air ducting manual

Ventiflex R

VENTIFLEXMANUAL

GB

Edited by:

Göran HanssonSvein Haaland

Peder Lien

Translated byInter-Set Oversettelsesbyrå AS of Oslo, Norway

November 2001

Trykk: Lier Grafiske - 08.2004

Ventiflex – the safest ducting – 3

Ventiflex R

The information in this manual is basedupon prevailing instructions and directions.Protan AS reserves the right to makechanges, and denies responsibility forconditions which might occur such aschanges in trade regulations.Contingent liability claims cannot becharged against Protan AS.No par t of this document must bereproduced without the express permissionof Protan AS.


Ventiflex R

Table of Contents

page

Preface ....................................................................................... 5

Product description .................................................................... 6

Manufacturing ............................................................................ 7

Material properties ..................................................................... 8

Quality control ............................................................................ 9

Selection of quality, size and coupling systems ....................... 10

Selection of supplier ................................................................ 12

General advice and tips ........................................................... 13

Installation ................................................................................ 14

Inspection and maintenance .................................................... 18

Repairs ..................................................................................... 19

Replacement of damaged ventilation ducts ............................. 23

De-installation .......................................................................... 25

Storage .................................................................................... 26

Computation of air requirements ............................................. 27

List of references ..................................................................... 30


Ventiflex R

Preface

The factory complex at Nesbyen.Photo: Fjellanger Widerøe AS

Protan’s head office in Drammen.Photo: Fjellanger Widerøe AS

Protan was founded in 1939.Its first product was a lifejacket madeof latex-impregnated linen cloth. Sincethen, the coating of technical textileshas comprised the core expertise ofthe firm.

At present the company has four prod-uct groups:– Roof coverings– Wall coverings– Technical textiles and– Ventiflex ventilation ducts

Ventilation ducts have been producedsince 1949. More than 750,000 run-ning metres are produced annuallywith diameters ranging from 20 cm to300 cm in different lengths and quali-ties, and with different coupling sys-tems.

Protan is one of the world’s largestmanufacturers of ventilation ducts.These are sold all over the world

Why?

Life-long experience in weaving, coatingand welding in addition to enthusiasticemployees results in products with a highlevel of quality and satisfied customers.

We hope that the information in thismanual will make you, as a user ofVentiflex, still more satisfied.


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Knitted textile.

Woven textile.

Product Description

Ventiflex ventilation ducts consist of awoven or knitted textile made frompolyester yarn coated on both sideswith softened PVC (polyvinyl chloride),normally yellow on the outer side andblack on the inner side.

The polyester textile gives the venti-lation ducts its mechanical strength.Different textile thicknesses are usedin the different duct qualities.More detailed information can befound in the material specifications.The textile is made in accordance withspecifications provided by Protan,including for the number of threads percm and type of yarn for warp and weft.

The coating on the textile makes theventilation duct air and water tight,protects the yarn against UV radiationand chemical effects of light, plus itmakes it possible to weld the individualsheets together into a circularduct. Thicker coatings provide betterwear resistance.

The coating consists of PVC, plasti-ciser, stabiliser, fire-retardant agentsand pigments.


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Coating the textile.

Turning and welding.

Finally packed for shipment.

Manufacturing

The textile, normally approx. 2 m wide,is coated on both sides in a coatingmachine in accordance with Protan’smaterial specification. See the mate-rial specifications for more specificdetails.

A specially made machine turns andwelds different lengths of the coatedtextile into a duct which is marked withthe brand name «Ventiflex», a qualitydesignation and production data (date,month and year). The suspension sys-tem is automatically mounted on theduct as well as it being cut to the rightlength and finally packed for shipment.

High-frequency welding is used, whichis the most reliable method for weldingPVC-coated textiles and the only weldingmethod that produces a weld just asstrong as the material.Hot air welding should only be usedfor repairs, see the section entitled«Repairs».


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Material Properties

The materials used for Ventiflex aremade to meet the requirements posedfor the operation of modern tunnelsand mines.

The textile provides the requisitetensile strength to withstand the highinternal pressure. Larger duct dia-meters require stronger textiles, andhence more and thicker threads.The specially developed knitted text-ile gives the material a high tearresistance and thus prevents smallholes and cracks from growing andcausing the entire duct to tear.

The coating gives very good protectionagainst most chemicals, water, sun-light (UV radiation) and gasses.Thicker coatings provide better wearresistance.

All Ventiflex qualities are self-extinguishing (tested regularly by anindependent institute), which is to saythat in the event of a fire the duct willburn as long as it is exposed to flames,but it will go out when the source ofthe fire is removed, as opposed to mostother organic materials which willcontinue to burn.

In the event of fire, the duct will emit gas-ses such as water vapour, carbon dioxideand traces of gaseous hydrochloric acid(the latter is dependent upon temperatureand the presence of other materials,for example copper). Smoke will alsobe released, consisting of soot andplasticiser.


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Quality Control

All raw materials are thoroughly testedfor a considerable time prior to beinggranted approval. Suppliers of yarnand chemicals are recognised inter-national firms.

Protan’s production system, includingits formulas, procedures and specifi-cations, are subject to an ISO 9001quality assurance system.

A well-equipped laboratory thoroughlytests raw materials and checks the coatedmaterials on an on-going basis.

Protan is also environmentally certifiedunder ISO 14001.


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Selection of Quality, Size and Coupling Systems

Having the best possible ventilationduct is of great importance to bothworkers and machines. A ventilationduct of good quality makes for morefresh air to the workplace, a lower num-ber of injuries, less extensive injuriesand requires less power from the fanin comparison with a ventilation ductof poorer quality.

If the ventilation duct is of good quality,a somewhat larger fan should beselected than is necessary. This willmake for a lower number of RPMs forthe fan and hence significant savings asregards electricity.In other words, for a lower total cost abetter ventilation system can be obtainedwhich requires less effort in terms ofmaintenance and which provides morefresh air to the workplace. In addition,you have some spare capacity whichcan be beneficial to have in the eventthat any unforeseen events occur.

What is good quality?

The strength originates from the yarnand the weave. Plastic on both sidesprotects the yarn and the weaveagainst both wear and externallyimposed stresses.

A good quality ventilation duct alwayshas:

– stabilised yarn in the weave.This provides a geometricallystable duct that provides lessturbulence.

– a yarn design which allows thethreads the possibility to move.When subjected to loads, thisprovides a collection of threadsthat makes it more difficult totear the textile apart .

– a plastic coating that is thickenough to protect the weaveand yarn against both wear andexternally imposed stresses.

– a plastic coating which is thickenough to provide good fireprotection.

Basically, a knitted weave with stabilisedyarn that has stronger weft threads thanwarp threads and a thick plastic coatingprovides the strongest and mostoptimum material for ventilation ducts.

The diameter on the ventilation ductmust always be computed to be aslarge as possible. A duct with a largediameter provides more air than asmaller duct, alternatively it gives thesame quantity of air but with signifi-


Ventiflex R

cantly lower energy costs. If you donot have room for as large of a diame-ter as is needed in order to have goodventilation, it can pay to select twoventilation ducts with a smaller diame-ter. The increased purchase expensesthis causes will in turn be saved a num-ber of times over in the form of lowerelectricity consumption.

High pressure makes for large stresseson the entire ventilation system andcosts large sums in terms of energyconsumption. By using ducts with alarger diameter, or alternativelymultiple ventilation ducts, you can savelarge quantities of energy and agreat deal of money.

A rule-of-thumb. If you reduce theRPMs of the fan by 20%, you will saveapprox. 50% in power expenses!


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The reliable injection of air through aventilation duct of high quality iswithout a doubt the best investmentthat can be made in an undergroundproject. Both workers and machineswill be more productive when the airsupply has the best possible con-ditions.

Many examples exist of projects onwhich savings of 2-3% have beenmade in purchasing prices for theventilation system, but which havesubsequently endured many produc-tion stoppages because damages hadcaused such large leaks that nearlyno air was being transported to theworkplace. Every stoppage costsmany times more than the normal pricedifferential between a good and lessgood ventilation duct.

The best guarantee is to purchase theventilation duct from a serious supp-lier, a supplier with longstandingexperience and with continuous andprofessional production.

A good piece of advice would be torequire ISO 9001 certification. It is alsogood to require ISO 14001, whichshows that the supplier is not just

Selection of Supplier

producing the product, but is alsointerested in it being produced andused in an environmentally appropriatemanner. A supplier who has thesequality certifications has a good know-ledge of how the product is used andcan make a great deal of expertise aswell as a high level of service availablefor both installation and operation.


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A ventilation duct is intended to be ableto provide a certain quantity of fresh airto the people who work in the tunnel aswell as to machines that are not poweredby electricity. A proper ventilationcalculation takes into account minordamages which can arise whenmachines hook into the the ventilationduct. If the damaged areas are toonumerous or too extensive, the air will leakout on its way through the duct and lessair will reach the people who are workingfurthest inside the tunnel.

Example: How large is the leakage ina ventilation duct with a diameter of 1m and a pressure of 3000 Pa?

Through a damaged area (tear) thatis 10 cm long approx. 0.5 m3 of air willdisappear per second.

Through a damaged area (tear) thatis 30 cm long approx. 5 m3 of air willdisappear per second, i.e.10 times asmuch.

Thus it is extremely important that theventilation duct be constantly main-tained and that damaged areas berepaired as soon as possible.The maintenance expenses are mini-

General Advice and Tips

mal in comparison with what the extraconsumption of electricity costs. A10% increase in the fan capacity inorder to increase the quantity of airincreases the power consumption by22%. The risk of a significant incidentin which work needs to be stopped dueto the lack of air also increases withthe number of unrepaired damagedareas.


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Flexible ventilation ducts can beconnected together in many differentmanners. The most simple and reliableis with a steel ring on the end of theduct which is inserted into a loose endon the next duct and a coupling ringof steel which is fitted over the jointand fastened. This provides a simpleand reliable connection. For larger dia-meters, it can be simpler to use two-piece coupling rings. There can alsobe steel rings on both ends of the duct.In this case one ring is inserted intothe other and fastened with an externalcoupling ring.

Coupling rings are available with dif-ferent profiles for one or two innerrings.

A coupling system with an inner ringand a loose duct end gives a largeamount of flexibility, and different ductlengths can easily be cut in order tobe adapted to the geometry of the tun-nel.

Zip couplings have been used since1984 and can be a good alternativefor long lengths of ventilation duct andlarge diameters. Suitable projects arelong, straight TBM tunnels.

Installation

The zip coupling is permanently mountedin the end of the duct and is joinedtogether with the end of the next ductin a simple manner.

Probably the best coupling at presentis a soft coupling. It has a mecha-nically interlocking fabric strip that ispermanently mounted on the duct. Itcannot be ruined and can be used formany years.


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A) Cable hanging

1

2

A

FA

F

1. Fasten the cable with acable lock to bolt A.Drill and fix bolt F in alow point on the tunnel roofapprox. 25 m from Aand at the same distancefrom the mid-line as bolt A.

2. Stretch the cable withsuitable tools and fix it witha cable lock to bolt F.


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Fasten the duct with suspension wirewhich is adjusted such that the ventila-tion duct is hanging absolutely straight.

3

A EDCB F

3. Drill holes for bolts B-E atdistances of approx. 5 metres.Mount the cable on bolts B-E withgalvanised steel wire of diameter3 mm, with the straightest possibleline between A and F.The cable must not be drawnthrough the bolt eyes.


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B) Installing ducts

4

5

4. Fix the duct with the sus-pension wire. Use the wireto adjust the distance fromthe cable to the duct to en-sure that the latter is alwayshanging straight. The wiremust not be lashed to thecable, but form a looparound it, allowing the ductto move freely.

5. Pull the next duct sectionwith approx. 10 cm overlapover the welded-on steel ringat the end of the duct alreadyin position. Fit the couplingring over the steel ring andfasten it to the cable.


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Inspection of duct.

When a tunnel is being bored, thelength of the ventilation line will becontinually increasing, and as a con-sequence of this the pressure in theducts will increase.Small scratches in the duct textile willalso be able to crack due to the increasein pressure such that what once was ascratch becomes a hole. For this reason,periodic inspections must thus beperformed of the entire length of theventilation line, also on the upper side,for example once per week. Operationaland on-site conditions determineprecisely how often such inspections arenecessary.

Inspection and Maintenance

During inspections, all defects andomissions must be corrected,such as:

– all holes should be repaired– loops and sharp bends in the

ventilation line must bestretched out

– defective or damaged couplingrings must be replaced

– defective suspension wiresmust be replaced or repaired

– suspension wires which arehanging against a bolt shouldbe moved past the bolt

– bolts which have come loosemust be refastened

– slack suspension wires mustbe tightened

– check the fan, motor, gratingsand other equipment

During the inspection, the airspeedand pressure in the ventilation line aswell as the power consumption meteron the fan should be read and rec-orded.


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Repairs

Leister Triac 1460 W hand-held hot airwelder, pressure roller and spare ele-ment.

Washing of the duct textile around a tear.

Hot-air welding of a patch seen from theoutside .

Welding course at Protan.

Hot-air welding of a patch and use of thepressure roller.

Repairs of Ventiflex using a hand-held welder


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All holes and damage to the ventilationline must be repaired as soon aspossible. Holes in the duct textile aremost easily repaired by welding apatch on with a Leister Triac hot-airwelder while the duct is suspendedand the air is flowing:

1. Cut out the damaged area if it isfrayed.

2. Wash around the damagedarea with VENTANON cleaningliquid.

3. If the hole is spreading, then sewit together first with narrow stripsof textile or sewing thread.

4. Size the patch for the hole.Allow 5 cm for welding around thehole. Corners should be roundedoff.

5. Spot-weld the patch to the ducttextile so that it is firmly attached.

6. Weld the patch to the duct textileby running the hot air welderbetween the duct textile and thepatch from the hole and outtowards the edge of the patchand then press it afterwardswith the pressure roller at adistance of 1 – 1.5 cm from thenozzle opening.Begin at the middle of the patchand weld outwards to each end.A good and properly executed

patch will be just as strong as theduct textile itself. It is importantthat the temperature on the hot airwelder is set properly and adjustedfor the skill level.

During the welding, a small amount ofsmoke will be generated. You shouldavoid inhaling this for an extendedperiod of time. Let the natural draughtin the tunnel remove the smoke.Always cool off the hot air welderbefore turning it off.


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Cans with VENTLIM, VENTANON,pressure band and adhesive brush.

Pressure band applied.

Application of adhesive.

Repairs of Ventiflex with VENTLIM

If the duct textile is dry, repairs withadhesive can be performed in thefollowing manner:1. Cut out the damaged area if it

is frayed.2. Wash the duct textile with

VENTANON cleaning liquidaround the hole.

3. Size the patch to the hole.Allow a minimum of 6 cm for theadhesive surface around the hole.

4. Smear VENTLIM adhesive onboth the duct textile and the patch.Let the adhesive dry for a numberof minutes until it ceases to besticky. Press the patch into placeover the hole. It is advantageousto go over it with a pressure roller.

5. Tighten a pressure band aroundthe duct so that it covers the patchand then let this sit for severaldays.

If the hole is too large or if the ducttextile is thoroughly wet, then the ductshould be taken down and dried. Rep-air the hole in the same manner asdescribed above, however a loadinstead of a pressure band is used.Make sure that the patch does not stickto the duct textile oppositethe hole.


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The Ventiflex repair kit contains Ventlim,adhesive brushes, Ventanon washingpreparation, pressure band, needle,thread and ventilation duct textile.

If VENTLIM adhesive thickens in thebox, it can be thinned with VENTANONcleaning liquid. Patching materials areavailable in a standard kit. For largerrepairs, the duct should be sent to Pro-tan AS.


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Dismounting a damaged duct.

Replacement of damaged ventilation ducts

A ventilation line which has a damagedduct in the middle and an adjacent ducton each side is reinforced with straps

next to the damaged duct, with thestraps being fastened to the bolt above.

When replacing one or more ventilat-ion ducts in a ventilation line, it is veryimportant that adjacent parts of theline are secured before the ducts aredismounted. The following procedureis recommended:

1. Some lifting straps are requiredas well as a lashing belt, i.e. alifting strap with a ratchet.

2. Approx. 5 m in on the adjoiningduct, fasten a lifting strap aroundthe duct.

3. With the ratchet between them,fasten the opposite end of the beltto a bolt above the duct that is tobe replaced.

4. The adjoining duct is then ratchetedtowards the duct(s) that are to bereplaced such that there clearly isslack in the ventilation line.


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Insertion of new duct.

5. Open the couplings and takedown the ducts concerned.

6. Suspend new the duct(s) andtighten as best as possible beforecoupling.

7. Detach the lashing belt and liftingstraps, and remove them.

8. After approx. one week, inspectthe ventilation line. If there is anyslack or kinks in the line, then theymust be tightened up.


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Prior to de-installation (while every-thing is still hanging up) the ducts inthe ventilation line should be sortedand marked such that they can bepacked into the following three sepa-rate classes:

Class 1: Ducts which are free ofdefects and have nodamage.

Class 2: Ducts which have damage/holes and need to berepaired

Class 3: Ducts which are in suchbad condition that it can-not be regarded as profi-table to repair them, i.e.scrap.

The content of all pallets must beclearly marked, i.e. quality, dimension,number of ducts (running metres) andclass.

Suspension hooks should be new foreach installation of the ducts. Hencewhen de-installing, the suspensionhooks should be cut with wire cuttersso that they are not sitting in the eyes.

Due to considerations for the workingenvironment, all ventilation ducts

De-installation

should be cleaned when they arereused. This is most easily done whilethe ducts are hanging up and rightafter de-installation. Vehicles and/orequipment which are used in the de-installation should also be cleaned.Take the ducts down one at a time andpack them up, sort them by class andplace them on pallets which are tieddown. Since the duct textile does notrot, it is not necessary to dry the ductsbefore storing them. If it is not possibleto perform cleaning while the ducts aresuspended, then they must be cleanedprior to packing.

Prior to reuse, ducts with damageshould be repaired, and in such casepreferably at Protan. Used ductsshould preferably be used at the endof a ventilation line.


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Storage

Several pallets with used ventilationducts that have been properly packedand tied down with tension straps.

Ventilation ducts should always by sto-red on pallets which are securely tieddown and marked (see the section onde-installation). Ventiflex can be sto-red outdoors, however it is beneficialfor the ducts to be screened fromstrong sunlight and extreme heat,either by covering the ducts or, evenbetter, by storing them indoors.


Ventiflex R

It is extremely important for the peoplewho work underground to have freshair to breathe. If the air is full of dieselgas, blasting gas or dust, there is alarge risk that life-threatening accidentscan arise.Ventilation computations for under-ground work are normally performedusing a computer program. This isbased upon SIA 196. It is howeverquite simple for anyone who wishes toacquire a sense for the magnitude ofthe amount of air required to performa simple computation on their own.In order to efficiently dilute dangerousgasses and dust, a return speed forair in the tunnel of between 0.3 and0.6 m/s is normally required (if a riskexists of the presence of methane gas,then 1 m/s should be used).The objective is to determine howmuch air in m3/s is needed at the bot-tom of the tunnel in order for the returnvelocity to be sufficient and in order tobe able to dilute gasses so that it ispossible to breathe the air without itposing a health hazard.In order to clear diesel gas out, a mini-mum of 4 m3 of air/kW/min. is requiredat the bottom of the tunnel (6 m3/kW/min. for a motor without a particle fil-ter). An estimate is made of how many

Computation of Air Requirements

kW are being used simultaneously inthe tunnel and then the computationis made to determine the total amountin m3 of air/second.Each person who is in the tunnel needs3 - 5 m3 of air/minute and a comp-utation is made to determine howmany people are normally in the tun-nel at the same time, then the totalamount is worked out in m3/minute.The two results obtained are thenadded together and approx. 10% isadded for blasting gas. The end resultis what at a minimum is needed interms of air at the bottom of the tun-nel in m3/minute.In order to compute how many m3/sec-ond have to come out of the fan, theleakage in the ventilation ducts haveto be computed.A well-mounted ventilation line of goodquality has a leakage of less than 1%/100 metres. If the ventilation line ispoor, a higher amount of leakage mustbe reckoned with. This value is addedto the quantity of m3/minute that hasbeen computed for the bottom of thetunnel.The minimum value arrived at in m3/minute should then be increased by amargin of safety.


Ventiflex R

Correct computational formulas look like the following:

Once you know how much air isneeded in terms of m3/second, thenyou go to the Ventiflex Nomogram

where you can read off the pressurein the duct for different diameters aswell as the power that is required fromthe fan.

a) Computational formulas:Static pressure in the duct:

∆p = λ • ∆x/D • ρ/2 • Ux2

∆x = length (m)∆p = pressure loss over ∆xλ = average coefficient of frictionD = diameter of the duct (m)ρ = specific gravity of 1 m3 of air (kg)Ux = average velocity in the length concerned (m)

b) Dynamic pressure in the duct:

∆p = ρ/2 • U2

c) Pressure loss at intake, bends, outlets and also changes of diameter, etc.For each, we have to calculate:

∆p = ζ • ρ/2 • U2

ζ = Zeta coefficient for singular loss

d) In order to arrive at the total pressure (pt) required, we must add:

pt = ∆p + ∆p dynamic + ∆p2 + ∆p2 .....

e) Computation of energy consumption for the fan is based upon the following formula:

N = (Q • Pfan)/( ηv • ηm)[kW]

Q = airflow from the fan (m3/s)Pfan = total pressure from the fan (Pa)ηv = efficiency of the fan (0,4 → 0,85)ηm = efficiency of the motor (approx. 0,95)


Ventiflex R

In order to avoid electricity costs whichare too high, the ventilation line musthave as large a diameter as possible.A large diameter makes it easier for theair to flow and requires less power fromthe fan.

If the pressure in the ventilation line istoo high (requires a lot of power fromthe fan), the diameter must be in-creased. If this is not possible due toinsufficient room, then two ventilationlines should be mounted instead ofone. The same quantity of air in twoducts instead of one duct requires 1/2the quantity of air, 1/4 of the pressureand 1/8 of the energy consumption (thepower from the fan).

It is always economically sound toinvest in high quality for the ventilationline and to treat it well. A good, properlyinstalled and non-leaking ventilationline provides not only a good workingenvironment for the employees, bit italso provides such large energysavings that a 20 - 40 % difference inthe price of the ventilation line isinsignificant.


Ventiflex R

List of references

AF SpesialprosjektAlpine Bau GmbHBeton- und Monierbau GmbHBilfinger + Berger Bauaktiengesell-schaftBalfour Beatty Ltd. UKBoliden Mineral ABBouygues FranceCaledonian MiningCarbosulcisDillingham Construction USADragados Constructiones S.A.DumezZüblin AGEntrecanales S.A.Fletcher UKIlbau AustriaGammon India Ltd.Hindustan Construction Ltd.Hochtief AGImpregilo SpaJ.F. Shea Co USAJaiprakash Ind. Ltd.Kali und Salz GmbHLarsen & Toubro Ltd.Lämminkainen OyLeonard Nilsen & SønnerLKAB KirunaOutukumpu OyNCC International ABNCC Tunneling ASNishimatsu Construction Co. Ltd.

OdebrechtPhilip Holzman AGSargin ConstructionSelmer Skanska ASSkanska International ABStatens VegvesenStatkraft Anlegg A/STara Mines Ltd.Traylor Bros.Inc.Jay DeeWayss und Freitag AGVägverket ABZinkgruvan Ammeberg ABWalter Bau AGUniversale BauMount Isa Mines

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Protan ASP.O. Box 420 Brakerøya,

N-3002 Drammen, NorwayTel. +47 32 22 16 00 Fax +47 32 22 17 00

www.protan.com

air ducting manual

Documents

ventiflex rthe information

safest ducting

ventiflex rknitted textile

selection of quality

express permissionof

highlevel of quality

quality control

coating of technical