Mixed-air humidity ratio from OA fraction

Oct 16, 2026 · America/New_York

psychrometricsPE

A 100% outdoor-air lab AHU is converted to 25% outdoor air by mass. Outdoor-air humidity ratio is 110.0 gr/lb; return air is 62.0 gr/lb. Neglect leakage and condensation. What is the mixed-air humidity ratio?

Practice only — not PE exam credit, not an NCEES item, not a PE stamp, and not a substitute for licensed professional judgment or licensure. Original workbench questions for discussion. Verify against current codes and your own calculations. Terms