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How To Measure Air Volume - Amount Of Exhaust

Machines require properly balanced exhaust for safe and efficient machine operation. Exhaust velocity pressure should be measured in the center of the straight section with a Pitot tube and manometer. This can then be converted to exhaust flow and balanced with the blast gates according to the EDS specifications for each type of machine. Note that dampers should be installed downstream of the smooth, straight section of ducting for proper balancing. It is important that the pressure measurement be taken in a long, straight section of duct with no restrictions or transitions (elbows, tees, etc.) near the point of measurement. Refer to the diagram below.

Air velocity is rarely uniform in an air duct since the shape of the duct, frictional forces, bends, branches, dampers and transitions all affect the movement of air.  For this reason, several velocity measurements should be taken in the cross-sectional area of a duct to ensure the most accurate estimate of average velocity is determined.  

An Exhaust Flow Calculator has been attached for your use.

Michael is the author of this solution article.

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