TEST
METHODS
Physical
Properties of Carpet and Cushion
Density
Thickness
Compression
Resistance
Physical
Property Guidelines
Chart
Compression
Set
Resiliency
Acoustics
Thermal
Resistance
Flammability
Radiant
Panel Test
Steiner
Tunnel Test
Comfort
Underfoot
PHYSICAL
PROPERTIES OF CARPET AND CUSHION
Additional
information about the various test methods
discussed below is available through
the American
Society for Testing and Materials
at www.astm.org.
Density
Brief
Description
Density
is measured using a standardized, specifiable
test, ASTM D3574-95 "Standard Test Methods
for Flexible Cellular Materials-Slab,
Bonded, and Molded Urethane Foams",
which defines the amount of material
in a given volume of the cushion, typically
reported in units of pounds per cubic
foot.
Why
is it important?
Density
is a measure of the amount of material
in the cushion. Higher density means
that there is more cushioning material
available to do the work of protecting
the carpet and providing comfort underfoot.
It follows that density generally determines
the expected performance of carpet cushion,
with higher density equating with superior
performance. When developing a cushion
specification, it is important to consider
the requirements of the application.
For example, a busy office corridor
that receives high traffic will subject
the carpet and cushion to significant
demands, justifying a higher performance,
high-density cushion for long-term retention
of properties. Contrast this with an
executive conference room that receives
little traffic, requires a luxurious
feel underfoot, and has a need for castered
chairs to be reasonably movable. In
this case, lower density commercial
quality cushion might suffice. For help
in determining the appropriate density
for a given application, see the Physical
Property Guidelines, below. When in
doubt over the demands of the application,
it is prudent to err on the side of
a higher density cushion to ensure adequate
performance.
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Thickness
Brief
Description
Thickness
is measured using a standardized, specifiable
test, ASTM D3574-95 "Standard Test Methods
for Flexible Cellular Materials-Slab,
Bonded, and Molded Urethane Foams",
which reports the thickness of a carpet
cushion in units of inches.
Why
is it important?
This
test provides a measurement of the cushion
thickness which is a critical factor
in commercial carpet applications to
achieve the desired performance. Additionally,
commercial carpet demands consistency
of thickness, and specifications should
include a tolerance limit on the nominal
thickness. Consult your carpet and cushion
representatives for the requirements
in a particular application.
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Compression
Resistance
Brief
Description
Compression
Resistance is measured using a specifiable,
standardized laboratory test, D3574-95
"Standard Test Methods for Flexible
Cellular Materials-Slab, Bonded, and
Molded Urethane Foams", which measures
the force required to compress a backing,
particularly a cushion, to a certain
percentage of its original height.
Why
is it important?
Compression
resistance relates to how a cushion
will feel underfoot, as well as the
ability of the cushion to provide support
without "bottoming out." From the Facility
Manager's perspective, the ability of
a cushion to support traffic without
bottoming out is important to achieve
long-term carpet appearance retention.
Further
Information
This
property is specified under several
related tests.
Indentation
Force Deflection (IFD) is a compression
resistance measurement that "indents"
the cushion using a presser foot that
is smaller than the surface of the sample.
A measure of the load bearing capacity
of flexible polyurethane foam, IFD is
generally measured as the force (in
pounds) required to compress a 50 square
inch circular indentor foot into a four
inch thick sample (typically 15 inches
square or larger) to a stated percentage,
(typically 25 and 65 percent), of the
sample's initial height.
Compression
Force Deflection (CFD) is a compression
resistance measurement where the entire
sample is compressed using a larger
presser foot.
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Physical
Property Guidelines
Following
are suggestions by the Carpet
Cushion Council for density, thickness,
and compression resistance of the major
types of polyurethane foam cushion.
Of course, each installation is unique,
and appropriate specifications should
be developed through consultation with
your carpet and cushion representative.
|
TYPES
OF
POLYURETHANE
FOAM CUSHION
Commercial
Application
|
CLASS
I
MODERATE
TRAFFIC
Office
Buildings: Executive or
private offices, conference rooms
Health Care: Executive,
administrative
Schools: Administration
Airports: Administration
Retail: Windows and
display areas
Banks: Executive areas
Hotels/Motels:
Sleeping rooms
Libraries/Museums: Administration
|
CLASS
II
HEAVY
TRAFFIC
Office
Buildings: Clerical areas,
corridors (moderate traffic)
Health Care:
Patients' rooms, lounges
Schools:
Dormitories and
classrooms
Retail: Minor
aisles, boutiques, specialty
Banks: Lobbies,
corridors (moderate traffic)
Hotels/Motels: Corridors
Libraries/Museums:
Public Areas (moderate traffic)
Convention Centers:
Auditoriums
|
CLASS
III
EXTRA HEAVY
TRAFFIC
Office
Buildings: Corridors (heavy
traffic), cafeterias
Health Care: Lobbies,
corridors, nurses' stations
Schools: Corridors,
cafeterias
Airports: Corridors,
public areas, ticketing areas
Retail: Major aisles,
check outs, supermarkets
Banks: Corridors (heavy
traffic), teller windows
Hotels/Motels: Lobbies
and public areas
Libraries/Museums:
Public Areas
Country Clubs: Locker
rooms, pro shops, dining areas
Convention Centers:
Corridors and lobbies
Restaurants: Dining areas
and lobbies
|
|
Grafted
Prime Polyurethane*
|
Density:
2.7 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 2.5 psi
min.
|
Density:
3.2 pcf - 5%
Thickness:
0.25 - 5%
CFD: 65% 3.5 psi
min.
|
Density:
4.0 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 5.0 psi
min.
|
|
Densified
Polyurethane*
|
Density:
2.7 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 2.4 psi
min.
|
Density:
3.5 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 3.3 psi
min.
|
Density:
4.5 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 4.8 psi
min.
|
|
Bonded
Polyurethane**
|
Density:
5.0 pcf - 5%
Thickness: .375
- 5%
CFD: 65% 5.0 psi
min.
|
Density:
6.5 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 10.0 psi
min.
|
Density:
8.0 pcf - 5%
Thickness: 0.25
- 5%
CFD: 65% 8.0 psi
min.
|
|
Mechanically
Frothed Polyurethane***
|
Density:
13. pcf - 5%
Thickness: 0.30
- 5%
CFD: 65% 9.7 psi
min.
|
Density:
15. pcf - 5%
Thickness: .223
- 5%
CFD: 65% 49.9 psi
min.
|
Density:
19. pcf - 5%
Thickness: .183
- 5%
CFD: 65% 30.5 psi
min.
|
*Densities
must be 100% polymer.
**Particle size not to exceed 1/2".
***Ash content = 50% max.
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Compression
Set
Brief
Description
Compression
Set is a specifiable, standardized laboratory
test, D3574-95 "Standard Test Methods
for Flexible Cellular Materials-Slab,
Bonded, and Molded Urethane Foams,"
which measures the thickness loss under
a load at room or elevated temperature
after a given recovery time.
Why
is it important?
Compression
set relates to the performance of a
cushion in situations in which heavy
objects will be periodically moved (e.g.
repositioning of furniture such as a
desk). Products with high compression
set will leave noticeable, long-term
indentations.
Further
Information
A
high value of compression set indicates
that the particular flexible polyurethane
foam cushion will quickly lose its original
appearance and thickness with use. Compression
set is measured in the lab by compressing
a foam sample 90% of its thickness and
holding it at 70 degrees C (or 158 degrees
F) for 22 hours. Compression set is
most commonly expressed as a percentage
of original compression. Other deflections,
times and temperatures can be used.
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Resiliency
Brief
Description
Resiliency
is measured by a standardized, specifiable
laboratory test, ASTM D3574-95, which
is intended to measure the ability of
the cushion to return the energy that
is used to compress it. Resiliency is
commonly assessed using a ball rebound
procedure.
Why
is it important?
Resiliency
is an indicator of the amount of "spring
back" a cushion yields when walked on.
It is a factor in the ergonomics of
the cushion and the feel underfoot.
The carpet and cushion need to be resilient
to return some of the energy of compression
back to the foot to aid in lifting it
to take the next step. Floor covering
that exhibits insufficient resilience
may contribute to the fatigue of the
occupants. To illustrate, consider bare
concrete as one extreme. This is a very
hard surface with a high level of support,
but no cushioning. Working on such a
substrate has been shown in scientific
studies to be much more fatiguing than
working on a cushioned mat. [1]
[2] Walking in sand is another
extreme, with a relatively high level
of cushioning, but no resilience. Such
conditions also quickly lead to fatigue.
Properly designed polyurethane cushion
provides the desired level of cushioning,
support, and resilience.
[1]
Redfern, M. S. and Chaffin, D. B. "The
effects of floor types on standing tolerance
in industry.", Trends in Ergonomics/Human
Factors V 401-405; Elsevier Science
Publishers B. V. (North Holland), 1988.
[2]
Bousseman, M.; Corlett, E. N. and Pheasant,
S.T. "The relation between discomfort
and postural loading at the joints.",
Ergonomics 25(4)" 315-322, 1982.
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Acoustics
Brief
Description
Two
measurements are generally used to determine
the acoustical contribution of floor
coverings. The Noise Reduction Coefficient
(NRC) measures how well a material absorbs
airborne noise. The Impact Insulation
Class (IIC) indicates how well a material
prevents the transmission of impact
noise (e.g. through a floor to a room
below). In both cases, higher values
indicate better acoustical contribution.
Why
is it important?
Together,
these tests provide a measurement of
the flooring system's ability to improve
acoustics in a room. Not surprisingly,
carpet and cushion combinations enhance
acoustical contribution over that of
the same carpet alone. Improved acoustics
are a contributing factor in creating
an improved workspace, whether that
space is for office, educational, or
other use.
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Thermal
Resistance
Brief
Description
The
thermal resistance of a floor covering
is its ability to impede the flow of
heat. This property is reported in units
of either "R per inch" or R for a given
thickness on the floor. The higher the
R-value, the greater the insulating
ability of the flooring system.
Why
is it important?
Carpet
and cushion both contribute to improved
insulation over that of hard surface
floor coverings. The combination of
carpet and cushion provide enhanced
insulation over that of the same carpet
alone.
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FLAMMABILITY
Radiant
Panel Test
Brief
Description
The
Radiant Panel Test is a specifiable,
standardized laboratory test for flammability,
ASTM E648-00, that is intended to simulate
conditions that floor-covering systems
are likely to experience in a building
whose upper surfaces are heated by flames,
hot gases, or both.
Why
is it important?
This
test is the most common flammability
test specified for commercial carpet
applications. As such, it is desirable
for the carpet/cushion specifier or
facility manager to have a general understanding
of the method. This method provides
a basis for estimating one aspect of
the fire exposure behavior for floor-covering
systems. It was developed to simulate
an important fire exposure component
of fires that may develop in corridors
or exit ways of buildings. It is important
to note that the test protocol requires
that a sample be tested in a configuration
consistent with the way it will be installed.
Relative to carpet cushion, this means
that if carpet and cushion are to be
installed using the "double stick" method,
then the test samples for radiant panel
testing should also use the "double
stick" method for installation onto
the cement boards.
Further
Information
The
test protocol is described in ASTM E648-00
"Standard Test Method for Critical Radiant
Flux of Floor-Covering Systems Using
a Radiant Heat Energy Source." The floor
covering being tested is adhered to
a heat-resistant board, typically made
of concrete. The sample is installed
into the radiant panel chamber and allowed
to condition for a specified period
of time. One end of the sample is then
ignited, and the resulting flame is
encouraged to spread by the input of
heat from an overhead gas-fed panel.
This overhead "radiant panel" angles
up from the test sample and contributes
less heat energy as the carpet burns
along its 100-cm length. In many nylon-face
carpets, the carpet stops burning at
some point during the test when there
is no longer enough contributed heat
energy to sustain combustion. The distance
of the burn is measured and converted
through formulas provided in the test
protocol to "critical radiant flux"
with units of watts per square centimeter.
It
is important to note that the test method
specifies that tests on individual components
of a floor system are of limited value
and not necessarily valid for evaluation
of a flooring system. The test must
be conducted on the flooring system
as it is to be installed, i.e., with
cushion if specified, and using a recommended
adhesive. In the case of a specified
cushion, an alternative provided in
the scope of the test protocol is to
use a "standard cushion". This is defined
as a particular hair and jute pad with
specific characteristics. This alternative
was arrived at after the committee responsible
for defining the test protocol conducted
significant testing. However, according
to carpet test laboratory managers,
the "standard cushion" is no longer
readily available, rendering this alternative
practically obsolete.
The
critical radiant flux demonstrated by
the product puts it into a specific
class of performance* as defined
by this test:
Class
1 has a CRF of 0.45 watts/sq. cm or
higher
Class
2 has a CRF of 0.22 - 0.44 watts/sq.
cm.
Products
with a CRF less than 0.22 watts/sq.
cm are termed "non-classifiable"
The
requirements as to the class needed
for commercial buildings varies from
state to state, depending on the specific
building and fire codes in place. The
requirements are often tied to the type
of building, the section of the building,
and the presence of sprinklers. For
example, when Class 1 performance is
required in certain areas of a building
without sprinklers, that same area may
carry a Class 2 requirement if sprinklers
are present. It is always advisable
to understand the local code requirements
prior to publishing a specification
for products.
*This
numerical rating is not intended to
reflect hazards presented by this or
any material under actual fire conditions.
NOTICE:
This standard should be used to measure
and describe the response of materials,
products, or assemblies to heat and
flame under controlled conditions but
does not by itself incorporate all factors
required for fire- hazard or fire-risk
assessment of materials, products, or
assemblies under actual fire conditions.
This standard does not purport to address
all of the safety concerns, if any,
associated with its use. It is the responsibility
of the user of this standard to establish
appropriate safety and health practices
and determine the applicability of regulatory
limitations prior to use.
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Steiner
Tunnel Test
Brief
Description
The
Steiner Tunnel test for flammability,
ASTM E84, is an older test method still
used by some areas of the building materials
industry. For many years it was the
flame spread test for carpet as well,
but was replaced by the Radiant Panel
test in the interest of implementing
a more predictive methodology.
Why
is it important?
For
background information only
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COMFORT
UNDERFOOT
Brief
Description
This
is a subjective response to the feel
of the carpet/cushion as it is walked
on. No standardized test is available,
although some studies have demonstrated
an ability to measure and quantify the
comfort of a given substrate.
Why
is it important?
Comfort
is certainly an expected quality of
cushion, whether under carpet or in
a favorite easy chair. But the quantification
of comfort parameters is not straightforward.
There are several factors, namely load
bearing, shock absorption, and resiliency
that are good indicators of the comfort
to be expected from a particular cushion.
Below is some general background information
on comfort factors. However, expectations
for comfort underfoot are likely to
be met by the use of quality polyurethane
carpet cushions that meet the appropriate
performance levels discussed above under
PHYSICAL PROPERTY GUIDELINES.
Further
Information
Although comfort underfoot is complex,
there are three factors that contribute
significantly to the overall contribution
to comfort by a cushion in a floor covering
system:
Load
bearing: Sufficient load bearing of
the carpet and carpet cushion over the
expected life of the installation ensures
that people and objects will be firmly
supported, and not allowed to bottom-out.
It is important to consider the flooring
system, not the cushion alone. The impact
of adhering a carpet to a cushion is
one of "load spreading," i.e. the force
that the cushion is exposed to in a
given area is lessened by the load spreading
action of the carpet.
Shock
absorption: The shock absorption ability
of the carpet and cushion leads to a
pleasing feel underfoot and is important
to minimize jarring and eventual muscle
fatigue.
Resiliency:
The energy returned to the foot after
stepping down on the carpet/cushion
is a measure of the resiliency of the
flooring system. Appropriate resiliency
is required to avoid a "dead" feel to
the carpet-cushion composite and the
related contribution to fatigue of the
walker.
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