Flexible duct having 8 in / 20.32 cm diameter for axial blowers, available in 3 lengths 6, 15 or 25 ft

8" Flexible Duct — Confined Space Ventilation and Exhaust, 3 Available Lengths

The Allegro 8" / 20.32 cm diameter flexible duct is designed for use with an 8" diameter axial blower such as the RA9533. It is available in three lengths: 6 ft / 1.82 m, 15 ft / 4.57 m, and 25 ft / 7.62 m, to accommodate the varying dimensions of confined spaces encountered on job sites. This duct operates in both directions, allowing both extraction of contaminated gases (purging) before a worker enters and ventilation by pushing fresh air into the confined space during operations. Its design maximizes airflow while minimizing friction along the duct run. Allegro Industries manufacturer's codes are: 9500-15 for the 15 ft model and 9500-25 for the 25 ft model. Please select your length from the menu above.

This duct is made of vinyl and polyester coated with polyvinyl chloride (PVC), a flexible, lightweight material that resists water spray and common job-site chemicals. Its high-visibility yellow colour with black trim makes it easy to spot on site and reduces tripping hazards. The internal class 1 steel reinforcement maintains the duct's circular cross-section and keeps it deployed even under slight tension. It is also compressible, which greatly simplifies transport and storage between uses. This duct meets ASTM 227 standards.

Ducting Specifications

• Diameter: 8" / 20.32 cm
• Available lengths: 6 ft / 1.82 m, 15 ft / 4.57 m, 25 ft / 7.62 m
• Material: vinyl and polyester coated with PVC (polyvinyl chloride)
• Plies: 1
• Operating temperature range: -20°F to 180°F / -28.8°C to 82.22°C
• Compressible for easy storage and transport
• Class 1 steel reinforcement
• Meets ASTM 227 standards
• High-visibility yellow colour with black trim
• Quick-release clips at both ends
• Operates in both directions: exhaust and ventilation
• Non explosion-proof

Advantages of the RA9500 Flexible Duct for Your Job Sites

Maximum Airflow, Minimum Friction

The uniform circular cross-section and smooth interior surface of the RA9500 duct allow air to flow with minimal resistance. This maximizes the volume of air moved by the blower and ensures effective atmosphere renewal inside the confined space, even at 25 ft from the opening.

Bi-Directional Versatility

The quick-release clips at both ends allow the duct to be attached to the blower in either direction, depending on whether the goal is to exhaust contaminated gases (purge mode) or push in fresh air (ventilation mode). No duct modification is needed to switch between modes.

Compact Storage and Easy Transport

Thanks to its compressible design, the duct folds down accordion-style to occupy minimal space in a work vehicle or safety equipment cabinet. It can be fully deployed on site in seconds.

Industries and Work Sites Where This Product Is Required

• Municipalities — ventilation of sewer manholes, valve chambers, and underground reservoirs
• Oil and gas (non-explosive spaces) — tanks and vessels
• Chemical and pharmaceutical — cleaning and inspecting reactors and mixing tanks
• Food processing — cleaning grain silos and fermentation tanks
• Civil engineering and construction — ventilation of wells, caissons, and deep trenches
• Utilities — maintenance of underground electrical vaults and technical galleries
• Water treatment — pump wells, settling basins, and buried structures
• Mining (non-explosive atmosphere spaces) — underground confined spaces

Installation and RA9500 Duct Selection

To choose the right length, evaluate the distance between the confined space opening and the work zone inside. Always allow a slight extra margin to ease installation and prevent the duct from being stretched to its maximum, which would reduce airflow. The duct must be used with an 8" diameter blower — it is not compatible with 12" blowers. To join two 8" ducts and achieve a greater length, use the RACONN-8 galvanized steel connector.

To select the right blower for your confined space, we recommend using the application developed by Allegro Industries. First read the user guide (in English): https://www.allegrosafety.com/how-to-use-our-confined-space-blower-selector/ — then access the blower selector directly: https://www.allegrosafety.com/blower-selector/.

FAQ — Allegro RA9500 8" Flexible Duct

Is this duct explosion-proof?

No. The RA9500 duct is designed for confined spaces that do not present an explosion hazard. If your confined space contains or may contain flammable gases or vapours, you must use the antistatic explosion-proof duct RA9550X (12") with the explosion-proof blower RA9548-25EX.

Which length should I choose for my confined space?

For a standard vertical access (average-depth sewer manholes), the 15 ft / 4.57 m model is generally sufficient. For deeper spaces or configurations with bends, choose the 25 ft / 7.62 m model. If even greater length is needed, join two ducts using the RACONN-8 connector.

Can I use this duct with any 8" blower?

This duct is designed for use with Allegro 8" blowers. The quick-release clips are compatible with the connection rings on Allegro blowers. To ensure a tight connection and optimal airflow, it is recommended to use ducts and blowers of the same brand. The reference 8" blower is the RA9533.

Complementary Equipment Suggestions for Your Confined Space Ventilation

To complete your installation, the compact 8" axial blower (RA9533) is the blower designed to work with this duct. To extend your duct network, the galvanized steel connector (RACONN) joins two flexible ducts without airflow loss. If your needs require a 12" duct, the 12" flexible duct (RA9550) offers a higher flow rate for larger confined spaces.

For power supply, the 50 ft weatherproof 15 A extension cord (RA9540-50) extends power to the source. The Altair 4X 4-gas detector (DETEC4GC) is essential for monitoring the atmosphere before and during entry. The manhole barrier (EPTBB) secures the perimeter, and the Peakworks 6 D-ring confined space harness (FPH2000APLE), stored in its carry bag (FPBAG), protects the worker during descent.

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