as the supply line 20 is that in the event that
the tank
100 is tilted or toppled, the supply line is not easily cut off, thus
preventing a spill.
Furthermore, the cap 10 may be screwed on to the fill pipe 5 and sealed up
with a
rubber gasket or the like. In addition, the cap may be locked by a butterfly
screw.
The fill pipe 5 is thus sealed to prevent any spills.
The shutoff valve assembly of the present invention may be manufactured
using a host of natural and synthetic materials. These may include, but are
not
limited to, alloys such as brass, bronze, steel; metals such as, copper, iron,
aluminum, titanium; and, synthetic materials such as plastic, poly-carbons,
fiber
glass, etc.
In an alternate embodiment of the present invention, the shutoff valve
assembly can be combined with a fiexible hose adapted for connection to an
outlet of
the tank and a replaceable cap for the fill pipe to provide a safety kit for
tanks.
Although specific embodiments refer exclusively to a fuel tank, it will be
appreciated by those skilled in the art that the invention may be employed for
any
storage tank that requires a similar shutoff protection. As will be apparent
to those
skilled in the art, many alterations and modifications are possible in the
practice of
this invention without departing from the spirit of the essential
characteristics thereof.
The present embodiments are therefore illustrative and not restrictive.
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