A quick introduction to textile ducting and how to work with textile ducts for air distribution in class rooms, industry, laboratories, offices etc. Textile ducts will provide you with a healthy indoor climate and energy savings. Read more on http://www.ke-fibertec.com/en/products/why-textile-ducts/

1. Textile Based Ventilation
Design Guide for Textile Ducting

2. AIR THE WAY YOU WANT
Fire approved materials
Efficient air distribution and good indoor climate
Unique materials and colours
Draughtfree air distribution - no dead zones
No condensation problems and no need for insulation
Light-weight textile ducts that can be installed in any type of ceiling
Hygienic and easy to maintain
Easy to transport and install
1600 different colours
CHOOSE SUSTAINABLE
VENTILATION
All KE Fibertec textiles are tested and
approved according to the Oeko-Tex®
Standard 100.
Our production is certified according to
the ISO 14001 standard (Environmental
Management System).
Transportation and disposal of textile
duct systems produce less CO2
pollutants than conventional steel
ducts.
W H AT I S A T E X T I L E D U C T ?
In principle a textile duct (also called a ventilation duct) is a round, semi-round or quarter round duct made of a light-weight
textile material instead of e.g. galvanized steel, stainless steel or aluminium, designed for delivery and distribution of cooled or
heated air.
Majura Recreation Centre, AUS
Astra Zeneca, UK
B E N E F I T S O F T E X T I L E D U C T S
Jorgensen Engineering, DK
Read more on ke-fibertec.com

3. AIR THE WAY YOU WANT
Q U O TAT I O N A N D D E S I G N P R O C E S S E S
KE Fibertec offers advice and support from our experienced in-house sales engineers, who have all undergone extensive train-
ing on ventilation products and particularly on our TBV products. All the calculations are proven using our unique software
WinVent 3D, which is offered to all our customers, regardless of the size of their project and, of course, free of charge.
Our quotation and design processes are described in detail in our ISO 9001 quality assurance system. This ensures that we
prepare the basis for the quotation and the quotation itself according to the standardised guidelines, making sure that the
customer’s requirements are specified and documented in sufficient detail. KE Fibertec puts large emphasis on ensuring that
the final solution is designed correctly even at the quotation stage. After all, it is not only about ensuring that the textile based
ventilation system works properly, but also, to just as large extent, that the customer’s indoor climate requirements have been
met. This is why we ask about the system’s functional requirements and the requirements for the indoor climate at the quota-
tion stage.
Our quotation is based on the following information:
• Air volumes (possibly partial air volumes per socket) [m3
/h]
• Temperature-set cooling and possibly heating [°C]
• Pressure available from the fan [Pa]
• Dimensions of the room L x W x H [m3
]
• Location of the air inlet(s)
• Requirements on number of ducts and maximum duct dimensions
• Requirements on the room’s use (room category)
• Requirements on maximum permissible air velocity in the room [m/s]
• Requirements on the temperature in the room [°C]
• Requirements on the maximum sound pressure level in the room [dB(A)]
• Selection of duct colours
• Selection of suspension type
Given that an infinite number of combinations of sys-
tem solutions and layout features can be designed
for textile based ventilation, it is important that its
function is specified precisely at the quotation stage.
In our role as consultants, we always endeavour
to meet the relevant need with the solution that we
have agreed with the customer to offer. We are highly
innovative in our way of thinking, which is why you
must not always expect just a “plain” solution which
ultimately cannot meet the requirements you set in
terms of the system’s appearance and the indoor
climate.
Our solution is based on the concept “AIR THE WAY
YOU WANT” for the same reason.
Arla Foods, S
Dublin Zoo, IE

4. AIR THE WAY YOU WANT
D I M E N S I O N I N G T B V S Y S T E M S
To be able to dimension a textile based ventilation system, it is important to understand a number of essential parameters and
concepts. A textile based ventilation system is not fundamentally different from conventional ventilation systems, but there are
a number of key points where it is important to be extra cautious. A brief description is given below of the key parameters and
concepts used when dimensioning KE Fibertec’s textile based ventilation systems.
The entire surface of the KE-Low Impulse System is permeable,
which means that the total delivery area corresponds to the
geometric surface area. The geometric surface area, A, is given in
[m2
].
KE Low Impulse®
System
KE DireJet®
System
KE Inject®
System
n the case of the KE-Inject System and KE-Inject Hybrid System,
KE Fibertec has, for the sake of manufacturability, grouped the
holes in different standard patterns, depending on which type is
selected. A standard pattern is made up of an exact number of hole
steps and the delivery area can only be modified by changing the
number of hole rows. Consequently, the unit, number of hole rows,
is used as a parameter for the delivery area of the KE-Inject System.
In the case of the KE-Inject Hybrid System, the whole of the duct’s
surface, including the holes, will act as the delivery area.
In the case of the KE-DireJet System and KE-DireJet Hybrid
System, the delivery area depends on whether a Ø12 mm, Ø18
mm, Ø24 mm, Ø48 or Ø60 mm nozzle is selected, as well as how
many nozzles are used per running meter of ducting. With the KE-
DireJet Hybrid System, the whole of the duct’s surface, including
the nozzles, will act as the delivery area.
D E L I V E R Y A R E A
KE-Low Impulse System: A = diameter · p · duct length
KE-Interior System (D) A = (1/2) · diameter · p · duct length
KE-Interior System (½D) A = (1/4) · diameter · p · duct length
P E R M E A B I L I T Y
Air permeability through the textile material’s surface is crucial to how great the static pressure will be for a given volume flow.
The tighter the material’s weave, the higher the pressure will be as a function of volume flow. For all KE Fibertec’s low impulse
materials, the static pressure increase is given as a function of volume flow per m2
of the textile material’s surface. Permeability
is expressed in the unit [m³/m²/h]. See datasheet 6 for more information.

5. Ps
Pt
Pd
Flow
Pt
Flow
Pt
Ps
Ps
Flow
AIR THE WAY YOU WANT
Where:
Pt
Total pressure in the duct [Pa]
Ps
Static pressure in the duct [Pa]
Pd
Dynamic pressure in the duct [Pa]
P R E S S U R E C O N D I T I O N S I N T E X T I L E D U C T S
As in any other air distribution system, pressure losses also occur in textile based ventilation systems. Calculating the pressure
losses in a textile based ventilation system is not basically any different from the generally known practice. The flow in a duct
system is only dependent, to a limited extent, on whether the material is made of steel or fabric. However, what is important to
be clear about is that textile material is very flexible and it is only kept inflated by the static pressure in the system. As a result,
even small turbulences can cause pulsations. This is why it is very important to perform pressure loss calculations to ensure
that the textile based ventilation system is operating as it is supposed to without any pulsations, as well as ensuring the best
possible energy economy.
D E F I N I T I O N S O F P R E S S U R E
The types of pressure that occur in a textile based ventilation system are
shown in the figure on the right.The total pressure (Pt
) can be calculated
anywhere in a textile based ventilation system as the sum of the static
and dynamic pressures.
The following expression applies:
Pt
= Ps
+ Pd
Total pressure
The total pressure is the pressure that needs to be produced by the fan to
overcome the total resistance in the textile based ventilation system, i.e.
the loss from the individual types of resistance, such as elbows, frictional
loss and the static pressure in the system.
Static pressure
The static pressure, which is measured in relation to atmospheric
pressure, has an identical impact in every direction and keeps the textile
material inflated, as well as pushing the air out through the holes/nozzles.
Dynamic pressure
The dynamic pressure, or velocity pressure, has an impact on the
direction of the air and carries it from A to B. The dynamic pressure is
related to the mean air velocity in the duct and is calculated using the
following expression:
Where:
r Density of the air [kg/m3
]
v Mean air velocity in the duct cross section [m/s]
Pd
= ½ · r · v2

6. DPe
= x · Pd2
AIR THE WAY YOU WANT
• Across cross section modifications
• Across branches
• Across elbows
• Friction
• Across flow components (SRD’s)
• Across holes, nozzles and textile material (“fittings loss”)
The pressure loss which occurs in a textile based ventilation system originates from the following sources:
It is very obvious when a textile based ventilation system has been dimensioned incorrectly because the ducts will be oval and
“sagging” when you look at them. The difference in the static pressure between two parallel ducts may be quite considerable
too. This not only has an impact on the aesthetic appearance, but to a great extent also on air distribution. If the pressure
distribution is uneven this can cause draught problems below and around the duct with the highest static pressure, while in the
opposite case, the air quality will be poor in the area where the static pressure (and therefore the volume of air) is not sufficient.
P R E S S U R E L O S S I N T E X T I L E D U C T S
Where:
x Pressure loss coefficient [-]
Pd2
Dynamic pressure after the component [Pa]
KE Fibertec AS has documented pressure loss measurements for all the components featuring in our TBV systems. Contact
KE Fibertec’s development department for further information.
The pressure loss across these various components is a loss that is related to the velocity, and thus is proportional to the
dynamic pressure, Pd
, and dependent on what is known as the pressure loss coefficient, which is found when measurements
are taken in KE Fibertec’s full-scale laboratory. The pressure loss across a component (DPe
) is determined using:
Nasjonalmuseet, N Guldfaageln Arena, S

7. 120
110
100
90
80
Flow
Pt
Pd
Ps
[Pa]
0 25 50 10075
[%]
Flow
Pt
Pd
Ps
120
110
100
90
80
[Pa]
0 25 50 10075
[%]
Pt
Pd
Ps
5,0
4,0
3,0
2,0
1,0
Længde af kanal [m]
0 10 20 30 40 50 60 70 80 90 100
0
P P [-]s d
AIR THE WAY YOU WANT
P s
/ P d
R AT I O
As a result of their permeable surface, the volume of
air and air velocity in textile ducts, unlike in ordinary
steel ducts, continually decreases along the duct.
This means that the dynamic pressure falls along the
duct, while the static pressure rises. This results in a
large portion of the air being delivered at the end of
the duct where the dynamic pressure is zero. As the
volume of air continually decreases along the duct
friction loss may often be ignored. This means that
the total pressure and static pressure will be more or
less identical at the bottom of the duct.
One solution frequently used to ensure that air is
distributed uniformly through very long ducts is
to restore the dynamic pressure in the system by
inserting a duct reduction, in the middle of the duct,
for instance. This will break the static pressure in the
duct, thereby achieving a more even distribution of
air. This is also the most economical solution if duct
reductions are acceptable. To facilitate installation,
single suspended ducts should have duct reductions
with flat edge on top, while double suspended ducts
should have centred duct reductions.
In order to produce a uniform distribution of air
along the entire system’s longitudinal direction,
the static pressure in the middle of the textile duct
should always be at least double that of the dynamic
pressure in the duct’s inlet. KE Fibertec recommends
that the ratio between the static pressure, Ps
, and
dynamic pressure, Pd
, should at least follow the curve
on the right. The longer the duct is, the higher the
static pressure needs to be in the middle of the duct
in relation to the dynamic pressure in the inlet, in order
to ensure that the air is distributed uniformly.
M A X I M U M I N L E T V E L O C I T I E S
The inlet velocity is a critical design parameter for tex-
tile based ventilation systems as it has a major im-
pact on aspects such as pulsation, noise generation,
the material’s durability and the air distribution from
the duct. The recommended inlet velocity for round
ducts is no more than 6-8 m/s, depending on the
entry method.
Length of duct [m]

8. AIR THE WAY YOU WANT
Already, many consulting engineers and contractors have discovered MagiCAD for the designing of ventilation
solutions.
As the first manufacturer of Textile Based Ventilation ducts, KE Fibertec is now ready with a product database
enabling the engineer to design and calculate textile ducts directly in MagiCAD.
See documentation and cases on www.ke-fibertec.com
KE Fibertec AS
Industrivej Vest 21
6600 Vejen
Denmark
Tel. +45 75 36 42 00
Fax +45 75 36 20 20
info@ke-fibertec.dk
www.ke-fibertec.com
KE Fibertec AS is market leader in Textile
Based Ventilation. We create good indoor
climate through our tailored textile
ducts for installation in sports arenas,
offices, laboratories, schools etc.
Textile ducts are customizable, easy to
install, washable, hygienic, and come
in all shapes and colours.
For more information please visit our
website: www.ke-fibertec.com.
This Guide is an extract of KE Fibertec’s technical
catalogue. E-mail to info@ke-fibertec.dk to order
the entire catalogue.