CA1130221A - Drain layer for coalescing filter tube assemblies - Google Patents

Abstract

ABSTRACT OF DISCLOSURE
The specification discloses an improved wrapped fiber felt drain layer for use in conjunction with one or more filter layers and/or a plastic retaining tube, in whatever order desired, to provide improved drainage for coalescing filter tube constructions. The wrapping of said drain layer is not limited to circular filter tubes, but may be used on filters of square or rectangular cross section and the like, and also on filter constructions of pleated cross section, there being no practicable limit as to the cross section of the filter assembly on which the drain layer can be mounted. Additionally, such drain layers can be used both on in-to-out and out-to-in filter constructions.

Description

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The pre~ent lrlve~ion relaces to draln layer~ for fllter assem-blies, and more partlcularly to a ~ynthetic flber fel~ ~rain layer whlch may be wr~pped about the ~therwise completed fllter tube asBembl~elB and '~ ~

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to such a drain layer which rnay be manufactured in place as a part of a pleated filter tube assembly. During the research which led to the discovery of the advantages of formed in place and/or wrapped glass fiber drain lavers for compress~d gas filter appl'ications, it was discovered that synthetic fiber felt drain layers also produced significant benefits when used in more conventional filter construcF
tions not subject~to the high temperatures.
Basically, in the compressed gas field, one will fina ~' filters which are subjected to high temperatures when they are placed next to the source of the air,such as an air compressor. The - other type of filter application involves smaller filters placed at the point of use of the air supply such as immediately'before an air operated router, turbine, etc., or placed at the intake of testing devices, such as devices for measuring hydrocarbons and~
carbon monoxide in exhaust gas analysis, and there are many othér types of applications toonumerous to mention herein.
However,~a problem common to at least some of these applica-tions concerns the advent of the need to use such compressed gas filters in envirOnments which are contaminated with synthetic oils such as used in modern air compressors or other contaminants which are destructive to the foam drain layers commonly used on filters.
Such drain ~3~2~L

layers, even ~hough no~ ~ub~ec~ed ~o hl~h temperature~ will begin to dislntegrate rapldly under ~he ef~ec~ of ~yn~hetlc oil~. One ~uch foam drain layer I am fam~1iar wl~h i~ made of an open celled ur~th~ne foam and i9 u~ually applied ln ~ ~leev~ over a fllter tult:~e in a layer thlckne~s of from .12S ~o .150 inche~ h~s draln layer 18 used with olther tha vegetable and m~neral oil~, ~ will rap~dly dl~lntegrate, and in any event can o~y stand temperatures up ~o 140 F, whlch i~ much le~
~han our fil~er can tolerate.

Fur~hermore, ~uch draln lay~r~ as men~loned are ln the ~orm of an expandabl~ ~leev~ placed o~r the ou~lde of th~ fllter con~eruction by a slight expaD~lon, and thu~ ~uch draln layer~ do not e~rt grf3at pre~ure on the fiker body and are ~ubject ~o separation and channeling problem~, Another problem with such foam draln }ayers ~arne ln filter applica~lon~ wherein lt i8 nece~ary to have a high flow ~hrough a rela-tlve1y small fllter area, In thl~ ca~e ehe i~lter material lt~elf was plea:ted by pleating machine~ well known ln the a~, ~uch a~ ~qodel No. 101 manu~actured by the Chandle~ Manu~cturlng Co. of New York, New York, ~nd the pleated circular ~ilter then had a conventional foam drain layer placed there over. However, instead o~ solving the problem of how ~o malce a filter w~th a greatly increaaed fll~e~ing area whlch could handle hlgh flows w~th a rela~lvely 6mall ~lze, this con~trucl:lon completely negated any advantage of the plea~ed fllter construction becauje the foam only contacted ~he filter layer~ at the ed~e~ o~ ~he pleat~, and could not dralrl the ~n~rea~ed ~llter area, arld Ul:ltil the presen~ ventlon there was ~3-~3~22~

no way ~o have a d.alll layer, foain or otherwlse, in co~a~acE wl~h ~he en.ire sur~ace o~ ~he plealts, and ~hus such plea~ed ~ ex~ were sev~rely lilruted in ap-pllca~lon, The pre~en~ applica~ion dlscloseæ a me~hod of manu~c~urln~ a pleated ~ibPr glass ~l~er wi~h a fiber ~el~ draiLn lay~r in intimc~e con~ac~
wi~h ~Ae ~ er layer over ~he en~ire ~ur~ace area of ~he ple~ed la~er.
Thu~, our plea~ed drain la~re~ construe~lon ~olve~ thls long s~md.in~
problem ill the a~t and allow~ an ef~c~en. plea.ed ~ er con~truc~.Lon, as well as solving the problem in ~he ar~ of 110W to supply a fll~er for high ~empera~ure and/or remo~e appllcation whlch can ~and up to ~ynthetic oil~ and other a~mo~ph~rlc con~amLnen~.

Thus, one o~ ~he ob~eccs ~ ~h~ p~ent lnv~ntlon i~ ~o provlde a filter con~ruction whereln a ~tanda~d ~ er tube 1~ wrapped with ~everal layers of a syn:he~lc ~iber f.elt ~hich i8 sui~ably secured ~hereto ~o provlde ~ filter capable o~ wi~hst~ndin~ high eempe3:a~u~e~ and atmos-pheric or o~her contaminent~.

~ Pu~ther o~ec~ o~ ~he pre~en~ inven~ion i~ ~o provlde a pre -er-precoale~cer fll~er ~ub~ con~ruc~lon havln~ a ~ynthe~lc fl~r felt dr~in layer o~ the above cons~ruct~oll wxapped about ~he periphery ~hereof to provlde a ~l~er capa~e of w~thstandin~ ~yn~hetic oll~.

A fu~her ob~ect o~ ~he p~e~en~ in~en~io~ o p~ovide an improved drairl layer ~o~ ~ilter 'CU~8 cal2able 0~ withs~anding high tem~
pera~ures and coIl~aminen~ sommonly Iound ln air supplies used in lndus~ry,.

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A stil~ fuir~her objec~ o~ ~he pre~erlt inve~ion ls ~o provide a pleated filter cons~rllcEion having a s5~hetic ~i~er :~el~ drain layer ~n in~ima.e contac~ with ~he entire 3urface area of ithe o~ter layer of the ~ilter ~o provide an ef~icien~ drain layer for such ~er.

A s~lll fur~her obJec~ o~ the present inven~ion i~ to pxovide an lmproved drain layer which can easily be applled ~o fil~er ~u~es of all ~ypes and ~i~es, ~ st~ll further object o~ ~he present inven~lon ls ~o provlde an improved draln layer, ancl fll~er construc~ion utUlzlng the ~ame, whlch ia xelatlvely sirnplc~ ~n nature and lnex~rl~ive ~o manu~actur~.

lFurther objec~s and advansa~ea o~ our invention wi~l be apparen~
~rom the following description and appended clalm~, xe~3rence beln~
made to the accompanying draw~n~ ~orming a par~ of the ~peci~cation, wherein llke re~erence characters designate corre~pol~ding parts in ~he several vlew3.

Flgure 1 ia a cu~away perspec~ vlew o~ a cons~ructiorl ernbodying ~he pre~ent inren~lon showin~ our novel comblna~ion of a fll~er tube with a wrapped syn~he~lc ~iber felt dr~in layer.

Figu~e 2 is a cut-away perspec~ive vlew ~imilar in part to ~igure 1, but showing in addition a rigid perforated re~ainer ln~erpo~ed ~etween ~he ~ilter tube and ~he wrapped ~ felt drairl layer.

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Figure 3 i~ a cut-away perspective view of a cons~ruction embody~ng our inventlon sho~in~ a pre ~ll$er lay~r, a gl~:er 13yer and a wrapped ~iber fel~ drain layer ~orming a ~lter con~ructlon~

Figure 4 is a view subs~an~i~lly similar ~o Figure 3, buE
showing in addition a rigid per~ora~ed ~etaining tube in~erpo~ed ~etween ~he ~l~er layer and th~ he~ic ~r ~el~ draln layer of ~he filser con-s~ruc~ion.

Fi~ure 5 ls an eleva~lonal view of a fll~er coII~truc~ion havlng a pleated cro~ sec~io~l~

Figure 6 is a ~ectional view o~ the con~t~uctlon shown in Figure 5 ~aken in the direc~lox~ o~ ~he arrow3 along the Sectlon lllle 6~6 o~ ~;'lgure S.

Fig;ure 7 i8 a plan vlew similar ~n part to tha~ shown ln Flg-ure 5, bu~ ~howln~ the construction o~ Fi~u~e 5 inserposed between ~n inner and an ~uter porous re~aining ~ube.

Flgure 8 is an e~larged view of the area o~ the fil~er indicated by the numeral 8 in Pigure 7.

Fl~ure 9 1~ a dlagramma~lc view o~ a proce~ whlch may be used ~o manu~ac~ure one o~ :he embodimenE~ o~ ~he pres~nt invent~on.

~ ig~re 10 i~ a ~eclional v~ew take~ he ~rection of the arrow3 along ~he 5ection llne 10~10 o~ ~lg~re 5.

o be understood ~hat the inv~ ion is not limi~ed ln lt3 application to ~he deta~l~ o~ construc~lon and arxangeme~ of part~

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illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practised or carried out in various ways within the scope of the claims. Also, it is to be unde`rstood that the phraseology and terminology employed herein is for the purposes of description and not of limitation.
Referring to Figure 1, to practice the present invention one may make a rigid self-supporting filter construction or obtain a commercially available filter tube. Such filter tube with or without an outer retaining tube would be cut to the desired length.
One would then cut a pie~e of synthetic fiber felt, of which fiber glass is one variety of a width equal to the length of the filter tube and allow a slight overhand. It should be under-stood that any type of synthetic fiber felt may be used depending on the application intended for a particular filter construction~.
Although for purposes o illustration, fiber glass is sho~n, the use of polypropylene, nylon, and polyester drain layers and the like is clearly within the scope of the claims of the present appli-cation, In other words, one ~.~ould make the piece of synthetic fiber felt of a width slightly greater than the length of the filter tube, and one would make the length sufficient to go around the filter tube at least once, with twice being the preferred embodiment. To fasten the ~iber glass drain layer to the filter, one may use any practicable means, but the preferred method of doing the same is to place a web of hot melt glue of a suitable composition to bind the fibers together at one end of the fiber glass sheet, wrap said sheet about the filter and then heat the glue to seal the ends. Such process is generally called sideseaming in the art.

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A drain layer made ou~ of ~lber gla88 i~ suitable ~or tem~era-~ures to about 450 F. If i~ i~ de~lred tha~ ~he dxain l~yer flbers be re~rlcted ~rorn migratlon, a wrap oi non-woven rayon m~terial ~an be added dowIastream ~rom ~he glnss layer. Th~ rayo~a lay~r lim~t~ the applica~lon temperature ~o 300 F.

If extremely high ten~perature~ in ~he neighborhood o~ 400 F
will be erlcou~ered, or,e may cover the glas~ drain ~yer with a rayon polye~ter l~on-woven coml)ination and achle~ the ~ame re~ul~. These two an~lrmigra~on la~rs are pre~erred because they dralll like ~he fiber glaas draln laye~s.

To complete the fllter constructlon, wl~h the ~ber yiass drain l~yer one may add an ou~er layer o~ plaf~tic ~hrlnkable nettlng wh~ch can be applled in a manner well known ln ~he art by placillg a tube of plas~lc netting o~ larger d~ameter than the fll~er tube and shrinlcing lt in~o place. Al~o, if pre~erred, the ne~tlng may be chosen the right ~ize to be expanded, placed over the drain layer, and allowed to contr~ct to lt~
pre-expan~ion 8i2e. At thi~ point, one can trim ~he draln layer and ne~ting to the length of ~he ~lter, and thu9 complete the i~lt~r const~uction wlth our improved fiber gla~8 drain }ayer.

Tt should ~e under~eood that ~he properties of the ~ynthetic flber fel~ layer~ are lmportant ~o properly coale~ce the liquld pas~ing through the fllter. We have found ~at when a ~ynthetic fib~r felt ma~erial, 3uch as flbex g3a~s, which i~ thc preferred embodirnent, i~ cho~en in the range of ~om Itwelve to ~orty-fiY~ ~hou~ d~hs o~ an lnch in Shicknes3, alld hav-lng a de~siey of from 4. 44 to 17. 76 pounds p~r cubic ~oot and ~ r dlame-.

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ters o~ from 5 to 30 microns, a very satisfactory drain layerresults.
Depending on the intended application of the filter, the fibers can be bound by a wide range of binding agents such as a twenty percent urea formaldehyde, or epoxies, phenolics and the like.
A preferred construction for our drcJin layer utilizes a fiber glass sheet of thirty t~usandths of an inch in thickness, having a density of 8.88 pounds per cubic foot with fiber diameters of from 13 to 15 microns.
Now referring to Figures 1-4, various constructions using our improved drain layer are shown. Figure 1 shows a filter tube 10 which may be of conventional or be one with two layers of glass fiber 11 wrapped about the filter tube 10 and bound.
If a single stage filter having additional strength is required, an outerretainer 12 may be placed over the filter tube 10 and the wrap 11 then applied as mentioned. It should be understood that although it is preferred that two layers of glass fiber felt 11 be used about a filter for maximum efficiency, depending upon the job application fewer or greater number of layers of the glass fiber may be wrapped about the retainer tube 12.
Referring specifically to Figure 3, where a two-stage pre-filter filter construction is required because of the particular application ~' ~
~ ' g ~.

1~3~322 to whlch ~h~ fllter i~ ~o ~ appl~ a pre~llter ~ub~ 13 m~y ~ flr~
~uppil~d ~n~erlorly of ~he ~l~er ~u~ 10, wl~ e draiD layer 11 bel w~ap~d a~uL th~ exterlor ~ ~he fll~er ~ub~ 10 a~d ~3ecur~d i~ tl~
me~hod pre~ou~ly de~crl~dr For applica~lon~ ~equirlng high ~t~en~h arld exl:r~mely flne 11tratlon~, the colas~ructlon ~hown ln Flgure 4 may ~ u~ed hav~nOY a pre~ er tube~ 1~3 aupplled ln~e;rlo~ly of th~ fil~r eube 10 and havln&~ ~
peroraced re~alner ~ube 12 p1aced o~f~r th~ f~ter ~u~¢ lO. 'rhl~ would ~ followed by ~e w~ppl~3~ and ~ecur~; o~ th~ drain l~y~r ~ ~e~
viously d~c~ d.

It ~hould b~ llnder~t~4d that wh~t h~ een de~crlbed ~hua ~a~
1~ a ~llt~r dra~n layer for u~e wl~h a~ ~n-tvouc coal~cLr~ fileer~ How-ev~r, a rever~ l of the ~llt~ layer~ wher63 r~qul~ed 1~ ~omplet~1y wlthln thB BCOpe 0~ th~ p~e~en~ v~ntiol .

One pa~leular advanca~ o~ our pre~n~ con~t~uctlon wlll læcome e~ldsnt uporl a sho~t ~e~lp~ioll of ~he pr~lem which ~ro~
~he prlor art when a pl~ate~i fll~r was d~alrable t)ecau~e o~ til~ llece~ y fo~ hlgh ~ltra~lo~ area~ a~d ~low wl~h ~ ~e~at~v~ly ~ r.

In ~h~ prlor ar~ when a p~a~ed ~llter ~uch a~ chat ahown i~
Flgure 5 WU8 requlred, 1~ wa~ c:o1~mon ~o bav~ a pleate~ er core wlth ~ ~oam ru~er dxaln l~yer p~aced thereoYer. Asld~ ~rom the fact ~ha~

ae~ra1 appllca~ions~, ~uch as mode~n air corn~ress~r~ operatlng ~ hlgh temper~ure~ with ~ he~ic oll~, rapld dl~înte~atlo~ ~ ~UCil goan,~
ru~ber dr~in ïay~r re~ul~d, ~uc~ a ~on~truciiorl ha~ atlo~h3x ~ ou~ d~

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~dvantage~ Since the drain layer was slmply expanded and placed over the plea~ed ~lter core, only ~he e,xtrernltie~ of the filter cvre ~ouched ~he drain layer in a line ~o sur~ace contac~, and d;rainage wa~ only af~ected at rhose area~ o~ ~urface contact. Tbus, much o~ the exp~nded fi1ter area brought about by the pleatlng of ~he ~lter core wai3 not dralned ~t ~ alld the ~ffectlveness Or the expanded area ~v~n by the plea~ing wa3 comple~e1y lo~t because the unit area flow rates had to be recluced to pre~en~ ~luid carryover into the cleansed ga~ ~tream. A~ a re~ult, ~he l~rge area of the plea~ed unit6 could no~ be u~ed to com?etitive advsntage. However, we have now solved th~ problem by provldi~g for a synthetic fiber ~ek drain layer whlch ean be manuractured ~irnul~aneously wi~h ~he osher layer~ of a pleated ~ er. Rer~rrlng to Figure ~, there l~ ~hown in a slmpllfied dlagrarnmatlc v~ew a pxocess well known ln the art ~r mechani-cally formlng a multl-layered ~heet.

The flr~t step in the process o~ manufac~uring a ~lter construc-tion with our in~proved draln layex l~ to ~imultaneou~ly ple~ ~wo or three layer~ con~l6ting of a pre-filter 1ayer 15, if de~ired, and ln any event comprlslng a fllter layer 16 of the desired~, which may be from four to elght mlcrons ~liquid) abaolu~e, wi~h the pre-fil~ex lay~r being of from ~OUI ~o ~ixty microns (liqu~d) absolu~e, and one or ~wo layer~ o~ a synthe~lc flber fel~ drain layer such ~18 a fiber glaa~ matte OI the den~ity men~ioned.

In ~igure 9, ~hese layers could ~ ~he rolls of ma~erial lndicated by the numerals 15, 16 and 17 re~p~ctively. The~e three lay~rs axe ltaneou~ly fed to the pleater by th~ roller~ 20 and fo~m the compo~ite sheet indicated by ~he numexal 21. The~e layers are then pa~sed through ~ plea~ing machlne ~o produce a pleated ~hxee-layer compo~ite generally deslgnated by the s~umeral 23. These are then sheered to~th~
rl~h~ len~hs by the sheer ~4 after a pred~rmlned nu~er ~ c,ounts or p1eats.

One would theII ~elect a sul~able glue ~has would ~lnd all three material~ together and then, as shown in ~gure 10, one would ~lde ~eam th~s along ~he edge~ of ~wo pleats ~o ma~e a unl~ary eo~3truction.
An enla~ged vlew of ~uch ~lter con~truction can be ~een ln Figure 6 wherein the pre-filter layer 15, the ~llter laycr 16 and two layer~ of ~ynthetlc Ilber felt 17 are ~hown. It can 110W be seen cha~ th~ draln layer 17 l~ in lntlma~e con~ac~ with the fllter layer 16 a~ all polnt6 of contact alo~g the boundary between the twc, layer~, chus drainlng the entire area of the ~llte~ layer, someth~ng whlch l~o construction untll the prese~ tlme ha~ been able to do~

I~ #hould be und~r~tood that if only a ~ingle ~ca~e fllter con~
91sting of a ~lter layer 16 and the draln layer 17 was desirad, the roller conta~ning the pre~filter paper lS m~y b~ ellmln~ed~ and a ~wo~layer composlte may be used Ln the re~t o:~ the proceas. However, lt ~s preferable that the pre-~llter layer be in~luded ln the construction, as it i8 more pleatable and help~ wlth the plea~ing o~ the coalesclllg lay~r, whlch i~ otherwi~e Yery brlttle and hard to pleat.

To ~omplege the ~llter constructio~, one would then place a retalner 18, as ~hown iIl F~re 8. at the in~de of the plea~ed ~-ub~, , .. ~", "

ZZl and an outer retainer 19 about the outside of the pleated tube, and one would then pot this construction to suitable end caps, this making a completed filter construction having a pleated ~xoss section. The method of potting the retainers and the pleated tube to the end caps is well known in the art and need not be described herein.
It should be understood, that just as in the case wher~
our improved drain layer is being used with a filter tube of circu-lar cross section, the layers of the pleated filter construction may be reversed to have an out-to-in filter construction, rather than the in-to-out construction shown, and be well within the scope of the claims.
Thus, by abandoning the use of conven~ional dra1n ~ayer materials, and moving to the use of a synthetic fiber felt drain layer, we have provided a unique drain layer construction wPIi~h can be in intimate contact with a filter tube regardless of the cross section thereof. . -~

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A filter construction comprising a unitary formed filter tube of any practicable cross-section having one or more layers of a synthetic glass fiber felt material wrapped about the exterior thereof to provide a drain layer in intimate contact with said filter tube, wherein said glass fiber felt material has glass fibers ranging from 13 to 15 microns in diameter and having an average density varying from 4.4 to 17.76 pounds per cubic foot.

2. The construction defined in Claim 1, and having an additional layer of rayon wrapped about the synthetic fiber felt.

3. The construction defined in Claim 1, and having an additional layer of a polyester rayon non-woven material wrapped about said synthetic fiber felt.

4. The filter construction defined in Claim 1, including a pair of end caps, with said construction potted between said end caps.