Confirm fan duty before fabric weight
Send the fan model, airflow, static pressure and outlet dimensions first. Fabric construction and duct diameter should follow the real pressure environment rather than a generic “heavy-duty” description.
Positive-pressure flexible air delivery
Layflat Ventilation Duct
Collapsible PVC-coated fabric ducting configured for mine headings, tunnel faces and underground work zones where crews need a practical positive-pressure air route that can be extended, handled and stored without rigid pipe sections.
Airflow dutyNormally selected for forced-air / positive-pressure supply.
Primary buyersMines, tunnel contractors, fan suppliers, distributors and OEM programs.
Key RFQ variablesFan duty, diameter, route length, couplings, suspension and test requirements.
Supply formatFinished duct sections, accessories and coated textile support where required.
Selection starts with pressure direction
Do not choose layflat ducting from diameter alone.
The phrase layflat ventilation duct describes a product shape, but it does not define whether a duct run will perform as intended. For underground ventilation procurement, the more useful starting point is the complete air route: fan airflow and static pressure, total line length, target delivery point, changes in direction, available clearance, expected handling and the way each section will be joined and suspended.
A properly scoped lay flat ventilation duct can be attractive for positive-pressure supply because it is lightweight relative to rigid duct, packs compactly when not inflated and can be extended as a mine heading or tunnel face advances. Those handling advantages become less useful if the selected connection leaks excessively, the suspension layout twists the duct, the fabric is under-specified for abrasion, or the section length is impractical for the crew.
DERFLEX approaches the product as an assembly rather than a generic flexible tube. The coated textile, welded seams, hanging reinforcement, end connection, color or marking and accessory package are reviewed together so buyers can approve a repeatable construction for project or distribution supply.
Pressure-mode note: unsupported layflat ducting is generally evaluated for positive-pressure blowing air. Suction or negative-pressure extraction can collapse an unsupported tube and usually calls for a spiral wire-reinforced or otherwise shape-retaining construction matched to the suction duty.
Engineering the purchase
Five decisions that shape a workable duct line
These fields help turn a general request for flexible ventilation ducting into a specification that production, installation and inspection teams can all understand.
Design the line around delivered air
Total distance, bends, transitions and coupling count influence the pressure available at the working end. The objective is not simply to inflate the duct but to maintain the intended air route with manageable leakage and resistance.
Choose section length around handling
Longer sections reduce the number of joints, while shorter sections can be easier to carry, repair and replace. Diameter, access restrictions, crew practice and staging method should determine a practical balance.
Specify suspension as part of the duct
Reinforced fins, patches, eyelets and single- or double-line hanging layouts should be coordinated with diameter and clearance. A stable suspension path helps reduce local deformation and installation stress.
Match the connection to extension frequency
Steel rings, zipper closures, hook-and-loop systems, eyelet connections and project-specific cuffs each create different tradeoffs in speed, sealing, repair and replacement. Standardize the interface before repeat ordering.
State FR and antistatic criteria precisely
Where flame-retardant or antistatic behavior is required, identify the governing standard, target value, test method, market and documentation package before production. A generic “FRAS” label is not a substitute for a project requirement.
Quotation framework
Typical layflat ventilation duct configuration range
The following ranges are useful for early project discussion. Final dimensions, textile construction, pressure suitability and test documentation should be confirmed on the approved datasheet or drawing.
| Product form | Finished collapsible layflat ventilation duct sections for positive-pressure air supply. |
|---|---|
| Body material | Polyester technical textile with PVC coating on both sides; structure selected for service conditions. |
| Typical fabric weight | Approx. 400–900 g/m2 as a project selection range; final construction follows pressure, abrasion and handling review. |
| Diameter | Commonly 300–3000 mm; custom dimensions may be assessed against airflow, fan interface and installation space. |
| Section length | Common options include 5, 10, 20, 30, 50 or 100 m; longer sections depend on diameter and handling strategy. |
| Connections | Steel ring, zipper, hook-and-loop, eyelet system, drawstring cuff or custom transition. |
| Suspension | Reinforced fin or patch, single or double hanging line and project-defined eyelet spacing. |
| Color | Yellow, orange, black and selected custom colors subject to production confirmation. |
| Optional formulation | Flame-retardant, antistatic, abrasion-focused or cold-weather options where requested and technically confirmed. |
| Accessories | Reducers, bends, Y-pieces, repair material, transitions, joining hardware, labels and packing identification. |
Choose the right duct architecture
Layflat, spiral or oval?
Flexible ventilation duct types solve different pressure and clearance problems. Selecting by duty first is usually more reliable than trying to use one duct form everywhere.
Layflat duct
- Inflates under forced-air supply.
- Collapses for compact transport and storage.
- Well suited to extendable mine and tunnel air lines.
- Section length and connection system can be adapted to site handling.
Spiral reinforced duct
- Wire or ring support helps preserve the airway.
- Common direction for suction, exhaust, bends or fan connections.
- Requires more storage volume than unsupported layflat duct.
- Reinforcement should be matched to negative pressure and bend radius.
Oval / low-profile duct
- Useful where round geometry conflicts with vehicles or services.
- Can reduce vertical space demand in constrained headings.
- Suspension and equivalent airflow area require project review.
- Selected from tunnel envelope and equipment clearance, not aesthetics.
What buyers should inspect
Four details that often matter more than the headline GSM
Fabric weight is easy to compare, but long-run ventilation reliability also depends on how the duct body is fabricated and installed.
Seam continuity
Review weld consistency, seam width and local wrinkles. Weak or discontinuous weld zones can become leakage or failure points under repeated inflation.
Coupling seal
Every joint creates a potential loss point. Connection geometry, overlap and sealing face should be inspected together rather than treating the coupling as separate hardware.
Suspension reinforcement
Eyelets and hanging fins transfer the duct load into the installation line. Reinforcement placement should match the section size and expected handling frequency.
Repair strategy
Underground ducting can be damaged by equipment or wall contact. A repair method and compatible patch material should be planned before the first section enters service.
Pre-production approval
Use an approved datasheet, drawing or sample to lock in the details that must remain repeatable from batch to batch.
- Finished diameter and usable section length
- Base textile / PVC construction and target weight
- Connection dimensions and sealing method
- Suspension spacing and reinforcement geometry
- Color, print, label and packing identification
Lot inspection focus
Incoming and final inspection can be organized around measurable or visually confirmable fields rather than broad marketing descriptions.
- Dimensions and section count
- Weld appearance and continuity
- End connection workmanship
- Hanging point placement and reinforcement
- Requested test report / certificate matching the quoted construction
Typical applications
Where lay flat ventilation ducting is commonly evaluated
Positive-pressure collapsible ducting is particularly useful where the air route moves with the work and rigid piping would add handling complexity.
Development headings & drifts
Fresh-air delivery from auxiliary fans toward advancing headings, equipment areas and localized underground work zones.
Road, rail, metro & utility tunnels
Extendable duct runs for construction phases where the face advances and the ventilation line needs periodic extension or repositioning.
Shafts, hydropower & service tunnels
Temporary or semi-permanent forced-air paths for access, maintenance and construction zones with restricted transport space.
Matched blower + duct packages
Duct sections configured around fan outlet size, pressure direction and project interface details for equipment supply programs.
Standardized repeat-order SKUs
Common diameters, section lengths, couplings, colors and packing can be documented for regional distributors and service companies.
Private-label duct programs
Color, marking, label, bag or pallet identification can be discussed for repeat programs after the technical construction is approved.
DERFLEX manufacturing approach
Source the coated textile and finished duct as one engineering package.
DERFLEX works across PVC-coated technical textile selection and finished flexible duct fabrication. For buyers, that creates a more direct path between the material structure and the parts that determine installation performance: seam welding, suspension reinforcement, couplings and accessories.
Rather than relying on broad claims, a project can be defined through an approved construction sheet. Diameter, section length, connection, hanging system, color, identification and requested testing can then be used as the reference for quotation, sampling, inspection and repeat orders.
01
Material + duct coordinationPVC-coated textile, weldability and finished duct details can be reviewed within one sourcing discussion.
02
Project-configured geometryDiameter, length, end connection and suspension can be adapted to the approved air route and handling method.
03
Specification-led safety optionsFlame-retardant or antistatic constructions are discussed against the requested standard and test method instead of a generic label.
04
Repeat-order controlApproved dimensions, construction, marking and packing can be retained as the commercial reference for future lots.
Related DERFLEX resources
Continue the ventilation duct selection
Use these six related pages to compare pressure modes, underground applications and safety-oriented duct constructions.
Buyer FAQ
Layflat ventilation duct questions
Is layflat ventilation duct suitable for positive pressure or negative pressure?
Unsupported layflat duct is normally selected for positive-pressure air supply because the fan inflates the duct body. Negative-pressure extraction can collapse an unsupported tube, so suction duty generally requires spiral wire reinforcement or another shape-retaining structure designed around the pressure condition.
What information is needed to select the duct diameter?
Provide the required airflow, fan static pressure, total duct length, number of bends or transitions, fan outlet size, target work-zone airflow and any clearance restrictions. Diameter should be reviewed as part of the complete pressure and route calculation rather than selected only from the fan outlet diameter.
What connection methods are available for lay flat ventilation ducting?
Common project options include steel end rings, zippers, hook-and-loop closures, eyelet connections, drawstring cuffs and custom transitions. The preferred system depends on installation speed, sealing expectations, extension frequency, repair practice and compatibility with existing duct sections.
Can DERFLEX provide flame-retardant and antistatic layflat duct?
Flame-retardant and antistatic constructions can be discussed where required. The buyer should state the applicable standard, target value, test method and documentation requirement before material and finished duct approval. Final compliance should be confirmed against the actual supplied construction and project jurisdiction.
Can the duct length, color and suspension be customized?
Yes, project-specific section length, diameter, selected colors, connection and suspension details can be reviewed. Practical limits depend on duct diameter, material construction, handling method, production setup and the approved specification.
How should a buyer compare quotations from different layflat duct suppliers?
Compare more than price per meter. Check body material, fabric weight and reinforcement, finished diameter, usable length, seam construction, coupling geometry, suspension spacing, included accessories, requested test documentation, packing method and whether the quotation is for finished duct or fabric only.
Turn your fan data into a duct specification.
Send DERFLEX the fan model, airflow and static pressure, total route length, diameter or clearance requirement, section length preference, coupling, suspension, safety standard, quantity and destination. The quotation can then be built around the actual project rather than a generic duct size.
Product-selection information is provided for procurement discussion. Final ventilation design, fan matching, safety compliance, test acceptance and installation suitability should be confirmed for the specific project and local requirements.