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Make-Up Air Volume
Requirements:
The recommended method for calculating Make-up Air Volume is to
determine the total CFM capacity of exhaust fans, blowers, stacks, etc.
in the building and add 10%. This will create a positive pressure in
the building. When information is not available, the following
estimates may be used to determine approximate requirements:
- Paint / Spray Booth: 100 to 200 CFM per sq. ft. of face opening.
- Oven Exhaust: One air change per minute.
- Fume Exhaust: Area of Pipe (in square feet) x velocity (3,000
feet/min average) = CFM.
- Roof Ventilator: same as Fume Exhaust.
- Canopy Hoods: 100 to 300 CFM per square foot of hood open area.
- Furnace Combustion Air: Minimum CFM = BTU/hr rating / 6,000.
- Drying, Baking, Curing Ovens: 100 CFM per square foot of booth cross
section.
- Pickling or Cleaning Tanks: 150 CFM per square foot of door opening
or 200 CFM per square foot of hood face opening. Fan performance curves
and data show how much pressure and airflow a given fan can produce at
a given speed. This data is based on the system resistance (pressure)
occurring away from the fan. Fan performance curves are developed by
fan manufacturers based on the testing of a prototype fan fabricated
based on the theoretical design.
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