FILTRATION NEWS January/February 2014
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INTERNATIONAL
FILTRATION
NEWS
Your Global Source
January/February 2014
Volume 33 No. 1
www.filtnews.com
Adhesive’s Increasing Role in
HVAC Filtration Efficiency
Clean-In-Place Filtration
Technology Can Make Refineries
Safer and More Productive
Smog and Haze Lead to High
Demand for Filter Materials in China
Testing and Evaluation
of Liquid Bag Filters
IN THIS ISSUE
January/February 2014, Vol. 33, No. 1
Published by
Editorial Advisory Board INTERNATIONAL
Industry Experts Join Editorial Board 5 MEDIA GROUP, INC.
6000 Fairview Road, Suite 1200
Charlotte, NC 28210 USA
Phone: +1-704-552-3708
In-Place | Filtration Email: info@filtnews.com
Clean-In-Place Filtration Technology Can Make Refineries Safer, Internet: www.filtnews.com
More Productive and More Environmentally Sustainable 6 Carol and Arthur Brown, Founders
Klaas DeWaal, Publisher and CEO
Antoinette DeWaal, Associate Publisher
Cover Story | Franklin Adhesives & Polymers and Vice President
The Growing Role of Adhesives in Increasing HVAC
Editorial Department
Filtration Efficiency 12 Ken Norberg, Editor in Chief, Ken@filtnews.com
Adrian Wilson, Intl. Correspondent
Chen Nan Yang, China Correspondent
Filtration | Markets Editorial Advisory Board, See page 4
Smog and Haze Lead to High Demand for Filter Administration Department
Materials in China 14 Barbara Ragsdale, Barbara@filtnews.com
Circulation Department
Coolant | Filtration Cherri Jonte, Subscribe@filtnews.com
Progressive Dilution for Cleaning Metalworking Coolants 18 Advertising Sales Representatives
USA
Joan Oakley, Joan@filtnews.com
Testing | Liquid Bag Filters Debra Klupacs, Debra@filtnews.com
Testing and Evaluation of Liquid Bag Filters 22 Europe
Sabine Dussey, sabine.dussey@dussey.de
Martina Kohler, m.kohler@iff-media.ch
Testing | Science Judy Holland, jholland@textilemedia.com
Determining Filter Cut Points and Pore Size Distributions Ferruccio Silvera, ferruccio@silvera.it
Using Microsphere Standards 28 China
Zhang Xiaohua, ifj-china@yahoo.com.cn
Gas/Liquid | Separators Publication Data
Eaton Gas/Liquid Separator Solves Ineffective Air Filtration News (ISSN:1078-4136) is published
bi-monthly by International Media Group, Inc.
Ventilating System 36 Printed in U.S.A., Copyright 2014.
This publication has a requested and controlled
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Filtration News is not responsible for statements
Conference 35 published in this magazine. Advertisers, agencies
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assume responsibility for any claims arising
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Reach $13 Billion in 2017 38 Mailing Address for advertising,
news releases and address changes:
International Filtration News
CLARCOR Acquires Bekaert Advanced Filtration Business 39 International Media Group, Inc.
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Charlotte, NC 28210 USA
Phone: +1-704-552-3708
Email: info@filtnews.com
Internet: www.filtnews.com
POSTMASTER:
Send address changes to:
Cover courtesy of Franklin Adhesives & Polymers International Filtration News
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Charlotte, NC 28210 USA
2 • February 2014 • www.filtnews.com
Editorial Advisory Board
Editorial Board Chairman Haluk Alper, President Robert Burkhead
Edward C. Gregor, MyCelx Technologies Corp. Blue Heaven Technologies
Chairman Tel: 1 502 357 0132
Tel: 1 770 534 3118
E.C. Gregor & Assoc. LLC Cell: 1 502 819 0204
Tel: 1 803 431 7427 Fax: 1 770 534 3117 Email:
ecg@egregor.com alper@mycelx.com bob@blueheaventech.com
M&A, Filtration Media Oil Removal – Water and Air Air Filtration product develop-
ment and performance testing
Peter S. Cartwright, PE Wu Chen Peter R. Johnston, PE
Cartwright Consulting Co. The Dow Chemical Company Tel/Fax: 1 919 942 9092
Tel: 1 952 854 4911 Tel: 1 979 238 9943 ddandp3@aol.com
Fax: 1 952 854 6964 wuchen@dow.com Test procedures
pscartwright@msn.com Process Filtration (liquid/gas)
Membranes, RO, Equipment and Media
Ultrafiltration
Jim Joseph Dr. Ernest Mayer Robert W. Mcilvaine
Joseph Marketing E. Mayer Filtration Tel: 1 847 272 0010
Tel/Fax: 1 757 565 1549 Consulting, LLC Fax: 1 847 272 9673
josephmarketing@verizon.net Tel: 1 302 981 8060 mcilvaine@
Coolant Filtration Fax: 1 302 368 0021 mcilvainecompany.com
emayer6@verizon.net www.mcilvainecompany.com
Mkt. Research & Tech. Analysis
Henry Nowicki, Ph.D. MBA Richard Jacobs Katariina Majamaa
Tel: 1 724 457 6576 Eaton Corporation The Dow Chemical Company
Fax: 1 724 457 1214 Tel: 1 732 212 4747 Tel: 1 952 897 4357
Henry@pacslabs.com Email: Email: kmajamaa@dow.com
www.pacslabs.com richardjacobs@eaton.com Membrane filtration,
Activated Carbons Testing, Liquid Filtration Technologies wastewater reuse,
R&D, Consulting, Training industrial water treatment
Dr. Graham Rideal Andy Rosol Clint Scoble
Whitehouse Scientific Ltd. Global Filtration Products Mgr. Filter Media Services, LLC
Tel: +44 1244 33 26 26 FLSmidth Minerals Tel: 1 513 528 0172
Fax: +44 1244 33 50 98 andy.rosol@flsmidth.com Fax: 1 513 624 6993
rideal@ Tel: 1 800 826 6461/1 801 526 2005 cscoble@filtermediaservices.com
whitehousescientific.com Precoat/Bodyfeed Filter Aids Fabric Filters , Filter Media,
Filter and Media Validation Baghouse Maintenance
Tony Shucosky Scott P. Yaeger
Pall Microelectronics Filtration and Separation
Tel: 1 410 252 0800 Technology LLC
Dr. Bob Baumann
Fax: 1 410 252 6027 Tel/Fax: 1 219 324 3786
Advisory Board
tony_shucosky@pall.com Mobile: 1 805 377 5082
Member Emeritus
Cartridges, Filter Media, spyaeger@msn.com
Membranes Membranes, New Techn.
4 • February 2014 • www.filtnews.com
Industry Experts Join Editorial Board
International Filtration News welcomes three new members to their Editorial Board. Together, Katariina Majamaa from
Dow Water & Process Solutions, Richard Jacobs from Eaton Corporation and Robert Burkhead from Blue Heaven Tech-
nologies, brings with them vast expertise from their respective areas.
Katariina Majamaa Majamaa is currently located in Minneapolis, Minn. She
End User Marketing Manager - Heavy Industry joined The Dow Chemical Company in 2007 as a technical
Dow Water & Process Solutions service and development engineer for reverse osmosis,
Katariina Majamaa is the end user marketing manager at nanofiltration and ultrafiltration membranes in Rhein-
Dow Water and Process Solutions. She is responsible for de- muenster, Germany, serving the regional markets of
veloping and implementing short to medium term strategies, Benelux, Nordic, Baltic, the U.K. and Ireland. She later
on a global basis, for growing value to end users and generate moved to Tarragona, Spain, to support the expansion of
pull through demand within the heavy industry market seg- pilot capabilities and the opening of the Tarragona Water
ment with Ultrafiltration, Reverse Osmosis, Nanofiltration, Technology Application Center in 2011. Most recently, Ma-
Ion Exchange, and Fine Particle Filtration technologies. jamaa spent time in Shanghai, China, exploring the needs
Previously, Majamaa was the global application development of the greater China market.
leader for Industrial Water & Power Generation and the leader In Finland, Majamaa earned her Master of Science degree
of the North American Application Development team. Here, in Chemical Engineering from Helsinki University of Technol-
she was leading technology strategy and new product develop- ogy. She also recently completed graduate studies with research
ment projects from concept exploration through market launch in the area of biofouling with Delft University of Technology,
based on identification and assessment of market needs, emerg- the Netherlands, towards her doctorate in Chemical Engineer-
ing and complementary technologies, products and solutions, ing. She has more than 10 peer-reviewed scientific publications
as well as developing intellectual property strategy and strategic and over 30 conference presentations/alternative publications,
external partnerships. and is a certified Six Sigma black belt. FN
Richard Jacobs corporate vice president, supply chain management for Eaton
Liquid Filtration Technologies globally. There he was responsible for a budget of $7B, pur-
Eaton Corporation chasing products and services from 87 countries. Prior to join-
As president of Eaton’s Filtration Division, headquartered ing Eaton, Jacobs was vice president and general manager for
in Tinton Falls, New Jersey, Richard Jacobs oversees a division Bendix CVS, a former division of Honeywell/Allied Signal, re-
considered a leader in liquid filtration that helps companies sponsible for a $260M business selling desiccant filters and
improve product quality, increase manufacturing efficiency, wheel end products. He also served as a corporate director in
protect employees and equipment, and achieve sustainability Honeywell’s supply chain function. In addition, Jacobs is a
goals. He is responsible for the division’s business operations graduate of the University of Tennessee Lean Certification Pro-
and performance in worldwide markets with manufacturing gram as well as a graduate of the Six Sigma Institute.
locations in the U.S., Mexico, Brazil, Germany, Belgium, India Earlier in his career, Jacobs spent eight years with General
and China as well as its worldwide sales offices in 22 coun- Electric and is a graduate of GE’s Manufacturing Management
tries. He holds several U.S. Patents in manufacturing liquid Program. He holds several degrees including a Masters of Indus-
filtration. trial Management, Bachelors of Science in Mechanical and In-
Jacobs joined Eaton in 2004 as vice president, supply chain dustrial Engineering from Clarkson College in Potsdam, New
management for the Fluid Power Group, responsible for a York, and graduated from the Harvard BMS program and the
spending budget of $2B globally. He was later promoted to Columbia General Management program. FN
Robert Burkhead tions at AAF International (for 15 years) and the U.S. filtra-
Air Filtration Product Development and Performance Testing tion business group of Freudenberg Nonwovens (for 10
Blue Heaven Technologies years). In both these positions he was accountable for over-
Robert Burkhead is president and founder of Blue Heaven seeing the filtration media/product design and manufactur-
Technologies in Louisville, Kentucky. Blue Heaven is a third ing as well as laboratory construction and management.
party testing laboratory with a focus on air filter product per- Burkhead has a Bachelor of Science degree in Mechanical
formance assessment testing. In his capacity at Blue Heaven Engineering Technology and holds product design awards
over ten years, he has also instructed and trained a wide and patents for various filtration products. He has been ac-
range of customer’s internal personnel in the technical details tively involved in ASHRAE technical committee activity for
of air filtration product and market specifics. 30 years and also remains involved with INDA, AFS, ASTM
Burkhead has also held engineering management posi- and Underwriters Laboratory. FN
www.filtnews.com • February 2014 • 5
In-Place | Filtration
Clean-In-Place Filtration Technology Can
Make Refineries Safer, More Productive
and More Environmentally Sustainable
By Richard Jacobs, President, Eaton’s Filtration Division
Eaton’s ClearAmine™ automatic self-cleaning system helps ensure a
continuous supply of pure amine for the removal of acid gas (H2S and CO2).
rocessing toxic, corrosive to both operator safety and overall “amine units.”
P and explosive chemicals at
high temperatures and pres-
sures creates a uniquely hostile and
productivity while reducing a refin-
ery’s carbon footprint and environ-
mental impact.
An amine unit is used to remove
hydrogen sulfide (H 2S) and carbon
dioxide (CO 2) contained in many
dangerous environment. The fact That is not conjecture. The safety crude oil feedstocks prior to refining.
that it is safely done every day in re- enhancement and other benefits of The process uses an amine, typically
fineries around the world is a tribute modern, “clean-in-place” filtration diethanolamine, monoethanolamine
to the skill and expertise of the engi- systems have been proven in hun- or methyldiethanolamine (DEA,
neers who design and operate them, dreds of refineries. The technology is MEA, MDEA) to remove H 2S and
but there is always room for improve- widely used in catalyst protection CO2 from hydrocarbon gases.
ment. Modern filtration technologies and coking applications and is now As the amine circulates through
can make a significant contribution being applied in a growing number of the process, it picks up contaminants
6 • February 2014 • www.filtnews.com
Xinxiang Tiancheng Aviation
Purification Equipments Co. Ltd.
For airplane For special vehicle
For coal machinery
For ultrafilter
For dust For fluid cleaning system
collector
of cement
industry
Our company specializes in designing & manufacturing and supplying many kinds of filters,
complete filtrating equipments and their elements with different materials according to your
drawings or new & old samples.
Xinxiang Tiancheng Aviation Purification Equipments Co. Ltd.
Chuangye Road No.1, Dvelopment Area, Xinxiang City 453003, Henan
P.R. China
Contact Person in China: Mr. Li Minghao
Tel: +86-13673735086 Fax: +86-373-3520026 Website: www.tchkjh.com
Email: lmhao116@163.com • renchenghua@tchkjh.com
In-Place | Filtration
Pipe scale, rust, iron sulfide, sand and other solids build-up in closed-loop amine systems fouling flash drums, heat exchang-
ers, strippers, re-boilers, and carbon filters. They also attract hydrocarbons, which cause system foaming. Eaton’s Clear-
Amine™ system provides an efficient method of removing harmful solids to protect and extend equipment life, and maximize
amine systems’ effectiveness.
including pipe scale, rust, iron sul- stream after regeneration. This ulti- Since clean-in-place filter systems
fide, sand and a variety of other mately exposes everything upstream minimize or eliminate the need for
solids. These foul system compo- of the regenerator to a full load of operators to open the filter system
nents include flash drums, heat ex- contaminants. during operation, the safety impact is
changers, strippers, re-boilers and Rich-side filtration is a better so- obvious. These systems typically use
carbon filters. The amines also at- lution in terms of protecting the a backflush and purge cycle with a
tract hydrocarbons, a major cause of equipment, but opening a cartridge- backpressure-sensing control. The fil-
system foaming, which reduces type filter system unnecessarily ex- ters are installed both as single units
process efficiency. poses workers to dangerous and with a bypass and as multiple banks
The process is continuous, with potentially explosive H 2S and other to provide continuous protection.
the “rich” contaminant-bearing hazards when changing cartridges. The enhanced operator safety pro-
amine being regenerated and reused The cartridges themselves also repre- vided by a clean-in-place system
as “lean” amine. The most common sent an inventory expense and must makes it much more practical than
amine filtration solution today uses be disposed of as hazardous waste cartridges to filter the rich amine
cartridge-type filters to remove con- creating both cost and environmental side of the process. This can extend
taminants from the lean amine impact issues. the life of costly system components
8 • February 2014 • www.filtnews.comIn-Place | Filtration
while dramatically reducing operat- Removing contaminated bags able and above all safer than ever be-
ing and maintenance costs. and/or cartridges from the waste fore is a huge challenge. Fortunately,
These are not the only benefits. A stream reduces the gaseous emissions it is one the filtration industry is
clean-in-place filtration system also associated with their decomposition well prepared to help their cus-
can significantly reduce a refinery’s as well as the associated hazardous tomers meet. FN
environmental impact and carbon waste landfill fees. Over a ten-year
footprint. Compared to the com- period, these savings can add up to For more information contact:
monly used disposable media sys- nearly a 60 percent cost reduction Richard Jacobs
tems, an automated clean-in-place compared to today’s commonly used Eaton
system dramatically reduces the disposable media systems. Tel: 1-732-212-4747
number of bags and/or cartridges that Making the refineries that fuel our Email: richardjacobs@eaton.com
must be purchased, inventoried, han- modern, global society more produc- Website: www.eaton.com/filtration
dled and eventually disposed. tive, more environmentally sustain-
Download the entire issue of
International Filtration News at
www.filtnews.com
10 • February 2014 • www.filtnews.comCover Story | Franklin Adhesives & Polymers
The Growing Role of Adhesives in Increasing H
By Dan Pikula, Director, Filter Market Development, North America
The FilterFAB 3000 series introduces PVA technologies that act as binders. The adhesives are sprayed directly onto the filter
or years, filter manufacturers in residential and commercial air filters. FilterFAB PSA takes on far different
F have relied on adhesives to put
together various components of
the HVAC filters they make, so as to as-
The series offers adhesive technologies
designed to increase particle entrap-
ment, including one that also functions
roles in the filter manufacturing facility.
As a permanent PSA, this surfactant-sta-
bilized vinyl acrylic adhesive can both
semble the filter media or bond it into a as a binder. It also includes an adhesive laminate layers of filter media together
frame or end cap. Now, they are looking technology developed strictly for use as and increase particle entrapment.
to this versatile substance to increase a versatile media binder. The FilterFAB 3000 line also in-
performance of the filter media itself. The company, which also offers a cludes water-based surfactant-stabilized
The ability of adhesive to bond filter wide range of adhesives for many other polyvinyl acetate emulsions developed
media together or to a frame also en- filter assembly applications, plans to as binders to stiffen filter media. The
ables it to capture and hold in place broaden the FilterFAB 3000 series over binder is designed to ensure easy pleat-
particles in an air stream during filtra- time to meet additional filter media ing and crimping of media and to min-
tion. Atomizers along the production manufacturer specifications. It also is imize pore clogging during filtration.
line spray an adhesive formulated prepared to customize FilterFAB 3000 Filter manufacturers get the best of
specifically to entrap the matter directly formulations for specific production both worlds with the final adhesive
on the filter media. The adhesive bol- equipment, filter media type and man- technology in the current FilterFAB
sters filtration efficiency throughout ufacturer requirements. line-up – a unique combo-adhesive that
the expected life span of the media. The initial product in the FilterFAB fuses the above PSA and polyvinyl ac-
At least one adhesives manufacturer 3000 series draws on technology used etate (PVA) technologies to offer the
that serves the filter industry has taken for pressure sensitive adhesives (PSAs) dual functionality of enhanced particle
a lead in developing products to meet – adhesives that typically are coated entrapment and media binding. A sin-
the growing interest in spray-on adhe- onto a substrate to make tapes and la- gle sprayer can simultaneously apply a
sives for improved HVAC filtration effi- bels. PSAs can either be removable binder and filtration enhancement PSA,
ciency. Franklin Adhesives & Polymers (such as painter’s tape), permanent (a both increasing plant productivity and
recently launched FilterFAB 3000, a se- label on a prescription bottle) or repo- end-product performance.
ries of adhesive technologies for media sitionable (sticky memo paper). The Despite their ability to provide specific
12 • February 2014 • www.filtnews.comHVAC Filtration Efficiency
media. This digitally altered photo depicts entrapment of particles.
solutions to the filter manufacturer, the ically can be incorporated directly into both safe for the plant crew to apply
technologies that comprise the FilterFAB existing media equipment, without and for use in residential and commer-
3000 series share a number of character- need for additional equipment or reduc- cial HVAC systems.
istics that position them to easily meet tion in productivity. Once sprayed onto Filter manufacturers continue to
varied application and production re- the media, the adhesives set and dry seek cost-effective, viable methods to
quirements, offer the convenience of easy quickly, without significant impact on increase filtration efficiency. Recent re-
clean-up in the plant and meet regula- overall production time. And minimal search and development in the adhe-
tions for environmental friendliness. clean-up requirements can increase pro- sive laboratories strive to provide them
First, the adhesives manufacturer ductivity: The FilterFAB 3000 series easier and better ways to achieve it. Ad-
can easily customize key performance easily cleans up with water when wet, hesives manufacturers, such as
characteristics of any of these technolo- decreasing time required to keep equip- Franklin Adhesives & Polymers, are
gies to meet specific application re- ment clean, free of clogs – and operating willing to work with filter manufactur-
quirements. Any of the formulations smoothly, with minimum downtime or ers to develop the best way to produce
can be matched to media type, produc- unnecessary maintenance costs. the highest-quality filtration media for
tion equipment, end use, viscosity, etc. HVAC filter manufacturers make a healthy world. FN
Customized adhesives will be tested in equipment for customers who require
the lab to ensure ideal performance in – and value – air purity. Likely, it’s im-
the actual production facility. Further, portant both to the manufacturers and For more information contact:
the formulations are compatible with a end-users that products used in the
wide range of conventional additives, manufacture of filters follow guidelines Franklin Adhesives & Polymers
increasing their versatility and ability to for environmental friendliness. All Fil-
meet specific manufacturer needs. terFAB 3000 adhesives – indeed, all ad- Tel: 1-800-877-4583
As a group, the FilterFAB 3000 ad- hesives under the FilterFAB brand – are Website:
hesives help filter manufacturers maxi- formaldehyde-free. “Green” formula- www.franklinadhesivesandpolymers.com
mize filter efficiency at minimal cost tion ensures that they meet environ-
and effort. The application process typ- mental regulatory requirements and are
www.filtnews.com • February 2014 • 13Filtration | Markets
Smog and Haze Lead to High
Demand for Filter Materials in China
By Jason Chen, China Correspondent
Smog and haze is not uncommon around industrial hubs in Northern China, leading to a demand for filter materials.
n the past few months, public been shrouded for months in thick ber 2013.
I concerns over China’s severe air
pollution forced the government
to take a series of new measures to
smog and haze. In eastern China,
where most of the country’s manufac-
turers are located, the Air Quality
To tackle the hiking air pollution,
the Chinese central government set
up a series of measures late last year,
tackle the ever-growing environmen- Index (AQI) kept rising during most including limiting car driving ac-
tal challenges. Production of filtra- of 2013. An AQI of 0 to 50 is re- cording to license plate numbers and
tion fibers in the Chinese market will garded as excellent, 101 to 150 is phasing out polluted production ca-
be boosted by the new governmental considered light pollution, and above pacity. They also included a project
plans and reach 1,5 million tons by 300 is severe pollution. But the AQI with a total investment of 1,750 bil-
2020, according to industry experts. in Beijing constantly sat between 400 lion RMB ($290 billion), which aims
or 500 during the entire 2013, and in to reduce the smog and haze and im-
SMOG AND HAZE Shanghai, China’s commercial center, prove air quality in the country’s
The market for air filtration is the AQI even reached 700, a level three most important economic
booming in China as the country has deemed “poisonous” in early Decem- zones by introducing advanced tech-
14 • February 2014 • www.filtnews.comnologies, new products, and new fossil fuels in vehicles, power plants, such as short life span, low accuracy,
mechanisms during the next five and manufacturing industries. low abrasion resistance, and wastes
years. These three zones include Bei- Among these sources, high-tempera- pollution,” said Sun.
jing circle (Beijing, Tianjin, and ture waste gases from power plants Professor Liu Jingxian of the Filter
Hebei Province), Shanghai circle and manufacturing industries such as Materials Testing Center (FMTC) of
(Yangtze River Delta Region), and cement and steel contribute to most Northeastern University also admit-
Guangzhou circle (Pearl River Delta of China’s PM2.5 emissions, accord- ted electrostatic precipitators can’t
Region). This project will also reach ing to the government. catch PM2.5 effectively, though they
the final goal of eliminating all the Electrostatic precipitators, bag fil- can catch 99% of the dust. He said
heavy air pollution (AQI 251 to 300) ters, and electrostatic and bag com- bag filter had become the main
in China by 2023. Chinese industry pound filters are used to eliminate stream in China’s high-temperature
experts expect the investment will high-temperature waste gases in filtration efforts.
boost the growth of the country’s fil- China. But most of the products cur- According to recent research from
tration industry, especially of those rently used in China have a low effi- FMTC, main filter materials cur-
for high-temperature waste gases re- ciency, according to Sun Maojian, rently used in China to eliminate
duction. president of the Yantai Tayho Ad- PM2.5 emissions include:
vanced Materials Co., Ltd. (Tayho).
PM2.5 AND FILTER MATERIALS “Electrostatic precipitators (used FOR COAL-FIRED POWER PLANTS
In China, the main harmful mate- by Chinese manufacturers) can only Currently, more than 80% of
rial in the air is particulate matter 2.5 catch around 60% of the particulate China’s power consumption is sup-
(PM2.5). With a small diameter of matters, which diameters are smaller plied by coal-fired power plants. The
only 2.5 micrometers, a PM2.5 than 10 micrometers. On the other main filter material in these plants is
spreads through the air and can di- hand, most of the Chinese companies polyphenylene sulfide (PPS) needle
rectly enter the human alveoli of still use traditional materials such as punched felt. A PPS needle punched
lungs, which can cause severe health glass fibers as the main materials in felt filter can catch around 78% of
problems. PM2.5 mainly come from bag filters, which have problems the PM2.5 in the waste gases, accord-Filtration | Markets
ing to the FMTC research. Some filter filter materials for the cement indus- this replacement process. Currently
companies use spunlace process to try include polyimide fibers, also China’s supplies of aramid fibers are
increase the efficiency. A filter made known as P84 fibers. China-made dominate by global brands such as
of spunlaced PPS felt can catch up to P84 filters can effectively catch Du Pont and Teijin, and most of the
85% of the PM2.5 in a coal-fired PM2.5 in the environment of high Chinese manufacturers prefer to use
power plant. temperature, according to a recent re- the relatively cheaper filter materials
As the government seeks to port of the Jiangsu Aoshen Advanced such as glass fibers.
tighten the PM2.5 emission limit, Materials Co., Ltd. The government’s 1,750-billion-
polytetrafluoroethene (PTFE) mem- But today most of the Chinese ce- RMB investment could help Chinese
brane PPS felt will be more widely ment producers still have dust emis- manufacturers reduce the aramid
used by power plants. PPS needle sions of much more than the national cost. Chinese government subsidizes
punched felt is dipped, laminated, or standard, which is 10mg per cube domestic companies for technologi-
coated with PTFE to improve high meters of gases emissions. This cal innovation and other efforts that
temperature resistance, corrosion re- means many cement producers still fit the government’s plan. The subsi-
sistance, and the ability to catch don’t use bag filters made of P84 dies could reduce the cost of usage of
small particulate matters. The PTFE- fibers and other advanced materials aramid bag filters.
laminated filter material can catch to reduce gases emission. Another possible momentum will
more than 99% of the PM2.5. be the decrease of aramid prices. As
FOR THE STEEL INDUSTRY Chinese aramid fiber manufacturers
FOR CEMENT PLANTS In China, more than 90% of the have started to expand their produc-
Bag filters have been used in filtration products in the steel indus- tion capacity, the prices of aramid
China’s production of cement since try are bag filters, according to Liu. fibers are expected to decline, and
early 2000 and have dominated the Main filter materials include glass aramid bag filters will have better
market since early 2010. The main fibers and their composites with cost performance in the market. Cur-
other fibers such as P84 fibers and rently, Tayho is China’s largest para-
aramid. Glass fiber-based bag filter aramid producer, with an annual
can catch up to 97% of the PM2.5 capacity of 1,000 metric tons. China’s
emissions in steel production. total para-aramid capacity was only
1,500 metric tons by 2013. But the
ARAMID FILTERS capacity will reach, respectively,
Comparing to most other prod- 5,000 metric tons in 2015 and 16,000
ucts for high-temperature waste metric tons in 2020, according to Ye
gases filtration in China, aramid bag Yongmao, chief consultant of the
filters have better performance, ac- China Chemical Fibers Association
cording to Sun. He said a bag filter (CCFA).
made of aramid fibers could catch
98% to 99% of the particulate mat- FILTRATION FIBERS
ters, with diameters as small as one In China, the main filtration fibers
micrometer. But currently only 5% of include polyester, nylon, polypropy-
the filtration products for high-tem- lene, polyacrylonitrile, PTFE,
perature waste gases are made of aramid, glass fiber, P84, and PPS.
aramid in China. As the governmen- Polyester fibers account for around
tal efforts to tackle air pollutions will 70% of China’s filter materials con-
force the manufacturers to use more sumption, but it can’t be used in a
efficient filters, Sun estimated China high-temperature environment. For
would consume 50,000 metric tons high-temperature filtration, the main
of aramid fibers for producing new materials are PTFE, aramid, glass
bag filters to replace the current elec- fiber, P84, and PPS.
trical precipitators and glass-fiber China’s production of filtration
bag filters in the next few years. This products consumed 740,000 metric
would be a billion-dollar market, tons of fibers in 2012, a 14% growth
said Sun. rate from the 2011 level, according to
But the high cost of aramid fibers China Nonwovens & Industrial Tex-
will still be the main obstacle to slow tiles Association (CNITA). CNITA es-
16 • February 2014 • www.filtnews.comtimates that the annual growth rate the consumption of PPS fibers. were good since 2012. On the con-
will continue at double digits in the Zhang Daming, CEO of China Lu- trary, China’s PPS fiber sales were
following eight years, which means mena New Materials Corp. (Lumena) weak before 2011, while PPS fiber
the country’s consumption of filtra- expected China’s annual PPS fiber manufacturers’ operating rate was
tion fibers could overtake 1.5 million consumption will remain at more usually below 50%.
metric tons by 2020. than 20,000 metric tons in the next China’s output and consumption of
few years. Lumena is one of China’s glass fibers reached, respectively, 2.9
The market of each fiber is de- largest PPS fiber suppliers, with an million and 1.7 metric tons in 2012,
scribed in the following: annual capacity of 30,000 metric according to the China Composites In-
tons of PPS resins and 5,000 tons of dustry Association (CCIA). CCIA es-
Polyester fiber will continue to be PPS fibers. Zhang said Lumena had timated 11% of the domestic glass
the largest sector. China’s consump- high gross profits and strong bargain fiber consumption was for industrial
tion of polyester for filtration pur- power for their PPS fibers, as sales textiles, including filtration. FN
poses was about 500,000 metric tons
in 2012. By 2017, the annual con-
sumption of filtration polyester fibers
could reach 760,000 metric tons.
Aramid will be one of the fastest-
growing sectors. In 2013, more than
60% of China’s annual para-aramid
consumption of around 8,400 metric
tons was imported from the United
States, Japan and Europe. Para-
aramid will remain an average annual
growth rate of around 15% between
2012 and 2020. According to Ye
Yongmao, by 2015 domestic fiber
manufacturers will supply half of
China’s annual para-aramid fiber
consumption of 10,000 metric tons;
by 2020 domestic fiber makers will
supply 80% of the annual para-
aramid consumption of 20,000 met-
ric tons in China.
PPS fibers will welcome a strong
growth in the next few years. China’s
capacity of PPS resins and PPS fibers
reached, respectively, 30,000 and
20,000 metric tons by middle 2013.
The demands from bag filters in
power plants have started to boost
Visit us online
for more news
www.filtnews.com
www.filtnews.com • February 2014 • 17Coolant | Filtration
Progressive Dilution for
Cleaning Metalworking Coolants
By James J. Joseph
Figure 1: Sidearm Sump Cleaning
ump-side cleaning of metal- The remove and repair concept is can be used and the range of possibili-
S working coolants is growing in
popularity because of all the
advantages of cleaning at the machine
easy to understand. However, the pro-
gressive dilution concept has many
subtle fundamentals, which influence
ties includes centrifuges, most filter de-
signs and typical separators such as
magnetic, settling and hydrocyclonic.
without all the extra handling. There its success in cleaning a sump. Many Of course the selection and size must
are two basic concepts: believe that all they have to do is to be in keeping with the application and
hook up a sidearm cleaning device to a flow rate.
•Remove the total volume to a machine’s sump and let it run for a The success of the progressive dilu-
portable cleaning device, which has short time to clean the fluid; usually tion cleaning function depends upon
its own holding tank. Then send the the quicker the better. However, the many factors, but the two most impor-
cleaned fluid back to the sump. This importance of the cleaning time is a tant parameters are the efficiency of the
is a remove, repair and replace major component to successful per- cleaning device and turnover rate of the
maintenance procedure. formance. This article explains the nu- volume in the sump.
ances of progressive dilution.
•Constantly recirculated a portion of Figure 1 shows a simple schematic EFFICIENCY
the sump’s volume through a of a sidearm device connected to a In this industry the term “efficiency”
portable cleaning device without sump. is a difficult parameter to measure
removing the total volume at one Figure 2 shows a typical bag filter while a unit is working. A filter’s effi-
time. This is a progressive dilution with a pump designed to work as a ciency changes as it loads with the con-
procedure. sump-side cleaner on a sidearm con- taminants. Centrifuges have a high and
cept. Almost any transportable device fairly consistent efficiency but it could
18 • February 2014 • www.filtnews.comchange when the ratios of solids to liq- Figure 3 is a family of curves that re-
uids vary. Other separators have a lower flects the amount of contaminants re-
efficiency, which is also dependent on maining in the fluid versus time at four
the ratio of solids to liquids. different device-efficiency levels: less
All of this is treating the suspended than 25 percent, 25 to 50 percent, 50 to
material, which can be drawn into the 75 percent, and 75 to 100 percent. The
pump’s suction. Another part of sump unit for operating interval is one
cleaning is to take the steps to remove turnover of the reservoir. The title uses
settled and floating material if they can the term “clarification” to cover all
not be drawn into the feed pump. cleaning devices regardless of their
mode of operation. These curves are
TURNOVER developed with established models
Turnover is defined as a point where from filtration studies on a wide range
the entire volume of liquid passes of applications. They are prepared to fit
through a cleaning device at its de- known factors found in typical applica-
signed flow rate. For example, a filter tions and to compensate for some of
flow rate of ten GPM, working on a the realities of data collection and in-
tank with 100 gallons, will turn over terpretation.
the volume every ten minutes. The curves are not absolute because
of the many other factors and un-
PROGRESSIVE DILUTION knowns which take place during the re-
Progressive dilution is when a por- circulation of liquid through a cleaning
tion of the volume of liquid in a sump, device. They are not really smooth
with a fixed amount of suspended ma- since most devices will react differently
terial, is continuously recirculated as the amount of suspended material in
through a cleaning device and returned the fluid changes in concentration. Figure 2: A typical bag filter with a
to the tank. As it is recirculated, the just However, it is possible to use these as pump designed to work as a sump-side
cleaned portion mixes with the balance guides to project a feasible performance cleaner on a sidearm concept.
of the fluid to dilute the concentration
of remaining contaminants. The fluid is
progressively being cleaned as long as
no other contaminates are introduced
during the cleaning period.
The phenomenon of progressive di-
lution has an axiom that a 100 percent
efficient cleaning device will remove
over 99.9 percent of the original sus-
pended material after the flow rate
through the cleaning device has
achieved seven turnovers. This state-
ment has a direct applicability to actual
practice, but caution is advised to rec-
ognize the practical limits of this think-
ing. There is more on this in the book
Coolant Filtration 2nd Edition- Addi-
tional Technologies.
Obviously, the 100 percent efficiency
factor is the ultimate accomplishment
and there are few devices, which are
economically justified to achieve this
target. Less efficient devices attempt to
reach the 99.9 percent goal, but they
need more than seven turnovers to ac-
complish the task. Regardless of the ef-
ficiency, the majority of the
contaminants are removed at seven
turnovers.
www.filtnews.com • February 2014 • 19Coolant | Filtration
or make flow rate adjustments to achieve better turnover-
rates. Also, it can be seen that a device with low efficiency
could be “acceptable” for an application.
APPLYING PROGRESSIVE DILUTION
Knowing that seven turnovers is a key factor, here are
points to consider:
1. Initial thoughts should be to see what is needed to
approach seven turnovers.
2. A large sump should have a higher flow rate than
a small sump.
3. Time to reach a turnover is an important parameter
for machine downtime.
4. Sump cleaning is intended to extend the fluid’s life;
not keep it totally clean.
5. The machine can operate with some contaminants;
it does once it starts working.
6. Seven turnovers may be too long and not really needed.
7. Time to service the device, as needed, during
the cleaning cycle.
8. Note the different turnovers at a given level of
Figure 3 contaminants left in the system.
20 • February 2014 • www.filtnews.com9. A small increase in flow rate could If downtime is too long for the ma- refill with cleaned fluid from the
make a significant difference in chine’s production schedule, here are remote operation.
turnover rates. some options to reduce the time:
10.There are four factors: sump size, CAUTION
downtime, device selection and flow 1. Select a higher capacity cleaning Since progressive dilution is a com-
rate. device for a flow greater than 20 plex phenomenon, it is important to
GPM. Probably this step is the most understand that the information offered
Of the four factors in the progressive practical; i.e., if bag filters are used, here is presented in good faith as a
dilution concept, two are fixed: sump add more bags in parallel. Or, with guide to understanding the basics of
size and maximum time the machine centrifuges use a larger unit. sump cleaning. All factors should be
can be down. The other two, device se- 2. Use the most efficient device evaluated by everyone involved to
lection and flow rate are flexible within possible; most of the time a filter or make sure there are no unknowns,
a reasonable range of options. centrifuge is already at the best which could influence the selections of
level. The filter must be sized for equipment and time. FN
The following typical scenario re- the application to avoid frequent
veals some thought processes. stopping to change the media. James J. Joseph is a consultant who has
3. Run it at the number of turnovers also written the book Coolant Filtration 2nd
Given: the machine’s downtime can Edition, Additional Technologies.
• Sump capacity of 250 gallons tolerate and see if the clarity level is
• Filter selected for 20 GPM and has acceptable. For example, the curves For more information contact:
been properly sized for the show what can be achieved if 20 Joseph Marketing
application percent left in the system is 120 Richmond Hill Court
• Turnover every 12.5 minutes acceptable; 1.5 to 3.3 turnovers. Williamsburg, Virginia 23185
• Seven turnovers would have the 4. If none of the above is feasible, Tel/Fax: 757-565-1549
machine down for about 1.5 hours drain the sump, transport the fluid Email: josephmarketing@verizon.net
to a remote cleaning operation, and
www.filtnews.com • February 2014 • 21Testing | Liquid Bag Filters
Testing and Evaluation of Liquid Bag Filters
By Dr. Ernest Mayer
iquid filter bags are univer- micron ratings. This paper addresses of primarily flat sheet media, includ-
L sally used in a variety of in-
dustries particularly for
paint, ink jet, chemicals, pigments
how Capillary Flow Porometry
(CFP) and to some extent NIST
Glass Bead challenge testing can be
ing felts. This method was also com-
pared to conventional Capillary Flow
Porometry (CFP) where some inter-
and wastewater filtration. Needle- used to unambiguously assess mi- esting correlations were found. Al-
punched felt bags are primarily used, cron ratings; how actual ISOCTD most all flat sheet media that were
and a discussion of the needled-felt challenge testing can be used; and tested by both NIST glass bead chal-
punched process can be found in var- how full-scale testing can be done to lenge testing and CFP showed excel-
ious texts. More rigorous micron- assess efficiency and life. lent comparisons by both Whitehouse
rated media are becoming more and DuPont’s instruments except for
prevalent today. In addition, multiple NIST GLASS BEAD CHALLENGE TESTING needled felts. Apparently, the dry glass
geometries are now offered for Glass bead challenge testing with beads were trapped in the felt depths
greater surface area per individual NIST certified glass beads was pio- by static effects, which resulted in er-
bag. Another issue with bag filtration neered by Whitehouse Scientific in roneous efficiencies.
(other than simplicity and low cost) the U.K. and further developed by As a consequence, a wet method
is the lack of uniformity between DuPont to provide a rigorous method had to be used, but then significant
manufacturers and their confusing to determine the cut-point efficiency deviations occurred from the dry
* A small 0.1 ft2 Millipore filter holder was challenged with a based on samples collected for turbidity & particle counting.
200ppm water solution of ISOCTD at stated flux, and both tur- Note that >70 μm values result because the particle counting
bidity (NTU) and particle counting determined on samples col- instrument only went up to 70 μm maximum (except for the
lected. vendor data).
** PMI Capillary Flow Porometer (CFP) values for Bubble (2) Media life in minutes to 30 psid.
Point (B.Pt.) sizes in microns including the typical B.Pt./1.65 (3) Dirt Holding Capacity (DHC) in grams at end of cycle and
correction for the universal tortuosity factor based on dry 30 psid (expressed as grams/full size #2 bag & based on effi-
media challenge testing. ciency and grams ISOCTD fed over cycle).
(1) The 50 & 98% initial efficiency ratings are listed in microns
22 • February 2014 • www.filtnews.com* The used filter bags were soaked in solvent for 24 hours to lar bags; and the % Decreases (Decr.) calculated, which has
remove residual paint resin; and nine 25mmD. samples were been shown to be a measure of media blinding.
cut from each bag and evaluated via a PMI Capillary Flow ** Water Flux (gpm/ft2) obtained on these same 9-25mmD.
Porometer (CFP) for Bubble Point (B.Pt.), Mean Flow Pore samples by filtration of 0.2 μm filtered DI water at 5 psid
(MFP) size, and Frazier permeability (cfm/ft2). The results pressure.
were then averaged and compared to new samples from simi- (1) Average of all four parameter % Decreases.
method. This wet method combined for these thick needled-felts were still ISOCTD testing became necessary
with glass bead particle counters fairly high compared to glass bead ef- along with some full-scale testing.
proved to be accurate, but CFP results ficiency values such that actual
www.filtnews.com • February 2014 • 23Testing | Liquid Bag Filters
Figure 1
* Actual plant tests were conducted with the various bag pairs collected depending on bag life and averaged).
media evaluated in a 4-around Size #2 Pall vessel at a con- *** Approximate filter area for the 4 bags tested;
stant 150 gpm flow which translates into the normal ~11 (1) Terminal ΔP depending on plant operation and/or bag
gpm/ft2 flux for 4 standard Size #2 bags (as well as for the limitation;
molded BOSG bags); and ~2.5 gpm/ft2 for the ~60 ft2 (2) Bag life in minutes to 30 psid.
pleated bags. (3) Dirt Holding Capacity (DHC) in grams at end of cycle at
** Turbidities determined on collected influent and effluent 30 psid (based on actual grams contained in bag by weighing
samples across the bag filter, and averages over the entire dry dirty bag – new bag weight).
bag life to terminal ΔP, (i.e., at least 7 and up to 28 sample
24 • February 2014 • www.filtnews.comSMALL-SCALE FLAT-SHEET BAG MEDIA not shown here). Note that both of dle-punched felt bag in another test at
Table I details a few tests with typ- these two bags were tested on the equivalent filtrate quality. Note that this
ical bag filter media challenged with same tank of resin to terminal DP so test wasn’t taken to completion (e.g., 30
ISOCTD at a nominal 8 gpm/ft2 bag the comparison would be valid. It is psid) because the batch ran out. Nev-
filter flux and shows: believed that this lower blinding of ertheless, the 9097/9096 bag showed
the DuPont spunlaced media is due to about a 13.7 psig DP compared to
• Standard P050 felt has higher greater uniformity and the absence of about 18.9 psig for the PE25 bag; and
CFP values compared to DuPont’s needle-punched holes. the 9097/9096 bag has even lower MFP
9096 and 9097 and a poor >70 μ m and B.Pt. suggesting better filtration.
98% ISOCTD efficiency, but reason- • The 9097/9096 bag also opens up
able life and 101 g DHC (corrected to less than the corresponding PE25 nee- • Both spunlaced bag media
a Size #2 bag area, which agrees very
well with actual plant tests – see
Table III).
• A vendor test of P050 results in a
125 μm 98% efficiency, which agrees
very well with the CFP B.Pt./1.65
value, albeit they used a somewhat
higher 12 gpm/ft2 flux. However,
their life was somewhat shorter at 100
mins; and DHC also lower at 92 g
(which could be attributed to the
higher flux). The lower DHC could
also be attributed to slightly higher
ISOCTD ppm loading used (i.e., see
plant evaluations in Tables III & IV)
.
• Both DuPont 9096 & 9097
media exhibit lower DHCs (except
perhaps for 9097, which has similar
93 g DHC to the 101; 92 DHCs to
P050), but both are significantly
more efficient (i.e., 86 μm and 70 μm
98% efficiencies).
Thus, these small-scale 0.1 ft2
ISOCTD challenge tests demonstrated
that P050 has reasonable life and DHC
but poor 125-150 μm 98% efficiency;
that DuPont’s new 9096 felt media has
much better 86 μm 98% efficiency but
poor life and DHC; and that 9097 has
some potential since its life and DHC
are similar to P050, but at much better
70 μm 98% efficiency.
PLANT FULL-SCALE RESIN FILTRATION
Table II (and Figure 1) details the
~110°C resin filtration trials with ac-
tual size #1 bags; and shows:
• The 9097/9096 dual-layer bag
blinds much less than the correspon-
ding PE10 bag with low DP increase
(see Fig. 1) and equivalent filtrate
quality (as indicated by plant grit tests
www.filtnews.com • February 2014 • 25Testing | Liquid Bag Filters
* Actual plant tests were conducted with the various bag pairs collected depending on bag life and averaged).
media evaluated in a 4-around Size #2 Pall vessel at a con- *** Approximate filter area for the 4 bags tested.
stant 150 gpm flow, which translates into the normal ~11 (1) Terminal ΔP depending on plant operation and/or bag
gpm/ft2 flux for 4 standard Size #2 bags (as well as for the limitation.
molded BOSG bags); and ~2.5 gpm/ft2 for the ~60 ft2 (2) Bag life in minutes to 30 psid.
pleated bags. (3) Dirt Holding Capacity (DHC) in grams at end of cycle at
** Turbidities determined on collected influent and effluent 30 psid (based on actual grams contained in bag by weigh-
samples across the bag filter, and averages over the entire ing dry dirty bag – new bag weight).
bag life to terminal ΔP, (i.e., at least 7 and up to 28 sample
showed less blinding after water flux tests a short 1:15 life but a similar 100g 1.5 psid before the tests had to be ter-
were conducted on dried used bags (after DHC compared to the small-scale minated. Even so, their performance
solvent soaking overnight to remove en- ISOCTD challenge tests (Table I), but merited further study because of their
trapped resin) compared to new bag poor 25% NTU efficiency under ab- higher efficiencies and DHCs that
media, (i.e., 15 vs. 28% for 9097/9096 normal operating conditions, (i.e., simply could not be accounted for by
spunlaced vs. PE10; and -7 vs. 5% for high inlet feed turbidity). the area increase.
9097/9096 spunlaced vs. PE25.).
• DuPont’s 9096 and 9097 bags ex- • FSI’s new B0SG bags also have
Thus, these actual plant paint resin hibited higher efficiencies, longer merit due to much longer 9-hour life,
trials demonstrated the superiority of lives, but lower DHCs. However, increased DHC, and improved 35% ef-
the new spunlaced media compared to 9097’s DHC was reasonably close to ficiency (vs. 25% for P050).
typical needle-punched liquid felts. that of P050, (i.e., 92 vs. 100g); thus
9097 bags are worthy of further con- Thus, these full-scale bag tests
PLANT FULL-SCALE 4-AROUND SIZE sideration. demonstrated that 9097 bags com-
Table III details a series of full-scale pare quite favorably to P050 bags
plant tests with their 150 gpm waste- • Pleated 9096 and 9097 bags have (i.e., longer life and similar ~100g
water stream (flux ~11 gpm/ft2) using significantly longer lives and higher DHC, at higher efficiency); that a
four (4) Size #2 bags, and shows: efficiencies and DHCs than the stan- pleated 9097 bag of ~60 ft2 area has
dard P050 bags. Note that operating much longer life at higher efficiency
• The standard P050 bag exhibited problems limited the DPs to 0.6 and and DHC; and that FSI’s new molded
26 • February 2014 • www.filtnews.comB0SG depth bags also have signifi- ciency. However, the 9097 inlet feed SUMMARY
cant merit. turbidity was even higher (5.3 vs. 3.9 The extensive bag filter trials con-
NTU), which could explain the ducted here both with ISOCTD chal-
FINAL PLANT FULL-SCALE 4-AROUND shorter life. lenge and full-scale plant tests
Table IV details the final round of demonstrated that Capillary Flow
4-around bag trials with similar bags • The B0SG bags exhibited a very Porometry (CFP) analysis can predict
(except that insufficient 9097 media long 7:25 life, an excellent 72% effi- bag filter media efficiencies (or mi-
was available to make pleated bags so ciency, and good DHC despite the cron ratings) such that ambiguous
a similar 80 gsm spunlaced media fact that they had similar area as the vendor ratings can be compared. In
was substituted); and that all bags P050 bags. addition, full-scale tests must be done
were run to terminal DP. Basically, to validate ISOCTD tests since effi-
Table IV shows • The DuPont 80 gsm pleated bags ciencies and DHCs can vary signifi-
(60 ft2 area) exhibited an even longer cantly depending on the particular
• The standard P050 bags exhibit a 9:30 life at even higher 78% NTU ef- application. Furthermore, the test
slightly shorter 3:15 life, a similar ficiency, and an excellent 675g DHC. program here demonstrated the via-
28% efficiency and 100g DHC like This very high DHC cannot be ac- bility of pleated and molded-depth
previously, but a much lower 1:32 life counted for by the increased area, bags for increased efficiencies at much
and 68g DHC (but higher 46% NTU [i.e., 60/14 x (68-100) = 292-429g vs. longer lives and DHCs. FN
efficiency) at upset conditions of high 674g actually removed]; hence, these
inlet feed turbidity. pleated 80 gsm bags have significant For more information contact:
merit for this application. Dr. Ernest Mayer
• Under similar upset conditions, E. Mayer Filtration Consulting, LLC
the 9096 bags exhibit much shorter Thus, these final full-scale bag tests Tel: 1-302-981-8060
life and lower DHC even though its demonstrated the utility of pleated and Fax: 1-302-368-0021
NTU efficiency was 55%. On the other molded depth bags for extended life, in- Email: emayer6@verizon.net
hand, the 9097 bags have similar life creased DHC, and increased efficiency
at lower DHC but increased 49% effi- with much less operator changeouts.
www.filtnews.com • February 2014 • 27Testing | Science
Determining Filter Cut Points and Pore Size
Distributions Using Microsphere Standards
By Dr. Graham Rideal and Abi Stewart, Whitehouse Scientific Ltd., Chester, U.K.
orometry is probably the most
P well known method of meas-
uring pore size distribution.
This involves using air pressure to
expel a wetting liquid from the pores of
a filter. When the gas pressure is ap-
plied, large pores offer less resistance
and so are cleared first.
The appearance of the first bubble
(the “Bubble Point”) reflects the largest
pore size but different instruments use
different methods of detection. For ex-
ample, in the Coulter Porometer, incre-
mental “bands” of pressure are applied
and the fixed band within, which the
bubble first appears, is used for the cal-
culations of maximum pore size. There
therefore tends to be very good instru-
ment-to-instrument agreement.
In other instruments, there is a con-
tinuous increase in pressure and a par-
allel measure of flow. Deviations from
a linear pressure/flow relationship are
theoretically more precise but the diffi-
culty here is defining the exact position
of the divergence. In simple terms, how
much must the bubble be inflated be-
fore it is deemed significant?
The exact determination of the Bub-
ble Point, and from it, the maximum
pore size is critical as it is the bench-
mark from which the pore size distri-
bution is calculated. As the pressure on
the wetted filter is increased, interpola-
tion of the pressure versus flow rate can This method has the advantage that ical standards, where particle shape is
then be used to determine the pore size the particles can be reference to the In- not an issue. Filter cut points and pore
distribution. ternational Metre, for example through size distributions can now be deter-
The alternative method of measur- the NIST (National Institute for Stan- mined, even into the sub-micron re-
ing filter cut points (a defined “maxi- dards and Technology, USA). However, gion. Results will be presented for flat
mum”, pore size) and pore size a disadvantage is that particle-sizing sheet filter media and also 3-dimen-
distribution is the Challenge Test. In techniques are dependent on the sional small-scale filter elements.
this method, a range of particles, either method of analysis where particles are
as solids or liquids (aerosols) are pre- non-spherical. THE CHALLENGE TEST PARTICLES
sented to the filter and the particle size This work reviews the latest tech- Challenge test particles come in a
of the penetrating particles measured. niques of challenge testing using spher- range of sizes and shapes, but Figure 1
28 • February 2014 • www.filtnews.comYou can also read
