General Description
Engineered high-performance,
flexible polyurethane foams meet many design criteria for a variety of
filtration functions. These include removing dust and contaminating
particles from air, gases, and liquids (filtration); collecting vaporized
oils from industrial equipment (de-misting); acting as an evaporative
surface (humidification), and cleaning up oil spills (oil/water separation).
Applications Include: Air filters
for small engines, air conditioners, data processing equipment, electronic
air cleaners, humidifiers, furnaces, condenser coils, refrigerators, cold
drink dispensers, and other appliances where moving air is required either
by force or convection.
| Products |
| Functions |
SIF® |
SIF®
Felt |
SIF®
PVC-coated |
Applications |
| Filtering |
X |
X |
X |
air
filters for engines, air
conditioners, furnaces,
appliances |
| De-misting |
X |
X |
X |
liquid
filters for environmental use
and fuels |
| Evaporative
Media |
X |
|
X |
humidifiers
and evaporative coolers |
| Coalescing |
X |
X |
X |
oil
spill cleanup |
Matrix for Functional Applications of Foamex Cellular Plastic
Materials |
Benefits Are: Relatively
low air resistance and low pressure drop due to the open-pore skeletal
structure; large dust-holding capacity due to the 97 percent void volume,
and design potential for easy installation and space savings due to the high
tensile strength and tear resistance of Filter Foam (SIF®).
Other benefits are: ease by which it can be shaped, glued, sewn; long life
since the flexible foams are washable, reusable and have good depth loading
capabilities; benefits also include wide range of particle size filtration
due to a range of pore sizes available and the ability to separate
oil-based materials in water environments because the foams are oleophilic
polymers.
Foamex Filter Media Are:
Filter Foam (SIF®), polyvinyl chloride-coated foam (SIF®-PVC), and SIF
Felt® foam. These are reticulated flexible polyester urethane foams or
specially engineered physical and chemical variations of polyether foam.
Unlike ordinary urethane foams, they have a completely open cell, three-dimensional structure of
skeletal strands that give them special filtering properties. They are
exceptionally porous and permeable therefore, they are ideal for
any filtration applications where other foams cannot be used. SIF®
PVC-coated foam is a flexible open-pore polyurethane foam coated with
polyvinyl chloride. This coating preserves the foam strands without
significantly increasing their resistance to air or liquid flow. SIF®
PVC-coated foam resists chemical attack and has greater tear strength and
compression deflection than uncoated urethane foam. SIF Felt® is a
compressed, reticulated flexible foam made by compressing a 90
pores-per-linear-inch (ppi) foam with both pressure and heat.
Filtration
SIF® and SIF Felt® foams
filter air with relatively little air resistance or pressure drop because of
the special combination of dust-catching strands and dust-holding capacity
in their void space. For example, these foams are used in engine air filters
on lawn mowers, motorcycles, automobiles, and trucks. The high-performance
foam filters air in air conditioning units, furnaces, computers,
refrigerators, and many other products that require dust protection. SIF®
and SIF Felt® foams for air filtration can be fabricated in many special
ways, such as hot wire cut to complex shapes for lawn mower engine air
filters; metal or plastic framed sheets for a pre-filter and/or after-filter
use in electronic air cleaners; in addition, the foams can be glued or sewn
into bands for filter wraps on automobile carburetor air cleaners.
Stretchable Face Mask: A
comfortable mask of fine pore SIF® foam loops behind the ears and fits
snugly against the nose and mouth to diffuse the wearer’s breath and act
as an oral spray screen. For example, a mask used by a dentist while working on a
patient. The mask fits easily in a pocket when not in use and is
durable enough to be washed and reused.
Gasoline Fuel Filters: SIF
Felt® foam is used in place of felt to filter gasoline fuel in chainsaws
and other small engines.
Dust Removal Systems: SIF®
and SIF Felt® foams are used in this application because they can be
manufactured in the optimum pore size for removing the specific contaminant;
they are deep-loading and therefore long lasting; they can be oiled for
greater particle impingement; are easily cleaned by vacuuming, hosing, or
washing; and are easy on fan motors because of their low air resistance.
Automobile Power Brake Unit:
SIF Felt® foam is used to both filter and diffuse air entering the power
actuating cylinder where it helps protect the mechanism from dust and
provides for quieter operation.
Electro-Magnetic Door Lock
Actuator Wedge: Thumbnail-size tabs of SIF® foam are used in the
solenoid mechanism which must be vented and protected from dust. SIF® was
the choice for this application because it is economical, easy to
install, and stays in place by virtue of its own compression
deflection. It is not affected by rainwater in the event of window seal
leakage and it filters effectively for the normal life of the car.
De-Misting
SIF® effectively filters aerosols
or droplets from air drawn through it. The moisture coalesces, or gathers,
on the foam, trickles to the bottom, and is collected for reuse or disposal.
SIF® foam is an excellent de-misting medium due to its large surface
area—up to 2,300 square feet per cubic foot of foam.
| SIF®—Typical
Physical Properties |
| Porosity*
(ppi) |
Density
(lb/ft3) |
Tensile
Strength (psi) |
Ultimate
elongation (%) |
Tear
strength (lb/in.) |
50%
Compression set |
Compression
deflection
|
|
25%
(psi)
|
65%(psi) |
| 3 |
1.2 |
8 |
150 |
2 |
20(max) |
.25 |
.40 |
| 10 |
1.9 |
20 |
315 |
5.5 |
8 |
.48 |
.72 |
| 20 |
1.9 |
25 |
320 |
5.5 |
7 |
.42 |
.67 |
| 30 |
1.9 |
25 |
320 |
5.3 |
8 |
.40 |
.65 |
| 45 |
1.9 |
28 |
340 |
4.7 |
12 |
.40 |
.65 |
| 60 |
1.9 |
33 |
402 |
4.3 |
12 |
.40 |
.65 |
| 80 |
1.9 |
35 |
415 |
3.9 |
12 |
.40 |
.65 |
| 100 |
1.9 |
35 |
415 |
3.9 |
12 |
.40 |
.65 |
| SIF®
PVC-Coated—Typical Physical Properties |
| Porosity*
(ppi) |
Thickness |
Tensile
strength (psi) |
Ultimate
elongation (%) |
Tear
strength (lb/in.) |
50%
Compression set |
Compression
deflection |
| 25% |
65% |
| 10 |
.375 |
25 |
270 |
6 |
23 |
.6 |
1.2 |
| 20 |
.250 |
24 |
300 |
6 |
26 |
.5 |
1.1 |
| 45 |
.250 |
34 |
320 |
8 |
30 |
.6 |
1.2 |
| 60 |
.250 |
34 |
250 |
8 |
25 |
.5 |
1.4 |
| SIF
Felt®—Typical Physical Properties |
| Firmness |
Density |
Tensile
strength (psi)* |
Ultimate
elongation (%) |
Tear
strength (lb/in.) |
| 3-900 |
5.25 |
50-80 |
250-350 |
5-10 |
| 10-900 |
17.5 |
160-200 |
200-300 |
20-30 |
| 15-900 |
26.2 |
220-270 |
200-300 |
25-35 |
Tested in accordance with ASTM D3574 *Porosity (ppi) Foamex method.
Typical physical properties not to be used as a specification. |
| Nominal
Pore Size Ranges |
| Porosity
grade (ppi)* |
Minimum |
Maximum |
Suggested
minimum sheet thickness (in.) |
| 100 |
80 |
110 |
— |
| 80 |
70 |
90 |
— |
| 60 |
55 |
65 |
— |
| 45 |
40 |
50 |
1/8 |
| 30 |
25 |
35 |
3/16 |
| 25 |
20 |
30 |
7/32 |
| 20 |
15 |
25 |
1/4 |
| 10 |
8 |
15 |
1/2 |
| 3 |
3 |
5 |
1/2 |
*As
measured on Laminar flow pressure drop apparatus at 575 fpm. |
Machine Tool De-Misting:
Filters made of SIF® foam help inhibit the accumulation of oil
on floors, walls, equipment, and personnel.
Other Applications Include:
Automotive air conditioner "split screens,’’ paint spray booths,
and volatile oil de-misting (coffee oil de-misting, for example).
Humidification
Because SIF® has a
large surface area and low-pressure drop, it makes an excellent humidifier
evaporative medium. SIF® is also used as an "evaporative
cooler" medium.
Domestic and Industrial
Humidifiers: A band of coarse, open-pore SIF® foam lifts
water from a reservoir pan across the path of a fan-fed airstream. The
elasticity of the band of SIF® foam holds it firmly against the
drive elements for months of service. Available in several different strand
surface grades, its thickness and pore size can be varied to meet designer
specifications.
Oil/Water Separation
Being oleophilic, SIF®
can be used to attract and separate oil based materials in a water
environment.
Typical Applications Are:
In oil spill clean-ups, particularly in industrial environments. Since SIF®
foam is light, it floats, is washable with a large surface area, and it
is an ideal medium for some laboratory separation processes.
Product Description
Physical Properties: The
homogeneous structure of SIF® helps minimize the possibility of
open channels which could drastically affect filter efficiency. Each cell in
the medium is completely interconnected with all surrounding cells. This
allows for free passage of air and at the same time provides high
surface-area contact for impingement of dust particles. The resilience and
strength of the foam helps prevent strand displacement under normal
operating conditions.
 
Fabrication: The high
tensile strength and tear resistance of SIF®, together with its workability,
greatly facilitate design of mounting devices. It can be sewn, stapled, glued, or fastened with
a grommet. This
foam can be framed as a more conventional filter medium, or it can be used
simply as a filter pad with no additional fabrication. It is being used
successfully both ways. The material, however, is most practically and
economically used as a filter pad alone where design of original equipment
will accommodate this type of
application.
Pore Size: SIF® is
produced in many standard pore grades. Expressed as the average number of
pores-per-linear- inch, these grades range from 5 to 100 ppi. Their
resistance to airflow or pressure differential is measured in inches of
water. A 1/2-in. thick pad of 30 ppi SIF® has a resistance to airflow at
450 feet per minute of only 0.15 inches of water. Combining several pore sizes can
produce two or three-stage filters. Range in pore size
for each grade is controlled within specified limits.
SIF Felt®: Made from
a reticulated polyester or polyether polyurethane foam, SIF Felt® has
excellent permeability, high physical strength, outstanding filtration
efficiency, abrasion resistance, and oil-wicking characteristics. SIF Felt®
Grade 900 is manufactured by compressing 90-ppi (pores-per-linear-inch)
reticulated foam under heat to impart a permanent compression set. By
varying machine conditions and the ratio of initial foam thickness to final
felt thickness, the specific design properties of the end product can be
controlled. This compression ratio is called the firmness of the material.
Firmness as high as 20 is available. As the particle size to be filtered
decreases, the firmness increases and the resistance to fluid flow
increases. SIF Felt® is easy to work with and is easily cut, glued, or
shaped into unusual or curved configurations. Because it is a homogeneous
material, it does not fragment or fall apart.
Temperature Features: SIF®
and SIF Felt® foam have excellent high and low-temperature characteristics.
They can withstand intermittent temperatures as high as 225°F ( 121°C). At
temperatures above 500°F (260°C), these foams begin to melt with
decomposition and vaporization. At -40°F (-40°C), they show no evidence of
cracking or tearing when bent around a mandrel equal in diameter to the foam
thickness.
Chemical Properties: SIF®
and SIF Felt® foams are not adversely affected by water, soap, most
detergents, perspiration, oils, most cleaning solvents, or greases at
normal temperatures. Aliphatic hydrocarbons cause slight swelling and
aromatics cause considerable swelling. Removal of the hydrocarbons allows
the foam to regain its original dimensions and strength. Since these foams
contain no plasticizer, no migration difficulty from the foam itself is
expected. SIF® and SIF Felt® are attacked by strong acids, caustics, and
chlorine, and are not recommended for use in their presence unless protected
by a coating.
Click on the links below to view graphs on Pressure Drop (Foamex Method).
Pressure Drop Graph one
Pressure Drop Graph two
Pressure Drop Graph three
Pressure Drop Graph four
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