DERFLEX supplies fabricated flexible ventilation duct systems—not only duct fabric—for positive-pressure air supply, negative-pressure extraction and temporary industrial ventilation. Diameter, length, reinforcement, suspension and connections can be configured around the fan and project layout.
Category Overview
Flexible ducting is used where rigid metal ducts would be slow to install, difficult to route or expensive to extend as a tunnel face or work zone moves. The finished product may include a coated polyester duct body, welded seams, steel rings or helical wire, suspension fins, sealing flaps and a selected connection system.
The starting point is pressure direction. Layflat ducting is commonly considered for forced-air, positive-pressure supply. Wire-reinforced spiral ducting is generally considered when the duct must hold its shape during suction, exhaust or tight-radius routing. Oval configurations can reduce the space occupied in low-headroom headings.
Product Range
Each model can be quoted as a finished duct with project-defined dimensions, color, suspension, end connection and reinforcement.
Positive PressureCollapsible duct sections for delivering fresh air along advancing tunnel, mine and construction routes.
Positive / NegativeA shape-retaining flexible hose for extraction, suction, bends and equipment connections.
Low HeadroomAn alternative profile for tunnels and headings where round ducting would interfere with vehicles or equipment clearance.
Safety OptionConfigured for underground environments where a documented fire or surface-resistance requirement is specified.
PortableFlexible ducting for mobile fans, confined-space work, maintenance, drying, cooling and temporary exhaust.
Custom SystemProject-specific straight sections, reducers, bends, Y-pieces, repair panels and transition connections.
Key Attributes
The table consolidates common procurement attributes for flexible tunnel ventilation ducting. It is a quotation framework, not a universal guaranteed specification; final values should appear on the approved datasheet and test documents.
| Finished product | Fabricated ventilation duct section with welded body, selected suspension system, end connections and optional reinforcement |
|---|---|
| Base construction | Knitted or woven polyester fabric with PVC coating on both sides; formulation and fabric structure selected by application |
| Typical fabric weight | 400–900 g/m², or project-specific |
| Diameter range | 300–3000 mm, or customized after airflow and installation review |
| Section length | 1–100 m; practical length depends on diameter, handling and connection plan |
| Color | Yellow, orange, black and custom colors subject to production confirmation |
| Connection | Steel ring, zipper, drawstring cuff or custom coupling; sealing flap typically 10–20 mm where specified |
| Reinforcement | Optional spring manganese steel or cold-drawn steel rings, typically 5–10 mm depending on duct design |
| Suspension | Suspension fin, reinforced patch, eyelet or project-defined arrangement; typical eyelet spacing can be 50–80 mm |
| Mechanical references | Weld-joint tensile 1000–2500 N/50 mm; fabric tensile 1500–3000 N/50 mm; tear 400–600 N; adhesion 60–100 N/50 mm, subject to agreed method and construction |
| Pressure reference | Wind-pressure resistance can be configured within an approximate 3000–10000 Pa range; fan curve, total length and diameter must be reviewed |
| Safety options | Optional antistatic construction (reference level below 3 × 108 Ω) and flame-retardant options based on the required test method, such as DIN 4102 or another agreed standard |
| Processing service | Cutting, hot-air or high-frequency welding, seam reinforcement, ring installation, zipper assembly, suspension fabrication and finished-product inspection |
Reference ranges should not be used as a substitute for ventilation-system design. Confirm airflow, static pressure, leakage allowance, environment and local safety requirements with the project engineer.
Selection Method
Pressure direction determines whether a collapsible layflat body or a reinforced shape-retaining duct is more appropriate.
Diameter, inner-surface friction, bends, connections and leakage influence the pressure available at the working face.
Round, oval, spiral and transition sections can be combined around tunnel crown height, machinery paths and fan location.
Temperature, abrasion, water, chemicals, fire requirements and electrostatic concerns guide the material and reinforcement package.
Applications
The correct duct supports fresh-air delivery, local exhaust or temporary air transfer while the work area and routing continue to change.
Fresh-air supply and extraction for headings, drifts, underground equipment zones and localized work areas.
Extendable ventilation lines for metro, railway, highway, utility and water-conveyance tunnel projects.
Temporary intake, exhaust, dust or fume transfer during production, maintenance and equipment installation.
Portable ducting for tanks, shipyards, underground chambers and controlled-entry maintenance work.
Air movement for basement work, curing, drying, heating, cooling and temporary enclosure ventilation.
Private-label finished duct assemblies matched to mobile blowers, axial fans and packaged ventilation equipment.
Quotation Checklist
Why DERFLEX
DERFLEX's background in industrial coated textiles supports control over the duct body's tensile, tear, adhesion, surface and weldability requirements. For finished products, these material choices must be coordinated with seam construction, ring reinforcement, suspension and connection details.
Orders can be developed for contractors, mining and tunneling suppliers, ventilation fan manufacturers, industrial distributors and OEM brands. Project drawings, approved samples and inspection requirements can be incorporated into the production specification.
To avoid unsuitable claims, certificates and performance values are confirmed by the selected construction, test method and order documentation rather than presented as one fixed result for every duct.
Request A QuoteRelated DERFLEX Resources
These six internal resources support specification work without confusing this finished-product category with raw duct fabric.
FAQ
This category is for finished flexible ventilation duct products. A quotation can cover fabricated duct sections, welded seams, reinforcement, suspension, connections and optional accessories. Raw coated fabric remains a separate supply option.
Layflat ducting is generally used for positive-pressure air supply and collapses when airflow stops. Spiral wire-reinforced ducting holds its shape and is usually evaluated for suction, exhaust, equipment connections or routes with frequent bends.
Yes. Diameter, section length and total quantity can be specified. The practical section length should also account for installation labor, weight, storage, coupling frequency and available handling space.
Optional flame-retardant and antistatic constructions are available. The required standard, test method and target value must be stated so the correct formulation and finished construction can be quoted.
A reinforced spiral or semi-rigid structure is normally evaluated because reinforcement reduces collapse under suction. Required wire pitch and diameter depend on static pressure, duct diameter, length and bend radius.
Common options include steel rings, zippers, drawstring cuffs and project-specific couplings. A sealing flap can be added where the design calls for reduced joint leakage.
Custom reducers, bends, Y-pieces, fan adapters, repair sections and suspension details can be evaluated from a drawing, sample or measured connection data.
Provide application, pressure direction, fan data, diameter, section length, quantity, connection, suspension, temperature, safety requirements and delivery location. A drawing or installation photo improves quotation accuracy.
Send the fan data, pressure direction, diameter, line length, installation layout and required test standards. DERFLEX will review the construction and prepare a project-based quotation.
