filtration news september/october 2010

I N T E R N A T I O N A L

Your Global Source

FFIILLTTRRAATTIIOONN NNEEWWSS September/October 2010

Volume 29 No. 5www.filtnews.com

The Value of Specialty Manufacturing Equipment in a Competitive MarketA Special Report from Chase Machine & Engineering

In MemoriamWells Shoemaker 1922-2010A Special Tribute to an Industry Leader

Industry NewsChina’s Filtration and

Separation Industry Strongly Growing

Filtration | MediaPlasma Processing Changing Filtration

FiltratioNews-October2010:FiltNews 9/3/10 3:53 PM

2 • October 2010 • www.filtnews.com

IN THIS ISSUESeptember/October 2010, Volume 29, No. 5

Industry | EventsWorld-Leading Lineup for Filtration Society Conference in U.K. 4

In MemoriamWells Shoemaker 1922-2010 6

Filtration | MediaPlasma Processing Changing Filtration 10

Cover Story | Chase Machine & EngineeringThe Value of Specialty Manufacturing Equipment

in a Competitive Market 16

Industry | NewsChina’s Filtration and Separation Industry to

Grow as Country Cleans up Environment 18

Preview | Filtech 2011FILTECH 2011 Expecting an Increase in Exhibitors

and Visitors 20

Product | NewsGlobal Filter Launches New GTCHB Series

Band Clamp Cartridge Vessel Line 22

Filter Press | TechnologyCake Blowing Considerations in Filter Presses 24

Filter | TestingNew Method of Measuring Filter Cut Points and Pore

Size Distributions Using Multi-Modal Particle Size Standards 34

Proper Validation of Filter Test Stands is Critical for Product Development Programs 38

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Publication DataPrinted by: Allegra Print & Imaging,Wixom, MI 48393.Filtration News (ISSN:1078-4136) ispublished bi-monthly by Eagle Publications, Inc.Printed in U.S.A., Copyright 2010.This publication has a controlledcirculation - controlled by the staff of FiltrationNews; mailed bi-monthly by Bulk Mail.Filtration News is not responsible forstatements published in this magazine.Advertisers, agencies and contributing writersassume liability for all content of all submittedmaterial printed and assume responsibility forany claims arising there-from made againstpublisher.

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Cover courtesy of Chase Machine & Engineering

II N T E R N A T I O N A L

Your Global Source

FFIILLTTRRAATTIIOONN NNEEWWSS September/October 2010

Volume 29 No. 5www.filtnews.com

The Value of Specialty Manufacturing Equipment in a Competitive MarketA Special Report from Chase Machine & Engineering

In MemoriumWells Shoemaker 1922-2010A Special Tribute to an Industry Leader

Industry NewsChina’s Filtration and

Separation Industry Strongly Growing

Filtration | MediaPlasma Processing Changing Filtration


Editorial Advisory Board

www.filtnews.com • October 2010 • 3

Editorial Board ChairmanEdward C. Gregor, ChairmanE.C. Gregor & Assoc. LLCTel: 1 704 442 1940Fax: 1 704 442 [email protected]&A, Filtration Media

Haluk Alper, PresidentMyCelx Technologies Corp.Tel: 770.534.3118Fax: [email protected] Removal – Water and Air

Jim JosephJoseph MarketingTel/Fax: 1 757 565 [email protected] Filtration

Robert W. McilvaineTel: 1 847 272 0010Fax: 1 847 272 [email protected]. Research & Tech. Analysis

Dr. Graham RidealWhitehouse Scientific Ltd.Tel: +44 1244 33 26 26Fax: +44 1244 33 50 [email protected] and Media Validation

Tony ShucoskyPall MicroelectronicsTel: 1 410 252-0800Fax: 1 410 [email protected], Filter Media,Membranes

Scott P. YaegerFiltration and SeparationTechnology LLCTel/Fax: 219-324-3786Mobile: [email protected], New Techn.

Dr. Bob BaumannAdvisory Board Member Emeritus

Andy RosolGlobal Filtration Products Mgr.FLSmidth [email protected]: 1 800 826 6461/1 801 526 2005Precoat/Bodyfeed Filter Aids

Gregg PoppeThe Dow Chemical CompanyTel: 1 952 897 4317Fax: 1 942 835 [email protected] Water, Power,and Membrane Technology

Henry Nowicki, Ph.D. MBATel: 1 724 457 6576Fax: 1 724 457 [email protected] Testing and Training

Brandon Ost, CEOFiltration GroupHigh Purity Prod. Div.Tel: 1 630 723 [email protected] Filters, Pharmaceuticaland Micro-Electronic

Gerard J. Lynch, PESigma Design Co., LLCTel: 1 973 912 7922Fax: 1 973 912 [email protected] Machinery &Product Design

Dr. Ernest MayerDuPont Co.Tel: 1 302 368 0021Fax: 1 302 368 [email protected] Solid/Liquid Separationsin All Areas

Wu ChenThe Dow Chemical CompanyTel: 1 979 238 9943Fax: 1 979 238 0651Process Filtration (liquid/gas)Equipment and Media

Peter R. Johnston, PETel/Fax: 1 919 942 [email protected] procedures

Peter S. Cartwright, PECartwright Consulting [email protected], RO,Ultrafiltration

Wells ShoemakerAdvisory Board Member Emeritus


Industry | Events


he Filtration Society’s 2010(U.K.) annual conference andexhibition has once again at-

tracted an impressive array of speakers

who are world leaders in their fields. “Fil-ter Testing 5 – millimeter to nanometer”takes place October 13, 2010 in Chester,U.K., and will be preceded by a short

course and workshop on October 12 forthose new to filter testing, or who wishto further develop their knowledge inthis field.

Conference organizer Dr. GrahamRideal of Whitehouse Scientific is par-ticularly pleased with the enthusiasticresponse he has received from those in-vited to present. “The Filter Testing se-ries of conferences has been runningfor more than 10 years and continuesto grow,” he said. “Once again I am de-lighted that we have been able to attracta great line up of speakers. What’smore, a number of those presenting themain conference sessions are alsoteaching the pre-conference shortcourse, providing attendees with aunique learning opportunity.”

The main conference begins withtwo plenary presentations in whichMark Crooks of TSI, U.K., will present“A review of ISO standards in relationto the dry testing of filter media – theenvironmental driving force,” andChristope Peucheot of IFTS, Francewill discuss “Validation of liquid filtertest methods and equipment.” Havingset the scene, the rest of the conferenceis largely focused on the latest testmethods and equipment. The remain-der of the morning will be devoted toadvances in pore size distributionanalysis (Danny Pattyn, Benelux Scien-

T

World-Leading Lineup for Filtration Society Conference in U.K.By Ken Norberg, Editor

Pore size measurement of a filter using glass calibration microspheres.


FN

tific) and analysis of surface area andpore size in the nanometre range (MikeTucker, Quantachrome).

After lunch there is a look at filtertesting by nanoparticle tracking analy-sis (Bob Carr, Nanosight), real-timemeasurement of the available absorp-tion capacity of activated carbon cloth(Andrea Smith, Chemviron Carbon),the use of microsphere standards to de-termine filter cut points and pore sizedistributions (Graham Rideal, White-house Scientific), and essential im-provements for a reliable fractionalefficiency test of filter media and filters(Sven Schutz, Palas).

A trade exhibition running along-side the conference will also feature a“technology burst” session in which ex-hibitors are given the opportunity tomake 5-10 minute presentations abouttheir products or services – an efficientmeans of introducing delegates to allthat is available at the trade show.

In summing up the significance ofthe conference, Dr. Rideal noted, “Re-cent environmental issues have really

brought a wider recognition of theimportance of filter technology,whether we’re talking about protect-ing aircraft from volcanic ash or fil-tering sand from deep sea oil wells.Much has also been spoken about thereal or potential effects of nanoparti-cles on the environment and the im-portance of filtration. Our focus onfilter testing provides insight into theperformance of filter media and helpsguide people in correctly specifyingproducts that are appropriate for theirapplications.”

ABOUT WHITEHOUSE SCIENTIFICWhitehouse Scientific is a leading

producer of glass microspheres for cal-ibration and is the highest-ranking Eu-ropean certification laboratory forprimary methods of particle size analy-sis. The company’s standards cover allparticle-sizing techniques includinglaser diffraction, Coulter methods, op-tical sizing, sieve calibration and imageanalysis. Most of these reference mate-rials are NIST-traceable. They range in

size from 0.1 micron to 5.0 millimetersand are available as single sizes orbroad distribution standards. In addi-tion, Whitehouse offers a unique cali-bration procedure for NIST-traceablemeasurement of filter apertures be-tween 3 and 1000 microns, and alsoproduces general-purpose researchgrade microspheres.

Whitehouse Scientific has been pro-ducing calibration microspheres formore than 25 years. Founder and man-aging director Dr. Graham Rideal is apast chairman of The Filtration Society,and is now active as its Science Corre-spondent. He is also a member of theEditorial Advisory Board of Interna-tional Filtration News.

For more conference information visit:www.filtsoc.org For company information contact:Dr. Graham RidealTel: +44 (0) 1244 332626 Fax: +44 (0) 1244 335098 Email: [email protected]: www.whitehousescientific.com



In Memoriam

Wells Shoemaker1922 - 2010

A Personal Tribute from Ed Gregor

cannot think of anyone, who is more highlyadmired or has done more for the Americanfiltration industry than Wells Shoemaker who

passed away July 25, 2010. When consideringthe names of giants in filtration, Wells ranks withthe best of them, even though he never ran a fil-tration manufacturing company or invented anyfiltration media, filter or system. What separatedWells were his persona, exceptional industryleadership and organizational abilities, but whattruly set him apart was he made everyone whomet him feel important. You appreciated his easyway, the warmth of his personality, and his abil-ity with a few words or a nod to convince you tohelp him with whatever filtration endeavor hewas pursuing at the time. I learned this first handwhen I met Wells for the first time. He and HarrySandsteadt walked into my office at Gelman Sci-ences in 1983. Within 15 minutes I found myselfagreeing to give a presentation at a filtration con-

ference being held in three weeks, and much tomy surprise volunteered to be on a committee ofthe American Program Committee, the predeces-sor to the American Filtration & Separations So-ciety. It didn’t seem to matter that I had apending trip to Europe and was reorganizing afaltering business unit that occupied all my time.I’ve since learned, when Wells had an idea, anyidea, somehow everyone wanted to be part of it,and I was no exception.

After graduating from Cornell University with achemical engineering degree, Wells served in the U. S. Navy for 4 years. Following World War II,Lieutenant Shoemaker’s career began with early em-ployment at American Enka and Johnson and John-son where he was first exposed to filtration. Hislifelong devotion and enthusiasm for filtration wascemented when he joined Eaton-Dikeman (nowAhlstrom Filtration) in Mt. Holly Springs, PA in

I



1965. From his position in technical sales and re-sponsibilities to sell filtration media, his natural abil-ities blossomed and begin what would be fourdecades of leadership, planning skills, passion anddedication in organizing countless filtration Confer-ences and Filtration Days across the United States.

In 1981 Wells left Eaton-Dikeman to form his ownconsulting company, Filterex, Inc. Now on this own,Wells really went to town, promoting industry edu-cation while building a wide following of active par-ticipants, individuals, companies and competitorsalike at a torrid pace throughout all of Filterdom, aterm he coined and liked to use. He organized nu-merous events, Conferences and Filtration Days inMonterey, Williamsburg, Princeton, Valley Forge,Hersey, Flint, Ocean City and many other locations,as many of us fondly recall. His Membrane Confer-ences in conjunction with the BCC began in 1982and, under his guidance for almost 20 years, was the

foremost membrane conference of the industry.Wells always was ready to plow new ground. In 1991he ran a conference titled “The Pore” with FrankTiller and Ted Meltzer contributing. Consider hisimagination. Who would ever think to organize aConference to discuss the Pore…not the media, butonly the hole and get over 120 people to attend. Be-ginning in the early 1960s through the mid-1980sWells organized many Filtration Society regionalchapters under the American Program Committeeon behalf of the Filtration Society in the U.K. Chap-ters grew like mushrooms as leading filter expertswere recruited or “co-opted” to manage new chap-ters from New England, the Mid-Atlantic, Chicagoand Dixie and then on to California, with 11 activechapters – all this while managing his filtration mediaconsulting business, which flourished in spite of allthe time he devoted to his passion of bringing the in-dustry together. You always saw the light side ofWells at every conference, including his talk on the



“The Filtration Pill,” and what good it does for youif you swallow it. He organized and sang barbershopas part of the “Un-Filterable Four” at many a confer-ence, and once Wells even arranged a local high-school band to parade in with trumpets anddrummers filling the room with march music duringa networking reception. Something new and unex-pected always provided a lasting memory.

For his skills, the Filtration Society in the U.K.elected Wells as the first of only two [ever] Inter-national Filtration Society Chairmen. Following

his exemplary leadership as Chairman, the Filtra-tion Society awarded him the first World Filtra-tion Congress to the United States, held inDowningtown, PA in 1982. Again, Wells steppedforward to organize the event, which still remainsthe standard by which all World Congresses arejudged. However, in the mid-1980s relations be-tween the Filtration Society and the AmericanProgram Committee began to deteriorate to thepoint of ultimately culminating in the foundingof the American Filtration & Separations Society(AFS) in 1987 as a separate stand-alone Society. I

clearly recall the day wefounded the Society andI suggested we considercreating CorporateSponsorships. Immedi-ately, Wells took out hispen and wrote some-thing on his businesscard and handed it tome, which I still keeptoday. It read: “OneCorporate Membership.I.O.U. $1,000.” Len Or-tino was sitting to myleft and said, “Count mein as well.” Before the


day was out, I had corporate promises of $5,000!Wells never sought credit or held any office in theAFS, but was always there as a contributor, evenat the age of 85. Wells and Don Olds teamed up inNovember 2007 to run a Conference in Knoxville,where he drew the who’s who of the industry asspeakers. Wells still had that same old magic andreceived a stellar Conference review and as usualand most importantly, his lovely wife of 66 years,Sara, was at his side as she has been for over theyears at virtually every industry event. Even inretirement, Wells organized. It was just part of hisDNA. As Scott Yaeger said recently, “Wells un-doubtedly is organizing the Heaven Filtration So-ciety at this time.” When he and Sara moved toSparta, NC from Fairfield, PA in early 2007, at theage of 85 and shortly after heart surgery, Wellsfounded the Sparta Newcomers Club, and helpedwrite and participated in several plays as part ofthe local community theater group. His organiza-tional skills were honed with many years workingwith local church groups, and the Rotary Clubwherever he and Sara lived over the years.

Wells Shoemaker is the Father of the AmericanFiltration and Separations Society. He fostered moreinterest in filtration and separations at any level thanany individual I know. Today, filtration and separa-tions is a true growth industry with annual growthat 4-6 percent per year above GDP, whether theeconomy is up, down or sideways. The steady handof Wells Shoemaker has surely played a role in help-

ing to achieve this success. Wells was an idea manarmed with charm, wit and an innate ability to bringpeople together for a common cause and have funwhile doing it––everything about him was quality.

Wells left all of us with a great industrylegacy and he will forever be remembered in theannals of Filterdom. We all salute him and ex-tend our sympathies to his wife Sara and all theShoemaker Family. FN



embrane and nonwovenfilters are widely used bythe industry to separate

solids from liquids or gases. Filterscan range from the conventional,such as simple dust filters for air in-

takes, to the criti-cal, such asdialysis filters toprevent kidneyfailure. In fact,there are morethan 50 filters in asingle car. Theworldwide filterindustry is ex-pected to expand5.6% through2010 to a value of$45 billion.

F i l t r a t i o nmedia is generallyselected based onreasons of cost,ease of processingand performancer e q u i r e m e n t s .Many differentmaterials can beused, but wherefilters are in-tended for re-peated use, it isvitally importantthat integrity and

consistency of pore size is retainedthroughout a product’s lifetime de-spite the often harsh environmentsthey are exposed to, including clean-ing processes.

In order to achieve this level of re-liability, reusable filtration mediahave traditionally been made fromhighly resistant and rigid polymers,such as polyvinylidene fluoride(PVDF) and polytetrafluoroethylene(PTFE). However, these materialstend to be fairly costly and wouldstill benefit from complex chemicalfinishes to add further performancebenefits. A more desirable scenario,therefore, would be to use cheaper,easily formed filter media and thenmodify the surface using an addi-tional process to impart the desiredliquid resistance.

Thanks to the pioneering work ofP2i and its revolutionary liquid re-pellent nano-coating, it is now possi-ble to enhance alternative, moresustainable filtration media – such ascellulose or nylon – to a level thatmatches, or exceeds, the perform-ance of traditional, more expensivematerials that are more difficult towork with. Indeed, using the widelyaccepted American Association of

Filtration | Media

Plasma Processing Changing Filtration By Stephen Coulson, Ph.D., Chief Technical Officer, P2i

MPlasma processing of filtration media can increase oil and water repellency while maintaining pore size distribution and airflow.



Textile Chemists and Colorists con-ventions, P2i’s nano-coating has beenshown to create filters with the max-imum levels of liquid repellency inboth the AATCC 193-2007 water re-pellency test (resisting 100% iso-propyl alcohol) and the AATCC118-2007 oil repellency test (resist-ing n-heptane).

Using a special pulsed ionized gas(plasma), which is created within avacuum chamber, the patented P2itechnology attaches a nanometer-thin polymer layer over the entiresurface of a product. This dramati-cally lowers the product’s surface en-ergy, so that when liquids come intocontact with it, they form beads andsimply run off.

In filtration media, the P2i nano-coating increases oil and water repel-lency without affecting the material’sbulk properties or pore size distribu-

Filtration | Media

P2i’s technology can enhance the performance of a wide range of filter media andcomplete filtration systems.


Filtration | Media


tion and, therefore, airflow. It hasalso been shown to exhibit improvedcake release, no pressure drop or de-crease in water entry pressure and alower replacement frequency, mean-ing less waste. This allows productsto perform at a much higher level ina wide range of application sectors,including biosciences, industrial pro-cessing, laboratory testing, food &beverage, electronics and water treat-ment, as well as opening up new ap-plications altogether.

A PROBLEM SOLVEDP2i’s technology is genuinely revo-

lutionary for filtration because itsolves so many of the industry’s tradi-tional challenges. For example, untilnow the choice of filter material hasusually been dictated principally bydesirable bulk physical properties andease of processing. In many cases,however, this has led to a compromise

in material surface properties, whichmay not be ideal for the intended use,requiring treatment with complexchemical formulations and high cur-ing temperatures. In turn that has ledto manufacturing processes that arepower hungry, time consuming, andlimited to specific materials that willwithstand the chemicals and high cur-ing temperatures involved. Theseprocesses are expensive and can havesignificant environmental impacts.

P2i’s technology, by contrast, islow-energy, solvent-free and usesonly tiny quantities of protectivemonomer, resulting in minimal wasteand no adverse impact on the envi-ronment. Plus, because the nano-coating is applied within a vacuumchamber, there is no release to theenvironment during processing and,since the nano-coating is molecularlybonded to the product, there is nowash off, leachables or extractables.

COMPONENTS TO ASSEMBLIESIn addition to enhancing filtration

media, P2i’s technology is alsoequally effective at treating the oftencomplex structures they are formedinto. For example, filter media aregenerally manufactured in 2D formthough rarely used in this format.The sections required are cut into thedesired shapes and configured into el-ements contained in housings. Thesecan be used to form a larger system inorder for the filter element or systemto perform the desired function.

Because P2i’s protective polymer isformed in a gas plasma, it permeatesevery exposed surface of finished fil-ter structures, meaning that the mem-brane may be treated while sealed ina permanent housing. It also meansthat the same chemistry can be im-parted to a wider range of media, in-cluding surface and depth filtermedia, woven and nonwoven textiles,



Back Your Filters BetterExtensive Range of Expanded Metals & Polymers

Perfect for membrane support & backing

Assures media integrity & pleat spacing even under dynamic flow

Materials laminate for co-expansion/ contraction/flex

Openings down to 25 micron

Thickness: 0.001” to 0.2”

Dexmet Engineers welcome the challenge of your unique materials and applications

Custom-Expanded Materials from

203 294 4440 www.dexmetfilter.com

membranes and media combinationscreated to form a filter medium, ele-ment or system format. Other associ-ated benefits are increased liquidprotection and greater working effi-ciencies in harsh environments,which in turn translates into benefitssuch as longer filtration life, higherperformance (in terms of reducedpressure drop and higher particle cap-ture efficiency), and pleatability.

COST-EFFECTIVE Increasing environmental con-

cerns, demands for product cleanli-ness and the growing need forcontaminant reduction in sectorssuch as electronics, and medical andbiological industries means the mar-ket for filters is growing rapidly.

P2i’s liquid repellent nano-coating

technology allows reusable filtrationproducts to perform at a much higherlevel in their intended applicationthrough increased oil and water re-pellency without affecting airflow,porosity or other crucial indicators,such as cake release. Furthermore,this multi-patented innovation iscost-effective and environmentallyfriendly for enhancing cheaper filtermediums, such as cellulose or nylon,without compromising performance.

Both the wide variety of filtermedia and the complex structures in-volved make the P2i enhancementprocess highly sought after. The com-pany is already working with some ofthe world’s leading filtration manu-facturers and has been providingprocessed media into the marketplace for more than six years.

About the AuthorStephen Coulson, Ph.D., is the Chief Techni-cal Officer of P2i. Mr. Coulson invented theP2i technology while carrying out his Ph.D.at Durham University on ‘Liquid repellentsurfaces’. He was consequently employedby the MoD to set up a plasma capabilityand further scale-up the patented technol-ogy for industrial applications. In 2001, Mr.Coulson moved into project managing theUK Nuclear Biological and Chemical cloth-ing program, but continued to exploit theplasma technology for a range of commer-cial applications. Mr. Coulson was thefounding member of P2i when it was formedin January 2004 and has more than adecade’s experience in advanced materialsciences and plasma processing.

FN

Visit us online: www.filtnews.com


Cover Story | Chase Machine & Engineering


very equipment supplier hasspecial capabilities and ChaseMachine & Engineering Inc. is

no exception. Equipment is tradition-ally of a commodity nature or speciallydesigned to accommodate particularmanufacturing needs. Specialty equip-ment suppliers such as Chase Machineare often asked to suggest better con-cepts to enable lower processing costsor the manufacture of products withunique capabilities. Experience andknowledge of the industry and cus-tomer manufacturing processes are im-portant aspects in bringing suchconcepts to reality.

DIFFERENTIATION IS THE KEYWithout question, product differen-

tiation is the most important offering acompany can provide to its customers.Chase Machine differentiates itself in anumber of ways beyond simply offer-ing competitive pricing. They include:

•All products are made in Chase Machine’s manufacturing plant in theUnited States.

•In-house engineering capabilities employing state-of-the-art 3-D solidmodeling software, combined with web handling and pick and place automation expertise, sets the company apart in most cases.

•Filtration product design concepts, which allow customers to successfully sell against competition – that’swhat 56 years of business experienceand talented employees can provide.

•Custom engineered equipment and manufacturing processes that permitcustomers to gain market share through manufacturing efficiency and low-cost production.

•Vertical integration, including electrical panel building and PLC programming, machining, welding fabrication, painting and final machine assembly ensures full control from both a quality and delivery standpoint.

•Process filtration equipment made right the first time.

•Reliable and superior processes on the shop floor – as only an operationmanager and the CFO can truly

appreciate, sometimes “good enough” is not good enough.

EQUIPMENT NEEDS HAVE SHIFTEDThe shift from conventional glass

and cellulose filtration media to syn-thetic nonwoven meltblown, spun-bond and needlepunch fabrics hasopened the door for the introductionof new and exciting assembly meth-ods. Technologies such as ultrason-ics, hot air, band sealing, RF andimpulse welding are becoming com-mon practices within the industry.Engineers now select media not onlybased on filtration performance cri-teria, but also on assembly prefer-ence. Needle and threads combinedwith adhesives are slowly beingphased out – why incorporate an-other component (and expense) intothe final product, especially whenthere are safer and more environ-mentally friendly alternatives?

The Value of Specialty ManufacturingEquipment in a Competitive Market

HVAC Pocket Filter Line improves quality and reduces defects with ultrasonic bonding.Modular design allows customers immediate market entrance at a reduced cost.

E



SYNTHETIC NONWOVENS - GROWTHChase Machine & Engineering has

embraced the move from conventionalfiltration media to synthetic nonwo-vens. Heat sealing technologies, whenincorporated into a continuous process,can reduce labor and maintenance ex-penses since consumables such as ad-hesives or sewing supplies are nolonger required. While it is understoodthat some filter requirements call forthe use of cellulose and glass fibers thatrequire adhesives and/or sewing, appli-cations that lend themselves to the useof synthetic media have generated ex-citing new assembly alternatives.

The liquid filter bag market presentsan excellent example of multiple tech-nologies combining within the sameprocess to improve manufacturing per-formance. Employing hot air welding,Chase Machine joined the two edges ofa needlepunch fabric to create a tube ona continuous basis. At the same time,the company integrated Ultrasonics tocut and seal the bottom of the filter,freeing the end product of loose fibersand contaminants. The process gavethe end user complete control whilecutting labor expenses by more than50% and eliminating the need for an-cillary consumables. What’s more, thefinished bag could be joined to a plas-tic ring using ultrasonic plunge weldersand eliminating the conventionalsewing method for attachment.

Ultrasonics is also commonly usedin the synthetic HVAC filtration mar-ket. Chase Machine was instrumentalin this transition with the developmentof the extended HVAC pocket filter ma-

chine, which was designed, built andpatented incorporating ultrasonic tech-nology into the continuous assemblyprocess. Nonwovens manufacturers re-alized the importance of designingmedia for use with Ultrasonics. In theearly years of development, consistencyand uniformity across wide meltblownand spunbond lines was a challenge.The finished product, while suitable forthe filtration application, varied in itsdistribution of fiber. Although thisnever became an issue when sewing,ultrasonic welding required greateruniformity and consistency.

In the membrane market, nonwovensare chosen for their strength as a supportsubstrate. The synthetic component ofthe nonwovens affords the end user theability to splice membranes together oreven attach multiple layers to improvefiltration characteristics. Ultrasonics, im-pulse welding, or even simple bar seal-ing technologies may be incorporatedinto a process line. Chase Machine’s ex-perience with membrane casting andhollow fiber process lines helps cus-tomers decide which technology suitstheir specific application best. Then theysubstantiate their conclusions in theChase Materials Applications Lab.

CUSTOMER TESTING LABIn response to this need, Chase Ma-

chine established a Materials Applica-tions Lab, which enables companies totest materials and assembly methods be-fore committing to full production.Working with some of the largest filtra-tion media manufacturers in the world,Chase Machine has run thousands of

feet of media to verify process improve-ments. Many of these improvementshave gone on to benefit the marketplace.

MEMBRANE AND HOLLOW FIBERS Chase Machine is an important sup-

plier in the rapidly growing area of hol-low fibers and flat sheet membranes,building equipment ranging from singlefiber lab scale pilot lines, to large-scaleproduction systems. Hollow fibers andflat sheet membranes are highly effi-cient, offering greater flow rates, andlower differential pressure and energyrequirements. Chase works hand inhand with customers to understand thestrict design and manufacturing speci-fications required to make their partic-ular machinery. Like its nonwoven filtermanufacturing equipment, Chase Ma-chine’s hollow fiber and flat sheet mem-brane process capabilities rely uponmany years of building equipment andprocesses confidential to each customer.

CONCLUSIONToday’s filtration industry is constantly

evolving. Ongoing improvements tochemistry and manufacturing processesoffer infinite possibilities for new productdevelopment. With companies such asChase Machine offering testing, prototyp-ing and full-scale process solutions, thetransition from concept to final product isnow faster than ever before.

For more information contact:Chase Machine & Engineering, Inc.

324 Washington StreetWest Warwick, RI 02893

Tel: 401-821-8879 Fax: 401-823-5543Website: www.chasemachine.com

MADE IN USA

Liquid Filter Bag Machine produces awide range of products for varying fil-tration needs, including needle punchand spunbound/meltblown filter media.

Single Position Ultrasonic Ring Welderallows maximum operator efficiency withergonomic engineering practices, and isdesigned to be safe and operator-friendly.

Chase Machine’s Materials ApplicationLab allows customers to test materialsand assembly methods.

FN



Industry | News

hina faces serious environ-mental problems due to thefast growing economy. It is

the largest carbon dioxide (CO2) emit-ter in the world and its emissions ofsulfur dioxide (SO2) and chemical oxy-gen demand (COD) reached, respec-tively, 23 million and 30 million metrictons in 2007.

To reduce pollution and protectthe environment, China has set tar-gets to reduce 10% of its SO2 emis-sions and COD emissions by 2010from 2005, and reduce CO2 intensityby 40% to 45% from 2005 to 2020. Atthe same time, the Chinese economywill keep on growing over the next

decade. As a result, the Chinese fil-tration and separation industry is en-tering a sizeable growth-period.

FILTRATION AND SEPARATION INDUSTRYAccording to Professor Wang

Yanxi and Dr. Yao Gongbi of CFS(Chinese Filtration Society), China’sfiltration and separation industry hasa total market scale of more than 150billion Yuan ($22 billion): more than60 billion Yuan for air pollution con-trol, more than 50 billion Yuan forwater purification and waste waterdisposal, and approximately 25 bil-lion Yuan for solid-liquid separationof industrial production.

China’s filtration and separation in-dustry can satisfy more than 90% of thedemand from the domestic market. Theremaining 10% are mainly importedfrom the United States, West Europeand Japan.

There are more than 2,000 compa-nies in the Chinese filtration and sep-aration industry. Most of thecompanies are based in the YangtzeDelta Area (Shanghai, JiangsuProvince, Zhejiang Province andAnhui Province), Pearl River Delta(Guangdong Province), and BohaiGulf Area (Beijing, Tianjin, LiaoningProvince and Hebei Province).

C

China’s Filtration and Separation Industryto Grow as Country Cleans up EnvironmentBy Jason Chen, China Correspondent



Market details for the Chinese filtra-tion and separation industry:

1. Filtration machinery market. This market amounts to 20 billion Yuan. Chinese companies’ main products include –

Pressure filter: Chinese manufacturers can produce plate and frame filter, recessed plate filter, pressure leaf filter, automaticpressure filter, and candle filter. Currently they don’t produce rotarypressure filter (BHS); Vacuum filter: Chinese manufacturers can produce horizontal belt filter, tilting pan filter, table filter, drum filter, and disc filter; Chinese companies also produce belt pressure filter for mining selection and silt dewatering.

2. Separation machinery market. This market amounts to 19 billion Yuan. Chinese companies’ main products include –

Solid-gas separation machines suchas cyclone separator; Solid-liquid

separation: Chinese manufacturerscan produce horizontal pusher centrifuge, siphonic scraper-unloaded centrifuge, vertical axis basket centrifuge withautomatic discharge, horizontal scroll discharge decanter centrifuge, top-suspensory-basket centrifuge, tubular centrifuge, discseparator, centrifugal extractor, andhydrocyclone.

3. Bag filtration. This market amounts to 14 billion Yuan – more them 4 billion Yuan forfilter media. The growth rate of high-temperature resistant bag filter will exceed 20% each year. China can produce sintered metal net, metal fiber felt and ceramic filter media (tube, plate or other forms). Currently there are more than 100 nonwoven producers engaging in theproduction of filter media in China.

4. Membrane filtration products. This market amounts to more than 10 billion Yuan. Currently China still

needs to import a lot of membrane from the United States and other countries.

5. Filters & cartridges. This market amounts to more than 10 billion Yuan. China is the largest filters & cartridges manufacturing center in the world.

6. Filter media. This market amounts to more than 10 billion Yuan. The processing measures include: woven, nonwoven, wet-laid (paper-making), metal sintering, and composite (lamination, coating, and impregnation). FN

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ith all five halls of morethan 7,400 square metersfilling up the FILTECH

2011 tradeshow in the Rhein-Main-Hallen in Wiesbaden, Germany, it isonce again becoming a guaranteed suc-cess for the vast Filtration and Separa-tion Industry in Europe. The FILTECHshow expects a 40 percent increase inexhibitors and 25 percent more visitors.Besides this, the scheduled FILTECH2011 Conference, which takes place atthe same location, is currently ready topresent 200 technical papers.

In short, it seems that from March22 – 24, the beautiful town of Wies-baden will once again become the cen-ter point for all European filtration andseparation experts.

European machinery and equip-ment producers will provide the largestnational group of exhibitors at theshow, however, ample participation ofcompanies from both Asia and theAmericas will ensure that visitors willbe offered a growing international per-spective on technical innovationsacross the entire filtration and separa-tion processing sequence.

The FILTECH 2011 CONFERENCEis promising to becoming the educational

platform of the year for the industry.Once again there will be a strong focuson the latest advances and techniques inliquid/solid and gas/particle separation(dust, gas & air filtration) over a 3-dayperiod. At this moment the organizers ofthe conference are still inviting engineers,managers, researchers and scientists tojoin them in Wiesbaden to present theirlatest findings to the worldwide Filtrationand Separation Community. The topicsare fundamentals, equipment and strate-gies to “Solid-Liquid-Separation” by fil-tration and sedimentation, as well as “Airand Gas Cleaning” by filtration, settling,electrostatic precipitation, scrubbing and“Membrane Separation Technology”.

International Filtration News’ up-coming November/December issuewill further preview this importantEuropean event.

To discuss your attendance at FILTECH contact:Filtech Exhibitions GermanyPO Box 12 2540637 Meerbusch - GermanyTel: +49 2132 9357 60Fax: +49 2132 9357 62Email: [email protected]: www.filtech.de

Preview | FILTECH 2011FILTECH 2011 Expecting anIncrease in Exhibitors and Visitors

W

FN

Filtration

Mergers, Acquisitions

and Divestures

GL Capital, LLC

We understand the nuances ofthe domestic and internationalfiltration industry and bringover 70 years of combinedbusiness, technical and finan-cial expertise. The current eco-nomic climate is an ideal timefor sellers to locate buyersseeking to diversify and forbuyers to identify growth op-portunities through acquisition.

For a confidential conversation contact:

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Rhein-Main-Hallen in Wiesbaden, Germany, is once again the location for FILTECH 2011. Among the international exhibitors are A2Z Filtration Specialists (top left) from Gurgaon, India.



arly in 2009 Global Filter,LLC began a broad marketstudy to understand the

trends and needs for various filter ves-sels in both the North American andEuropean Marketplaces. Global Filterhad already begun making marketshare gains with the launch of itsASME designed bag and cartridge ves-sels. However, with the addition of a30,000 square foot vessel facility inCedar Rapids, Iowa, there was amplespace and capacity to evaluate the po-tential of other stainless vessel lines.

In late 2009 Global Filter realizedthat there was a real market demandfor an improved version of the exist-ing band clamp style vessels beingmarketed by Watts Flowmatic, Shelco,and several other companies. With thegoal of offering an improved “drop-in-replacement” for these units, GlobalFilter launched its GTCHB Series

Band Clamp Vessel Line.While looking to improve the

quality and durability of the “bandclamp” style vessels, the companyknew it was essential to keep anidentical footprint to what was al-ready being sold in the marketplace.In addition, after discussions withmany OEM buyers of band clampstyle units, they learned of severalimprovements that were needed. Indeveloping the GTCHB Vessel Line,Global Filter listened to what themarketplace was saying and incorpo-rated the following features into theirnew GTCHB line:

•Heavier wall thickness for a more robust unit

•Improved lid sealing by using the optimum lid profile

•DOE/222 Universal Cups are standard on all GTCHB Vessels

•All units accept 2.5” wound and meltblown cartridges in addition to2.7” pleated cartridges

•Legs are standard on all units

With the state of today’s economyand pressure on many OEM’s to limitinventory costs, Global Filter deter-mined that a key to success with theGTCHB Vessel Line would be rapidshipment from inventory. With thisgoal in mind, Global purchased a30,000 square foot vessel and train-ing facility and now maintains astock of over 300 vessels ready forsame day shipment.

For more information contact:Global Filter, LLCTel: 1-877-603-1003 Website: www.globalfiltercorp.com

Product | News

Global Filter Launches New GTCHB Series Band Clamp Cartridge Vessel Line

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Global Filter’s new GTCHB series band clamp vessel line

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Filter Press | Technology

Cake Blowing Considerations in Filter PressesBy Reuben G. Neumann, Global Product Manager, Filter Press Technologies – FLSmidth

ake air* blowing of filter cakesis not new technology. The useof air and sometimes other

gases to sweep out liquids from inter-stitial gaps in formed filter cakes hasbeen used for many years. Air is by farthe most prevalent medium used forporous filter press cake blowing but isnot the only medium used. Many ap-plications require alternate compressedgases such as nitrogen.

*For the purposes of this article theterm “air” will be used generically andassumes the reader is basically familiarwith filter press operating principles.

Some contend that the basic princi-ple of drawing air through a filter cakefor dewatering comes primarily fromvacuum filtration technology. Conven-tional vacuum filters such as Drum,Disc, and Horizontal Pan or Horizontal

Belt types relyon atmosphericconditions toproduce thedriving forceneeded to formand dry the fil-ter cake. At-m o s p h e r i cconditions arevariable mostlydue to altitudebut also due toother factorssuch as temper-ature and hu-midity all ofwhich have im-pact on the design of the equipmentand the long-term effectiveness of theinstalled dewatering device.

The use of an enclosed chamber asfound in the typical filter press tech-nology allows the dewatering impact of

C

Figure 1.0



variable atmospheric conditions to bemitigated by isolating the filter cake inthe chamber. If the cake is porousenough to pass air through, the isolatedcake can now be dewatered by usingcompressed air, which can be ideallyconditioned to achieve the desired re-sult. Enclosed chambers also allowcake-dewatering forces during cake for-mation to be mechanically produced bypumping and/or membrane squeezing.

Figure 1.0 illustrates a cross sectionof the typical recessed chamber config-uration showing cake formation inside

the chamber and will help familiarizeus with a filter press chamber. For pur-poses of this article, only vertically ori-ented chambers are considered.

For porous filter cakes, air can be in-troduced into one side of the chamber,which is then forced through the filtercake carrying interstitial liquid with itto the other side of the chamber, whichthen exits the filter through portingprovided. The direction of feed, filtrateand air is controlled by piping andvalves similarly shown in Figure 2.0.

There are different ways to configure

filter plate porting in order to allow thepassage of air through the cake. Figure2.0 illustrates just one typical way.

CONSIDERATIONSThe impact of air consumption both

on filter plant operating and capitalcosts can be enormous. In any filterplant design, careful consideration ofhow filter configurations impact air de-mand is required to keep costs down.

There are two phases to blowing afilter cake. Phase I is simply the appli-cation of air pressure, which then

Figure 2.0



pushes the liquid through the cake. Inthis phase the rate of airflow is con-trolled by the rate at which the liquidwill pass through the cake. Phase II isthe “air sweep” phase. This occurs afterthe liquid is completely pushedthrough the saturated cake. At thispoint air “break through” is achievedand the airflow begins to “sweep” sur-face moisture from the solid particles.Phase II will account for the maximumair demand. Phase II is where we willfocus the remainder of this discussion.

Some of the variables that can im-pact air consumption include:

1. Filtration area of filters required by the various filter press configurations. This is often variable from manufacturer to manufacturer and can be impacted by:

A. Pumping methods and timerequired to form the filter cake.B. Mechanical time needed for cake discharge.C. Frequency and time required for cloth washing.

2. Permeability of the filter cake, which is impacted by particle size and shape.

3. Homogeneity of the filter cake4. Filter cake cross sectional profile.5.Viscosity of the liquid to be

removed.

For the purposes of considering theabove variables, let’s take a look at atypical copper concentrate application.The material releases water freely andwhen formed into a filter cake is porousalmost always, requiring air blow toachieve desired moisture levels.

Specifications:• Production rate: 50 mtph• Cake form time: 3.0 minutes• Cake thickness: 50 mm• Measured airflow rate from testing: 18.3 Nm3/h/m2

• Required air blow time: 8.0 minutes• Cake moisture: 8.0 wt%

1. Filtration area required: For this evaluation, let’s compare two

different filter types. One that employshigh-speed mechanical functions for dis-charging the filter cakes vs. one that usesmore conventional methods. In the caseof FLSmidth we might use our AFP IVTM

Automatic Filter Press vs. our Shriver®filter press. In the case of the AFP, me-chanical functions associated with cakedischarge are performed in about 2 min-utes. In the case of the Shriver filter itmight take about 5 minutes. The resultsshown in Table 1.0 indicate that theShriver filter would require 1.23 times thefiltration area to process the same amountof tonnage as the AFP option. Aside fromother implications such as larger feedpumps, valve, piping, etc., the installedcompressed air system would need to pro-duce 23% more instantaneous air flow asderived from the total time comparison16/13. This is perhaps a simplistic viewbut it provides an idea of the impact ofequipment type selection. Other factorssuch as cloth washing frequency, avail-



ability and hours per day of operation cangreatly exacerbate the issue.

2. Permeability of the filter cake:Experience has shown that cake air

blow dewatering can be considered amass for mass function (“it takes somany kg of air to remove so many kg ofwater”). The values of this relationshipcan only be determined by testing the in-dividual application. If we can acceptthat, we can assume; “provided that thesolid particles are similarly formed andcompacted, the volume of air required toachieve any given moisture level is thesame per ton of solids regardless of cake

thickness or plate type. The power re-quired/ton is also the same.”

The impact of cake permeability on airconsumption becomes more significantwhen we consider the next two points.

3. Homogeneity of the filter cake:A filter cake that is not homogeneous

means the existence of particle stratifica-tion and/or non-uniform particle com-paction and the development of cracksdue to the shrinkage of the cake during theblowing process. Both of these will havesignificant impact on air consumption.

The homogeneous formation of fil-ter cake inside a filter press chamber

can be affected by a number of factorssome less obvious than others. Thesecan include: feed port location (top,center, and bottom), feed pumping athigher vs. lower rates, terminal fillingpressure and whether or not membranesqueezing is utilized.

Feed Port Location can have signifi-cant impact on cake homogeneity in ap-plications where solids densities arehigh, like the copper concentrate exam-ple. In that case it typically means thatthe slurry when placed in contact withthe filter cloth will release water rapidlyeven by gravity.

Figure 3.0 Figure 3.1



To achieve true homogeneity, it is im-portant that the chamber is fed in such away as to promote the formation of thecake in layers over the entire filtrationsurface simultaneously. This will ensure

that particles are evenly distributed andcompacted. To accomplish this usuallymeans that the chamber needs to be fedat a fairly high rate in order to create suf-ficient turbulence to prevent stratifica-

tion of particles.Feeding a filter chamber from an ele-

vated position can promote cake, whichis non-uniformly formed and compactedwith stratified particles creating a non-homogeneous filter cake. Figure 3.0 pro-vides a cross sectional view of how cakeformation might look. As the cake de-velops from the bottom up and pressurebuilds inside the chamber, it is evidenthow the lower sections of the cakewould not experience the pressurespresent in the upper portions and con-sequently would not exhibit the sameconsolidation properties. The final cakeprofile shows evidence as to how air by-passing would occur. Some manufactur-ers using this upper eye technologyattempt to mitigate the problem byadding membranes to compress the par-ticles more tightly. Membranes also tendto eliminate cracks that may haveformed. The use of membranes them-selves can have air flow implications,which will be discussed later.

Figure 3.1 provides a cross sectionalview of how cake formation looks in achamber that is feed from a lower center

Figure 4.0



position. The lower extremities of thechamber are kept turbulent and cake isformed more uniformly over the entirefiltration surface. The center core of thecake remains in slurry form so pressureincreases are applied over the entire sur-face uniformly.

Full-scale, side-by-side field testingof this configuration by a prominentcopper producer in South Americashowed an increase of air demand in ex-cess of 50% over the alternate lowercenter feed system.

4. Filter Cake Cross Sectional Profile:Air flow at any given pressure in-

creases as (T/t)2 (where “T” is thethickest section of the cake and “t” isthe thinner section). Figure 4.0 showsa typical recessed chamber filter cakecross section. Figure 4.1 illustrates theair-flow factors associated with thecross sectional change.

Likewise, variable air pressure in-creases or decreases the air flow as(P/p)2 (where “P” is the base pressureand “p” is the desired pressure). If we

increased the air pressure to 827 kpagfrom 689 kpag, the average design airflow would increase by (827/689)2 orfrom 18.28 Nm3h/m2 to18.28(827/689)2 = 26.33 Nm3h/m2, asignificant jump. Since velocity in-creases as the pressure drop squared,the time to blow the cake will similarlydecrease. Naturally a reduction in airpressure will decrease the instanta-neous flow but also will increase the re-quired blow time, commensurately.

With respect to the edge thinning ofthe cake around the perimeter of theplate, many manufacturers will coat thefilter cloth on one side of the chamberin the tapered zone. This does not sig-nificantly effect cake formation butblinds the cloth to prevent air from trav-eling through horizontally, which miti-gates the spike in airflow factor in thiszone. Coated filter cloths do come withan increased cost. It is recommendedthat an evaluation be made to determinethe lesser-cost impact between that anda higher average air demand.

Use of membranes will also have anaffect on filter cake profile. Membrane

Figure 4.1 (689.5 kpag)



filter plate manufacturers typicallylimit the cake formation pressure to689 kpag at 20-30 deg C. Higher tem-peratures reduce this allowable pres-sure. The increased time requirementto inflate and deflate membranes in afilter press drives the filter size up tomaintain any given throughput. Fig-ure 5.0 illustrates the differences inprocessing time between high pres-sure feeding vs. low pressure with

membranes in a minerals applicationas it relates to time.

To control this overall processingtime, chambers are not filled com-pletely. The result is that the final fil-ter cake thickness is less than thenominal chamber depth and may evenhave irregular thickness over the en-tire area of the cake. Figure 5.1 illus-trates the cross sectional effect ofmembrane squeezing. Normally the

dry cake densities have very little vari-ation. The use of membranes can in-crease the variability of airflow due tofinal cake thickness variations in anygiven filter cake.

CONCLUSIONThe impact of air consumption

during cake blow can have critical im-pact on plant capital and operatingcosts. Careful consideration must begiven to the selection of filter pressconfigurations to avoid excessive airconsumption.

For the most efficient air demandthe filter system should incorporate asystem that provides:

• High-speed mechanical functions to help minimize filtration surface area.

• Feed systems and filter plate designs that promote uniform and homogenous formation of the filtercake inside the chamber.

• Uniform compression of the filter cake where membranes are used.

For more information contact:Filter Press Technologies – FLSmidth7158 South FLSmidth DriveMidvale, UT USA

About the Author Reuben G. Neumann; Educated in Mechani-cal Engineering Disciplines has been em-ployed by FLSmidth since 1973 in variouscapacities including development engineer,design engineer, pressure filtration engineer-ing manager and product management.

Figure 5.0 Figure 5.1

FN



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orometry is probably the mostwell known method of measur-ing pore size distribution1. This

involves using air pressure to expel a wet-ting liquid from the pores of a filter. Whenthe gas pressure is applied, large poresoffer less resistance and so are cleared first.

The appearance of the first bubble (the‘Bubble Point’) reflects the largest poresize but different instruments use differ-ent methods of detection. For example, inthe Coulter Porometer, incremental‘bands’ of pressure are applied and thefixed band within which the bubble firstappears is used for the calculations ofmaximum pore size. There, therefore,

tends to be very good instrument-to-instrument agreement.

In other instruments, there is a con-tinuous increase in pressure and a parallelmeasure of flow. Deviations from a linearpressure/flow relationship are theoreti-cally more precise, but the difficulty hereis defining the exact position of the diver-gence. In simple terms, how much mustthe bubble be inflated before it is deemedsignificant?

The exact determination of the BubblePoint, and from it, the maximum poresize is critical as it is the benchmark fromwhich the pore size distribution is calcu-lated. As the pressure on the wetted filter

is increased, interpolation of the pressureversus flow rate can then be used to de-termine the pore size distribution.

A second factor, which can limit theaccuracy of the method, is the principleassumption that the pores are cylindricalin shape. The various uncertainties havelead to reproducibility issues not just be-tween different manufactures but alsofrom instruments made by the same man-ufacturer, and unless stringent operatingprocedures are used, there can be signifi-cant uncertainties in the results2,3.

In the so-called ‘Challenge Test’, poresare challenged by various powders eitherin air or as a suspension and the cut point

Filter | Testing

New Method of Measuring Filter CutPoints and Pore Size Distributions UsingMulti-Modal Particle Size StandardsBy Dr. Graham Rideal, Whitehouse Scientific Ltd.

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or maximum pore size determined by themaximum particle just penetrating the fil-ter1. Spherical particles are to be preferredbecause the results are not affected by par-ticle shape or orientation.

Because the challenge particles can beunambiguously measured, especially ifthey are spherical, there is a much greatercertainty in the accuracy of the result thanin the Bubble Point method.

In addition to the maximum pore sizeof a filter, it has been possible in the pastto determine pore size distributions incertain types of filters, for example wirewoven media, using the ‘near mesh’ prin-ciple. The method involves a challengetest where trapped microspheres in thepores are released and measured. The par-ticle size distribution of the ‘near mesh’microspheres then correspond to the porediameters4,5.

Unfortunately, the ‘near mesh’ methodis restricted to large pore sizes, typicallyover about 50 microns, because increas-ing attractive forces cause the micros-pheres to stick to the mesh filamentsurfaces as well as lodging in the pores.

Measuring pore size distributions atfines sizes, especially below 1 micron has

not been possible so far using the chal-lenge test method.

PRECISION PARTICLE SIZE ANALYSERCentral to the success of this research

is a means of accurately measuring parti-cle sizes in the sub-micron region. TheCPS disc centrifuge is a sedimentation in-strument employed in particle size analy-sis. The unique feature of the instrumentis that a ‘line start’ technique is usedwhereby the particles are injected onto thesurface of a spinning fluid and all startsedimenting at the same time. As theytransverse into the depth of the clear liq-

uid, largest first and smallest last, concen-tration is measured optically as they passa light beam. The principle of the tech-nique is shown in Figure 1.

The reason that the resolution is sohigh in the Disc Centrifuge is that theparticles are separated before they aremeasured. In the case of a multimodalmixture, a series of concentric ringscan be seen sedimenting as the parti-cles move to the perimeter of the disc.Figure 2 shows the effect in a 3-com-ponent blend of 3 latex standards. Thecomplete CPS disc centrifuge isshown in Figure 3.



MULTI-MODAL CHALLENGE TEST The new approach to Challenge Test-

ing described herein seeks to develop a setof wide particle size distribution, sphericalstandards based on a blend of non-over-lapping single sized latex microspheres inthe size range 0.1 – 1.5 microns. By study-ing the suppression of the individualpeaks in the ‘Multistandard’ as a result ofpassing a filter, it should be possible to de-termine a pore size distribution.

In the past, the main limitation to thisnovel Challenge Test approach has been acombination of producing a large numberof closely sized latex standards and a high-

resolution particle sizing technique capa-ble of differentiating the individual peaksin a multi-modal blend.

The provision of suitable particle sizestandards was solved by BS-Partikel6

while the CPS disc centrifuge7,8,9 pro-vided a unique solution to the high-res-olution analysis.

APPARATUSA simple split filter holder mounted on

a Buchner flask is all that is required forfilter testing. 20ml of a 0.02% aqueoussuspension of the standard is then drawnthrough a 47mm diameter fil ter and theparticle size after filtration is compared tothe original. The 0.02% concentrationwas used as the best balance between in-strument resolution and minimizing sec-

ondary filtration through cake build-upon the surface of the filter.

The initial studies were carried out on4 membrane filters of nominal ratings 1.2,0.8, 0.45 and 0.2 microns.

HIGH RESOLUTIONThe first phase of the program was to

ensure the repeatability of the testmethod. The first observation was thatthere is evidence of pores up to 1.5 mi-crons as this peak is not completely elim-inated from the Multistandard. The filtercut point is therefore likely to be approx-imately 1.7 microns.

Secondly, the peak positions after fil-tration are almost identical, with the ex-ception of the 0.15 and 0.1 micron peakswhere there is a variation of approxi-mately +/-0.01 microns.

The small deviations at the minimumsizes are probably due to particle diffusioneffects during sedimentation in the cen-trifuge as the duration of the analysis wasabout 50 minutes.

In addition to the cut point, multi-modal standards can be used to estimatethe pore size distribution. While the cutpoint determines a maximum pore size,the smallest peak can be used to bench-



mark the minimum pore size. Themethod assumes that the concentration ofthe 0.1 micron peak will be largely unaf-fected as it passes the filter so can be nor-malized or overlaid on the correspondingpeak from the Multistandard.

The percentage suppression of eachremaining peak as the microspheresare trapped in the pores then repre-sents the concentration of pores at thatparticular size.

The results from the cut point testsshow that the 1.2 micron filter removedalmost everything above 1.1 microns, al-though there was still a very small residueof the 1.6 micron peak.

The 0.8 micron membrane, however,performed better than its nominal ratingin that the 0.75 micron peak was totallyeliminated as well as a significant part ofthe 0.55 micron peak. The cut point isprobably about 0.65 microns.

The other interesting feature of the 0.8micron filter is that the concentrations ofall the peaks below the 0.4 microns peakremain unchanged after passing, indicat-ing that this membrane may have a highuniformity of pore sizes. Further work isneeded to determine whether the 0.8 mi-cron filter is indeed a track-etched mem-brane or whether a spurious result hasbeen obtained.

The 0.45 micron membrane per-formed as expected according to its nom-inal rating, having the 0.4 micron peakalmost completely removed. However, thecut point of the 0.2 micron membranewas significantly higher as there was stillevidence of a small peak at 0.26 microns,giving an estimated cut point of approxi-mately 0.3 microns.

To confirm that no secondary filtrationtook place, 0.2%, 0.02% and 0.002%solids concentrations of the ‘Multistan-dard’ were passed through the 0.45 mi-cron filter. There was no difference in theresults. However, the 0.002% concentra-tion was a little too low to give a good sig-nal-to-noise ratio. This result confirmedthe 0.02% suspension as the optimalsolids concentration for the test.

CONCLUSIONThe use of a Multi-modal standard in

combination with the CPS Disc Cen-trifuge has shown great potential in meas-uring both the filter cut point and the pore

size distribution of submicron filtermedia. Although no information was sup-plied with the filters under test, the resultsclearly show that the 0.8 micron filter hada much narrower pore size distributionand so, unlike the others, was probablymade by the ‘track etched’ process.

The major advantage of this novelChallenge Test method is that NIST trace-able microspheres are used, so the resultsare totally unambiguous. It will be inter-esting in future work to compare the re-sults with Porometry.

References 1. D B Purchas and K Sutherland, Handbook of Filter Media, 2nd Ed.,El-sevier Advanced Technology, ISBN 1 85617 37552. G R Rideal and J Storey, ‘A new high precision method of calibratingfilters’, J. Filt. Soc., Vol 2(3),2002, p 18–203. R Lydon, E Mayer and G Rideal, Comparative Methods for the Pore SizeDistribution of Woven and Metal Filter Media, World Filtration Congress(9) 2004, Reprinted in www.WhitehouseScientific.com/library’, paper 224. G R Rideal, J Storey and T R Morris, ‘A New Simple, but High PrecisionApproach’, Particle and Particle Systems, 17 (2000), 1 – 7 Wiley, Repro-duced in www.WhitehouseScientific.com/library, paper 125. G R Rideal, Pore Size Distribution Analysis in Critical Filter Applications –a Question of Definition, www.WhitehouseScientific.com/library’, paper 306. www.BS-Partikel.de7. B. Schied, S T. Fitzpartick, ‘The Use of Nano-sized Particle Standardsfor Particle Sizing Instrument Validation’ GIT Laboratory Journal Europe,5/2005, pp44 - 478. www.CPSinstruments.com9. Allen T. Particle Size Measurement, p120 (Chapman and Hall, London)The full scientific article can be found in FILTRATION, vol 10, number 2,April 2010, pages 115-120.

FN



arbage in equals garbage out.The age-old adage that hasbeen repeated in many un-

dergraduate engineering courses forthe past decade is still an importantprinciple to remember for many oftoday’s engineering challenges – in-cluding filter testing.

Today’s designers rely heavily ontesting and simulation data comingfrom a number of sources around theglobe to make their design decisions.If today’s designers are basing their de-cisions off of “garbage,” what can weexpect as an end product? With poortesting and simulation data, the start-ing point for future development anddesigns has already been skewed.

SIMULATE DESIGN TEST VALIDATEGlobal manufacturers work hard to

utilize an iterative validation processfor new product development. Unfor-tunately, more often than not, the sim-ulated results vary significantly fromthe physical test data. The two areasthat contribute to the majority of thesediscrepancies are:

Too often in new product develop-ment there is a misunderstanding ormisinterpretation of the true physicswithin the device or system being de-veloped, tested, and measured. Theproduced results show test data thatcan differ from original simulationmodels and data by as much as 100%

Data acquisition inaccuracies due to

electronic noise and accuracy of the testinstruments used may occour.

So What Are the Major Factors ThatInfluence Test Accuracy and Reliability?

Based on Chart 1 from ISO 16889we can see the many factors that affecttesting results. Some of the most chal-lenging being: viscosity, differentialpressure, solids loading, and flow rate.

FILTER TESTING CONDITIONSMonitoring testing conditions and

parameters is certainly an importantstep to insure accurate results. Specifi-cally, viscosity plays a most importantrole and, as a temperature-dependentfunction, temperature must be pre-cisely monitored and controlled, typi-

Filter | Testing

Proper Validation of Filter Test Stands isCritical for Product Development ProgramsBy Gerard J. Lynch, P.E., IFTS Inc. USA and Nicholas A. Faust, Sigma Design Company

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cally within 0.5 degrees. Uncertaintiesin temperature measurement can leadto more than 8% uncertainty in themeasurement of pressure differential.iLikewise, flow rate measurement is an-other important parameter shown tohave high-impact on the influence ofretention capacity.

For every parameter however, it typ-ically boils down to the accuracy of in-struments and data acquisitionsoftware. This can vary as high as 10%(or more), and should be carefully cal-culated and accounted for when per-forming and analyzing tests.ii

SIMULATION DATASimilarly, simulation and CFD

analysis is becoming a more and morewidely used tool in a design engineer’stoolbox. However, the level of detail,and nuances of setting up a computersimulation, varies from software to soft-ware, including mesh size and meshcontrols, operating conditions, inputparameters and even the features of theCAD model.

TEST STANDSNot all test stands are equal. Recent

discrepancies in testing between labscaused our experts to look more closelyat the differences between filter teststands. We had heard that with somestands the injection circuit reservoir didnot mix well and test dust was oftenfound in the bottom of the reservoir aftertesting during cleanup. What we foundis that differences in tank mixing designapproaches produced different results.

Test dust, which settled on the tank bot-tom was assumed to be injected andtherefore would over state the dirt hold-ing capacity of the sample test filters.

Near zero fluid velocities on the in-jection tank inner surfaces indicate lessthan adequate mixing.

TEST DUSTCorrectly selecting test dust and un-

derstanding the differences betweenthem, is an important step in filter test-

Chart 1



ing and can contribute significantly tothe level of uncertainty in filter testing.All international filter-testing standardsclearly identify the test contaminant(test dust) to use. Some examples in-clude:

SAE ARP 4205 Aerospace Fluid

Power - Hydraulic Filter Elements -Method for Evaluating Dynamic Effi-ciency with Cyclic Flow uses ISO FineTest Dust per ISO 12103-A2.

NSF/ANSI 42 Drinking water treat-ment units – aesthetic effects requiresISO Fine Test Dust per ISO 12103-A2for filter ratings from 1 to 80 micronand ISO Course Test Dust per ISO12103-A4 for filters rated up to 120 mi-

cron.ISO 16689 Hydraulic fluid power fil-

ters — Multi-pass method for evaluat-ing filtration performance of a filterelement uses ISO Medium test dust perISO 12103-A3.

Not only is the test dust used a con-tributing factor to repeatable test re-sults, but so is the concentration of thetest contaminant. In many specifica-

Near zero fluid velocities on the injection tank inner surfaces indicateless than adequate mixing.

Chart 2.



tions this is called the Basic UpstreamGravimetric Level abbreviated BUGLand reported as mg/l or ppm. Onlineparticle counters are affected by con-centration and dilution is used to main-tain consistent results. Most standardfuel oil, diesel and hydraulics filter test-ing use BUGL between 5 – 15 mg/l.

Repeatability is the measure of thevariation of outcomes in an experimentcarried out using the same conditions.Repeatability and Reproducibility areimportant factors to consider, and canbe maximized by taking proper care insetting up identical testing conditions.Additionally, post-test validation, eitherwith previous data, simulation data orestimated results, should be conducted.As a final check using a control chartfor statistical analysis will show if theprocess is within the desired level of re-peatability.

Chart 2 shows temperature, injec-tion flow rate and main flow rate.

Ultimately, the best way to get con-sistent results between filters is to al-ways test within the same operatingconditions. This includes the sametest setup, particle counters, appara-tus and dust. There will, however, al-ways be some level of uncertainty,which will need to be accounted for.However, understanding and estimat-ing this uncertainty with a reasonablelevel of accuracy will provide a betterstarting point for designers and de-sign decisions.

Engineers must realize that evenwhen following the above recom-mended guidelines, sometimes we de-sign experiments that are too largeand complicated to validate in a prag-matic cost effective way. With a recentsystem being developed at Sigma De-sign, the team had no way to validatethe simulation and experimental field-testing of the entire system. The solu-tion was to simplify the problem. Bybreaking the system down intosmaller problems, the team could val-idate individual components on a sim-plified scale, before moving up totesting the complete device.

If one understands the challenges indata collection and recognizes testingand validation problems early on, engi-neers can usually develop a smart and

useful solution.Gerard J. Lynch, P.E. and Nicholas

Faust are with Sigma Design Companyand International Filtration ServicesInc., (IFTS Inc. USA) both located inSpring field, New Jersey. Jerry Lynchserves as President and Nicholas Faustas a Mechanical Engineer.

IFTS is an independently regulated labora-tory and res earch center for liquid filtrationand separation science. IFTS has locationsin Europe, the USA and China, providing fil-tration testing and research services tomany industries.

Sigma Design Company develops and buildsnew products, prototypes and specialtyequipment. Sigma Design provides clientswith cost-effective mechanical engineering,electronics PCB, controls and microproces-sor development, manufacturing engineeringand laboratory services.

References1. Petillon, N., Peuchot, C. 2005, “Impact of Filter Test Pa-rameters Upon the Uncertainty of Filtration Efficiency, Re-tention Capacity and ( P vs. Q) Test Results”, AFS, Atlanta,GA.2. Petillon, N. 2007, “About Validation of Liquid Filter Effi-ciency Test Stands”, Filtech, Wiesbaden, Germany.

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44 • October 2010 • www.filtnews.comDownload PDF-version of magazine at www.filtnews.com


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