Manual D Friction Rate (Available Static Pressure)
ASP = blower ESP - component drops, friction rate FR = ASP x 100 / total effective length (in wg/100 ft). 0.60 ESP, 0.42 drops, 180 ft TEL -> 0.18 ASP, 0.10 FR (a healthy target); a 300 ft run softens it to 0.06, needing larger ducts. Drops above the blower static flag an unworkable system. The full Manual D layout governs.
Formula and source
ASP = blower_ESP - component_drops; FR = ASP x 100 / TEL (in wg per 100 ft).
The ACCA Manual D friction rate (available static pressure over total effective length), by name.
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