William Alldays Alcosa BI

Max Flow: 15,000 cfm | Max Pressure: 15" w.g. | Blade Type: Backward Inclined | Efficiency: High

The William Alldays Alcosa BI centrifugal fan uses a backward-inclined impeller design to deliver high-volume airflow with good efficiency and a non-overloading power characteristic. With performance up to 15,000 cfm and static pressures to 15" w.g., the BI is well suited to clean-air HVAC, process air supply, and general ventilation duties where efficiency and reliability are priorities. The backward-inclined blade profile naturally limits power draw as flow increases, protecting the motor from overload.

Specifications Enquire Now

Backward-inclined blades offer a non-overloading power characteristic — as system resistance drops and airflow increases, power demand does not continue to rise. This protects the motor from overload and makes the fan inherently safe across its operating range.

The BI is best suited to clean-air applications such as HVAC supply and extract, general process air, clean room ventilation, and commercial building services where high volumes of clean air need to be moved efficiently at moderate to high static pressures.

The BI offers higher airflow capacity (up to 15,000 cfm vs. 6,500 m³/h for the RB) and is optimised for clean air with superior efficiency. The RB uses radial blades for contaminated-air duties where fouling resistance is the priority.

Specifications — Backward-Inclined Performance

The Alcosa BI combines high-volume capability with the efficiency and motor protection benefits of the backward-inclined impeller design, making it a versatile choice for clean-air ventilation duties.

Maximum airflow: 15,000

maximum static pressure: 15" w.g.

Backward-inclined impeller

Non-overloading power characteristic protects the motor.

Suited to clean

Air HVAC, process air supply, and general commercial/industrial ventilation.