Three-quarter view of a replacement FFU backward-curved centrifugal fan impeller

Cleanroom Equipment Spare Parts

FFU Fan Impeller

A balanced backward-curved centrifugal wheel that replaces a damaged or contaminated FFU impeller while retaining the existing motor and housing.

Backward-Curved Blades
Low-Profile FFU Geometry
Balanced Rotating Assembly
Matched Hub Interface

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Product Introduction

The FFU fan impeller converts motor rotation into the pressure and airflow required to move room air through the final filter. Its shallow centrifugal geometry suits the limited plenum depth of a ceiling-mounted fan filter unit. Backward-curved blades, a formed inlet rim and a rigid backplate guide air through the wheel while limiting recirculation. Replacement selection must match the original outside diameter, wheel depth, rotation direction, hub bore and motor speed so the assembled fan operates within its intended airflow range.

Key Features

Backward-curved blades provide stable non-overloading centrifugal fan characteristics.

A shallow wheel profile fits compact ceiling FFU housings without obstructing the inlet path.

The formed rim and rigid backplate retain blade spacing during high-speed rotation.

Machined hub options match common direct-drive motor shafts and fastening methods.

Customer Product Concerns

Impeller geometry and balance directly affect FFU airflow, sound and motor loading.

A wheel with the wrong diameter or depth changes the fan operating point.Replacement dimensions are matched to the original wheel envelope and FFU inlet clearance.

Incorrect blade direction produces weak airflow and excessive turbulence.Clockwise or counter-clockwise blade orientation is selected for the installed motor rotation.

Hub mismatch causes runout or prevents secure shaft attachment.Bore, keyway, set-screw and bolt pattern options are configured for the original drive shaft.

An unbalanced replacement transmits vibration to the filter and ceiling grid.The completed wheel is balanced as a rotating assembly after blade and hub fabrication.

Typical Applications

Cleanroom ceiling fan filter unitsLaminar-flow workstationsMini-environment circulation modulesFFU preventive-maintenance replacement

Technical Parameters

Typical construction ranges for low-profile FFU centrifugal impellers are shown below.

Core Material	Formed aluminum alloy or galvanized-steel backward-curved blade assembly
Panel Thickness	60-180 mm nominal wheel depth
Effective Width	250-500 mm nominal outside diameter
Maximum Length	Up to 500 mm overall impeller diameter
Steel Facing Thickness	0.8-1.5 mm formed sheet-metal blades and backplate
Core Density	2700 kg/m³ for aluminum or 7850 kg/m³ for steel components
Thermal Conductivity	160-205 W/(m·K) for aluminum or 45-60 W/(m·K) for steel
Surface Finish	Natural aluminum or corrosion-resistant zinc-coated silver finish
Joint Type	Formed blade tabs or welded blade roots with machined bolted or set-screw hub
Customization	Available based on the intended application and operating environment.

Available Options

Aluminum or galvanized-steel constructionClockwise or counter-clockwise rotationCustom hub bore and fasteningMatched diameter and wheel depth

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