Allegro 12" diameter axial fan with molded polyethylene shell without ducting

12" Axial Blower — Polyethylene Shell, Stackable, 2180 cfm

The Allegro 12" / 30.4 cm diameter axial fan is a high-performance blower designed for ventilating confined spaces without explosion hazard. It can both extract (purge) or ventilate a confined space depending on the orientation chosen by the user: in extraction mode, it evacuates contaminated gases before entry; in ventilation mode, it pushes fresh air toward the worker inside. In practice, contaminated gases are extracted first, then a reading is taken with a gas detector equipped with a sampling pump (DETEC4GC); if everything is correct, the fan is reversed to push fresh air into the confined space. Because of the hazards of toxic vapours or particles in a confined space, be sure to equip your workers with gas detectors even if you have purged and ventilated the space. Allegro Industries manufacturer's code: 9539-12.

The housing is made of lightweight polyethylene, a material that resists corrosion, UV rays, and most industrial chemicals, ensuring a long service life even in harsh environments. The six polypropylene blades offer excellent resistance to moisture and chemical agents. The blower also features a powdered steel grill and a carrying handle moulded directly into the housing. The bottom housing provides safe and convenient storage of electrical components. Both sides of the blower are equipped with connection rings for duct attachment, enabling a quick switch from exhaust mode to ventilation mode simply by reversing the fan. This blower is equipped with a single-phase electric motor certified to UL/CSA C22.2 No. 113 standards.

Motor Specifications

• Power: 1 HP
• Supply: 115 Volts AC, 60 Hz, 1 phase
• RPM: 3400 (at 115 V, 60 Hz)
• Current: 5 A (60 Hz)
• Power cord: 20 feet / 6.09 m AWG
• Plug type: NEMA 5-15P
• Motor certification: UL/CSA C22.2 No. 113

Blower Specifications

• 6 polypropylene blades
• Airflow: 2180 cfm / 3703.84 m³/h without ducting
• Powdered steel grill
• Moulded carrying handle
• Moulded polyethylene housing
• Connection rings on both sides for duct attachment
• Flexible duct NOT included (add RA9550-15 or RA9550-25)

Advantages of the RA9539-12 Axial Blower for Your Job Sites

Stackable — Inline Booster Blower for Ventilation Networks

This model has the unique feature of being stackable: it can be used as an inline booster blower on series ventilation networks. When the duct run is long or airflow must be maintained over a great distance, multiple RA9539-12 units can be chained together to amplify airflow without significant pressure loss. This flexibility makes it a preferred choice for complex job sites or deep confined spaces.

Versatile Exhaust/Ventilation Operation

The connection rings on both sides of the housing allow a quick switch from exhaust mode to ventilation mode simply by reversing the fan. No tools are required for this operation.

Durable and Lightweight Construction

The polyethylene housing combines light weight with resistance to chemical attack, UV rays, and corrosion. The polypropylene blades will not rust and resist water and common job-site chemicals.

Industries and Work Sites Where This Product Is Required

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

Installation Tips and Usage Guidelines for the RA9539-12

The manufacturer recommends installing the blower more than 5 feet from the opening entrance. To choose the safest location, make the wind your ally: when purging, position the blower and yourself so that fumes disperse with the wind without returning toward you; when ventilating, place the blower with your back to the wind to avoid gas mixtures expelled from the confined space.

The flexible duct is not included with this product. Two lengths are available for this 12" model: 15 ft / 4.57 m and 25 ft / 7.62 m, available under references RA9550-15 or RA9550-25. If your blower needs a small repair, you can also consult the list of components under the download tab.

To choose the right blower for your confined space, we recommend using the application developed by Allegro Industries. This application allows you to select the correct fan based on the specific parameters of your space: gas hazard level (explosive or not), size and shape of the space, number of duct elbows, and more. First read the user guide (in English only): 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 RA9539-12 Axial Blower

Is this blower explosion-proof?

No. The RA9539-12 is designed to ventilate 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 explosion-proof model RA9548-25EX.

What is the difference between exhaust and ventilation with this blower?

In exhaust (purge) mode, the blower removes contaminated, toxic, or oxygen-depleted gases from the confined space before entry. In ventilation mode, it pushes fresh air inside to maintain a breathable atmosphere while workers operate within the space. To switch modes, simply reverse the blower — the connection rings on both sides make this a quick, tool-free operation.

Can this blower be used as a booster station or stacked in series?

Yes. The RA9539-12 is stackable and can be used as an inline booster blower on series ventilation networks. When the duct run is long, multiple units can be chained together to maintain sufficient airflow over the entire ventilation length.

Complementary Equipment Suggestions for Your Confined Space Ventilation

To complete your ventilation installation, the 12" flexible duct in 15 or 25 ft (RA9550) connects directly to this blower, and the weatherproof 50 ft 15 A extension cord (RA9540-50) extends power to the source. For sites with explosive atmosphere risk, the 12" explosion-proof blower with 25 ft conductive duct (RA9548-25EX) is the certified alternative. For atmosphere monitoring, the complete Altair 4X 4-gas detector kit with pump (DETEC4GC) is essential even after purging.

For confined space entry safety equipment, the compact 8" portable blower RA9533 is a complementary portable option for narrow access points (831 cfm, with included 8" duct). The manhole barrier (EPTBB) secures the perimeter around the opening, and the Peakworks 6 D-ring confined space harness (FPH2000APLE) protects the worker during descent, stored in a heavy-duty carry bag (FPBAG).

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