Fan Selection & System Curve Analyzer
Estimate air-system pressure and power, then compare a sourced user fan curve.
Engineering use case
For an AHU at 2 m³/s with 300 Pa static pressure and 200 Pa losses, review the 500 Pa duty before comparing a sourced fan curve.
Method & limitations
Volumetric airflow Q (m³/s) is used directly. This engine does not convert airflow to velocity (V = Q/A is outside this tool). Design total pressure is Δp = Δp_static + Δp_loss. The air-system curve is Δp(Q) = Δp_static + K Q², with K = Δp_loss,design / Q_design² (K = 0 when design loss is 0). Air power is P_air = Q_design · Δp, in watts when Q is m³/s and Δp is Pa. Estimated input power is P_in = P_air / (η_fan · η_motor). Efficiencies are user-entered fractions in (0, 1]; omitted values default to 0.65 and 0.90 and are not back-calculated. A fan curve must be manufacturer or other external user data. This engine does not generate or certify it. The operating point is a linear interpolation where the user curve crosses Δp(Q); no crossing inside the supplied flow range means no operating point. Preliminary screening only: fan-law scaling, density correction, system effect, sound, controls and certified selection are out of scope.
Formulas, source and scope
Formula source: site methodology / engineering assumption in this repository. No standard edition is pinned for this tool.
FAQ
Why is velocity not on this page?
The engine takes volumetric airflow directly and does not divide by area. Use the duct tool when you need velocity.
Can I select a fan without a manufacturer curve?
You can screen pressure and power. The engine will not invent an operating point. Add at least two sourced curve points for a comparison.