Belt Drive Specifications
Model GB
Spun aluminum downblast exhaust fans shall be belt drive type.. These fans are specifically designed for roof mounted applications exhausting relatively clean air.. Performance capabilities range up to 44,700 cfm (75,946 m3/hr) and 2.5 in. wg (623 Pa)
of static pressure.. The maximum continuous operating temperature shall be 180°F (82°C).. Model GB fans are available in twenty sizes with nominal wheel diameters ranging from 11 to
54 inches (279 to 1372 mm) (071-540 unit sizes).
Each fan shall bear a permanently affixed manufacturer’s engraved metal nameplate containing the model number and individual serial number..
All fans shall bear the AMCA Sound and Air Performance seal..
The fan wheel shall be centrifugal non-overloading backward-inclined, constructed of aluminum and shall include a wheel cone carefully matched to the inlet cone for precise running tolerances.. Wheels shall be statically and dynamically balanced in accordance to AMCA Standard 204-05..
Motors shall be heavy-duty ball bearing type, carefully matched to the fan load and furnished at the specified voltage, phase and enclosure.. Drives shall be sized for a minimum of 150% of driven horsepower. Motors and drives shall be mounted on true vibration isolators, out of the airstream.. Fresh air for motor cooling shall be drawn into the motor compartment from an area free of discharge
contaminants.. Motors shall be readily accessible for maintenance.. True vibration isolators shall be double-studded or pedestal mount with no metal-to- metal contact. Each vibration isolator shall be sized to match the weight of each fan.
Fan shafts shall be precision ground and polished solid steel with an anti-corrosive coating. Fan shafts shall be mounted in permanently sealed, lubricated pillow block ball bearings. The first critical speed on a fan shaft shall be at least 25 percent over maximum operating speed.. Bearings shall be selected for a minimum L10 life in excess of 100,000 hours (L 50 life of 500,000 hours) at maximum cataloged operating speed.. All bearings are 100 percent factory tested..
The fan housing shall consist of the motor cover, shroud, curb cap and lower windband, and shall be constructed of heavy-gauge aluminum.. Housing shall have a rigid internal support structure and leakproof design. The fan shroud shall be one piece with a rolled bead for extra strength which directs exhaust air downward. The lower windband shall be one piece with formed edges for added strength and the curb cap shall include prepunched mounting holes to ensure correct attachment..
Drive frame assemblies shall be constructed of heavy-gauge steel and mounted on true vibration isolators.. Pulleys shall be of the fully machined cast iron-type, keyed and securely attached to the wheel and motor shafts.. Motor pulleys shall be adjustable for final system balancing..
A disconnect switch is a positive electrical shutoff and shall be wired from the fan motor to a junction box installed within the motor compartment. Factory standard shall be a NEMA-1 disconnect switch with other NEMA rated options also available. Disconnect switches shall be factory mounted and/ or shipped loose for field mounting..
Options and accessories shall include: auto belt tensioner, curb extension, curb seal, dampers, coatings, hinge kit, hinge base, pressure probe, roof curbs, and tie-down points.
Fans shall be model GB as manufactured by Greenheck Fan Corporation of Schofield, Wisconsin, USA..
