• What is a Fabric Duct, and why use it?
ducts are a cost effective, attractive, easy to install
alternative to traditional metal ventilation ducts (open
architecture / exposed ductwork). A traditional metal system
will use metal ducts to transport the air, and then diffusers are
installed intermittently to distribute the air which can cause
drafty conditions right under the diffuser and "dead spots" where
the diffuser is not able to effectively condition. With fabric, the
entire duct is your diffuser, with the air being supplied through a
porous material and/or orifices. This ensures a draft-free, evenly
conditioned indoor environment. Click here to learn about the many
advantageous and features of fabric ducts. Note: Fabric ducts are
used for supply applications only.
• What is the cost comparison to traditional metal
Typically the cost of the actual fabric duct system is about even
with the cost of metal components, however the metal index is very
volatile and constantly rising where as textile prices are quite
predictable. As weaving/manufacturing technology advances
production becomes more efficient reducing costs. The big cost
saving factor will be in the installation of the product where
50-70% reduction in labor cost can be seen.
• How long does it take to install typical KE Fibertec
Please see our installation assistant
• What diameter should the fabric duct be? Is there a
On a general note KE Fibertec offers diameters from 8" - 64", but
diameters outside of this range have been done for custom
applications. The volume of air supplied to the duct will determine
the diameter, recommended is design around 1500 fpm inlet velocity
to reduce the risk of the duct fluttering and uneven air
distribution (entrainment). The higher the inlet velocity (above
1500 fpm) the more static pressure will be required to counter the
• How long should the fabric duct be? Is there a
Length varies, depending on application, room dimension, and air
distribution requirements. Max/min length ultimately depends on
airflow and static pressure. KE Fibertec would be glad to assist
with designing a system to fit your needs.
• Can transitions/fittings/reducers be made in
Absolutely, almost any fitting that is done in metal KE Fibertec
can manufactured in fabric.
• What shapes can fabric ducts be?
Round, half round, and quarter round are the common shapes we
• Can fabric ducts be used with VAV
Yes, fabric duct manufacturers need the maximum and minimum
airflow settings and static pressure available to the fabric duct
(typically a 50% turn down recommended for round ducts). D shape
ducts are perfect for VAV systems because they retain their shape
even when the system is off.
• What is the life expectancy of a fabric duct?
A good quality fabric duct system should last for well over 20
• What is inflation "pop"? What causes this, and how
can it be prevented?
Inflation "pop" is when the fan supplying the fabric duct is
initially turned on, the fan ramps up immediately and inflates the
duct instantaneously. Depending on the volume and size of the duct
this can generate a loud "popping" noise. Not only is this noise
objectionable but the energy from the "pop" must go somewhere and
will have negative effects on the lifetime expectancy of the fabric
and suspension system. This can be prevented with a Variable
Frequency Drive / motorized damper or someway to introduce the air
at a slower rate into the duct. Another option to reduce
inflation pop is to use the Safetrack 360 system that keeps the duct
open at all times eliminating 99% of the inflation pop.
• Do the fabric ducts need to be balanced on
No, KE Fibertec designs the duct to a certain volume and static
pressure. As long as these two values are correct at the inlet, the
duct is a factory balanced device ready to go out of the box.
• What throw lengths can be expected from a fabric
This varies, depending on product type, airflow, and pressure in
the duct. KE Fibertec will design the duct to meet the throw
requirements whether it be a little to no air movement application
System) or > 65 ft throw application with the use of nozzle
technology (DireJet System). KE offers the most
flexible fabric duct line on the market, period.
• Do fabric ducts require
Yes, fabric ducts must be washed to maintain the permeability
properties of the material. If the duct is never washed the
material can clog up and change the performance of the system. Wash
cycles will vary with applications and material weave; can range
from every three months to once a year (KE Fibertec can typically
give a wash cycle recommendation if room conditions and application
• Do fabric ducts offer any green
Yes, fabric ducts offer a number of environmentally friendly
benefits including lower fuel consumption for shipping, less power
used onsite because of reduced installation time, improved indoor
air quality / even air distribution, and running at low static
pressure for reduced energy consumption (visit www.buildinggreen.com to learn more and www.USGBC.org to
explore possible LEED credits)
Also, read about CradleVent, the world's first Cradle to
Cradle certified fabric duct.