Chapter 4 GAS FILTRATION MEDIA. T. J Ptak, PhD Columbus Industries, Inc. VP of Research and Development. OVERVIEW. 4-1 What is filter media 4-2 Parameters of filter media 4-3 Filter media classification Depth S urface 4-4 Types of filter media Fibrous filter media
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T. J Ptak, PhD
Columbus Industries, Inc.
VP of Research and Development
pressure drop, efficiency,
filter life, cost
fiber or granule diameter
basis weight, thickness,
permeability, pore size
Defined as the weight of media per unit area. Expressed in pounds per 3,000 sq. feet. Metric values are expressed in g/m2 and can be calculated by multiplying basis weight in lb./3000 ft2 by 1.627.
Thickness of flat papers is measured with dead weight type caliper gauge having typically a pressure foot of 0.25” diameter and exerting a load of 4 lb./in2.
Air permeability is the flow rate of air at 23oC through a sheet of paper under a specified pressure head, usually expressed as CFM per square foot of area at the 0.50 in. water pressure. Often called as Frazier permeability.
What parameters describe filter media.
Defined as the largest pore. Expressed as a pressure (P) of air in inches of water recorded when the first air bubble appears in the fluid. The size of largest pore (r) can be calculated:
gis the surface tension and is the contact angle.
Is defined as the hydrostatic pressure in psi required to produce rapture of paper sample when pressure is increased at the controlled rate through a rubber diaphragm to a circular area of 1.2 in. diameter.
Ability to resist an applied bending force.
The Tensile Strength Test is a measure of the directional strength of the media, measured in pounds per square inch.
Particulate capture efficiency is a test that results in a filter media performance characteristic. A fractional efficiency characteristic curve is generated, which describes the ability of a filter media to capture particles of differing sizes.
DESCRIPTION: Polypropylene meltblown with wet-laid PET carrier
TEST METHODUNITTARGETMIN - MAX
BASIS WEIGHT TAPPI T410 g/m2 105 95 - 115
THICKNESS TAPPI T411 mm 0.74 0.66 - 0.81
FRAZIER PERMEABILITY TAPPI T251 cfm/ft2 20 17 – 23
STIFFNESS TAPPI T543 mg TBD X 20%
TENSILE MD TAPPI T494 lb/in 7.0 6.3 – 8.0
PRESSURE DROP @ 10.5 fpm TSI 8130 mm H20 6.2 5.7 – 6.7
PENETRATION @ 10.5 fpm TSI 8130 (NaCl) % 0.03 <0.03
How industry classified filter media.
Fibrous cellulose, glass, polymeric, metal,
polymeric PTFE, PFA, nylon, polycarbonate, cellulose, etc.
Sintered metal 316L SS, nickel, etc.
Ceramic aluminum oxide, silicon carbide
Fabric cotton, glass, polymeric
Foam polymeric, metal
Granular bed sand, activated carbon
How industry classified filter media
Nylon 6,6 Formic acid
Polycarbonate, PC Dimethyl formamide:tetrahydrofuran
Polyvinyl Alcohol, PVA Distilled water
Polylactic acid, PLA Dimethyl formamide
Polyacrylonitrile, PAN Dimethyl formamide
Polyethylene terephtalate, PET Dichloromethane
Polystyrene, PS Tetrahydrofuran
Cellulose acetate, CA Acetone
Nanofiber 0.05 80
Meltblown 2.0 2
Spunbond 20 0.2
Test methods for flat sheet media.
Parameter #1 #2 #3 #4 #5
ΔP at 32 lpm, [mm H2O] 26.2 28.8 30.7 30.3 28.8
P at 32 lpm, [%] 0.180 0.229 0.180 0.154 0.191
Correlation between filter media and filters.
Face Velocity Face Velocity Media Velocity
ΔP ~ ρ V2
ΔP ~ µ V
Nonwoven Membrane Electret Cotton sheet
Triboelectric Wet laid process Corona None
YES Partially NO
2-5 microns < 0.1 micron 0.1 – 0.8 micron >1.0 micron