Electret fibrous filter media achieve high efficiencies while maintaining low air flow resistance by incorporating electrostatic charges on their fibers. However, captured ultrafine particles reduce electrostatic effects. Existing test methods specify preconditioning to detect the minimum efficiency by eliminating electrostatic effects. ASHRAE 52.2 exposes media to nanoparticle KCl aerosols. ISO/TS21220 and EN779 immerse media in isopropyl alcohol (IPA). These approaches have some problems: - Nanoparticle generation is fairly complicated and needs to be kept under control; - The structure of some media may be changed by liquid immersion; - Soaking full scale air filters requires large amounts of IPA. A new procedure, exposure to IPA vapor, has been shown to be effective. We summarize these studies and ISO/TC142 activities related to the

Tronville P., Rivers R.

PORTO Publications Open Repository TOrino

Looking for the minimum efficiency of fibrous air filters during their service life

Electret fibrous air filter media achieve high efficiencies while maintaining low air flow resistance by incorporating electrostatic charges on their fibers. However, captured ultrafine particles reduce this electrostatic enhancement. It is important to evaluate the behavior of such media when their electrostatic enhancement has been completely suppressed, leaving only "mechanical" effects such as sieving, impaction, interception and diffusion. Existing standards EN779:2002 and ASHRAE 52.2-2007 specify preconditioning procedures to eliminate or reduce electrostatic effects. ASHRAE 52.2 exposes the full air filter to KCl nanoparticle aerosols. ISO/TS 21220:2009 and EN 779 precondition filter media by a 2 minute soak in isopropyl alcohol (IPA), after which the filter media are dried before further efficiency measurement. These approaches present problems: • To control the size distribution of KCl nanoparticles requires additional expensive equipment and, even after completing this procedure, the electrostatic charge can be still partly active. • The structure of some media may be affected by immersion in liquid IPA. • Soaking full scale air filters is not practical and requires large amounts of IPA, which is then dispersed into the environment. The most recent efforts in getting the discharged efficiency of a filter have been made by ISO/TC142 "Cleaning equipment for air and other gases" Working Group 9, which is devoted at developing standards for gas turbine air intake applications. A new procedure proposed by Hayashi (Japan) eliminates electrostatic effects by exposing filters to IPA vapor for 8 hours or longer. This procedure has been successfully duplicated by Cai (China), at the Politecnico di Torino and in other laboratories. WG9 of ISO/TC142 organized inter-laboratory tests comparing IPA vapor treatment to liquid IPA immersion on samples of five media types. The data obtained indicate that IPA vapor treatment can replace the immersion approach successfully. The main result of these tests was the adoption of IPA vapor treatment on a flat sheet of medium in ISO/FDIS 29461-1 "Air intake filter systems for rotary machinery -- Test methods -- Part 1: Static filter elements". The discharge of full scale filter elements is still under study. We summarize all these studies, and describe the new test protocols that could be adopted by future national and international test methods. The results presented here could also be useful to evaluate the need for further research in this are

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[Proceeding] Looking for the minimum efficiency of fibrous air filters during
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Tronville P., Rivers R. (2012). Looking for the minimum efficiency of fibrous air filters during their
service life. In: 11th World Filtration Congress & Exhibition, Graz - Austria, April 16-20, 2012. p. 57
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Jll> r l 
I 
WFCll 
11th World Filtration Congress 
Abstract Book 
CONTENT VOLUME I 
Scientific Committee 
Page Indicator & Session Chairmen 
Plenary Lecture 
Keynote Lectures 
Papers G-Sessions 
Papers L-Sessions 
Papers M-Sessions 
Keyword List (Page Indicator) 
Conference Dates: 
April 16 - 20, 2012 
Venue: 
Messe Congress Graz · Messeplatz 1 · 8010 Graz · Austria 
hosted by 
GOCH - Austrian Chemical Society 
www.goech.at 
WFCll Congress Organizing Secretariat: 
Filtech Exhibitions Germany 
PO Box 1225 · 40637 Meerbusch - Germany 
phone: +49 (0) 2132 93 57 60 
fax: +49 (0) 2132 93 57 62 
e-mail: lnfo@wfc11.at 
web: www.wfcl Lat 
Abstract Book 
USB-Stick 
ISBN 978-3-941655-04-1 
ISBN 978-3-941655-05-8 
WFC 11 April 16-20, 2012 · Graz - Austria 
4 
5 
10 
11 
15 
99 
174 
327 
3 
SCIENTIFIC COMMITTEE CHAIRMEN 
• Prof. Wilhelm Hi>flinger 
Vienna University of Technology, Austria 
• Prof. Gerd Mauschitz Vienna University of Technology, Austria 
SCIENTIFIC COMMITTEE 
•Dr. Harald Anlauf, 
Karlsruhe Institute ofTechnology, ·Germany 
•Prof. Jan Baeyens, University of Warwick, Great Britain 
•Dr. Roger BenAim, Scientific Advisor IFTS, France 
•Prof. Rolf Berndt, RBFM Consulting, Germany 
•Dr. Reinhard Bott, Bokela, Germany 
•Dr. Roger de Bruyne, Belgium 
•Prof. George Chase, University of Akron, USA 
•Prof. Liang-Yin Chu, Sichuan University, P.R. China 
•Prof. Ching-Jung Chuang, Chung Yuan University, Taiwan 
•Prof. Jose Coury, Federal University of Sao Carlos, Brazil 
•Prof. Enrico Drioli, University of Calabria, Italy 
•Ulrich Esser, Bayer, Germany 
•Prof. Anton Friedl, Vienna University ofTechnology, Austria 
•Prof. Rolf Gimbel, IWW, Germany 
•Prof. Nigel Graham, 
Imperial College London, Great Britain 
•Prof. Michael Harasek, 
Vienna University of Technology, Austria 
•Dr. Haio Harms, Lenzing, Austria 
•Lloyd Holliday, Outotec, Great Britain 
•Prof. Kuo-Jen Hwang, Tamkang University, Taiwan 
•Prof. Eiji lritani, Nagoya University, Japan 
•Dr. Tadeusz Jaroszczyk, USA 
•Prof. Chikao Kanaoka, 
National College ofTechnology, Japan 
•Prof. Gerhard Kasper. 
Karlsruhe Institute ofTechnology, Germany 
•Prof. Esko Kauppinen, VTT Processes, Finland 
•Prof. Kristian Keiding, Aalborg University, Denmark 
•Ir. Hermanes H. Kleizen, Dutchap bv, Netherlands 
•Prof. Gemot Krammer, Andritz, Austria 
•Dr. Thomas Langeloh, Bokela, Germany 
•Prof. Markus Lehner. Montanuniversitat Leoben, Austria 
•Prof. Dietmar Lerche, L.U.M., Germany 
•Prof. Wallace Leung, 
The Hong Kong Polytechnic University, P.R. China 
•Prof. Andrew Livingston, 
Imperial College London, Great Britain 
•Prof. Richard Lydon, Clear Edge Group, Great Britain 
• Prof. lngo Marini, Vienna University ofT echnology, Austria 
• Prof. Petr Mi ku lasek, 
University of Pardubice, Czech Republic 
•Prof. Karoly Molnar, Budapest University, Hungary 
• Prof. Hermann Nirschl, 
Karlsruhe Institute ofTechnology, Germany 
•Prof. Marianne Nystrom, 
Lappeenranta University ofTechnology, Finland 
•Dr. Dietmar Oechsle, EBG lnnowa, Germany 
•Dr. Thomas Peters, Consulting, Germany 
•Dr. Christophe Peuchot, l.F.T.S., France 
•Prof. Urs Peuker, Technical University of Freiberg, Germany 
•Dr. Jaroslav Pridal, Mikropur, Czech Republic 
•Dr. Graham Rideal, Whitehouse Scientific, Great Britain 
•Prof. Siegfried Ripperger. 
Technical University of Kaiserslautern, Germany 
• Prof. Wolfgang Samhaber. 
Johannes Kepler University Linz, Austria 
•Prof. Peter Scales, University of Melbourne, Australia 
•Prof. Hans-Joachim Schmid, 
University of Paderborn, Germany 
•Prof. Eberhard Schmidt, University ofWuppertal, Germany 
•Prof. Radmila Secerov Sokolovic, 
University of Novi Sad, Serbia 
•Prof. Peter Stelter. Heinkel Process Technology, Germany 
•Dr. Steve Tarleton, Loughborough University, Great Britain 
•Prof. Hans Theliander. Chalmers University, Sweden 
•Prof. Chi Tien, Syracuse University, USA 
•Prof. Paolo Tronville, Politecnico di Torino, Italy 
•Dr. Barry Verdegan, Cummins Filtration, USA 
•Dr. Jean-Francois Vicard, Stratene, France 
•Prof. Eugene Vorobiev, Technical University of Compiegne, 
France 
•Dr. Matthias Waldenmaier, 
Freudenberg Filtration Technologies, Germany 
•Prof. Stanislav Wronski, 
Warsaw University ofTechnology, Poland 
•Prof. Nanping Xu, Nanjing University, P.R. China 
• Prof. Yang Zhao, 
Hefei General Machinery Research Institute, P.R. China 
4 WFC 11April16-20, 2012 · Graz - Austria 
PAGE INDICATOR AND SESSION CHAIRMEN 
TUESDAY, APRIL 17, 2012 
Plenary Lecture - Evolutionin Separation -
Technical development by mutation and selection · 
Dr. Harald Anlauf,Karlsruhe Institute of Technology (Kin - Germany 
L 1 - SLS-Fundamentals I 
Session Chair: Richard Wakeman 
L2 - Filter Media I 
Session Chair: Richard P. Lydon 
----------------------
L3 - SLS Adsorptive Separations 
Session Chair: Gernot Krammer 
Ml - Modelling Membrane Processes 
Session Chair: Kuo-Jen Hwang 
M2 - Application of Membranes I 
Session Chair: Jaroslav Pridal 
Key-Note 1 - Fine particle emissions from pulse-cleaned 
Filters · Prof. Gerhard Kasper, Karlsruhe Institute of Technology (KIT) 
- Germany, Session Chair: Eberhard Schmidt 
L4 - SLS-Fundamentals II 
Session Chair: Stephen Tarleton 
LS - Water and Waste Water I 
Session Chair: Gernot Krammer 
Key-Note 2 - Geomimetic membrane: A new route to develop 
novel inorganic membranes· Prof. Kuo-Lun Tung - Chung, 
Yuan University - Taiwan, Session Chair: Siegfried Ripperger 
G1 - Gas Filtration Fundamentals I 
Session Chair: Gerhard Kasper 
G2 - Nanoparticle & Depth Filtration I 
Session Chair: Leon Gradon 
G3 - Cyclone I 
Session Chair: Steffen Schutz 
L6 - SLS-Filter Testing I 
Session Chair: Kristian Keidiing 
L7 - Centrifugal SLS 
Session Chair: Thomas Langeloh 
M3 - New Membranes & Materials I 
Session Chair: Kuo-Jen Hwang 
M4 - Crossflow Processes 
Session Chair: Siegfried Ripperger 
GS - Nanoparticle & Depth Filtration II 
Session Chair: MArkus Lehner 
G6 - Cyclone II 
Session Chair: Arunangshu Mukhopadhyay 
Time 
11:00-12:00h 
13:15-14:30 h 
13:15-14:30 h 
13:15-14:30 h 
13:15-14:30 h 
13:15-14:30 h 
13:15-14:30 h 
15:00-16:15 h 
15:00-16:15 h 
15:00-16:15 h 
15:00-16:15 h 
15:00-16:15 h 
15:00-16:15 h 
16:45-18:25 h 
16:45-18:25 h 
16:45-18:25 h 
16:45-18:25 h 
16:45-18:25 h 
16:45-18:00 h 
WFC 11 April 16-20, 2012 · Graz - Austria 
Page 
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5 
WFC 11 - Page Indicator and Session Chairmen 
WEDNESDAY, APRIL 18, 2012 
LS - SLS-Fundamentals Ill 
Session Chair: Christian Keiding 
L9 - Filtration Post-Treatment & Filter Aids 
Session Chair: Reinhard Bott 
MS - New Membranes & Materials II 
Session Chair: Wolfgang Samhaber 
M6 - Water Treatment I 
Session Chair: Ching-Jung Chuang 
·~~~~~~~~~ 
G7 - Cleanable Dust Filtration I 
Session Chair: Eberhard Schmidt 
GS - Nanoparticle & Depth Filtration Ill 
Session Chair: Leon Gradon 
G9 - Heating, Ventilating, Air Conditioning (HVAC) 
Session Chair: Markus Lehner 
PL 1 - Solid-Liquid Separation I 
Session Chair: Harald Anlauf Discussion at the Poster Area 
PL2 - Solid-Liquid Separation II 
Session Chair: Eugene Vorobiev Discussion at the Poster Area 
PM1 - Membrane Separation I 
Session Chair: Herrmann Nirschl Discussion at the Poster Area 
Time Page 
09:00-10:15 h 121 
09:00-10:15 h 124 
09:00-10:15 h 188 
09:00-10:15 h 191 
09:00-10:15 h 31 
09:00-10:15 h 34 
09:00-10:15 h 37 
10:45-12:00 h 254 
12:00-12:45 
10:45-12 :00 h 264 
12:00-12 :45 
10:45-12 :00 h 294 
12:00-12:45 
·~~~~~~~~~~~~~~~~ 
PM2 - Membrane Separation II 
Session Chair: Thomas Peters Discussion at the Poster Area 
PG1 - Solid Gas Separation I 
Session Chair: Markus Lehner Discussion at the Poster Area 
PG2 - Solid Gas Separation II 
Session Chair: Wallace Woon-Fon Leung Discussion at the Poster Area 
G 10 - Cleanable Dust Filtration II 
Session Chair: Leon Gradon 
Key-Note 3 - Separation challenges for the biotechnology: 
SMART is one answer · Dr. Kasten Keller - Solae/Dupont - USA, 
Session Chair: Richard Wakeman 
M7 - New Membranes & Materials Ill 
Session Chair: Allan Kuo-Lun Tung 
MS - Water Treatment II 
Session Chair: Dietmar Oechsle 
G11 - Cleanable Dust Filtration Ill 
Session Chair: Gerd Mauschitz 
G12 - Mist Droplet Separation I 
Session Chair: Hans-Joachim Schmid 
G13- Filter Testing I 
Session Chair: Christophe Peuchot 
10:45-12:00 h 
12:00-12:45 
10:45-12:00 h 
12:00 -12:45 
10:45-12:00 h 
12:00-12:45 
10:45-12:00 h 
14:00-15:15 h 
14:00-15:15 h 
14:00-15:15 h 
14:00-15:15 h 
14:00-15:15 h 
14:00-15:15 h 
6 WFC 11 April 16-20, 2012 • Graz - Austria 
301 
232 
239 
40 
13 
194 
197 
43 
45 
48 
WFC 11 - Page Indicator and Session Chairmen 
WEDNESDAY, APRIL 18, 2012 
L 10 - Vacuum & Pressure Filter I 
Session Chair: Ulrich Esser 
L 11 - Force Enhanced Solid Liquid Separation 
Session Chair: Eiji lritani 
M9 - New Membranes & Materials IV 
Session Chair: Dietmar Oechsle 
M10 - Membrane Special Applications 
Session Chair: Michael Harasek 
G14 - Electrostatic & Wet Separators 
Session Chair: Gerd Mauschitz 
G 15 - Mist Droplet Separation ff 
Session Chair: Sunil Sharma 
G16 - Filter Testing ff 
Session Chair: Gerd Mauschitz 
THURSDAY, APRIL 19, 2012 
L 12 - Vacuum and Pressure Filter ff 
Session Chair: Urs Peuker 
L 13 - Chemical Enhanced Solid Liquid Separation 
Session Chair: Christophe Peuchot 
M11 - Membrane Fouling I 
Session Chair: Radmila Secerov Sokolovic 
M12 - Membrane Bioreactor 
Session Chair: Liang-Yin Chu 
G17 - Baghouse Filters I 
Session Chair: Sunil Sharma 
G18 - Filter Media I 
Session Chair: Martin Lehmann 
G 19 - Filter Testing Ill 
Session Chair: Paolo Tronville 
PL3 - Solid-Liquid Separation Ill 
Session Chair: Urs Peuker 
PL4 - Solid-Liquid Separation IV 
Session Chair: Hermann Nirschl 
Time 
15:45-17:25 h 
15:45-17:25 h 
15:45-17:25 h 
15:45-17:25 h 
15:45-17:25 h 
15:45-16:40 h 
15:45-16:40 h 
Time 
09:00-10:15 h 
09:00-10:15 h 
09:00-10:15 h 
09:00-1 0:15 h 
09:00-10:15 h 
09:00-10:15 h 
09:00-10:15 h 
10:45-12:00 h 
10:45-12:00 h 
WFC 11 April 16-20, 2012 · Graz -Austria 
Page 
127 
131 
200 
204 
51 
55 
57 
Page 
135 
138 
208 
211 
59 
62 
65 
272 
282 
7 
WFC 11 - Page Indicator and Session Chairmen 
THURSDAY, APRIL 19, 2012 
PM3 - Membrane Separation fll 
Session Chair: Liang-Yin Chu 
PM4 - Membrane Separation IV 
Session Chair: Michael Harasek 
PG3 - Solid Gas Separation Ill 
Session Chair: Wilhelm Hoflinger 
G20 - Baghouse Filters II 
Session Chair: Hans-Joachim Schmid 
G21 - Simulation of Filtration Processes I 
Session Chair: Martin Lehmann 
L 14 - Pretreatment 
Session Chair: Wallace Woon-Fon Leung 
L 15 - SLS Applications & New Processes 
Session Chair: Lloyd Holliday 
L 16 - SLS-Fundamentals IV 
Session Chair: Anthony Stickland 
M13 - Dynamic Filtration 
Session Chair: Wolfgang Samhaber 
M 14 - Membrane Bioreactor & Water Treatment 
Session Chair: Eugene Vorobiev 
Key-Note 4 - Modelling and simulation of filtration processes -
a practitioner's overview, Dr. Andreas Wiegmann -
Fraunhofer Institute for Industrial Mathematics ITWM, Germany 
Session Chair: Martin Lehmann 
L 17 - SLS Filter Testing II 
Session Chair: Eiji lritani 
L 18 - SLS Filtration Applications II 
Session Chair: Hans Theliander 
L 19 - Filter Media II 
Session Chair: Wallace Woon-Fon Leung 
M15 - Membrane Fouling II 
Session Chair: Rolf Berndt 
G22 - Baghouse Filters Ill 
Session Chair: Arunangshu Mukhopadhyay 
G23 - Filter Media II 
Session Chair: Siegfried Ripperger 
G24 - Simulation of Filtration Processes II 
Session Chair: Michael Harasek 
Time 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
14:00-15:40 h 
14:00-15:40 h 
14:00-15:40 h 
14:00-15:40 h 
14:00-15:40 h 
14:00-15:40 h 
16:10-17:50 h 
16:10-17:25 h 
16:10-17:50 h 
16:10-17:50 h 
16:10-17:25 h 
16:10-17:50 h 
16:10-17:50 h 
8 WFC 11 April 16-20, 2012 · Graz - Austria 
Page 
309 
318 
246 
68 
71 
141 
145 
147 
213 
216 
14 
151 
155 
158 
219 
74 
77 
81 
WFC 11 - Page Indicator and Session Chairmen 
FRIDAY, APRIL 20, 2012 
L21 - SLS Filtration Applications II 
Session Chair: Rolf Berndt 
M16 -Application of Membranes II 
Session Chair: Ching-Jung Chuang 
M17 - Enhanced Membrane Separation 
Session Chair: Jaroslav Pridal 
G25 - Emissions Control I 
Session Chair: Wilhelm Hoflinger 
G27 - Pleated Filter Media I 
Session Chair: Paolo Tronville 
L22 - SLS Filter Testing Ill 
Session Chair: Christophe Peuchot 
L23 - Simulation and Scale-Up 
Session Chair: Thomas Langeloh 
L24 - Water & Waste Water II 
Session Chair: Wallace Woon-Fon Leung 
M18 - Water Treatment Ill 
Session Chair: Tung-Wen Cheng 
G28 - Emission Control II 
Session Chair: Sunil Sharma 
G29 - Filter Media Ill 
Session Chair: Paolo Tronville 
G30 - Pleated Filter Media II 
Session Chair: Gerd Mauschitz 
Time 
09:00-10:15 h 
09:00-10:15 h 
09:00-10:15 h 
09:00-10:15 h 
09:00-10:15 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
10:45-12:00 h 
WFC 11 April 16-20, 2012 · Graz - Austria 
Page 
162 
223 
226 
85 
88 
165 
168 
171 
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94 
97 
9 
WFC 11 - G 16 · Filter Testing 11 
LOOKING FOR THE MINIMUM EFFICIENCY 
OF FIBROUS AIR FILTERS DURING THEIR SERVICE LIFE 
Paolo Tronville, Politecnico di Torino - DEN ERG, Corso Duca degli Abruzzi 24, 
- +10129 Turin, Italy 
Richard Rivers, EQS Inc., 1262 Bassett Avenue, Louisville, KY 40204, USA 
ABSTRACT 
Electret fibrous air filter media achieve high efficiencies while maintaining low air flow 
resistance by incorporating electrostatic charges on their fibers. However, captured 
ultrafine particles reduce this electrostatic enhancement. It is important to evaluate 
the behavior of such media when - their electrostatic enhancement has been 
completely suppressed, leaving only "mechanical" effects such as sieving, impaction, 
interception and diffusion. Existing standards EN779:2002 and ASHRAE 52.2-2007 
specify preconditioning procedures to eliminate or reduce electrostatic effects. 
ASHRAE 52.2 exposes the full air filter to KCI nanoparticle aerosols. ISO/TS 
21220:2009 and EN 779 precondition filter media by a 2 minute soak in isopropyl 
alcohol (IPA), after which the filter media are dried before further efficiency 
measurement. These approaches present problems: 
• To control the s!:;i;.e distribution of KCI nanoparticles requires additional expensive 
equipment and, even after completing this procedure, the electrostatic charge can 
be still partly active. 
• The structure of some media may be affected by immersion in liquid IPA. 
• Soaking full scale air filters is not practical and requires large amounts of IPA, 
which is then dispersed into the environment. 
The most recent efforts in getting the discharged efficiency of a filter have been 
made by ISO/TC142 "Cleaning equipment for air and other gases" Working Group 9, 
which is devoted at developing standards for gas turbine air intake applications. 
A new procedure proposed by Hayashi (Japan) eliminates electrostatic effects by exposing 
filters to IPA vapor for 8 hours or longer. This procedure has been successfully 
duplicated by Cai (China), at the Politecnico di Torino and in other laboratories. 
WG9 of ISO/TC142 organized inter-laboratory tests comparing IPA vapor treatment 
to liquid IPA immersion on samples of five media types. 
The data obtained indicate that IPA vapor treatment can replace the immersion 
approach successfully. The main result of these tests was the adoption of IPA vapor 
treatment on a flat sheet of medium in ISO/FDIS 29461-1 "Air intake filter systems 
for rotary machinery -- Test methods -- Part 1: Static filter elements". The discharge 
of full scale filter elements is still under study. 
We summarize all these studies, and describe the new test protocols that could be 
adopted by future national and international test methods. The results presented 
here could also be useful to evaluate the need for further research in this area. 
KEYWORDS 
Air Filters, Air Filter Media, Conditioning Agents, Intake Filters, Nonwovens, Filter 
Media Testing 
WFC 11 April 16-20, 2012 · Graz - Austria 57 


Looking for the minimum efficiency of fibrous air filters during their service life

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