Handbook of Nonwoven Filter Media (eBook)

Front Cover 1
Handbook of Nonwoven Filter Media 4
Copyright Page 5
Contents 6
Preface 14
Chapter 1 Introduction to Nonwoven Filter Media 20
1.1 Introduction 20
1.2 Filtration and Separation Defined 20
1.3 Nonwovens Defined 21
1.4 Definition of Filter Media 25
1.4.1 Adsorbent media 25
1.4.2 Absorbent media 26
1.4.3 Coalescing media 26
1.4.4 Electro-filtration 26
1.4.5 Antimicrobial media 27
1.4.6 Extraction 27
1.4.7 Filter support 27
1.4.8 Composite structures 27
1.5 Nonwoven Filter Media Defined 28
1.6 What Is Not a Nonwoven Filter Medium 28
1.7 Classification of Nonwovens by Process 29
1.7.1 Dry formed processes 29
1.7.1.1 Air laid 29
1.7.1.2 Dry laid webs and felts 32
1.7.1.3 Spunbonded 37
1.7.1.4 Melt-blown 38
1.7.1.5 Electrospun process 39
1.7.2 Wet laid 41
1.7.2.1 Forming of wet lay webs 41
1.7.2.2 Bonding of wet laid nonwovens 42
1.7.2.3 Converting processes for wet lay webs 43
1.7.3 Composite structures 43
1.8 The Challenges of Nonwoven Filter Media 45
Chapter 2 Filtration Mechanisms and Theory 48
2.1 Filtration Mechanisms 48
2.1.1 Types of filtration mechanisms 48
2.1.2 Mechanisms of particle capture 49
2.1.3 Reentrainment and media migration 52
2.1.4 Membrane processes 52
2.1.4.1 Microfiltration 52
2.1.4.2 Ultrafiltration 52
2.1.4.3 Nanofiltration 52
2.1.4.4 Reverse osmosis 53
2.1.4.5 Membrane process summary 53
2.2 Filtration Theory 53
2.2.1 Flow dynamics 53
2.2.2 The equations of motion and continuity 55
2.2.2.1 The equation of continuity 55
2.2.2.2 The equation of motion 55
2.2.3 Flow through porous media: channel theory 56
2.2.3.1 Darcy's law 56
2.2.3.2 The Hagen–Poiseuille equation 58
2.2.3.3 The Kozeny–Carman equation 58
2.2.4 Flow through porous media: cell model theory 61
2.2.4.1 Davies equation 61
2.2.4.2 Langmuir's theory 63
2.2.4.3 Happel and Kuwabara models 66
2.2.4.4 Advances in cell model theory 70
2.2.4.5 Drag model theory 72
2.2.4.6 Computational fluid dynamics 75
2.3 Particle Filtration 75
2.3.1 Single fiber theory 76
2.3.2 Particle capture based on the Kuwabara flow model 78
2.3.2.1 Justification for Kuwabara flow model 78
2.3.2.2 Mechanisms of particle capture 79
2.3.2.3 Dimensionless numbers 79
2.3.2.4 Results of various investigators 81
2.3.3 Structure of fibrous filters 84
Chapter 3 Properties of Nonwoven Filter Media 90
3.1 Characteristics and Properties of Air Laid Webs 90
3.2 Characteristics and Properties of Dry Laid Webs 90
3.2.1 Needle punched felts 90
3.2.2 Hydroentangled webs 92
3.2.3 High loft filter media 92
3.3 Characteristics and Properties of Spunbonded Webs 93
3.4 Characteristics and Properties of Melt-Blown Webs 98
3.5 Characteristics and Properties of Wet Laid Webs 100
3.5.1 Base sheet 100
3.5.2 Resin treated filter media 101
3.5.3 Glass microfiber filter media 104
3.6 Electret Filter Media 106
3.6.1 Electrostatically spun fibers 106
3.6.2 Fibrillated electret film 107
3.6.3 Corona treated melt-blown fibers 109
3.6.4 Carded blends of triboelectric fibers 111
3.7 Coalescing Media 114
3.8 Composite Structures 115
3.9 Adsorptive Media 116
3.10 Antimicrobial Media 121
Chapter 4 Raw Materials for Nonwoven Filter Media 122
4.1 Introduction 122
4.2 Polymers 122
4.3 Fibers 131
4.3.1 Classification 131
4.3.2 Physical characteristics 131
4.3.3 Physical chemical characteristics 132
4.3.4 Fiber properties for filtration media 132
4.3.4.1 Diameter 134
4.3.4.2 Length 135
4.3.4.3 Aspect ratio 137
4.3.4.4 Density 137
4.3.4.5 Linear density 138
4.3.4.6 Cross-section shape 138
4.3.4.7 Moisture content and moisture absorption 139
4.3.4.8 Thermal properties 140
4.3.4.9 Strength properties of fibers 141
4.3.5 Fiber types 141
4.3.5.1 Natural fibers 141
4.3.5.2 Synthetic fibers: organic 164
4.3.5.3 Inorganic fibers 178
4.3.5.4 Specialty fibers 187
4.4 Resins and Binders 194
4.4.1 Formaldehyde resins 194
4.4.1.1 Phenolic resins 194
4.4.1.2 Melamine formaldehyde 197
4.4.1.3 Urea formaldehyde 197
4.4.2 Latex resins 197
4.4.2.1 Introduction to latex resins 197
4.4.2.2 Polymer systems for latex resins 202
4.4.2.3 Solution polymers 204
4.4.2.4 Cross-linking agents for water-based resins 207
4.5 Additives and Finishes 207
4.5.1 Adsorbent materials 207
4.5.2 Flame retardants 209
4.5.3 Water repellents 212
4.5.4 Antimicrobial agents 213
Chapter 5 Processes for Nonwoven Filter Media 214
5.1 Dry Formed 214
5.1.1 Air laid 214
5.1.2 Dry laid webs and felts 215
5.1.2.1 Forming of dry laid webs 215
5.1.2.2 Bale opening, feeding, and blending 219
5.1.2.3 Bonding of dry laid webs 221
5.1.3 Spunbonded webs 228
5.1.4 Melt-blown webs 234
5.1.5 Electrospun webs 238
5.2 Wet Lay Process 239
5.2.1 Forming of wet lay webs 240
5.2.2 Drying of wet lay webs 245
5.2.3 Bonding of wet laid nonwovens 246
5.2.3.1 Wet end bonding 246
5.2.3.2 Resin application to the web 247
5.2.4 Converting processes for wet lay webs 248
5.2.4.1 Corrugating 248
5.2.4.2 Creping 249
5.2.4.3 Rewinding and slitting 250
5.2.4.4 Stamping and dye cutting 252
5.2.4.5 Bag making 252
5.2.4.6 Pleating 252
5.3 Composite Structures 252
5.3.1 SMS process 253
5.3.2 Multi-ply forming 253
5.3.3 Laminating 253
5.3.4 Entanglement 253
5.3.5 Collectors 253
5.4 The Pleating Process 254
5.4.1 Gear pleaters 254
5.4.2 Blade pleaters 254
5.4.3 Knife pleaters 257
5.4.4 Rotary pleaters 258
Chapter 6 Testing of Nonwoven Filter Media 264
6.1 Grammage or Basis Weight 264
6.2 Volatiles and Moisture Content 265
6.3 Formaldehyde Content 265
6.4 Caliper or Thickness 266
6.5 Air Permeability 267
6.6 Density and Bulk 267
6.7 Solidity and Porosity 269
6.8 Pore Size and Pore Structure 273
6.8.1 Bubble point 273
6.8.2 Mean flow pore size 275
6.9 Other Techniques for Measuring Pore Size and Structure 277
6.9.1 Image analysis 277
6.9.2 Microscopy 278
6.9.3 X-ray microtomography 278
6.9.4 Liquid extrusion porosimetry 280
6.9.5 Liquid intrusion porosimetry 282
6.9.6 Gas/vapor adsorption (BET) 283
6.9.7 Summation 284
6.10 Strength Properties 286
6.10.1 Tensile properties 286
6.10.1.1 Dry tensile properties 286
6.10.1.2 Wet tensile strength 290
6.10.2 Other strength related properties 291
6.10.2.1 Grab tensile strength ASTM D4632 291
6.10.2.2 Burst strength 291
6.10.2.3 Tear strength 292
6.10.2.4 Stiffness 294
6.10.2.5 Internal bond strength 296
6.10.2.6 Fold endurance 297
6.11 Water Repellency and Water/Moisture Resistance 297
6.11.1 Water repellency 297
6.11.2 Water resistance 299
6.11.3 Moisture resistance 300
6.12 Flammability 301
6.13 Filter Media Filtration Testing 302
6.13.1 Efficiency 303
6.13.1.1 Filtration efficiency 303
6.13.1.2 Single pass efficiency 304
6.13.1.3 Cumulative efficiency 304
6.13.1.4 Micron rating 304
6.13.1.5 Multi-pass efficiency 305
6.13.1.6 Beta rating 305
6.13.1.7 Fractional efficiency 305
6.13.1.8 MERV rating 305
6.13.1.9 Arrestance 306
6.13.1.10 ASHRAE dust-spot efficiency 306
6.13.1.11 CEN ratings 306
6.13.1.12 HEPA and ULPA ratings 306
6.13.1.13 MPPS 307
6.13.1.14 Aerosol efficiency penetrometers 307
6.13.1.15 Filtration efficiency, bacterial filtration efficiency, and viral filtration efficiency 307
6.13.2 Pressure drop 309
6.13.3 Filter life testing 309
Chapter 7 Liquid Filter Applications 310
7.1 Introduction to Liquid Filter Applications 310
7.2 Nonwoven Filter Media for Liquid Filter Applications 311
7.2.1 Needlefelt products 311
7.2.2 Melt-blown media 312
7.2.3 Spunbond media 313
7.2.4 Electrospun media 313
7.2.5 Filter papers 313
7.2.5.1 Industrial filter papers 313
7.2.5.2 Laboratory papers 314
7.2.5.3 Filter sheets 316
7.2.6 Resin treated filter paper 317
7.2.7 Composite structures 317
7.3 Filters that Use Nonwoven Filter Media 318
7.3.1 Roll filters 318
7.3.1.1 Description of roll filters 318
7.3.1.2 Media for roll filters 320
7.3.2 Nonwovens for replaceable filter elements 322
7.3.2.1 Explanation of replaceable filter elements 322
7.3.2.2 Cartridge filters 323
7.3.2.3 Wound filter elements 330
7.3.2.4 Candle filters 330
7.3.2.5 Bag filters 330
7.4 Testing of Liquid Filters 333
7.4.1 Efficiency assessment 333
7.4.2 Multi-pass test stand 335
7.4.3 Test dust complication 337
7.4.4 Test comparison 338
7.4.5 Cleanliness levels 338
Chapter 8 Air Filter Applications 344
8.1 Industrial Air Filtration 344
8.1.1 Dust collection systems 344
8.1.2 Fume and vapor emissions 348
8.2 Heat Ventilation and Air Conditioning Systems 353
8.2.1 Filters for air cleaning systems 353
8.2.1.1 Panel filters 353
8.2.1.2 Pocket filters 355
8.2.2 HVAC standards 355
8.2.2.1 CEN EN 779:2002 E and Eurovent 4/5 355
8.2.2.2 ASHRAE 52.2-1999 358
8.2.2.3 ASHRAE 52.1-1992 361
8.2.2.4 Comparison and application guidelines for ASHRAE 52.1 and ASHRAE 52.2 363
8.2.2.5 Standard for portable air cleaners 363
8.2.2.6 Fire and flame resistant standards 366
8.3 High Efficiency Air Filtration 366
8.3.1 A brief history of high efficiency air filtration 366
8.3.2 HEPA filters 368
8.3.2.1 Traditional panel filters 368
8.3.2.2 Separator-less HEPA filters 369
8.3.2.3 Mini-pleat filters 369
8.3.2.4 Round filters 370
8.3.2.5 HEPA media description and standards 370
8.3.3 ULPA filters 373
8.3.4 Cleanrooms 373
8.3.5 Paint spray booth filters 375
8.4 Respirators, Gas Masks, and Facemasks 376
8.4.1 Respirators and gas masks – 42 CFR (US), Chapter 1, Part 84 376
8.4.1.1 Self-contained breathing apparatus 377
8.4.1.2 Gas masks 377
8.4.1.3 Supplied-air respirators 378
8.4.1.4 Non-powered air-purifying particulate arrestors 379
8.4.1.5 Powered air-purifying respirators 380
8.4.1.6 Chemical cartridge respirators 381
8.4.1.7 Filter media for respirators 381
8.4.2 Surgical and healthcare face masks 382
8.5 Vacuum Cleaners 383
8.6 Air Purifiers 384
8.7 Air Demisters 385
8.7.1 Air–moisture demisters 385
8.7.2 Air–oil demisters 386
Chapter 9 Engine Filtration 388
9.1 Introduction 388
9.2 Lube Oil Filtration 391
9.3 Air Intake Filtration 396
9.4 Cabin Air Filtration 400
9.5 Fuel Filtration 403
9.5.1 Engine fuel filtration 403
9.5.2 Fuel transportation systems 403
9.6 Gas Turbine Air Filters 405
9.6.1 Turbines description 405
9.6.2 Air inlet filtration for gas turbines 406
9.6.3 Filter media for gas turbine filtration 408
Chapter 10 Standards for Nonwoven Filter Media 412
10.1 Standards and Trade Organizations That Have Standards, Registrations, and/or Certifications Related to Filter Media 412
10.2 Standards Organizations 413
10.3 Standards Related to Nonwoven Filter Media 416
10.4 INDA–EDANA Harmonized Test Methods 428
Nomenclature 434
Glossary 442
A 442
B 443
C 444
D 446
E 447
F 448
G 450
H 451
I 451
L 452
M 452
N 454
P 454
Q 456
R 456
S 457
T 460
U 461
V 461
W 462
X 462
Z 462
References 464
Index 476
A 476
B 477
C 478
D 480
E 480
F 481
G 482
H 483
I 483
J 484
K 484
L 485
M 485
N 486
O 487
P 487
Q 488
R 488
S 489
T 490
U 491
V 491
W 492
X 492
Y 492
Z 492