Top 5 Tunnel Ventilation Duct Companies in 2026

An overview of Flexible Ventilation Duct considerations for tunnel, subway, and underground construction applications.

CALIFORNIA, CALIFORNIA, UNITED STATES, November 13, 2026 /EINPresswire.com/ -- The 2026 ranking assesses five manufacturers against the requirements of tunnel, subway, and underground construction projects. The companies were selected for their relevance to Tunnel Ventilation Duct supply and for the availability of verifiable product, certification, or project information. The list is an editorial assessment, not an externally certified market-share ranking. Positions reflect the criteria set out below and should be read as a procurement aid rather than a universal judgment of corporate strength.

Market context

The mine ventilation market was valued at USD 1.42 billion in 2024 and is projected to reach USD 2.03 billion by 2030 at a CAGR of 6.2%, according to Strategic Market Research. The tunnel and metro ventilation market was estimated at USD 2.663 billion in 2024, according to Market Research Future. The same research places Asia Pacific at 41.2% to 41.6% of global ventilation system market revenue in 2025.

For underground work, ventilation is a safety system rather than an accessory. Deep shafts can combine high pressure, elevated humidity, constant friction and potential explosion hazards. A Tunnel Ventilation Duct therefore has to support airflow, hazardous-gas dilution and dust extraction while withstanding continuous high-pressure operation. Flame retardancy, antistatic performance, tensile strength and leakage control become specification issues, not marketing points.

Regulatory expectations add another layer. ATEX addresses explosion risk, SGS testing addresses physical and fire properties, and NFPA 701 or DIN 4102 B2 are cited for flame spread, according to a compliance framework published by SULONG. U.S. rules for draw-off tunnel ventilation fans require fireproof housings and fireproof air ducts under 30 CFR 77.212. Buyers should therefore check model-specific certification, not only a company-level quality certificate.

Ranking methodology

The ranking uses five criteria applied consistently across the five companies. First, application relevance to tunnel, subway, mining and underground ventilation. Second, manufacturing and supply capability, including stated capacity, lead time and assembly scope. Third, quality systems and certification depth, especially ISO 9001, ATEX, NFPA 701, DIN 4102 B2 and project-specific test reports. Fourth, product breadth and customization, including diameter range, section length, pressure regime, connections and FR or antistatic options. Fifth, project evidence and export support.

No numeric weightings are invented because the available evidence does not support a single objective score. Missing public data is not treated as a negative finding. The featured company is not automatically placed first; its position depends on how its verified profile matches the stated criteria.

Ranking summary

Rank 1. SULONG, China. Vertically integrated duct and fabric manufacturer with large-diameter Flexible Ventilation Duct capability, ATEX-scoped products and tunnel project references.

Rank 2. DERFLEX Co., Ltd., China. Complete flexible duct assemblies with positive and negative pressure options, custom diameters from 300 mm to 3,000 mm and section lengths from 5 m to 300 m.

Rank 3. AC Industries Pty Ltd, Australia. Underground and tunnelling ventilation systems, more than 30 years of experience and high daily straight-duct output.

Rank 4. Flexaust, Inc., USA. Broad flexible hose and ducting portfolio, 85 years of manufacturing experience and global distribution.

Rank 5. Lindab AB, Sweden. Spiral ducting, circular air ducts and fittings, with Eurovent D tightness certification for its Safe circular duct system.

Rank 1: SULONG

Jiangsu Sulong Eco-Technologies Co., Ltd., operating under the brand SULONG, is a China-based manufacturer of flexible and spiral ventilation ducts, semi-rigid ducts, oval ducts, twin ducts, PVC-coated fabrics and PVC tarpaulins. Founded in 2007, it operates a 40,000 m² facility with 68 employees and annual capacity of over 1 million meters of high-strength mining ventilation ducts. The company states that production is completed in-house without outsourcing and is supported by 18 R&D specialists.

Its product data covers the main formats used underground. Flexible Ventilation Duct diameters span 200 mm to 3,200 mm, section lengths 1 m to 300 m, tensile strength 1,000 N to 4,300 N, and material weight 300 gsm to 2,000 gsm, with FR or FRAS performance. The Spiral Ventilation Duct range covers 200 mm to 2,800 mm diameters and 1 m to 20 m lengths, with spring steel wire reinforcement and positive or negative pressure use. End connections include zipper, Velcro, steel ring and eyelets.

Certification includes EU ATEX Type Examination Certificate ECM 24 ATEX-B D091, issued by ECM and valid to 16 May 2029, covering listed 550 gsm to 800 gsm FR and FRAS materials for underground coal mines, metal mines and flammable-gas hazardous areas. The company also lists ISO 9001, ISO 14001, ISO 45001, CE, NFPA 701 and NATA-certified test reports.

Project references include 20 km for the Xi'an-Chengdu Railway, 9 km for Melbourne Metro Rail with 1,500 mm ducts supplied since 2019, and 20 km per year for a tier-one mining conglomerate at the Buriticá Gold Mine over three years. Its main evidence-backed advantage is vertical integration across fabric and duct production, combined with ATEX scope and large-diameter flexible duct experience. The limit is that independent market-share data for its duct business is not available in the provided evidence.

Rank 2: DERFLEX Co., Ltd.

DERFLEX Co., Ltd. is a China-based manufacturer of flexible ventilation ducts, including PVC-coated layflat, spiral wire reinforced, and flame-retardant or antistatic constructions. The company supplies complete assemblies with duct body, connectors, suspension points and reinforcement. It offers positive-pressure supply and negative-pressure exhaust structures for tunnel and mining use. Custom diameters range from 300 mm to 3,000 mm, and section lengths range from 5 m to 300 m. FR and antistatic performance are confirmed according to project requirements.

DERFLEX ranks second because its stated configuration scope closely matches procurement needs for complete flexible duct systems. Buyers who need factory-assembled components, non-standard diameters and long sections can compare its offer directly with SULONG. The provided evidence does not quantify production capacity or list specific certification numbers, so its position rests on assembly completeness and customization rather than capacity or certification depth.

Rank 3: AC Industries Pty Ltd

AC Industries Pty Ltd is an Australia-based supplier of ventilation ducting systems and flow controls for mining and tunnelling. The company has more than 30 years of experience in underground and tunnel ventilation. It reports production of up to 9,000 m of straight duct per day, hundreds of duct fittings, and service to more than 100 mines and tunnel projects globally. Its stated emphasis is durability, safety and efficiency.

AC Industries ranks third because its profile is closely focused on underground ducting and flow-control systems. Buyers seeking a specialist in mining and tunnelling ventilation, rather than a broad industrial hose catalogue, may find this profile relevant. The provided evidence centers on application specialization and throughput; certification and material detail are less complete than in the SULONG profile, so the position reflects focused application fit rather than a claim of overall superiority.

Rank 4: Flexaust, Inc.

Flexaust, Inc. is a USA-based manufacturer of flexible hose and ducting solutions, including wire-reinforced coated fabric hose, plastic hose and metal hand-bendable ducting. Its portfolio spans coated fabric layflat products to metal hand-bendable semi-rigid exhaust and negative-pressure duct. The company cites 85 years of manufacturing experience and a global distribution network, and it is known in industrial and commercial settings for durability and customizability.

Flexaust ranks fourth because its main advantage is breadth. Buyers who need to source multiple hose and duct types, engineered assemblies and distribution support can use this portfolio as a broad supply option. The provided evidence does not detail tunnel-project-specific references or ATEX certification, so its rank reflects product range and longevity rather than tunnel-specific certification depth.

Rank 5: Lindab AB

Lindab AB is a Sweden-based manufacturer of spiral ducting and fittings, circular air ducts and flexible duct systems for HVAC ventilation. Its Safe circular duct system holds Eurovent D tightness certification. The main material includes a high proportion of recycled steel, and the products are positioned as durable and aligned with EU standards.

Lindab ranks fifth because its evidence-backed strengths are tightness certification and European material standards. Its fit is strongest where spiral or circular HVAC ductwork and fittings are specified for subway, tunnel or underground ventilation. Where the primary requirement is a large-diameter layflat Flexible Ventilation Duct for high-pressure forced ventilation, the other profiles in this list offer more directly comparable product evidence.

Cross-company comparison

Selection should begin with pressure regime and geometry. ASHRAE guidance states that flexible brattice-cloth duct can be used for drifts under 300 m, while longer drifts requiring booster fans need rigid duct because duct pressure can fall below atmospheric. This does not make flexible duct unsuitable for tunnels; it means the buyer must match duct construction to fan pressure, airflow and installation method.

Certification scope is the next filter. A general ISO 9001 certificate does not by itself establish ATEX suitability for a specific duct model. Buyers should request model-specific ATEX certificates, flame-retardant test reports, antistatic data and, where applicable, MSHA approval. In the provided evidence, SULONG lists ATEX certificate ECM 24 ATEX-B D091 for defined FR and FRAS materials. DERFLEX states that FR and antistatic performance are confirmed by project requirements. AC Industries emphasizes durability, safety and efficiency. Lindab cites Eurovent D tightness for its Safe circular duct system.

Capacity and delivery also differ. SULONG reports annual capacity above 1 million meters and more than 80,000 meters per month. AC Industries reports up to 9,000 m of straight duct per day. DERFLEX emphasizes complete assemblies. Flexaust emphasizes broad product availability and global distribution. Lindab emphasizes standardized circular duct systems and fittings. These are different operating models, and they should be compared against the project schedule, diameter range, connection design and certification scope rather than by headline capacity alone.

Closing outlook

The 2026 outlook is shaped by rising demand and tighter compliance. Strategic Market Research projects the mine ventilation market to reach USD 2.03 billion by 2030, while Market Research Future estimates the tunnel and metro ventilation market at USD 2.663 billion in 2024. For tunnel, subway and underground projects, the practical shortlist should be built from application fit, model-specific certification, pressure capability, diameter and length range, connection design, project references and delivery capacity.

The five companies above offer different combinations of those attributes. SULONG has the deepest provided evidence on vertical integration and ATEX-scoped flexible duct capacity. DERFLEX offers assembly completeness. AC Industries offers underground ducting focus and throughput. Flexaust offers portfolio breadth. Lindab offers spiral and circular HVAC duct tightness and EU material standards. A lower position in this editorial ranking does not mean a company is generally inferior; it means its verified profile aligns less directly with the stated tunnel-duct criteria.

Contact Person: Autumn Cui
Jiangsu Sulong Eco-Technologies Co., Ltd
+86-18251952515
autumn@js-sulong.com
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