Finished Duct Assemblies · OEM & Project Supply
Configure the duct around the fan, pressure direction, route and operating environment—not around a generic hose description.
DERFLEX supplies finished flexible air duct assemblies for portable blowers, temporary ventilation, industrial exhaust, confined-space work, tunnels and mines. Diameter, section length, body material, wire reinforcement, cuffs, suspension details and identification can be developed against a confirmed project specification.
A flexible air duct is a collapsible or shape-retaining passage used to move air between a fan and a work area. Compared with rigid sheet-metal ductwork, it can be routed through temporary layouts, around equipment, into confined areas and along projects where the airflow line must be extended or relocated.
The phrase covers several constructions. A layflat tube depends on positive pressure to inflate. A spiral wire-reinforced duct uses a continuous helix to preserve its cross-section through bends or under suction. A portable blower duct may add high-visibility fabric, wear strips, carrying straps and quick cuffs for frequent jobsite handling.
This page focuses on finished industrial duct assemblies rather than residential foil HVAC duct or an unprocessed roll of coated fabric. For project selection, the useful question is not simply “What diameter do you sell?” but “What airflow, pressure, route, connection and safety requirement must the duct support?”
Three operating questions separate a workable duct specification from a catalogue-only purchase.
Positive-pressure supply can use a collapsible layflat design. Negative-pressure extraction normally needs a spiral or ring-reinforced body to reduce the risk of collapse. Dual-direction systems should be discussed as a separate assembly requirement.
A duct that remains suspended for months has different needs from a hose that is dragged, coiled and moved between work zones every day. Wear strips, reinforcement pitch, carrying features and section length should reflect the actual handling cycle.
Temperature, moisture, dust, abrasion, chemicals, visibility, underground rules and required documentation can change the fabric formulation, seam method, hardware and test plan. State the named standard when compliance is required.
DERFLEX can discuss a finished duct configuration around the required airflow direction, equipment interface and site conditions.
Compressible ducting for mobile fans and frequently relocated ventilation equipment.
Collapsible sections that inflate when the forcing fan operates.
Helical-wire support for extraction, bends and routes that must remain open.
Fabricated transitions and accessories for non-standard fan outlets or duct layouts.
A finished flexible duct combines the textile body with structural and installation details. The coated fabric provides the air barrier and mechanical base. Welded or sealed seams close the longitudinal construction. Wire, rings or pressure maintain the intended cross-section. Cuffs connect the section to the fan or the next duct, while external strips and suspension points help manage handling loads.
Woven or knitted technical textile selected for flexibility, strength, coating adhesion and expected exposure.
Used when the duct must hold its section under suction, tight bends or low-flow conditions.
Hot-air or high-frequency welding can be selected according to body material, diameter and seam geometry.
Cuffs, belts, zippers, rings, hooks, tabs, grommets and fins are configured for installation and replacement practice.
Standard PVC constructions are widely used for ambient industrial airflow because they balance flexibility, weather exposure and fabrication. More demanding temperature or chemical conditions may require a different coated textile. Provide continuous and peak temperatures, not only a general description such as “hot air.”
The ranges below are procurement references. Final values are confirmed against diameter, fan pressure, route, connection system and required test documentation.
| Specification Field | Typical Project Reference | Selection Consideration |
|---|---|---|
| Product form | Finished flexible air duct assembly | Body, seam, reinforcement, end cuffs and selected accessories can be included. |
| Airflow mode | Positive pressure, negative pressure or project-defined dual direction | Pressure direction determines whether a layflat or shape-retaining structure is appropriate. |
| Body material | PVC-coated woven or knitted polyester technical textile | Fabric construction and coating formulation are selected by pressure, handling, weather and documentation needs. |
| Material weight | Approximately 300–900 g/m², project dependent | Lighter grades support portability; heavier constructions may be selected for pressure and wear exposure. |
| Diameter | Portable sizes and project diameters up to approximately 3000 mm | Calculate from airflow, velocity, fan pressure, line length, bends and allowable pressure loss. |
| Section length | 5 m, 10 m, 15 m, 20 m or custom sections | Longer sections reduce joints; shorter sections can simplify transport, extension and isolated replacement. |
| Operating temperature | Common PVC reference: approximately −20°C to +80°C | State continuous, peak and cold-flex requirements. Alternative materials should be reviewed outside the confirmed range. |
| Connections | Drawstring cuff, belt and buckle, steel ring, zipper, clamp cuff or custom connector | Provide fan outlet dimensions, photographs or a drawing to coordinate fit and sealing. |
| Suspension | Hooks, eyelets, webbing loops, tabs, reinforced patches or suspension fins | Spacing and reinforcement should match duct weight, support cable and route geometry. |
| Optional treatments | Flame-retardant, antistatic, cold-resistant or custom color options | Name the required test standard and report format before quotation. Availability depends on the complete construction. |
| Marking & packing | OEM identification, section labels, folded or coiled packing | Coordinate labels, batch traceability, carton or pallet method and container loading plan. |
The operating condition determines the duct—not the industry label alone. The following scenarios show common procurement contexts.
Fresh-air supply or controlled exhaust for tanks, chambers, utility spaces, shipyards and maintenance zones, subject to the site ventilation plan and safety procedure.
Temporary airflow for drying, cooling, heating distribution, dust management and work-zone ventilation where rigid ducts would be slow to install.
Flexible connections between portable fans, chillers, dehumidifiers, machines and temporary intake or exhaust points.
Project-configured fresh-air supply or extraction lines for headings and temporary work areas, with pressure mode and required safety standards defined in advance.
Extendable duct sections for metro, road, rail, hydropower and utility tunnel works where routes change as excavation progresses.
Directed hot or cold air movement in halls, temporary structures, storage zones and large rooms when the system needs relocatable duct sections.
A useful request includes the operating information needed to select the structure and verify the interface.
Provide target m³/h or CFM, fan model, outlet size, pressure curve and whether the fan supplies or extracts air.
State total length, bends, elevation changes, hanging method, clearance limits and expected extensions.
Include temperature, moisture, abrasion, dust, chemicals, outdoor use and handling frequency.
Share outlet dimensions, existing cuff details, connection photos, drawings and preferred section length.
List required fire, antistatic or material tests, report language, inspection needs and marking instructions.
Consistent repeat supply depends on a documented combination of material, dimensions, reinforcement, seam layout and connection details.
DERFLEX combines coated-textile knowledge with finished-product fabrication discussions. The enquiry can therefore cover both the duct body and the practical details that determine how crews connect, suspend, extend, repair and pack each section.
These DERFLEX website images show several flexible duct formats and operating contexts. Final supply is based on the approved specification.
Use these six related pages to compare pressure mode, safety options, finished duct types and the coated fabric used in tunnel ventilation systems.
Practical answers for project engineers, distributors, equipment suppliers and OEM procurement teams.
In industrial purchasing, the terms often overlap. “Flexible air duct” commonly emphasizes the finished airflow passage and its connection to a ventilation system, while “ventilation hose” may describe a smaller or more portable shape-retaining product. The required pressure mode, diameter, reinforcement, cuffs and environment are more important than the label.
Not automatically. A layflat duct is normally intended for positive-pressure air supply and may collapse under suction. A wire- or ring-reinforced duct can be evaluated for negative pressure because its structure helps maintain the cross-section. State both operating directions and the fan pressure when dual-direction use is required.
Provide target airflow, fan model and pressure, outlet diameter, required duct diameter and length, number of bends, airflow direction, operating temperature, handling conditions, connection style, suspension method, quantity, destination and any named fire or antistatic standard.
Portable and project-specific diameters can be discussed, with large ventilation sections extending to approximately 3000 mm in suitable constructions. Practical limits depend on pressure, body material, reinforcement, seam layout, installation handling and shipping method.
Yes, the finished-product discussion can include drawstring cuffs, belt ends, clamp interfaces, steel rings, zipper joints, hook-and-loop overlaps, suspension hardware and buyer-defined connections. A drawing, sample or clear fan-outlet measurements improves interface accuracy.
Options can be evaluated when the required standard, classification and test method are stated. Compliance should apply only to the confirmed construction supported by the agreed documentation; broad terms such as “fireproof” are not sufficient for a project specification.
This page addresses industrial and temporary ventilation. Applications involving breathing-air quality, medical use, food contact or other regulated service require a separate material, hygiene and compliance review before any product is selected.
Send the airflow direction, fan data, diameter, route length, connection drawing, environment and required documents. DERFLEX will review the finished duct construction and prepare a project-based quotation.