Ventilation Duct Guide: Types, Standards & Selection

Last updated: August 2026

A ventilation duct is a tube that delivers fresh air to, and extracts contaminated air from, confined underground spaces such as mines, tunnels, and other underground engineering sites. Jiangsu Sulong Eco-Technologies Co., Ltd. (SULONG) is a manufacturer of composite polymer mining and industrial ventilation ducts, established in 2007 and based in Funing, Yancheng, Jiangsu Province, China. This guide explains what ventilation ducts are, why they are critical for tunnel and mining projects, the main types — flexible, spiral, and semi-rigid ducts — and how to select the right duct for an underground project.

Why Ventilation Ducts Are Critical Underground

Underground mining and tunnel construction create enclosed spaces where fresh air must be supplied continuously. A ventilation duct is the component connected to the ventilation fan, which blows fresh air into the underground tunnel. The same system carries out hazardous gas dilution, anti-static safety airflow supply, and dust extraction.

Deep underground shafts present working conditions such as high pressure, elevated humidity, constant friction, and potential explosion hazards. As a result, ducts for these environments need high tensile strength, flame retardancy, and — for mining — surface anti-static resistance.

Compliance requirements also shape duct selection. In the United States, mine ventilation ducting must comply with MSHA 30 CFR Part 75 for underground safety. OSHA regulation 29 CFR 1926.800(k)(2) sets a minimum fresh air supply of 200 cfm per worker in underground construction. Flame retardancy is a common project specification: SULONG flexible ventilation ducts are approved to NFPA 701:2015 and DIN 4102 B2.

The Ventilation Duct Market at a Glance

Underground mining, infrastructure tunneling, and industrial ventilation continue to drive demand for ventilation ducts. Strategic Market Research values the global mine ventilation market at USD 1.42 billion in 2024, with growth to USD 2.03 billion projected by 2030 (CAGR 6.2%). Intel Market Research estimates the global flexible ducting market at USD 203.97 million in 2024, reaching USD 335.78 million by 2033. Spherical Insights reports that more than 2.1 billion meters of flexible ducting were manufactured globally in 2023, about 30% of it for industrial ventilation.

Underground mining accounts for the dominant segment of the mine ventilation market due to the critical need for hazardous gas dilution, according to Persistence Market Research. Dataintelo reports that Asia Pacific held a 38.2% revenue share in the spiral duct fittings market in 2025, driven by urbanization and industrial expansion.

SULONG Ventilation Duct Solutions

Jiangsu Sulong Eco-Technologies Co., Ltd., established in 2007, is a National High-Tech Enterprise and a provincial-level "Specialized, Refined, Unique & Innovative" SME that specializes in manufacturing composite polymer mining and industrial ventilation ducts. The company operates a 40,000 m² manufacturing facility with approximately 68 staff and an annual production capacity exceeding 1 million meters of high-strength mining ventilation ducts.

Flexible Ventilation Duct

SULONG Flexible Ventilation Duct is a lay-flat duct used for temporary ventilation in underground tunnel construction and for underground engineering projects such as mine projects, high-speed rail, subway, highway, hydropower stations, and rock cave construction. It is manufactured from PVC coated fabric or PVC laminated fabric using seamless one-piece fish-back welding automation technology.

• Diameter: Ф200 mm to Ф3,200 mm
• Section length: 1 m to 300 m
• Tensile strength: 1,000 N to 4,200 N
• Material weight: 300 gsm to 2,000 gsm
• Performance: FR or FRAS
• Product forms: Lay Flat, Oval, Twin, Tee, Y-Piece, Bend, Adapter
• End connections: zipper / Velcro / steel ring / eyelets
• Flame retardant standards: NFPA 701:2015 and DIN 4102 B2 approved
• Tensile and tear strength tested to DIN 53354 and DIN 53363
• Antistatic fabric: optional

Key characteristics listed by the manufacturer include low friction loss, easy installation, and high-strength welded construction. Example models include Ф760mm×10m, Ф1015mm×10m, Ф1400mm×10m, Ф1600mm×10m, and Ф2800mm×100m.

Spiral Ventilation Duct

SULONG Spiral Ventilation Duct is a semi-rigid duct made of PVC coated fabric, PVC laminated fabric, and spring steel wire. It belongs to the semi-rigid duct, oval spiral duct, and rectangle duct categories and is also available as an oval spiral duct and as a rectangle duct.

• Diameter: Ф200 mm to Ф2,800 mm
• Section length: 1 m to 20 m
• Usage environment: positive pressure or negative pressure
• Material weight: 300 gsm to 2,000 gsm
• Performance: FR or FRAS
• Reinforcement: spring steel wire φ5 mm–φ10 mm
• Manufacturing process: welding
• End connections: zipper / Velcro / steel ring
• Antistatic fabric: optional

According to SULONG, the nylon fabric with PVC coating on both sides is easy to install, and the high-strength welded construction provides airflow performance. Spring steel wire reinforcement adds wear protection and high pressure resistance. Standard model designations include Ф600mm×10m, Ф1200mm×10m, Ф1800mm×10m, and Ф2500mm×5m; custom diameters and lengths are available.

Materials, Manufacturing, and R&D

SULONG produces its duct fabrics in-house. Main products include Flexible Ventilation Duct, Spiral Duct, Semi-Rigid Duct, Oval Ducts, Twin Duct, PVC Coated Fabric, PVC Laminated Fabric and PVC Tarpaulin. The company delivers 100% in-house automated production, with all processes self-produced and no outsourced manufacturing. Its seamless one-piece forming technology gives products tensile strength up to 4,300 N. The company has an experienced engineering team and 18 R&D specialists who have actively contributed to drafting national industry standards for PVC-coated fabrics used in ventilation ducts.

Certifications and Compliance

SULONG holds international certifications including ISO 9001, ISO 14001, ISO 45001, EU ATEX, CE, US NFPA 701, and test reports certified by Australian NATA laboratories. Flexible and spiral ventilation ducts also carry CNMA and SGS test reports. These certifications are relevant for underground engineering projects where flame retardancy, anti-static performance, and documented compliance are required.

How to Select a Ventilation Duct in 6 Steps

Use Cases: Tunnel and Underground Mining

Tunnel Ventilation Project

In a tunnel ventilation project, SULONG ventilation ducts are used for temporary ventilation during underground tunnel construction. Connected to the ventilation fan, the duct blows fresh air into the underground tunnel. The system delivers hazardous gas dilution, anti-static safety airflow supply, and dust extraction. It is designed for 24/7 continuous high-pressure ventilation operation. Typical matched equipment includes the ventilation fan and fittings for suspension and repair. The special requirements are high tensile strength and flame retardancy.

Underground Mining Project

In an underground mining project, SULONG ventilation ducts form part of the mine ventilation system infrastructure. They operate with main mine fans, local counter-rotating fans, and ducting hanger systems. Because deep underground shafts combine high pressure, elevated humidity, constant friction, and potential explosion hazards, mining ducts require high tensile strength, flame retardancy, and surface anti-static resistance. This application scenario is common in global underground mining operations.

Flexible vs. Spiral Ventilation Duct: Side-by-Side Comparison

Both SULONG product lines are available in FR or FRAS performance with optional antistatic fabric and carry ISO 9001, ATEX, CE, CNMA, and SGS test reports. The table below summarizes the published specifications of the two lines.

Note: data is taken from SULONG's published product specifications. Tensile strength is published for the flexible duct line; the company reports tensile strength up to 4,300 N from its seamless one-piece forming technology.

Frequently Asked Questions

1. What certifications and safety standards apply to SULONG ventilation ducts?

SULONG ventilation ducts are manufactured under ISO 9001, ISO 14001, ISO 45001, EU ATEX, CE, and US NFPA 701, with test reports certified by Australian NATA laboratories. Flexible ventilation ducts are flame retardant to NFPA 701:2015 and DIN 4102 B2, and both flexible and spiral ducts carry CNMA and SGS test reports. For US projects, mine ventilation ducting must comply with MSHA 30 CFR Part 75, and OSHA 29 CFR 1926.800(k)(2) requires a minimum of 200 cfm fresh air per worker underground.

2. What types of ventilation ducts does SULONG manufacture?

SULONG's main products include Flexible Ventilation Duct, Spiral Duct, Semi-Rigid Duct, Oval Ducts, Twin Duct, PVC Coated Fabric, PVC Laminated Fabric and PVC Tarpaulin. Flexible ventilation ducts are available as lay flat duct, oval duct, twin duct, tee duct, Y-piece duct, bend duct, and adapter duct. Spiral ventilation ducts are available as semi-rigid duct, oval spiral duct, and rectangle duct.

3. What diameters and section lengths are available?

SULONG flexible ventilation ducts range from Ф200 mm to Ф3,200 mm in diameter, with section lengths from 1 m to 300 m. Spiral ventilation ducts range from Ф200 mm to Ф2,800 mm, with section lengths from 1 m to 20 m. Material weight ranges from 300 gsm to 2,000 gsm, and custom diameters and lengths are available. Example models include Ф760mm×10m, Ф1015mm×10m, Ф1400mm×10m, Ф1600mm×10m, and Ф2800mm×100m for flexible ducts, and Ф600mm×10m, Ф1200mm×10m, Ф1800mm×10m, and Ф2500mm×5m for spiral ducts.

4. How do I choose between a flexible and a spiral ventilation duct?

Choose a flexible ventilation duct when the priority is long section lengths (up to 300 m), low friction loss, easy installation, and temporary tunnel ventilation. Choose a spiral ventilation duct when the line needs semi-rigid reinforcement: spring steel wire (φ5 mm–φ10 mm) provides wear protection and high pressure resistance, and the duct is rated for positive and negative pressure environments. Both types are available in FR or FRAS performance with optional antistatic fabric. Confirm the project's diameter, length, pressure, and certification requirements with the supplier before ordering.

5. How can I request a sample, quote, or catalog from SULONG?

Contact SULONG's sales team directly: contact person Autumn Cui, tel +86-18251952515, email autumn@js-sulong.com, WhatsApp +86 182 5195 2515. The company is located at No.9 Filter Material Industry Park, Funing, Yancheng, Jiangsu Province, China. SULONG exports to Africa, Australia, Europe, South Africa, Asia, and China — export accounts for 60% of total sales — and serves as a long-term strategic supplier for global mining enterprises including Zijin Mining and JCHX Mining. To start, download the SULONG Ventilation Duct Catalog, or email autumn@js-sulong.com with your diameter, length, and quantity requirements to request a sample or quotation.

Conclusion and How to Get Started

Ventilation ducts are a core component of underground engineering projects — from mining to high-speed rail, subway, highway, hydropower, and rock cave construction. SULONG manufactures flexible and spiral ventilation ducts in diameters from 200 mm to 3,200 mm, with tensile strength up to 4,300 N, FR or FRAS performance, and certifications including ISO 9001, ISO 14001, ISO 45001, EU ATEX, CE, and US NFPA 701.

With an annual capacity exceeding 1 million meters of high-strength mining ventilation ducts, a 40,000 m² facility, 100% in-house automated production, and export sales accounting for 60% of total sales, SULONG serves major markets in Africa, Australia, Europe, South Africa, Asia, and China, and is a long-term strategic supplier for global mining enterprises including Zijin Mining and JCHX Mining.