12-BI, Backward-Inclined Blowers

Performance certified is for Installation Type B - Free Inlet, Ducted Outlet.
Power rating (BHP) does not include transmission losses.
Performance ratings do not include the effects of appurtenances (accessories).

Blower Specifications 12 1/4 Inch Wheel Diameter
Outlet Area (SQ. FT.) 0.855
Tip Speed (FPM) = 3.21 x RPM
Max. BHP = 0.079 x (RPM/1000)3
Performance Tables
Industrial Certification

Central Blower Co. certifies that the Belt Drive Blowers are licensed to bear the AMCA Seal. The ratings shown are based on tests and procedures performed in accordance with AMCA Publication 211 and comply with the requirements of AMCA Certified Ratings Program.

Constructed of heavy gauge, zinc-coated steel. The discharge can easily be changed in the field to any of eight different positions


Heavy gauge, zinc coated steel frames provide rigid support for housing, wheel, motor, shaft and bearings.


Self-aligning ball bearing pillow blocks are sup plied on all models. Bearings are pre-lubricated and sealed to retain lubricant and exclude dust. Both bearings are mounted out of the airstream for long life.


Ground and polished carbon steel, protected by a rust preventive coating.

Motor Base

Heavy gauge, galvanized steel base, pivoted at one end and supported at the other by two threaded rods for easy belt adjustment. Hinge-type construction insures the motor shaft will remain parallel with the blower shaft when adjusting belt tension.

Motors & Drives

Standard motors are NEMA, open drip-proof, 1725 RPM, single speed. TEFC, 2-speed and explosion proof motors are also available. All Central Blowers are equipped with adjustable pitch motor pulleys. They are easily adjustable to provide approximately 10 percent variation in blower speeds. Factory installed motor and drives are checked for smooth operation and compliance with specified RPM.

Weather Hoods

Rust resistant, galvanized steel construction protects the shaft, bearings, motor and drives. Also serves as an OSHA-approved belt guard.


Standard finish is baked enamel. Corrosion resistant coatings are also available.

Shaft Seals

While very effective, shaft seals do not seal 100%.

Drain Fitting

3/4 inch pipe coupling welded to the low point of the housing for draining water. Weep hole also available without pipe connection.

Spark Resistant Construction

AMCA-Type "B" spark resistant construction is available on all blowers. AMCA-Type "A" can be supplied for special applications.

Vibration Isolators

Rubber-in-Shear (RIS) Neoprene mounts are suitable for non-critical applications.

RIS Rails Rubber-in-Shear mounts on rails are available (needed when a stack is to be used).

Individual Spring Mounts provides approximately 1-inch vertical deflection. Designed for critical applications. Also available with "seismic" rating at an extra cost.

Spring Rails - Spring mounts attached to rails to provide more even distribution of weight.

Protective Screens

Inlet screens protect unit from debris when used on supply fan application. Outlet screens prevent entrance of birds and serve as safety guard for rotating blower wheel. (Not available with exhaust stack). Can be made of stainless steel, if applicable.

Cleanout Door

Provides access for cleaning or inspection of the interior of the housing. Cover bolted with stainless steel fasteners and fully gasketed.


Rain cap (also known as zero static) stacks for normal hoods. Straight stacks available for perchloric acid hoods.


Inlet and outlet flanges available on special order. Allow extra delivery time. Companion Flanges available with matching holes.

Stainless Steel

Housing and wheel (airstream parts) of 304 or 316 stainless steel. Allow six to eight weeks extra lead time for stainless steel wheels.

Weather Hood for corrosive atmosphere and/or esthetic value.


Central Blower Company is proud to offer a line of excellent chemical-resistant coatings. Our standard is a Baked Epoxy. This is an epoxy powder that is electrostatically applied and baked at 400 degrees for curing. All airstream blower parts are sandblasted prior to coating to provide a clean surface for maximum adhesion by the epoxy. This coating is recommended for most normal laboratory fume hood exhausts. Epoxy is not recommended for temperatures over 180º F.

For severe conditions we recommend Cen-FP, a fluoropolymer resin coating. This coating is especially resistant to highly corrosive chemicals, such as nitric, sulfuric or perchloric acids. In addition to its high degree of chemical resistance, Cen-FP withstands a wide range of temperatures.