Welded seam integrity
High-frequency or hot-air welded construction can be specified to reduce avoidable air loss at longitudinal and circumferential joints.
Mine air delivery / layflat forced-air duct
Positive Pressure Mine Ventilation Duct
Project-configured flexible ducting for carrying fresh air from auxiliary fans to underground headings, production zones and advancing mine faces.
DERFLEX fabricates complete collapsible duct sections with welded bodies, selected couplings, reinforced suspension details and application-specific material options. Diameter, section length and construction are matched to the ventilation route rather than treated as a one-size product.
Positive-pressure airflow
Inflates under fan pressure to form the air passage.
Mine-specific fabrication
Couplings, suspension and treatment selected by project.
Compact site logistics
Layflat sections fold for transport, storage and route extension.
Product formFinished layflat duct section
Airflow modeForced fresh-air / positive pressure
Diameter300–3000 mm configurable
Section length5–300 m project options
Material optionsFlame-retardant / antistatic by requirement
System role
The duct is the controlled air route between the fan and the working face.
Useful airflow underground depends on the complete route: fan duty, duct diameter, route length, seam leakage, coupling losses, bends, suspension and the distance from the discharge end to the active zone. A suitable positive pressure mine ventilation duct therefore begins with system data—not only fabric weight.
01
Auxiliary fan creates pressure
The fan supplies the static pressure needed to inflate the layflat duct and move the required air volume.
02
Welded sections carry the airflow
Correct diameter and controlled leakage help preserve useful fan output along the underground route.
03
Fresh air reaches the active zone
The final outlet position and extension plan should follow the mine ventilation design and local operating requirements.
Finished-duct performance
Six construction areas that influence underground airflow
Material selection matters, but pressure stability and practical service depend on how the complete duct is fabricated, connected, suspended and handled.
Smooth internal air path
A correctly formed and tensioned duct helps limit folds, abrupt restrictions and turbulence that add resistance to long air runs.
Reinforced suspension line
Single or double suspension fins, webbing, patches and eyelets can be arranged around diameter, section weight and installation spacing.
Connection compatibility
Zipper, hook-and-loop, steel ring, sleeve and eyelet formats can be coordinated with fans, reducers and existing duct systems.
Coated-textile durability
PVC-coated high-tenacity polyester construction can be selected for tensile, tear, flexing, moisture and abrasion demands encountered underground.
Project safety options
Flame-retardant, antistatic, cold-resistant or other formulations may be discussed against the tender specification and applicable local rules.
Specification matrix
Configure the duct around the fan duty and mine route
The ranges below are useful enquiry fields. Final values should be confirmed through the selected construction, test requirement, fan curve and ventilation plan.
| Selection field | Typical configurable range | Why it matters |
|---|---|---|
| Duct type | Layflat positive-pressure ventilation duct | Designed to remain open through internal fan pressure; not intended as an unsupported suction hose. |
| Diameter | 300–3000 mm | Must balance required airflow, air velocity, tunnel clearance, friction loss and available fan pressure. |
| Section length | 5, 10, 20, 30, 50, 100, 200 or 300 m options | Long sections reduce coupling count; shorter sections can simplify handling, repair and route changes. |
| Coated fabric | PVC-coated high-tenacity polyester; commonly 500–700 gsm configurations | Fabric construction is selected for tensile, tear, flexing, abrasion and handling requirements. |
| Pressure duty | Defined by diameter, fabric, seam, coupling and fan design | A pressure value should be confirmed for the finished duct system—not inferred from fabric weight alone. |
| Connection | Zipper, hook-and-loop cuff, steel ring, sleeve or eyelet format | Influences installation speed, air leakage, repair access and compatibility with existing equipment. |
| Suspension | Single fin, double fin, webbing tabs, grommets or custom reinforcement | Selected according to diameter, route geometry, support spacing and section mass. |
| Color | Yellow, orange, black, green or project color | Can support visibility, mine zoning, equipment identification or customer branding. |
| Performance treatment | Flame-retardant, antistatic, cold-resistant and other project options | Requirements should be tied to the named standard, test method and acceptance criteria in the tender. |
| Accessories | Reducers, adapters, tees, wyes, elbows, repair sections and fan cuffs | Fittings help form a complete route while controlling changes in direction, diameter and branching. |
Technical note: underground ventilation is a system-design task. The mine operator or qualified ventilation engineer should verify airflow, pressure, fire and antistatic requirements for the specific site.
Material and procurement logic
Specify what the finished duct must do—not only what it is made from
Typical finished-duct structure
1
Outer PVC coatingProvides the exposed surface for moisture, dirt, flexing and abrasion resistance.
2
High-tenacity polyester baseCarries tensile and tear loads created by inflation, handling and suspension.
3
Inner PVC coatingForms a continuous air-facing surface and supports welded seam construction.
4
Welded body and end detailsTurns coated fabric into a completed duct section with defined pressure and connection behavior.
5
Suspension reinforcementTransfers installation loads through fins, webbing, patches, eyelets or selected hardware.
What a useful RFQ should include
- Required airflow at the working face or discharge point
- Fan model, fan curve and available static pressure
- Total route length, gradients, bends and branch points
- Maximum permitted duct diameter and clearance envelope
- Preferred section length and underground handling limits
- Existing coupling, suspension and fan connection details
- Named flame-retardant or antistatic test requirement
- Operating temperature, abrasion exposure and repair strategy
- Quantity, packing method, delivery schedule and documentation
Mine route applications
Positive-pressure ducting for changing underground layouts
The collapsible format is especially useful where the fresh-air line must be extended, repositioned or stored as development work progresses.
Advancing headings
Extendable air-forcing lines for fresh-air delivery toward drilling, loading and excavation zones.
Declines and ramps
Suspended duct sections configured around gradients, vehicle clearance and periodic route changes.
Underground work areas
Temporary or relocatable air routes for maintenance, equipment zones and confined underground tasks.
Mine and tunnel projects
Fresh-air supply for mine development, civil tunnels, metro works, galleries and similar underground construction.
Airflow mode comparison
Positive-pressure layflat duct and negative-pressure spiral duct are not interchangeable
Air supply
Positive-pressure layflat duct
- The fan blows air into the duct and internal pressure creates the round section.
- Collapses substantially flat when airflow stops.
- Lower transport and storage volume than continuously reinforced ducting.
- Commonly selected to deliver fresh air toward the underground work zone.
- Requires attention to seam leakage, couplings, suspension and fan pressure.
Air extraction
Negative-pressure reinforced duct
- The fan pulls air through the duct and creates suction.
- Needs a wire helix or other structural reinforcement to resist collapse.
- Usually heavier and bulkier to handle than layflat supply duct.
- Selected for exhaust, dust collection or suction duties where appropriate.
- Requires bend-radius, reinforcement and vacuum-duty review.
Fabrication and customization
Build the connection and suspension details into the quotation
A mine duct should arrive in a format that can be integrated with the planned fan, route and installation practice.
Diameter and taper
Straight sections, reducers and transitions can be discussed where fan outlets or route clearances change.
Section connection
Zipper, hook-and-loop, ring, sleeve and eyelet arrangements are selectable by installation method.
Suspension layout
Single or double fins, grommet spacing, webbing and reinforcement can be configured to route loads.
Branch fittings
Tees, wyes, elbows and adapters can support junctions, fan relocation and changing underground headings.
Repair strategy
Repair sleeves, patches and replacement sections can be planned for sites where abrasion or mechanical contact is expected.
Marking and packing
Section numbers, airflow direction, project codes and compact packing can assist underground logistics.
Product images
Finished duct, underground installation and packing references
Images are sourced from the DERFLEX website and illustrate typical ventilation duct configurations. Final construction follows the confirmed project specification.
Production control
Checks should follow the finished duct configuration
Project quality planning can include material records, fabrication checks and agreed finished-product verification.
Material confirmation
Confirm coated-textile construction, color, weight and required treatment against the approved specification.
Cutting and forming
Control panel geometry, finished circumference and section length before welding and assembly.
Seam fabrication
Inspect longitudinal seams, end cuffs, suspension reinforcement and accessory attachment.
Finished-section review
Check dimensions, connection compatibility, visible workmanship and agreed pressure or leakage criteria.
Identification and packing
Mark sections, protect fittings and organize packing for delivery, storage and underground deployment.
DERFLEX project support
From coated textile to fabricated underground air route
DERFLEX combines PVC-coated fabric experience with finished-product fabrication, allowing the enquiry to cover the duct body, connections, suspension, accessories and packing as one project package.
Material-to-product coordinationCoated textile selection and duct fabrication can be reviewed together.
Project-sized productionDiameter, section length and quantity can be organized around tender or replacement needs.
Connection customizationFan cuffs, couplings and route fittings can be specified before production.
OEM and distributor supportMarking, packing and repeat-order specifications can be documented for supply programs.
Sample and document reviewMaterial samples, drawings or existing duct details can support, specification matching.
Export-oriented coordinationProject quantities, packing and shipping requirements can be included in the quotation discussion.
Related DERFLEX resources
Continue your ventilation duct selection
These six related pages cover finished ducts, ventilation materials and alternative duct configurations.
Finished product
Layflat Positive-Pressure Ventilation Duct
General finished-duct overview for tunnels, mines and underground construction.
Mine and tunnelPVC Flexible Ventilation Ducting
Background on flexible vent tubes and coated-fabric performance.
Configuration guideFlexible Ducting for Mine and Tunnel Ventilation
Alternative flexible duct arrangements for underground airflow systems.
Technical materialPVC Fabric for Tunnel Ventilation Duct
Coated textile selection for duct fabrication and industrial ventilation use.
Airflow comparisonPositive and Negative Pressure Ventilation Tubes
Basic distinction between layflat forcing duct and reinforced suction duct.
Industrial rangeFlexible Industrial Air Duct
Flexible air movement solutions for industrial, construction and temporary ventilation.
FAQ
Positive pressure mine ventilation duct questions
What is a positive pressure mine ventilation duct?
It is a flexible air-forcing tube connected to an auxiliary fan. The fan pushes fresh air into the duct, internal pressure opens the layflat body, and the duct carries airflow toward an underground heading or work area.
Can a layflat positive-pressure duct be used for exhaust suction?
Normally it should not. Without continuous structural reinforcement, a layflat duct can collapse under negative pressure. Exhaust or suction duties generally require a wire-reinforced or semi-rigid duct selected for vacuum service.
How should the duct diameter be selected?
Diameter should be evaluated against required airflow, acceptable air velocity, route length, friction, leakage, bends, tunnel clearance and the available fan pressure. Providing the fan curve and route drawing allows a more useful product discussion.
What section length is practical for underground mines?
Short sections can be easier to handle and repair, while long sections reduce the number of couplings and potential leakage points. DERFLEX can discuss lengths from 5 m to extended project sections, subject to diameter, site handling and production confirmation.
Are flame-retardant and antistatic versions available?
These options can be discussed for project-specific requirements. The enquiry should name the applicable standard, test method, acceptance value and documentation needed so the material and finished duct can be reviewed correctly.
What information is needed for a quotation?
Please provide the fan model or curve, target airflow, total route length, duct diameter or clearance limit, section length, connection and suspension format, required treatment, quantity and delivery destination. Photos or drawings of existing fittings are also useful.
Project quotation
Specify the duct around your fan, route and underground installation method.
Send the available fan data, ventilation route, target airflow, connection details and required test standard. DERFLEX can organize the quotation around the complete finished positive pressure mine ventilation duct.
Useful files to attach
Fan curve · route drawing · tender specification · coupling photos · suspension sketch
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