Commercial Make-up Air System

By Author: Oleg Tchetchel
Total Articles: 31
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When exhaust fans are used to provide ventilation, both for industrial and process exhaust and personnel comfort, a negative air pressure is created within the building. This negative pressure causes several problems:

- Process exhaust systems are less efficient and may not work properly.
- Down flow can occur through gravity vents and result in the back venting of products of combustionfrom flues and stacks of heaters and process equipment.
- Drafts are created that are a dsicomfort to employees. Safe operating of outside doors may even be impaired.

Buffalo Fan Co. makes a PT Power Tube Make-Up Air System a sone of the most economical options for larger industrial plants ventilation air make up.

Our Power Tube Fan Make-Up Air System solves all of these problems economically, even on the coldest winter day.

In the winter, conventional make-up air systems have to heat the cold outside air prior to introduction into the building. This is an expensive process in both equipment and continuing energy cost. The Power Tube Fan Make-Up Air System is a simplier system that utilizes wasted building ...
... heat and basic aerodynamic principles for supplying, tempering and distributing make-up air. And that makes it less expensive than conventional make-up air systems to purchase, to install and to operate.

PT Power Tube Fan Make-Up Air System uses a special propeller fan with straightening vanes and fan housing mounted to an opening in a building sidewall near the ceiling (an optional roof mounting model is available). A motor operated wall shutter is attached to the outside wall opening under a protective weather hood. A long specially constructed reinforced polyethylene tube is connected to the fan discharge orifice to carry fresh outside air throughout the building and temper it by mixing cold outside air with warm inside air near the plant ceiling before it reaches floor level.

Specially sized and spaced discharge holes in the polyethylene tube produce relatively high velocity turbulent jets of air. This turbulent jet flow swirls and mixes surrounding air particles resulting in the entrinment of the warm ceiling air and the complete tempering of very cold outside air within a relatively short distance. The result is heated make-up air at the price of unheated make-up air.

Power Tube Make-Up Air Fans are available in Sizes 18 to 48 for for air flows up to 40,000 CFM.

PT Power Tube Make-Up Air System tube is constructed of thick woven high density polyethylene fiber(8 x 8) laminated with poly coating to a thickness of 6 Mils. It is 3.8 oz. per square yeard material. Burst strength is 118 Lbs per square inch. The material is flame retardant and complied with NFPA Standard 701. Tubes are available in two colors: blue and white. One end of the polyethylen tube is factory dealed.

Sufficient make-up air should be provided to balance exhaust from general ventilation and process ventilation. Usually several Power Tube Fans will be required, located to distribute air throughout the plant. If additional tempering of make-up air in specific plant areas becomes necessary, unit heaters can be added.

Additional information can be found at the Buffalo Fan Co. web site http://www.buffalofan.com/custserv.html.

Oleg Tchetchel
Canadian Process Air Systems Designer
Buffalo Fan Co.
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