Fan and System Curve Operating Point Calculator
Find the positive operating intersection of a quadratic fan curve and an entered static-plus-quadratic system curve.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Fit a fan parabola from shutoff/free flow, fit the system coefficient from its reference point and solve the intersection analytically.
Pfan=P0−(P0/Qfree²)Q²; Psystem=Pstatic+kQ²
Worked example
Fan shutoff 500 Pa and free flow 1 m³/s, with system 500Q² Pa, intersect at Q=√0.5≈0.707107 m³/s and pressure 250 Pa.
Assumptions and input details
Fixed speed/density and approximate quadratic curves only. System reference pressure must exceed its static term. Static pressure at or above shutoff has no positive forward-flow intersection in this model. Shaft power is fluid power divided by your entered efficiency. Real measured fan maps, stall, reverse flow, sound, motor limits and duct compliance are not assessed.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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