Frequently Asked Questions

• What is a Fabric Duct, and why use it?

Fabric 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 systems?

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 Duct?

Please see our installation assistant section (link here)
  

• What diameter should the fabric duct be? Is there a minimum/maximum?

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 1500fpm) the more static pressure will be required to counter the increased turbulence.


•  How long should the fabric duct be? Is there a minimum/maximum length?

Varies, depends on application, room dimension & 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 fabric?

Absolutely, almost any fitting that is done in metal KE Fibertec can manufacture in fabric.


•  What shapes can fabric ducts be?

Round, half round and quarter round are the common shapes we use. 

•  Can fabric ducts be used with VAV systems?

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 years.


• What is inflation “pop”?  What is 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 a 3 point suspension system that keeps the duct held open (Safetrack Arch Link) so that there is minimal inflation of the duct.


• Do the fabric ducts need to be balanced on site?

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 duct?
Varies, depends 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 (KE-Low Impulse® System) or > 65 ft throw application with the use of nozzle technology (KE-DireJet® System). KE offers the most flexible fabric duct line on the market, period.

•   Do fabric ducts require maintenance?

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 is provided).

•   Do fabric ducts offer any green benefits? 

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, improving indoor air quality / even air distribution, can run at low static pressure for reduced energy consumption (visit www.buildinggreen.com to learn more and www.USGBC.org to explore possible LEED credits )

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