Cleanroom HVAC and Air Handling Equipment

Centrifugal Roof Exhaust Fan

A curb-mounted centrifugal exhaust fan that protects its motor and wheel beneath a weather-resistant hood while discharging clean air downward across the roof surface.

Weather-Resistant Spun Hood
Backward-Inclined Centrifugal Wheel
Downblast Roof Discharge
Gasketed Curb Mounting

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Product Introduction

The centrifugal roof exhaust fan mounts above a roof opening and draws building air upward through a curb into a backward-inclined wheel. A spun weather hood shields the motor, drive and wheel from rain, while the surrounding windband directs discharge downward toward the roof. The removable hood, ventilated motor compartment and prepunched curb cap provide an accessible outdoor exhaust solution for cleanroom support spaces and general clean-air ventilation.

Key Features

A spun aluminum hood combines low weight with corrosion resistance and sheds rain away from internal components.

The backward-inclined centrifugal wheel develops greater static pressure than a simple roof propeller for longer duct systems.

Outside cooling air circulates around the motor compartment instead of relying only on the warm exhaust stream.

A square curb cap with mounting holes and perimeter gasket creates a repeatable sealed connection to the roof curb.

Customer Product Concerns

Roof exhaust equipment must resist weather, keep water out of the duct opening and provide enough pressure for the vertical riser below it.

Rain entering the roof opening can wet insulation and contaminate the connected exhaust duct.The overlapping spun hood, windband and raised curb position shield the inlet from direct precipitation.

A roof propeller loses airflow when a filter, damper or long riser adds resistance.The centrifugal wheel provides a broader pressure capability for ducted exhaust than a low-pressure propeller arrangement.

Outdoor motors overheat when hot exhaust air recirculates through the motor compartment.A separated ventilated motor cover draws cooling air from outside the exhaust path.

Inspecting belts and bearings requires lifting a heavy one-piece fan from the roof curb.The removable or hinged weather hood exposes the drive assembly while the curb base and duct connection remain in place.

Typical Applications

Cleanroom gowning and support-area exhaustLaboratory general clean-air ventilationPharmaceutical warehouse and utility-room exhaustMechanical-room heat removalCommercial clean-process roof extraction

Technical Parameters

Representative construction ranges for a curb-mounted centrifugal downblast roof exhaust fan are provided below.

Core Material	Galvanized steel curb base with a backward-inclined steel wheel and corrosion-resistant spun aluminum weather hood
Panel Thickness	1.2-2.5 mm typical hood, windband and curb-cap material thickness
Effective Width	600-2200 mm nominal roof curb and fan base width
Maximum Length	Up to 2600 mm overall curb-base length according to fan size
Steel Facing Thickness	1.2-2.5 mm galvanized steel curb cap, motor plate and internal support sheet
Core Density	Approximately 7800-7900 kg/m³ for the galvanized steel base and wheel components
Thermal Conductivity	Approximately 45-55 W/(m·K) for the galvanized steel structural components
Surface Finish	Natural spun aluminum hood with dark green powder-coated base and galvanized internal support surfaces
Joint Type	Bolted square curb cap with perimeter gasket, prepunched mounting holes and removable hood fasteners
Customization	Available based on the intended application and operating environment.

Available Options

Direct-drive or belt-drive centrifugal wheelHinged base, motorized damper and extended roof curbBirdscreen, disconnect switch and weatherproof wiring channelCoastal-duty coating and stainless exterior fasteners

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