Table Of ContentHandbook of
NONWOVEN FILTER
MEDIA
s
Front cover image: Nanowave Filter Media by Hollingsworth and Vose Co (H&V).
East Walpole, Massachusetts USA. Courtesyof Hollingsworth and Vose (H&V)
Handbook of
NONWOVEN FILTER
MEDIA
IRWIN M. HUTTEN
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DEDICATION
Soon my lovely wife, Susan, and I will start preparing for our fiftieth wedding
anniversary.
During all this time, Susan amazed me with her love, support, and patience. She
understood the time it took to write the first edition of this book, and once again she
understood as I wrote this second edition. She provided encouragement, support, and
assistance for this endeavor. I am very fortunate to have a loving wife like Susan. It is
with great pride that I dedicate this book to her.
PREFACE
When I wrote the preface of the first edition of the Handbook of Nonwoven Filter
Media, I reported that the writing was a labor of love and there was an awful lot of
labor to love. Four years ago I undertook the writing of the second edition and
learned that upgrading and revising the first edition required as much love.
The intent of this book is to provide the reader with a fundamental understanding
of nonwoven filter media and to upgrade the technology from the 8 years since the
first edition was published in 2007. This edition provides the following information
on nonwoven filter media: how it is used, how it is made, its raw materials, how it is
processed, and how it is managed and regulated. Several new features were added in
this second edition. This includes a section on Computational Flow Dynamics (CFD)
prepared by Prof. George C. Chase, Ph.D., University of Akron, Akron, Ohio, USA,
and short sections on Global and North American marketing statistics prepared by
Brad Kalil, INDA (Association of the Nonwovens Fabrics Industry), Cary, North
Carolina, USA.
The definition of nonwoven filter media was modified to include membrane filtra-
tion technology. Membrane filtration has grown so much and so inter-wrapped with
nonwoven filter media that to write about the former without including the latter is
like trying to write about a large family without including the in-laws. It can be done
but it is awkward. Accordingly, the second edition’s discussion of membrane filtration
and separation is greatlyexpanded.
Another expansion is the discussion of nanofiber technology. Nanotechnology
is one of the emerging technologies of the twenty-first century. Nanofibers and
nanofiber webs, as used in filter media, are an important part of that emerging tech-
nology. The filtration and separation of nanoparticle sized contaminants is a major
concern of modern day nanotechnology.
The accelerating rate of global technology is demanding extensive legislation, reg-
ulation, standardization, and control. The emphasis is on safety and environmental
concerns. Sustainability has become an important issue in the marketplace and in
manufacturing. The demand includes the technology of nonwoven filter media. For
this reason, a whole new chapter (Chapter 10) on federal law and regulatory activity
has been added to the second edition. The new legislative and regulatory activities
place new burdens and hardships on the manufacturers of nonwoven filter media.
However, they create abundant opportunities for nonwoven filter media to solve the
problems of the environment and safety. The opportunities far outweigh the burdens.
xix
xx Preface
The manufacturers of nonwoven filter media should be prepared to take advantage of
these opportunities.
Other new items that have been added to the second edition include color tech-
nology and new separation processes. For example, barrier fabrics that separate oil
from water as a result of oil spills are described. The second edition includes mem-
brane separation processes such as ion exchange, electrodialysis, and pervaporation.
Much information in the first edition had to be updated. The products of many
companies had become obsolete and had to be updated. Standards and regulations
have been revised. The author has attempted to present the most recent ones at the
time of writing. Companies have been bought out and organizational names have
been changed. Again, the author has attempted to present the company and its most
recent form.
A guided tour of the second edition starts off with introductory remarks in
Chapter 1 followed by the marketing statistics prepared by Mr. Kalil. The
Introduction includes a description of what nonwoven filter media is all about and
how it is used. Definitions of filtration and separation, nonwovens, and nonwoven fil-
ter media are included in Chapter 1. These definitions are necessary to set the scope
of the book. In addition to the filtration of particulate matter from a fluid stream
other forms of separation phenomena are included. Among these are adsorption, elec-
trostatic and electrokinetic effects, coalescence, diffusion, membrane separation phe-
nomena, and others.
The definition of nonwoven filter media includes paper or wet lay media,
felts, and membrane media. These items are not necessarily included in the ISO defi-
nition of nonwoven filter media. The defining factor is that they be used as a filter
medium.
Chapter 1 classifies nonwoven filter media based on forming process. The major
processes come under the major headings of dry formed, wet laid, and composite
structures. The dry formed processes are further divided into polymer sourced and
fiber sourced. Polymer sourced are those processes in which a molten or solution
polymer is spun through spinnerets to form a random web. Fiber sourced are those
processes such as carding or air laid in which the raw feed to the process is in a fiber
form.
The mechanisms and theory of nonwoven filter media are presented in Chapter 2.
The theoretical presentation is classical. It includes the Monte Carlo techniques of
Piekars and Clarenburg (87) to demonstrate random web structure and how pores are
defined. It is in Chapter 2 that we find Dr. Chase’s introduction to Computational
Flow Dynamics (CFD).
Chapter 3 is an attempt to explain the broad range and variety of the properties of
nonwoven filter media. The intent is to relate the properties to the use of the medium
and provide guidance and its selection. The properties not only include classical
Preface xxi
engineering properties such as strength and rigidity, but also such as permeability and
pore size that relate to filtration performance.
To truly understand nonwoven filter media, one must understand how it is made.
Chapter 4 discusses the raw materials of nonwoven filter media and Chapter 5
describes the processes by which they are made. The raw materials of Chapter 4 are
subdivided into polymers, fibers, resins, and additives (finishes). The processes of
Chapter 5 not only include the forming processes by which nonwoven filter media
are classified, but also include the downstream converting and finishing operations.
For example, needle punching and/or hydroentanglement of carded webs are well
described. Since so much of nonwoven filter media is used in a pleated cartridge or
pleated panel form, the various pleating processes are detailed. The second edition
additions to Chapters 4 and 5 include the materials and processes for making filter
membranes, both organic and inorganic.
Test methods pertinent to nonwoven filter media are discussed in Chapter 6. The
methods are presented in a way to help the reader understand the property being
tested. For example, in the section on strength properties, the stress(cid:1)strain curve is
presented to help the reader identify and understand the relationship of each of the
strength properties to the medium. While many of the tests described are medium
sheet tests, also described are filtration tests in which the medium is tested as part of a
filter.
Applications of nonwoven filter media are broken down into Liquid Filtration
(Chapter 7), Air Filtration (Chapter 8), and Engine Filtration (Chapter 9). Engine
filtration is concerned with filters for automobiles, heavy duty vehicles, off-the-road
equipment, and rotating machinery. It is of sufficient market size to justify its own
chapter. Gas turbine air filtration, which was part of Chapter 9 in the first edition, is
reviewed in Chapter 7 of the second edition.
Chapter 10 has already been mentioned above as discussing federal law and regula-
tory activity that may relate to nonwoven filter media. Included is a review of major
federal laws that may affect nonwoven filter media. Among the major laws included
are the Clean Air Act, the Clean Water Act, OSHA, etc. Chapter 10 also provides a
review of the “Globally Harmonized System of Classification and Labeling of
Chemicals (GHS).” This is a system administered by the United Nations and adopted
by the USA. Chapter 10 also includes an attempt to explain the concept of “sustain-
ability.” I found this difficult to do. This attempt in Chapter 10 to introduce the
reader to federal and regulatory law that may affect his or her job and his or her busi-
ness is only a beginning. As this book was being written, there was so much regula-
tory activity in progress, that probably, by the time this book is published, many
changes in the business of filtration media will already be in place.
It is important to identify those organizations that are involved in developing,
coordinating, promulgating, revising, amending, reissuing, interpreting, certifying,
xxii Preface
regulating, or otherwise maintaining standards that are related to filtration and filter
media. This was done in Chapter 11. The list is by no means complete, but does pres-
ent a representative spectrum of those organizations involved. In Chapter 11, many of
the worldwide standards applicable to nonwoven filter media are tabulated. Included
is the table of contents for the most recent (2012) INDA (cid:1) EDANA Harmonized
Test Methods (347).
In the world of nonwovens, words are everything. A number of words are bandied
about that have different meanings to different people. Sometimes they are used in the
wrong context. For example, many people use the word porosity when they mean
permeability. These twowords are related to each other; however, they are two differ-
ent properties of nonwoven filter media. Another example is the variety of words
used to describe the distribution of particles in a fluid. Included are words such as sol,
aerosol, emulsion, latex, dispersion, suspension, and solution. In many cases they are
used interchangeably and incorrectly. This book includes a glossary of filtration terms
and terms related to filtration. The primary purpose of the glossary is to provide the
reader with meanings of words related to filtration and separation media that he may
not be familiar with, and to provide specific definitions to confusing words or terms.
There is a bibliography with approximately 350 references. They are numbered in
the order in which they appear in the book. In the text they are identified by a num-
ber in parentheses. When I wrote the first edition, much of my references came from
the archives of support organizations such as INDA, TAPPI, and the American
Filtration Society. In writing this second edition, I was able to take great advantage of
Google. I could Google just about every topic that I was researching and find all kinds
of information concerning that topic. Some of the best information came from the
websites of companies involved in the filtration industry. Some very good information
came from Wikipedia, although, I always had to check it out to make sure it was not
erroneous or misleading.
I found the following books very helpful:
Advances in Aerosol Filtration Editor: Spurny, LewisPublishers,1998
Air Filtration Brown, Pergamon Press,1993
Air Filtration Davies,AcademicPress,1973
FiltersandFiltration Handbook5th Edition, Dickensen,Elsevier, 2008
Filtration (cid:1)Equipment Selection Modeling and Process SimulationWakeman and Tarleton, Elsevier,
1999
Filtration Technology Handbook Butler,INDA,2000
Handbookfor Pulp and Paper Technologists 2nd Edition, Smook, Angus WildePublications, 1997
Handbookof Filter Media Purchasand Sutherland, Elsevier, 2002
Introduction toNonwovens Technology Batra and Pourdeyhimi, DEStechPublications, Inc.,2012
MembraneTechnology Cui and Muralidhara, Elsevier,2010
NAFAGuide toAir Filtration 4th Edition, National Air Filtration Association, 2007
Nonwovens: Theory,Process,Performance,and Testing Editor: Turbak, TAPPI Press,1993
Preface xxiii
Perry’s Chemical Engineers’Handbook7th Edition, Perryand Green,McGraw Hill, 1997
Transport Phenomena Bird, Stewart, and Lightfoot, JohnWileyand Sons, 1960
A “Handbook” like this cannot be written without the assistance of organizations
and people in the filtration industry. The following organizations and their people
were particularly supportive of this work and should be acknowledged as such:
INDA (Association of the Nonwovens Fabrics Industry) was particularly supportive.
Brad Kalil has already been acknowledged above for writing the sections on
Marketing Statistics. In addition, President David Rousse and his predecessor Rory
Holmes provided additional support by allowing me to visit their facilities, consult
with their personnel, review their research material, and provide me with contacts
and items of information that were of great value in writing the book. Personnel who
were extremely helpful included Jessica Franken, Steve Ogle, Phil Pitt (no longer
with INDA), Joan Izzo, Ian Butler (now retired), and Cindy Garcia.
AFS (American Filtration and Separations Society) was very important to me in pro-
viding reference material, and the names of contacts. Whenever I needed help,
Executive Manager Lyn Shol and her predecessor Suzanne Sower went out of their
way to provide it.
H&V (Hollingsworth and Vose Company), my former employer, was one of the big-
gest providers of information used in this book. Much of this required copyright per-
mission. Cathy Aikman and Angelika Mayman were very thorough in coordinating
my permission requests and making sure that I got the proper response. Other person-
nel who made themselves available were Bob Murphey, Andrew Shepard, Per
Lindblom, Eric Westgate, and Dr. John Fitzgerald.
Ahlstrom was another big contributor of information for this book. Many times I
consulted with Rod Komlenic who either provided the information I needed or
referred me to the person who could. I also received help from Kent Williamson,
Stephanie Mulligan, and Tomi Tekala.
Donaldson Company provided a large amount of information in this book. Laura
Russell was my prime contact and did an outstanding job in coordinating the large
number of permission requests that I had submitted. Joe Israel and Kristine Graham
were other personnel who I had consulted with. Donaldson Tetratex was another part
of the Donaldson organization that helped me. Sara Meyer did a lot of work in help-
ing to prepare the Tetratexs product tables. Ed Ricketts was also involved.
Cerex Advanced Fabrics provided powerful support to me in thewriting of the book.
President Jim Walker and his management team of John Hancock, Jim Bostick, Erin
Carter, Albert Ortega, and Warren Whitfield invited me to their facilities and provided
mewithawealthofinformationaboutnylon:itsfiber,itsfabric,anditsspunbondnon-
wovens.JohnHancockwasexcellentinhelpingmecoordinatewiththeorganization.
