Note: Descriptions are shown in the official language in which they were submitted.
W~ 9/05234 PC'TlI1S94109242
IS~° CO C R I
FIELD OF THE INVENTION
The p~°es~nt app~.~.c~ti~n relates t~ ~ a.st
HACRGR0UrID OF THE IPT~IENTI0I3
1
~~ 9/05234 ~~ ~ N I~(C~'/~JS~~1/092~2
A sysge~a~.dely g~ apse f~r per~s~1 ~~t c~~11~~~~~~
in some of the oil being forced through the bags,
contaminating the downstream air.
Consequently, these filters have a generally
declining efficiency as the oil collects in the filter.
As a result of the declining efficiency, the pressure drop
across the Filter does not increase, makir_g it difficult to
determine when the filter needs to be replaced. Disposal
of such filters is also difficult because of environmental
concerns over their oil content.
SL'?~MARY CF T'_~E I?~iE~T'_'CIV
The present filter system collects airbcrr_e
liquids in a filter media having vertical pleats wit:n a
separation therebetween. The separation between the
vertical pleats is maintained by a pleat spacing
arrangement. The filter media is treated with a low
surface energy material so that liquids contacting the
inner or outer surface of the media agglomerate and drair_
downward along the vertical pleats.
The low surface energy coating is preferably an
aliphatic fluorocarbon.
Liquid which accumulates on the inner surface of
the filter media drains downward into a bottom cover where
it is diverted away from the downstream air.
The filter media prevents airborne lic_ruid from
entering the downstream air. Consequently the
r~E~
_ ~~E~9~~
filter media has a predictable change in pressure across
the filter media over time. The predictable nature of the
change in pressure across the filter media allows for
predictive maintenance of the filter cartridge.
S The filter cartridge may include a pre-filter wrap
extending around the outer surface of the filter cartridge
to cause the formation of larger droplets of the airborne
liquid or_ the pre-filter wrap. These larger droplets more
easily drain off of the filter cartridge.
0 A variety of pre-filter wraps are contemplated,
including high loft air-laid or dry-laid materials, fully
open cellu~~.a= f~.ltra~ion foams, and fiber glass wool
products.
The filter cartridge retenticr_ system relates tc a
15 mechanism for releasably retaining a filter cartridge w=thin
a filtration system between an operational position and a
released position.
A support member is pivotally attached at one end
within the filtration system for supporting the filter
20 cartridge. End stops are provided on the support member for
retaining the filter cartridge in proper aligr_ment with an
exhaust port in the filtration system. A handle is
pivotally attached to the free end of the support member so
that the support member can be moved between a generally
25 horizontal operational position for engaging the filter
9
~Ir~E~~~~~
Image
~~ 9510523 ~ ; } l~c~~'/t~ls~~I/09~~s~
Figure 2 is ~ perspective view ~f ~ pr~f~r~°~~
filter cartridge retenti~n mechanism in the ~perat,a~nal
p~siti~n~
Fagure 3 as a perspective view ~f a preferred
falter cartridge retenti~n echanasm an tae reclaned aid
released p~sati~ng
Fi re ~ is a perspective view ~f ~ne a ~diment
~f the mist c~llect~r cartridge wath a multiple layer pre~
falter wrapo
~.0 Figure 5 is a t~p vaew ~f the mist c~llect~r
cartridge ~f Figure 4;
Fgg~xre 6 as a sects~aaal vaew ~f ghe pgeferred ~aast
c~llect~r cartridge sang multiple layers ~f n~n~~~ve~a aar~
laid material as a pre~filter wrap~ and
Fi re 7 is a fl~w chart ill~astrata~g the meth~d
~f manufacturing the preferred. mast c~llect~r cartradgeo
DETAIIaED DESCRIPTI~N ~F TFiE PREFERRED F.RM3~I~T~E
Figaare 1 illustrates a mist c~llecta~n system 1~
~0 fcr use with the preferred mist ccllectcr cartrade~e loo ~t
preferred falter cartridge retenta~n mechanasm 14 and ~aast
c~llect~r cartridge 12 nay be used in any suatahle
Image
~'~ 95/0523 ~~ ~ r; I~fC~'/13T~~~I0~2~~
retaaned ~n the ~~~er ch e~ 20 ~f the ~.~st ~~~2.~c~:~~~a
PC'TILT~94/09242
~V~ 95105234
horizontal position, the support members are angled
56
downward toward ~4 to allow easy
the door insertion or
removal of a mist collector The handle
cartridge 62
~.2~
operates as an extension 68 of the support members 56
to
20 facilitate insertion and removal of a mist collector
9
Image
W~ 95105234 ~ P~'~'11E11S94109242
The pre-filter wrap 91 may be constructed of a
foamed urethane material, also referred to as a fully open
cellular filtration foam. A foam material suitable for
this purpose is available under the trade n a Filter Fo
from Scott Foam Inc., Chester, P~.. The outer wrap 92 is
approximately 100 pores/inch. In operation, the foamed
urethane wrap 91 holds liquid, but does not build
resistance to air flow.
Figure 6 illustrates a sectional view of the
preferred mist collector cartridge 12' of the present
invention. The bottom end cap 90 preferably has a sloped
portion 100 which allows oil that is collected on the inner
surface 102 of cartridge 12~ to drain through filter media
104 and into the hopper 40.
The filter media 104 preferably comprises a
synthetic glass and polyester material arranged to fo a
cylindrical pleated filter cartridge. The filter media 104
preferably has a high efficiency, between 70 and 90 percent
at .778 micron particles.
To keep pleats 107 correctly spaced, the filter
media 104 is scored to create alternating rectilinear line
portions 118 and curvilinear line portions 120. wring the
11
CA 02169471 2004-10-26
corrugation process, dimples 109 are integrally formed in
the filter media 104 along the pleat tips 106 to maintain
the spacing between the pleats 107. Construction of a
corrugated filter media of this type is disclosed in U.S.
Patent No. 4,452,619, issued to Wright et al. on June 5,
1984.
As will be discussed below, as dirt and oil
accumulate on the filter media 104, the media 104 become
partially clogged so that the air flowing through the
filter media 104 accelerates to create additional pressure
on the filter media 104. In order for the filter media 104
to withstand the increased pressure, the pleats 107 are
preferably space more closely together than on an air
filter, giving the filter media 104 additional structural
integrity. Because pleats on an ordinary air filter are
generally spaced further apart, they would probably
collapse under the air pressure in the present mist
collection system.
The filter media 104 is preferably a low surface
energy synthetic fiber matrix constructed from fibers
having a thickness of less than .030". The filter media
104 may be treated with a low surface energy material,
such as an aliphatic fluorocarbon. One low energy coating
suitable for this purpose is sold under the trade name
Scotchguard~ or Scotchban~ Protector, by 3M Corporation,
St. Paul, MN. Scotchban~ Protector is described in
brochure entitled Introducing FX-845 Scotchban Chemistry
Takes On A New Life, dated 1991. Low surface energy
coatings and low surface energy materials create a low
surface energy on the filter media 104 which facilitates
agglomeration of the oil and promotes drainage. The pre-
12
CA 02169471 2004-10-26
filter wraps 91, 110 may also be treated with a low
surface energy material.
As is illustrated in Figure 6, the filter media 104
is preferably recessed or set back from the inside surface
of the outer liner 88 so that a space 89 is formed between
the outer liner 88 and the filter media 104. The space 89
allows most of the oil that penetrates the pre-filter wrap
91 to form droplets on the inside surface of the pre-
filter wrap 91 or the outer liner 88, rather than on the
filter media 104.
The pleats 106 are arranged vertically in the
cartridges 12, 12'. The filter media 104, and inner and
outer liners 86, 88 are retained in the top and bottom end
caps 82, 90 by a filter media adhesive 108, such as
plastisol. The hook portion 96' of a fastener material may
be retained between the outer liner 88 and the top end cap
82 around the perimeter of the mist collector cartridge
12' by the adhesive 108. The pre-filter wrap 91 may then
be attached directly to the mist collector cartridge 12,
12'
Oil mist too fine to collect on the outside surface
of the filter media 104 may emerge on the inner surface
102 of the pleats 106. The vertical pleats 106 allow
liquid collected on the inner surface 102 to drain
downward onto the bottom end cap 90 of the cartridges
12,12', where it passes through the filter media 104 and
into the hopper 40.
The filter media 104 is preferably constructed
according the flow chart illustrated in Figure 7. The flat
filter paper stock is preferably dipped in a low surface
energy coating material 130, such as an aliphatic
fluorocarbon. It should be understood that the paper stock
13
CA 02169471 2004-10-26
may be treated or wetted by a variety of methods,
including spraying. The excess coating material is removed
by compressing the coated paper stock between a pair of
compression rollers 132. The coated paper stock is then
dried in a convection drying oven 134.
Prior to pleating, the paper stock is corrugated 136
by pressing a series of grooves lengthwise along the paper
with a heated roller. The paper stock is then pleated 138
to form the filter media 104 and inserted into a filter
housing 140. The preferred corrugation process is
disclosed in U.S. Patent No. 4,452,619, issued to Wright
et al. It will be understood that the cylindrical filter
cartridge illustrated herein is set forth by way of
example only and that a variety of filter configurations
are possible. For example, generally planar filter
cartridges having suitable drainage mechanism may be used
in place of the cylindrical cartridge.
Figure 6 also illustrates the preferred pre-filter
wrap 110 of the present invention. The pre-filter wrap 110
is preferably constructed of multiple layers of non-woven
air-laid mediums, such as high loft air-laid or dry-laid
materials. Because of the nature of the pre-filter wrap
110, it may be attached directly to the hook portion 96'
without the use of the mating hook-portion.
In the preferred embodiment, the outer pre-filter
layer 112 is approximately 0.75" of open material having a
density of 6.7 ounces/sq.yd. and a solidity of 0.8%. A
product meeting these specifications is sold under the
trade name Airlaid Media by Comulus Fiber Corp. located in
Charlotte, NC. The two inner layers 114,116 are
approximately 0.25" of a high efficiency material having a
density of 3.62 ounces/sq.yd. and a solidity of 1.60. A
14
CA 02169471 2004-10-26
product meeting these specifications is available from
Chemwove Corp. in Charlotte, NC.
The preferred pre-filter wrap 110 accumulates oil 25
during operation of the mist collection system 10. As oil
accumulates, the pressure drop across the filters 12,12'
15
25
15
Image
not absorb the oil, but instead separates it and drains it
off so that it can be collected and disposed of apart from
the filter 12. In some applicaticns, it is pcssible to
recycle the collected fluid.
Further, because the filter media 104 is pleated,
it has a large surface area which allows air flowing
through the media 104 to move at a low velocity, reducing
the tendency of oil to be blown off the inner surface 102
of the filter 12 into the downstream air.
In the preferred embodiment, the efficiency and
pressure drop across the cartridges 12, 12' increase cver
i , r"" cartrir'ga 12, 12' fvinction ~Or a
ti me . _he m_st coi~.ect~,L ..
long period of time because the media 104 does net become
sa~.urated with oil. As the filters 12, ,~.2' become clogged
with dirt and other particulates, and t:2e pressure drcp
across the filters 12, 12' increases. Therefore, t:~e
pressure drop across the filter 12, 12' corresponds to the
amount of useful life remaining in the filters 12, 12',
which can be used to indicate when the filters 12, 12' need
to be replaced.
It will be understood by those skilled in the art
that the present inventions are not limited to the examples
discussed above, but may be changed or modified without
departing from the spirit or scope of the invention. For
example, a wide variety of filter cartridge configurations
may be used in cembinaticn with a variety of drainage
17
A,~~,~r.~ ~T
w ~ <u:_'~ ~~t
Image
