Air Solutions News

What are the benefits of fabric with high dust carrying capacity ? Does it mean more time between washes and what does the duct static for a dirty duct increase to ?

Exactly. The staple fibres and the special “Koperbindung” way of weaving the HDC material extends the washing intervals by 4 times compared to flat multifilament woven materials. If the ducts have nozzles or holes venting the air out the static can increase to 250-350 Pa. If there are no vents (KE Low-Impulse), and maintenance is thoroughly neglected the static pressure can overtime reach 500-600 Pa (Mind you, a multifilament duct will get there 4 times faster)

Which fire codes or standards does KE fibertec comply with  

KE fibertec comply with EN 13501-1 (Europe), UL NFPA90A (USA), M1 (France), B1 (Germany), SIS (Sweden), AS/NZS 1530.3 (Australia) and VKF (Switzerland).

How many years warranty on the fabric?

Standard 5 year warranty, up to 10 years, if we know exactly how the ducts are used and maintained.

Why does the HDC fabric have a higher permeability than the LDC fabric ?

It doesn’t. The permeabilities are the same, the range is just different. LDC goes up to 320 m3/m2/h, whereas HDC goes all the way up to 1380 m3/m2/h.  We have made it so, because when you work with open materials you work with comfort situations (leaking a lot of air out of the fabric, and virtually none through vents), and it does not make any sense to apply LDC (industrial optics, short washing intervals) in these applications.

Received a call from Sydney University, as they know we know what we’re doing.

“We have this room we would like you to come and fix for us”

The room had 2x 4way blow grilles on one side of the room and a return air grill on the other. If you stood in the middle of the room you could feel the draft tunnel try to walk through you. In a parabolic type curve. So Wanda, Christian and myself discussed for around 20 working hours until we all agreed on the length and breadth and permeation for the ducts. I think it was that Christian that came up with the 0.13m/s calculation. WHICH IS WHAT THEY ARE GETTING!

The problem was, the electron microscope was giving blurry images due to the draft going STRAIGHT THROUGH the head lens. The aim was for a maximum of 0.15m/s at the head. WinVent said they would get 0.17m/s, Christian said it would be more like 0.13m/s.

So I’m at Sydney University yesterday, installing the recently shipped MADSEN Rooms(arrived last week 1/3/2011). And the head of this department walks in. We reminisce about that time a year ago where I had that call. He was scared, I was scared. He was also worried about putting more metal in the room. They have an issue with interference from all the metal components in the rooms. It just so happened that KE Fibertec DK had some plastic support for the D-Duct systems, perfect for this project.

Again I reiterate my passion for the HDC (High Dust holding Capacity) material. This was from the story brought up by the department head..

“They had the maintenance crew in to replace the filter. The contractor removed the filter, then conveniently forgot to put a new filter in. Subsequently a lot of muck flew through the ducts and into the fabric duct. Our nice light grey fabric ducts went dark grey almost black, which sounded alarms. We investigated and found the problem of a new filter not being installed.”

Sitting in the new installation room and receiving praise for the fact that I (and KE)
insisted on the use of the HDC material [after giving a lecture about the HDC properties]…

“Because of those HDC ducts, they caught all that muck. It would have cost us thousands to clean the dust out of those micro-scopes, but those ducts with all the muck stuck in the fabric, just kept working like they did on day one. All we had to do was take them down and clean them. We couldn’t use that room for a day, instead of 2 weeks. Thank you so much, and thank you so much for coming in today and making sure all went well with this install.”

Nick Mascall – Sales Engineer Textile Based Ventilation email: ke@airsolutions.com.au mobile: +61 415 962 958

Download USYD_EM1 Case Study

No matter how well the air is pre-filtered, a certain amount of dust particles will always end up in the supply air. How frequently the textile ducting is washed therefore depends, to a large extent, on the fabric’s dust holding capacity. KE Fibertec classifies the materials into two material groups according to the fabric’s dust holding capacity. We therefore use the acronyms HDC for materials with a high dust holding capacity and LDC for materials with a low dust holding capacity.

The capability of the materials to carry dust is highly dependent on the structure of the weave. High Dust Capacity materials (HDC) are made of staple fibre yarns, i.e. yarns that are spun of 38 mm long thin fibres. The final yarn is made by twisting two yarns into one yarn that is used both in warp and weft direction (length- and crosswise of fabric). The result is a fabric that is capable of carrying a large amount of dust without blocking the air flow through the material. Such blocking would require washing of the textile duct to ensure the distribution.

Low Dust Capacity materials are woven of multifilament warp yarns (lengthwise), i.e. yarns that are made up of 128 thin uncut fibres. These fibres are plain and smooth with a small surface compared to that of the staple yarns. In weft direction (crosswise), the same
staple yarns are used as for the HDC fabric, however, the weaving-method is a more simple cotton bond with a much smaller surface than that of the HDC fabric.
In practice there will be no difference in strength or in durability of the two fabrics. Neither
in permeability accuracy nor shrinkage.

In practice there will be no difference in strength or in durability of the two fabrics. Neither in permeability accuracy nor shrinkage.

The surface structure of an HDC material compared to an LDC material. The HDC material has a huge surface and volume in relation to an LDC material, which is of great benefit to the dust holding capacity and therefore, the washing frequency.

KE Fibertec offers a variety of product types according to the relevant needs and type of installation. All low impulse systems and hybrid high impulse systems are basically dimensioned using materials with a high DHC, whereas we use materials with a lower DHC for very active systems (more than 30% of air through holes or nozzles). The reason for this is that the dust particles in these systems do not cause the same rise in pressure in the
duct as most of the dust just penetrates the holes or nozzles.

KE Fibertec always carries out recommended tests on the dust holding capacity of textile materials. For instance, we have tested both HDC materials and LDC materials in accordance with EN 779 at the approved PALAS Institute in Germany. The results of these tests showed that the Dust Holding Capacity was up to 4 times higher for the HDC material compared to the LDC material.