FILTER CARTRIDGE SEALING METHOD

MOYEN DE FERMETURE ETANCHE D'UNE CARTOUCHE DE FILTRE

English Abstract

The present invention is directed to a filter
cartridge that provides for a secure dust tight seal and is
easily inserted and removed from a filtration unit. The
filter cartridge comprises a cartridge unit having a filter
element, a bottom cap and a top boot and a sealing sleeve
for insertion into the interior of the top boot. The top
boot has an outside diameter which is slightly smaller than
the inside diameter of the opening in a tube sheet into
which the filter cartridge is to be inserted so that the
cartridge may be easily inserted into and removed from the
opening in a tube sheet. The top boot is also provided
with a sealing ridge, which is located in the inside of the
boot at the sealing point. The inside diameter of the
sealing ridge is smaller than the cartridge boot and the
sealing sleeve. When the sealing sleeve is inserted into
the cartridge boot, the sealing sleeve contacts the sealing
ridge and causes an increase in diameter of the sealing
ridge. This in turns causes the sidewall of the cartridge
boot to balloon outwardly to contact the side of the
opening in a tube sheet and form a dust tight seal around
the opening in the tube sheet into which the filter
cartridge is inserted. To remove the cartridge from the
unit the sealing sleeve is removed from the cartridge and
than the cartridge is easily lifted out of the unit.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A filter cartridge having a secure dust tight seal
and being easily inserted and removed from an opening in a
tube sheet of a filtration unit, the filter cartridge
comprising a cartridge unit having a filter element, a
bottom cap and a top boot constructed of a flexible
material, and a rigid sealing sleeve for.insertion into the
interior of the top boot, the top boot having an outside
diameter which is slightly smaller than the inside diameter
of an opening in a tube sheet into which the filter
cartridge is to be inserted so that the cartridge may be
easily inserted into and removed from the opening in a tube
sheet, the top boot further having a sealing ridge, located
in the inside of the boot at the sealing point, the inside
diameter of the sealing ridge being smaller than the top
boot and the sealing sleeve, whereby when the rigid sealing
sleeve is inserted into the top boot, the said sealing
sleeve contacts the sealing ridge and causes an increase in
diameter of the sealing ridge which in turn causes the side
wall of the top boot to balloon outwardly to contact the
side of the opening in a tube sheet and form a dust tight
seal around the opening in the tube sheet into which the
filter cartridge is inserted.
2. A filter cartridge according to claim 1 wherein the
side wall of said top boot is constructed of a flexible
material selected from the group consisting of urethane,
polyurethane, fluorocarbons or silicone compounds.
3. A filter cartridge according to claim 2 wherein
said rigid sealing sleeve is made of plastic or metal.
4. A filter cartridge according to claim 1 wherein
said top boot comprises an outer rim extending radially
outward beyond said side wall to provide support for the
cartridge when it is inserted into the opening in a tube
sheet wherein the side wall has an outside diameter, which

is less than the inner diameter of the opening of the tube
sheet and a contour that allows it to fit into the opening
of the tube sheet.
5. A filter cartridge according to claim 4 wherein the
side wall of said top boot adjacent the outer rim has an
inside diameter which is greater than the outside diameter
of the sealing sleeve.
6. A filter cartridge according to claim 1 wherein
said sealing ridge is made of a material that provides for
an expansion of the outside diameter of the side wall of
the top boot when the sealing sleeve is inserted into the
top boot.
7. A filter cartridge according to claim 6 wherein
said sealing ridge is a spring.
8. A filter cartridge according to claim 6 wherein
said sealing ridge is made of urethane, molded rubber or
silicone.
9. A filter cartridge according to claim 3 wherein the
sealing sleeve includes a tapered section that assists in
expanding the sealing ridge.
10. A filter cartridge according to claim 1 wherein
said sealing sleeve has an outside diameter that is larger
than the inside diameter of the sealing ridge.
11. A filter cartridge according to claim 10 wherein
sealing sleeve has a locking recessed groove located on the
outer wall of the sealing sleeve.

Description

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TITLE: FILTER CARTRIDGE SEALING METHOD
FIELD OF THE INVENTION
The present invention relates to cartridge filters,
and in particular to a means of sealing the cartridge
filters.
BACKGROUND OF THE INVENTION
Improvements in air quality through reduction of air
born pollutants has become increasingly important. One of
the most common methods of controlling air pollutants in
industry is the use of fabric filtration. The most widely
accepted system for controlling air pollution is the
baghouse which has the same operating principle as a vacuum
cleaner. In a baghouse or vacuum cleaner, dirty air is
drawn into the unit with a blower or fan, the dirt is
collected on the filtering media and clean air is then
discharged from the system. The collected dirt is then
removed from the system and disposed. Baghouses typically
employ a tubular bag as the filtering element. In this
type of system one end of the tubular bag is closed while
the other end is sealed into a tube sheet. The tube sheet
is the part in the baghouse which provides a physical
barrier between the sections of the baghouse containing the
dirty air stream and the clean air stream. In order to
maintain this physical separation, the filter element must
be sealed to the tube sheet to prevent passage of dirt
through the seal. Various methods have been proposed to
seal the tubular bag into the tube sheet. The two most
common methods are the use of a snap ring or a common hose
clamp.
Recent advancements in cartridge filter media have led
to the replacement of the baghouse tubular bags with
cartridge filters. In order for the cartridge filter to
perform at its peak collection efficiency, the cartridge
seal must be dust tight. Cartridge filters also require
occasional replacement or removal for inspection and to
facilitate the removal of the cartridges for inspection or
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replacement, this dust tight seal must be easily broken.
Since cartridge filters are a rigid structure and not
flexible like a filter bag, providing a dust tight seal
between the cartridge and tube sheet as well as providing a
method for easy removal of the cartridge presents a problem
and there have been many solutions presented.
Earlier attempts at sealing the cartridges into the
tube sheet utilized sections of the tubular bags. In one
design the top of the tubular bag, or "cuff" as it is more
commonly known, was cut off and sealed into the tube sheet
as it normally is. A cartridge dust tight seal was
achieved by mounting a metal tube with an outside diameter,
which is slightly larger than the inside diameter of the
cuff onto the top of the cartridge and then pushing the
cartridge into the cuff. This system did provide a dust
tight seal; however, it was very labor intensive to install
and costly to manufacture. An alternate design utilized a
rubber boot, which was attached to the top of the cartridge
with a hose clamp. The opposite end of the boot was than
attached to the tube sheet with a hose clamp. This system
did provide a dust tight seal; however, it is very labor
intensive to install.
Another sealing method was proposed in United States
Patent number 5,632,791. In this design the upper sleeve
of the cartridge is formed of a flexible material which has
a slightly larger outside diameter than the inside diameter
of the hole in the tube sheet. To insert the cartridge
into the tube sheet the upper sleeve is deformed, typically
into a figure "8", the cartridge is placed into the hole in
the tube sheet and then the sleeve is allowed to relax.
The dust tight seal is achieved because the sleeve's outer
dimensions are slightly greater than the opening in the
tube sheet so that the top sleeve is slightly compressed
when the sleeve is snugly fit into the opening in the tube
sheet. This design relies on the resilience of the
material in the flexible sleeve to provide a dust tight
seal. In most cases an adequate seal is provided however,
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if there are any changes in the physical characteristics of
the flexible sleeve due to aging, temperature or chemical
attack, the seal could be compromised. Removal of this
design of cartridge can be very difficult since the sleeve
must be deformed in order to break the seal.
There thus remains a need for a means of securing and
sealing a cartridge filter to a tube sheet to provide for
both a dust tight seal and easy removal of the cartridge
filter for inspection and replacement.
SUMMARY OF THE INVENTION
The present invention is directed to a filter
cartridge that provides for a secure dust tight seal and is
easily inserted and removed from a filtration unit. The
filter cartridge comprises a cartridge unit having a filter
element, a bottom cap and a top boot and a sealing sleeve
for insertion into the interior of the top boot. The top
boot has an outside diameter which is slightly smaller than
the inside diameter of the opening in a tube sheet into
which the filter cartridge is to be inserted so that the
cartridge may be easily inserted into and removed from the
opening in a tube sheet. The top boot is also provided
with a sealing ridge, which is located in the inside of the
boot at the sealing point. The inside diameter of the
sealing ridge is smaller than the cartridge boot and the
sealing sleeve. U~hen the sealing sleeve is inserted into
the cartridge boot, the sealing sleeve contacts the sealing
ridge and causes an increase in diameter of the sealing
ridge. This in turns causes the sidewall of the cartridge
boot to balloon outwardly to contact the side of the
opening in a tube sheet and form a dust tight seal around
the opening in the tube sheet into which the filter
cartridge is inserted. To remove the cartridge from the
unit the sealing sleeve is removed from the cartridge and
than the cartridge is easily lifted out of the unit.
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CA 02236517 2000-03-20
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention is
illustrated in the attached figures in which:
Figure 1 is an exploded cross sectional view of a
preferred embodiment of a filter cartridge and sealing
sleeve of the present invention for installation ~in a
typical tube sheet;
Figure 2 is a sequence of drawings, which
illustrates the installation and removal procedure for the
filter cartridge of Figure 1;
Figure 3 is a cross sectional view of the filter
cartridge and sealing sleeve of Figure 1 installed in a
tube sheet;
Figure 4 is a detailed cross section of the sealing
action when the sealing sleeve is inserted into the filter
cartridge of Figure 1; and
Figure 5 is a detailed cross section of the filter
cartridge and sealing sleeve of Figure 1 installed in an
alternate tube sheet arrangement.
_DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of a cartridge filter according
to the present invention is illustrated in Figures 1 to 5.
The cartridge filter has a cartridge B and a sealing sleeve
A. The cartridge filter is adapted to be inserted into an
opening in a section of tube sheet C, which is commonly
used in dust collectors. The opening in the tube sheet C
has an inside diameter of D1.
A section of a typical cartridge B and sealing sleeve
A is illustrated in Figure 1. The cartridge is typically
constructed of a bottom cap 5, inner core 6, pleated filter
media 7 and top boot 1.
The bottom cap 5 provides an air tight seal for the
bottom of the cartridge B and can be made of any sealing
material. For instance, the bottom cap 5 can be made of
urethane, polyurethane, fluorocarbons, silicone compounds
or metal caps sealed to the bottom of the cartridge B.
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The inner core 6 provides structural support for the
cartridge B. It is generally tubular in shape, runs the
full length of the cartridge B and is embedded into the top
boot 1 and bottom cap 5. The inner core 6 can be made of
any porous material such as expanded metal, plastic or
metal screening.
The pleat pack 7 may be constructed of any
conventionally known filtering media. In most cases the
filter media is pleated and runs the full length of the
cartridge filter B.
The top boot 1 may be constructed of urethane,
polyurethane, fluorocarbons, silicone compounds and the
like so long as the material forming the top boot 1 is
flexible and will expand outwards when the sealing sleeve A
is inserted into it as will be described further below.
Beginning at the top, the cartridge boot includes an outer
rim 2 extending radially outward beyond an outer wall 8 to
provide support for the cartridge B when it is inserted
into the opening in the tube sheet C. The outer wall 8 is
constructed so that it can be easily inserted into the
opening of the tube sheet C. The outer wall 8 has an
outside diameter, which is less than the inner diameter D1
of the opening of the tube sheet C and a contour that
allows it to fit into the opening of the tube sheet C. The
inner wall 9 adjacent the outer rim 2 has an inside
diameter D2 which is greater than the outside diameter D3
of the sealing sleeve A. This allows for easy insertion of
the sealing sleeve A into the opening of the top boot 1.
An integral part of the top boot 1 is a sealing ridge 4
located at the point of sealing. The sealing ridge 4 can
be made of any material so long as it provides for an
expansion of the outside diameter of the wall of the top
boot 1 when the sealing sleeve A is inserted into the top
boot 1. Some typical materials are a spring, urethane,
molded rubber, silicone etc. The sealing ridge 4 has an
inside diameter of D4.
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The sealing sleeve A is a rigid part that can be made
of metal, plastic or the like. Beginning at the bottom,
the sealing sleeve includes a tapered section 10 that
assists in expanding the sealing ridge 4. The outer wall
11 has an outside diameter D3 that is larger than the
inside diameter D4 of the sealing ridge 4 and generally
conforms to the contour of the inside of the filter boot 9.
The outside diameter D3 of the sealing sleeve is such that
when it is inserted into the filter boot 1 the outer wall
11 expands the boot sealing ridge 4 and in turn bulges the
boot's outer wall 8 to provide a seal against the tube
sheet C, as shown in FIG. 3 and FIG. 4. A locking recessed
groove 3 is located on the outer wall 11. This locks the
sealing sleeve A into the cartridge B when the sealing
sleeve A is inserted into the cartridge B.
With reference to the drawings in FIG. 2 and the
cross sectional view in FIG. 1, the installation procedure
is as follows. A filter cartridge B is placed into the
tube sheet C, the filter is pushed down so that the filter
boot's outer rim 2 rests on the tube sheet C. The sealing
sleeve A is then inserted into the cartridge B and pushed
down into the interior of the cartridge. As the sealing
sleeve is pushed into the cartridge the sealing ridge is
contacted by the lower tapered section, causing the sealing
ridge 4 to expand in diameter as the sealing sleeve
continues to enter the cartridge. The expansion in the
diameter of the sealing ridge in turn causing the outside
diameter of the top boot in the region of the sealing ridge
to increase, bulge outward and come into contact with the
tube sheet C. The sealing sleeve is pushed into the
cartridge until the sealing ring snaps into the sealing
sleeve locking ring 3. The filter is now sealed at the
contact point between the tube sheet and filter boot.
To remove the cartridge from the unit, the seal is
first broken by removing the sealing sleeve A, and then the
cartridge B is pulled out of the unit.
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A variation of the opening in the tube sheet is
illustrated in Figure 5. The opening in the tube sheet is
a punched hole as opposed to a drawn cup of the opening
illustrated in Figures 1 to 4. In this case the sealing
ridge would be located just below the tube sheet. In this
design the outer wall of the cartridge boot would bulge out
just below the tube sheet and it would form a lock and seal
at this point.
In the preferred embodiments illustrated, the sealing
ridge is shown as a separate element; however the same
effect could be obtained by molding any flexible material
into the boot. For example, a radial ridge could be molded
out of the same material as the boot and it will give the
same effect as the spring, as illustrated in all of the
figures.
The present invention provides for an improved filter
cartridge having a secure dust tight seal while being
easily inserted and removed from a filtration unit. The
top boot of the cartridge unit with an outside diameter
slightly smaller than the inside diameter of the opening in
a tube sheet into which the filter cartridge is to be
inserted provides for a filter cartridge which may be
easily inserted into and removed from the opening in a tube
sheet. The contact between the sealing sleeve and the
sealing ridge causes an increase in diameter of the sealing
ridge and the sidewall of the cartridge boot to result in
the sidewall ballooning outwardly to contact the side of
the opening in a tube sheet and form a dust tight seal
around the opening in the tube sheet into which the filter
cartridge is inserted. The cartridge is easily removed
from the unit by removing the sealing sleeve from the
cartridge and then the cartridge is easily lifted out of
the unit.
Although various preferred embodiments of the
present invention have been described herein in detail, it
will be appreciated by those skilled in the art, that

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variations may be made thereto without departing from the
spirit of the invention or the scope of the appended
claims.
g

Representative Drawing