Finished ventilation products · project customization

Underground Airflow Package

Custom Tunnel Ventilation Duct & Accessories

Q: Is this page for finished tunnel ventilation duct or only PVC fabric?

It is for finished duct products and accessories, including fabricated duct sections, fittings, couplings, suspension details, repair materials and project packing.

Q: Which accessories can be custom made?

Common options include fan adaptors, reducers, elbows, tees, wyes, laterals, discharge adaptors, oval-to-round transitions, suspension components and repair kits.

Q: How are custom sections identified for installation?

Section numbers, diameter, branch code, project name or other agreed markings can be added, and packing can be arranged by installation stage or tunnel zone.

Q: What information is needed for a quotation?

Provide duct type, diameter, section length, quantity, pressure mode, fan interface, fittings list, connection preference, suspension method, safety specification, color and destination.

Configure the duct line as a coordinated system—not a collection of unrelated parts. DERFLEX supplies finished flexible tunnel ventilation ducting together with transitions, directional fittings, fan connections, suspension hardware and field-repair accessories for mining, tunneling and underground construction projects.

Request a Project Quote Review Custom Options

Positive or negative pressureLayflat and spiral wire-reinforced configurations.

Fittings matched to the routeElbows, reducers, tees, wyes, adapters and transitions.

Project-defined interfacesZipper, ring-and-clip, grommet or other agreed couplings.

Finished flexible tunnel ventilation duct product supplied by DERFLEX — **Finished ducting—not fabric roll supply** Product sections can be fabricated, connected, marked and packed to the approved project list.

System-Level Supply

A duct line is only as practical as its interfaces

A tunnel ventilation design may look simple on a drawing, yet installation often depends on dozens of details: fan outlet size, changing tunnel clearance, branch routes, bends, coupling compatibility, hanging points and the ability to replace a damaged section without rebuilding the line.

DERFLEX approaches a custom tunnel ventilation duct order as a matched package. Straight sections, special fittings and accessories are reviewed together so that dimensions, fabric construction, connection method and suspension arrangement follow the same project logic. This reduces avoidable adaptation work at the jobsite and gives procurement teams a clearer bill of materials.

The product is fabricated from PVC-coated technical textile with welded seams. For forced-air lines, layflat ducting provides compact transport and fast extension. For suction or combined positive/negative pressure, a continuous steel-wire helix can be incorporated to resist collapse. Optional formulations can be discussed for flame retardancy, anti-static behavior, cold conditions, abrasion exposure and high-visibility requirements.

Procurement note

Final material grade, pressure rating and compliance documents should be confirmed against the project specification, fan curve, local regulations and the approved sample or technical data sheet.

Package Architecture

Five layers of a practical tunnel ducting package

The supply scope can be as narrow as a replacement fitting or as broad as a scheduled duct package for a full excavation stage.

Main air-transfer sections

Round layflat duct for positive pressure, wire-reinforced spiral duct for suction or bidirectional duty, and oval or low-profile constructions where clearance is restricted.

Fan and equipment interfaces

Fan adaptors, inlet or discharge adaptors and mixed-size transition pieces can be fabricated around the equipment flange, outlet diameter and preferred coupling method.

Directional and branch fittings

Smooth-radius elbows, tees, wyes, laterals and branch pieces route airflow around tunnel geometry or divide supply to separate working zones.

Coupling and suspension

Zipper, steel ring, clip, grommet, hook-and-loop and custom connection options can be combined with welded suspension tabs, hooks, ropes and reinforcing strips.

Maintenance and identification

Patch fabric, repair tape, compatible adhesive, spare connectors, section labels and packing marks support field maintenance and staged underground delivery.

Accessory Range

Configure the route without improvised jobsite fittings

Accessory geometry is finalized from diameter, bend angle, branch direction, coupling type and available installation space.

Equipment interface

Fan adaptor

Connects flexible duct to fan outlets or inlet assemblies with project-defined ends.

Diameter change

Reducer

Transitions between duct sizes while keeping the connection sequence clear for installers.

Direction control

45° / 65° / 90° elbow

Routes the duct around tunnel walls, equipment zones or changes in alignment.

Air division

Tee and wye

Creates branches for multiple work faces, headings or temporary ventilation points.

Offset branch

Lateral

Provides an angled branch connection where a conventional tee would create a tight turn.

Shape conversion

Oval-to-round transition

Links low-headroom ducting with standard round duct or fan equipment.

Outlet control

Discharge adaptor

Provides a defined end connection or localized discharge arrangement.

Installation support

Hanging and repair kit

Includes agreed hooks, straps, rope interfaces, patches, tape, adhesive or spare clips.

Key Attributes

Custom specifications aligned with the fan and tunnel layout

The ranges below are typical inquiry references rather than a universal rating. Final values are established for the selected construction and approved project requirement.

Finished product	Flexible tunnel ventilation duct, fittings and accessory package
Primary construction	PVC-coated high-tenacity polyester textile; welded fabrication
Pressure configuration	Positive-pressure layflat duct; negative-pressure or combined-duty spiral wire-reinforced duct
Typical diameter	300–2,000 mm; smaller or larger project sizes can be reviewed
Section length	5 m, 10 m, 20 m or project-defined; selected long sections available after engineering review
Fabric weight options	Common project range approximately 500–900 gsm, selected by pressure, diameter, handling and durability requirements
Connection methods	Zipper, steel ring and clip, grommet/lacing, hook-and-loop or custom interface
Suspension	Welded hanging fin or reinforced tabs with eyelets/hooks; single or dual suspension layout
Accessory shapes	Fan adaptor, reducer, elbow, tee, wye, lateral, transition, discharge adaptor and custom fabricated shape
Performance options	Flame-retardant, anti-static, abrasion-resistant, cold-resistant and high-visibility variants subject to specification and testing
Color	Yellow, orange, black, green or custom color subject to formulation and order requirements
Support	Drawing review, connection matching, sample confirmation, packing list coordination and online technical communication

Customization Workflow

From route drawing to labeled duct sections

A structured approval sequence helps prevent mismatched diameters, incompatible couplings and unclear section identification.

Define the duty

Share airflow objective, positive/negative pressure mode, fan data and underground operating conditions.

Map the route

Provide the straight runs, bends, branches, clearance restrictions and planned excavation stages.

Match interfaces

Confirm fan outlet dimensions, coupling sequence, suspension hardware and accessory geometry.

Approve the build

Review drawing, material option, reference sample, markings and project-specific packing method.

Inspect and pack

Check dimensions, welded seams, connector placement and package labels before shipment.

Applications

Built around changing underground work conditions

Custom duct packages can support fresh-air delivery, extraction or staged temporary ventilation where the route evolves with construction progress.

Flexible ventilation duct systems installed in tunnel and mine projects

Road and railway tunnels

Extendable duct lines for excavation faces, drilling, blasting and spoil-removal stages.

Underground mines

Fresh-air distribution or extraction in headings, drifts, stopes and temporary work zones.

Metro and utility works

Ventilation around shafts, cross passages, cable tunnels and confined civil works.

Hydropower and caverns

Large-diameter temporary ventilation for access tunnels and underground chambers.

Equipment and maintenance areas

Localized air supply, fume removal or connection to portable and axial fans.

Emergency and temporary airflow

Collapsible ducting and spare fittings for planned contingencies or short-duration work.

RFQ Preparation

Send a project brief that can be quoted accurately

Providing the following information helps the DERFLEX team identify the appropriate finished duct type, accessory list and connection sequence without relying on assumptions.

Submit Your Requirements

1. Tunnel and routeCross-section, total run, bends, branch points and available headroom.

2. Airflow and fanRequired air volume, static pressure, fan outlet size and operating mode.

3. Duct sectionsDiameter, preferred section length, quantity and expected extension schedule.

4. FittingsReducer sizes, elbow angles, tee/wye branches, transitions and adapters.

5. Safety specificationRequired flame-retardant, anti-static or local compliance documentation.

6. Installation detailsCoupling type, suspension row, hook spacing, markings and repair spares.

Build the right product around each part of the airflow system

Explore the duct configurations most closely related to custom tunnel ventilation packages.

DERFLEX Capability

Why source the duct and accessories as one coordinated package?

DERFLEX combines coated-textile knowledge with finished-product fabrication, helping buyers keep material, welding and connection decisions aligned.

Material-to-product control

Technical textile selection and finished duct fabrication can be discussed within the same project review.

Custom interface planning

Accessories can be dimensioned around fan outlets, branch routes and selected coupling systems.

Repeatable project lists

Approved section codes, colors and packing marks can support staged orders and replacement requirements.

International communication

Drawing review, sample discussion and export documentation support are available for overseas projects.

Buyer FAQ

Custom tunnel ventilation duct questions

Answers below explain the purchasing and specification issues most likely to affect a finished duct package.

Is this page for finished tunnel ventilation duct or only PVC fabric?

It is for finished duct products and accessories. DERFLEX can discuss fabricated duct sections, fittings, couplings, suspension details, repair materials and project packing. Material-only supply can be handled separately when required.

Can one order include positive-pressure and negative-pressure ducting?

Yes. A project may combine layflat forced-air sections with spiral wire-reinforced suction or exhaust sections. Each configuration should be matched to the operating pressure, diameter, fan and route.

Which accessories can be custom made?

Common options include fan adaptors, reducers, 45°, 65° and 90° elbows, tees, wyes, laterals, discharge adaptors, oval-to-round transitions, special branch pieces, suspension components and repair kits.

How should I choose the duct diameter?

Diameter should be calculated from the required airflow, total duct length, allowable pressure loss, leakage expectation, fan curve, bends and site clearance. A ventilation engineer or qualified project designer should confirm the system design.

Are flame-retardant and anti-static options available?

They can be specified for selected constructions. The required standard, test method and acceptance document should be stated in the inquiry so the material and testing route can be confirmed before production.

Can the couplings match an existing duct line?

Often yes, provided the existing diameter, connector construction and interface dimensions are supplied. Photos, samples or a dimensioned drawing are useful when compatibility is critical.

How are custom sections identified for installation?

Section numbers, diameter, direction, branch code, project name or other agreed markings can be added. Packaging can also be arranged by installation stage or tunnel zone.

What information is needed for a quotation?

Please provide duct type, diameter, section length, total quantity, pressure mode, fan interface, fittings list, connection preference, suspension method, safety specification, color and destination. A route sketch i, s recommended for complex systems.

Turn your airflow drawing into a coordinated duct package

Send DERFLEX the fan data, route sketch and accessory list. The team can review the finished duct configuration, connection sequence, custom fittings and packing requirements for your tunnel or underground project.

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