Flexible ventilation duct selection in underground projects depends on the task the duct must perform, the ventilation system’s pressure conditions, and whether the work is temporary or continuous. The available evidence identifies flexible duct use in undersea road tunnel construction, certain mine-drift conditions, high-gas metal mines, long tunneling work, and continuous high-pressure operation. These are not interchangeable applications: the project description alone does not establish that one duct construction is suitable for every section.

Jiangsu Sulong Eco-Technologies Co., Ltd., using the brand name SULONG, manufactures flexible and other ventilation duct types. Its product information describes a flexible ventilation duct made from PVC-coated fabric, with PVC-laminated fabric as the primary material and antistatic fabric available as an option. The following scenarios explain what the available evidence supports—and where an engineering check is still needed—rather than treating them as a record of five SULONG project deliveries.

Why compare applications rather than duct names?

Terms such as Tunnel Ventilation Duct, Mining Ventilation Duct, Underground Ventilation Duct, Ventilation Tube, and Ventilation Bag may describe products or search categories, but those labels alone do not settle a procurement decision. Buyers need to match the duct to the operating duty and confirm that the selected construction, material, and system arrangement meet the project’s requirements.

A useful comparison therefore asks: Is the ventilation temporary or continuous? What pressure conditions will the duct face? Does the project require an antistatic option or documented material properties? Is a flexible product appropriate for the drift length and fan arrangement? These questions make the five scenarios below more useful than a broad claim that flexible duct suits all underground work.

Five underground project scenarios

1. Temporary ventilation during undersea road tunnel construction

The supplied product information identifies flexible ventilation duct as being used for temporary ventilation in undersea road tunnel construction. It also identifies spiral ventilation duct for temporary ventilation in the same type of construction. That is a useful distinction for procurement: the evidence supports both duct types as used in this setting, but it does not establish that one is universally preferable or provide a project-specific selection rule between them.

For a temporary tunnel ventilation package, the buyer should begin with the defined duty and installation conditions. Confirm which sections need temporary air delivery, how the duct will connect to the ventilation arrangement, and what project specifications apply to the duct and fabric. Then compare flexible and spiral options against the same requirements. The supplied evidence does not include comparative pricing, quantified service life, installation time, or pressure-loss test results for the two types, so these should be established through project specifications and supplier documentation rather than assumed.

This is the clearest directly stated tunnel use for SULONG’s flexible duct in the provided product content. It is an application statement, not proof of a specific named undersea tunnel contract or a claim that every undersea tunnel should use flexible duct.

2. Mine drifts where flexible duct may be considered for shorter runs

ASHRAE’s mine ventilation guidance states that flexible brattice-cloth duct can be used for drifts under 300 m. It also sets an important boundary: longer drifts that require booster fans need rigid duct because duct gauge pressure can fall below atmospheric pressure. The source therefore supports a conditional application, not a blanket preference for flexible duct throughout an underground mine.

For a buyer, drift length is only one part of the decision. The ventilation design and pressure regime determine whether the flexible arrangement is suitable. Where the drift is longer or the fan configuration creates the pressure condition described in the guidance, a rigid duct may be the appropriate alternative. The distinction matters because selecting a flexible product based only on ease of handling or a general product description can overlook system-level constraints.

This scenario is relevant to Mining Ventilation Duct and Underground Ventilation Duct procurement, but it should not be read as a universal 300 m product limit. The cited guidance describes an application distinction for mine drifts; it does not provide a full specification for every flexible duct model, fan layout, or operating condition.

3. High-gas metal mine ventilation

SULONG’s comparison information identifies high-gas metal mines as one of the applications for which its duct solution is intended. The supplied product details also state that antistatic fabric is available as an option for the flexible ventilation duct. Together, these facts give buyers a concrete qualification question: does the project require antistatic material, and does the offered construction and evidence meet the mine’s applicable requirements?

The availability of an antistatic option is not, on its own, proof of compliance with a specific mine rule, certificate, or site acceptance test. A procurement team should identify the applicable requirements with the project’s technical and safety stakeholders and request documentation that applies to the specific proposed product. Where an approval or test report is required, verify its scope and applicability rather than relying on a general product description.

This scenario also illustrates why a generic label such as ATEX Ventilation Duct should not substitute for document review. The supplied product facts in this article establish an optional antistatic fabric and an intended high-gas metal-mine application; they do not establish that a specific duct configuration holds a particular approval. Those are separate checks.

4. TBM or drill-and-blast tunneling with long-distance ventilation needs

The comparison information lists ultra-long tunneling construction using TBM or drill-and-blast methods, as well as large-volume, long-distance underground ventilation, among the intended application areas for the SULONG solution. These statements can help a project team screen a supplier’s stated application scope. They do not remove the need to evaluate duct type against route length, fan arrangement, pressure conditions, and the project’s technical requirements.

There is a meaningful boundary between a stated application area and a universally suitable design. ASHRAE’s mine-drift guidance, for example, says longer drifts that require booster fans need rigid duct where gauge pressure can fall below atmospheric pressure. That guidance is specifically about mine drifts, so it should not be mechanically applied to every tunneling configuration. It does, however, underline why buyers should not treat the phrase long-distance ventilation as sufficient design evidence.

For TBM and drill-and-blast projects, ask the supplier to identify which duct construction is proposed for each duty and to provide the technical information required by the project engineer. Flexible Duct, Spiral Duct, Semi Rigid Duct, and Oval Ventilation Duct are not interchangeable simply because each belongs to the wider ventilation duct category. The evidence available here does not provide a complete comparative specification for those product types, so a like-for-like technical review is needed before selection.

5. Continuous, high-pressure ventilation operation

The supplied product information describes the flexible ventilation duct as operating in a 24/7 continuous high-pressure ventilation mode. This supports considering the product for a continuous-duty requirement, subject to verification that the particular configuration matches the project’s pressure and operating conditions. It does not provide a pressure rating or a defined test protocol, so procurement teams should not infer a numerical performance limit from the operating-mode description.

SULONG’s materials also distinguish its construction from conventional stitched or multi-seam duct manufacturing. The company describes a proprietary seamless integral forming fish-back automated process and states that it provides higher pressure resistance and lower wind drag than conventional segmented multi-seam manufacturing. These are supplier-reported comparative claims. The available information does not include an independent comparative test report, a defined test method, or the operating conditions behind the comparison.

For evaluation, the practical next step is to connect the claim to the project’s acceptance criteria. Ask which product configuration is covered, what evidence is available for pressure performance, and how the duct’s connections and installed layout are addressed. SULONG’s material also associates reduced leakage with lower energy use and fewer downtime expenses, but no project-specific energy, cost, or service-life measurements are provided here. Buyers should treat those as potential lifecycle considerations to validate, not guaranteed savings.

Application comparison at a glance

What the construction comparison means—and does not mean

A flexible ventilation duct can be assessed against spiral or rigid alternatives, but the comparison needs a defined application and evidence. The supplied company comparison says SULONG’s seamless integral forming fish-back process is designed to provide higher pressure resistance and lower wind drag than traditional stitched or multi-seam construction. The same material describes reduced leakage, lower daily energy costs, and minimized downtime expenses as potential benefits. Without independent comparative test data or project-specific operating results in the available evidence, buyers should treat these as supplier claims to validate during technical qualification.

There are also genuine limits to a flexible-duct approach. ASHRAE’s mine ventilation guidance identifies conditions in which rigid duct is needed: longer drifts requiring booster fans where duct gauge pressure may fall below atmospheric pressure. Separately, the supplied scenario information confirms that spiral duct is also used for temporary ventilation in undersea road tunnel construction. These facts make a blanket flexible-versus-spiral ranking inappropriate. The right comparison depends on the duty, system conditions, and project acceptance criteria.

Material, sourcing, and qualification considerations

The flexible ventilation duct is described as made from PVC-coated fabric, with PVC-laminated fabric as the primary material. Antistatic fabric is available as an option. These product facts give procurement teams a starting point for a specification review, but they do not replace checks for the required material grade, documentation, product configuration, or project-specific compliance.

SULONG states that minimum order quantities are flexible: there are no strict MOQs for standard stock items and mining trial orders, while custom specifications are negotiated according to raw-material minimum batch sizes. For buyers, this can be relevant when planning a trial or a custom order. It does not establish a particular price, lead time, or commercial term; those details need to be confirmed for the order under consideration.

A focused qualification sequence can help keep the comparison practical:

1. Define the duty. Record whether ventilation is temporary or continuous and describe the intended underground scenario.
2. Check system conditions. Review drift or route conditions, pressure regime, and fan arrangement with the responsible technical team.
3. Specify the material and options. State whether PVC-coated or PVC-laminated fabric is required and whether an antistatic option is relevant.
4. Compare construction types fairly. Evaluate flexible, spiral, semi-rigid, rigid, or other proposed solutions against the same acceptance criteria.
5. Verify evidence. Request documentation that matches the exact product and the project’s requirements, including any necessary test or approval evidence.
6. Clarify commercial scope. Confirm whether the order is stock or custom and agree on the applicable MOQ and terms.

Market context: avoid treating broad market figures as duct forecasts

Available market research reports a global mine ventilation market value of USD 1.42 billion in 2024 and projects USD 2.03 billion by 2030, with a reported compound annual growth rate of 6.2%. The report scope covers mine ventilation components, including fans, ducts, and monitoring, rather than ventilation ducts alone. A separate report estimates the tunnel and metro ventilation market at USD 2.663 billion in 2024. These figures describe different market segments and should not be combined or presented as a flexible ventilation duct market size.

For a duct buyer, the practical implication is limited but useful: broad ventilation-market estimates do not answer product-level questions such as price per meter, lead time, or the comparative cost of flexible and spiral duct. The available industry data package identifies those procurement details as gaps. Project-specific quotations and technical evidence remain necessary for a defensible sourcing decision.

Future outlook: make scenario fit verifiable

As underground project teams compare flexible ventilation duct options, the strongest procurement process will connect each proposed product to a defined operating scenario and documented acceptance criteria. The five applications considered here show why one general label cannot settle the selection: temporary tunnel use, shorter mine drifts, high-gas metal mines, long tunneling work, and continuous high-pressure operation raise different questions.

For SULONG, the available evidence establishes product material, an antistatic option, stated applications, and a supplier-described manufacturing distinction. It does not establish that every scenario is a documented SULONG project deployment, nor does it provide independent comparative performance results for every duct type. Keeping those distinctions clear helps engineers, buyers, and suppliers focus on verifiable fit rather than broad category claims.

Bottom line: Flexible ventilation duct may be relevant across several underground project scenarios, but suitability depends on the specific duty and system conditions. Compare it with spiral or rigid alternatives where appropriate, verify the proposed construction and evidence, and avoid assuming that a stated application is a substitute for project qualification.