DFO-103 - page 6

Select a fan for 20,000CFMat 3" SP.The intersectionof 20,000CFMand3"
SPshows aSize365as themost efficient fan.
Havingselected themost efficient fan, refer to themulti-rating table for that fan,
either theDesign51or theDesign51RA, and find thespeedandhorsepower
required todeliver theCFMandSPspecified.Comparisonof bothdesigns is
Often themost efficient fan isnot themost practical selectionbecauseof available
space, initial cost, or other considerations. Smaller fan sizes,including the RA
models, shouldbe considered.
Energy consumption is often amajor
consideration in every engineer’s
equipment selection procedure. This
Chicago Quick Selection Method
selects themost energy efficient fan
size for any requiredduty.
To determine the most efficient fan
size, locate the intersection of the
required volume (CFM) and static
pressure (SP) on the graph below.
Theareacontaining the intersection is
labeledwith themost efficient fansize.
For theEnergy
Efficient Fan
1,2,3,4,5 7,8,9,10,11,12,13,14,15,16,...52
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