Ventilation Guidelines & Calculator
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PROPELLOR FANS
(Axial Fan) An air moving device in which the air flow is parallel to the shaft on which the propellor is mounted. These fans have good efficiency near free air delivery and are used primarily in low static pressure, high volume applications. Usually mounted in a venturi or other housing featuring simple construction and low cost.

TO DETERMINE FAN SIZE REQUIRED
(General Data for Exhaust Ventilation and People Cooling)

Fan Selections and CFM Determinations:
CFM required for ventilation = Building Cube divided by Minutes per Air Change

Example: Building Size is 100 ft. L x 75 ft. W x 12 ft. Ceiling Height; factory with typical air change required every 4 minutes...

CFM Required for Ventilation= 100x75x12=90,000. 90,000 Divided by 4=22,500 CFM

Fan Selections:(1) One 22,500 CFM Industrial/Heavy Duty Exhaust Fan @ 1/8 or .125 static pressure or several smaller fans totalling 22,500 CFM at 1/8 or .125 static pressure.

Building Dimensions:Minutes
Per Air Change:
Length:   ft. min.
Width:   ft. 
Height:   ft.

RECOMMENDED AIR CHANGES
Area to be Ventilated Minutes
Per Air Change
Assembly Halls, Auditoriums, Banks, Barns, Bowling Alleys, Churches, Clubs, Factories, Dining Rooms, Garages, Gymnasiums, Shops, Laboratories, Markets, Offices, Printing Shops, Pool Rooms, Sales Rooms, Schools, Stores, Warehouses, Restaurants 3--10
Bars, Beauty Parlors, Dairies, Dry Cleaners, Foundries, Kitchens, Theaters, Toilets, Transformer Rooms, Cafeterias 3--5
Bakeries, Boiler Rooms, Laundries 1--3
Attic Ventilation (entire home) 2--2 ½
Attic Only (usually for air-conditioned home) 4--6