Assembly designed to maintain airflow at the entrance of a manhole, 8 or 12" diameter duct, 6 or 15 feet long

Allegro MVP Assembly — Manhole Ventilation Passthru, 8 or 12 in (RA9510)

The Allegro Industries MVP (Manhole Ventilation Passthru) kit is the first integrated ventilation system engineered specifically for confined space operations in manholes, sewers and tanks. Its core innovation is a patented design (U.S. Patent D673.668) that combines a low-profile air vent, a 90° elbow and an integrated mounting plate into one single assembly — a first in the industry. The system maintains adequate airflow at the manhole entrance while allowing workers to move in and out with minimal obstruction. Available in 8 in (models 9510-55 / 9510-60) or 12 in (models 9550-10 / 9510-65) diameter, and in duct lengths of 6 ft (1.83 m) or 15 ft (4.57 m), it fits the vast majority of field configurations.

The low-profile elbow installs directly under the bottom crossbar of the manhole guardrail. The manhole cover fits into the flat fluted corners to stabilize the assembly, ensuring reliable positioning without risk of accidental displacement during operations. The collapsible liner folds flat to allow workers to pass through, then reshapes itself once the worker has descended — maintaining continuous airflow at all times.

The ducting is stored in a compact storage bag built directly into the product. A quick-release drawstring deploys the duct into the manhole in seconds. Once work is complete, folding the duct and returning it to the integrated bag takes only a moment.

Construction materials were selected for durability and performance in demanding industrial environments. The deflector is made of linear low-density polyethylene (LLDPE) in high-visibility yellow — a fully recyclable material. The duct is constructed from polyester and vinyl coated with polyvinyl chloride (PVC), reinforced with steel around the perimeter. This compressible duct withstands temperatures up to 180°F / 88.2°C and meets the specifications of ASTM 227 and the UL 94V-0 flame resistance standard.

Advantages of the Allegro MVP System for Your Confined Space Operations

Patented integrated system — unique on the market

No other manhole ventilation device combines a low-profile vent, a 90° elbow and a mounting plate into a single unit. This concept eliminates the adjustments and extra parts typically required, reducing setup time and the risk of leaving a component behind on the job site.

Collapsible duct with quick-release deployment

The collapsible duct stored in the integrated bag deploys and retracts without tools. The quick-release drawstring provides immediate duct access, while the polyester/PVC liner reshapes automatically to resume ventilation as soon as the worker has entered the confined space.

Materials compliant with ASTM 227 and UL 94V-0

Thermal resistance up to 180°F / 88.2°C and compliance with the UL 94V-0 flammability standard make this duct a safe choice even in hot environments or those with exposure to heat sources. ASTM 227 compliance guarantees standardized mechanical performance.

Industries and work sites where this product is required

• Municipalities — maintenance and inspection of sewer manholes, valve chambers and underground reservoirs
• Water services — work in pump wells, settling basins and buried structures
• Oil and gas — ventilation during entry into tanks or separators
• Chemical and pharmaceutical — air purging in reactors and mixing tanks
• Civil engineering and construction — deep trenches, caissons and access tunnels
• Mining — underground confined spaces requiring controlled fresh air supply
• Utilities — maintenance of underground electrical vaults and utility galleries
• Food processing — access to silos, fermentation tanks or storage vessels

Installation, Use and Inspection of the MVP RA9510 Assembly in Confined Spaces

This product is offered in two diameters (8 in or 12 in) and two duct lengths (6 ft / 1.83 m or 15 ft / 4.57 m) — select the combination suited to your blower or fan and to the depth of the confined space using the selection menu. Before each use, visually inspect the LLDPE deflector (no cracks or deformations), the polyester/PVC duct (no tears or perforations), the integrated storage bag and the quick-release mechanism. Position the low-profile vent under the bottom crossbar of the guardrail and engage the mounting plate in the fluted corners. Pull the quick-release drawstring to deploy the duct, connect it to your blower or fan, and verify that there are no obstructions before allowing personnel to descend. After each operation, carefully fold the duct back into the integrated storage bag. In accordance with applicable regulations (CSA Z1006, OSHA), confined space ventilation equipment must be inspected before each use and subjected to an annual documented inspection by a qualified competent person.

FAQ — Allegro MVP RA9510 Manhole Ventilation Assembly

What is the difference between the 8 in and 12 in models of the MVP RA9510?

The choice of diameter depends primarily on the required airflow rate and the duct diameter of your blower or fan. The 8 in model (codes 9510-55 / 9510-60) suits standard confined spaces and 8 in axial fans. The 12 in model (codes 9550-10 / 9510-65) delivers higher airflow and is used with 12 in axial blowers or explosion-proof ventilation kits. Select the duct length (6 ft or 15 ft) based on the entry depth of the manhole.

Is the collapsible duct of the MVP RA9510 resistant to heat and chemicals?

Yes. The polyester/PVC duct with steel reinforcement withstands temperatures up to 180°F / 88.2°C and meets the UL 94V-0 flame resistance standard, making it suitable for hot industrial environments. It also offers good resistance to dust and dirt common on job sites. For explosive environments with flammable vapours or gases, consider the antistatic explosion-proof flexible ducts available in our confined space ventilation range.

Can the MVP RA9510 system be used with any blower or fan?

The MVP assembly is designed to couple with Allegro Industries axial blowers and fans whose diameters match the available options (8 in or 12 in). It is particularly compatible with the 8 in axial fan (RA9533), the 12 in axial fan (RA9539-12) and the explosion-proof kit RA9548-25EX. For integration with equipment of another brand, verify connector and diameter compatibility before use.

Complementary suggestions for your confined space ventilation system RA9510

To optimize your confined space ventilation, see the compact 8 in axial fan with integrated ducting compartment, choice of 15, 25 or 50 ft (RA9533), the 12 in axial fan with moulded polyethylene shell for deeper confined spaces (RA9539-12), the 12 in explosion-proof axial blower kit with 25 ft conductive duct for explosive atmospheres (RA9548-25EX), the explosion-proof socket Allegro 110 V or 220 V with triple-layer iron housing for EX blowers (RA9503) and the flexible 12 in duct available in 6, 15 or 25 ft lengths to extend your ventilation system (RA9550).

Under "Accessories" at the bottom of the page, complete your setup with the antistatic explosion-proof 12 in antistatic duct with conductive link for EX atmospheres (RA9550X), the 50 ft / 12/3 AWG weatherproof extension cord with NEMA 5-15 connection (RA9540-50) and the galvanized steel connector for flexible ventilation duct, 8 or 12 in (RACONN).

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