Fan Affinity Laws Calculator

Input Parameters

Imperial (°F, BTU, ft)SI (°C, kW, m)

Original Flow Rate (CFM)

Original Speed (RPM) (RPM)

Original Pressure (in WG)

Original Power (BTU/hr)

New Speed (RPM) (RPM)

8,571

New Flow Rate CFM

New Pressure in WG

New Power BTU/hr

Flow Ratio

Pressure Ratio

Power Ratio

Formula:

R_{speed} = \frac{N_2}{N_1}

Calculation:

R_{speed} = \frac{1500}{1750}

Result:

0.857 \text{ }

Formula:

Q_2 = Q_1 \times \frac{N_2}{N_1}

Calculation:

Q_2 = 10000 \times 0.857

Result:

8571 \text{ CFM}

Formula:

P_2 = P_1 \times \left(\frac{N_2}{N_1}\right)^2

Calculation:

P_2 = 4.00 \times 0.857^2

Result:

2.94 \text{ in WG}

Formula:

W_2 = W_1 \times \left(\frac{N_2}{N_1}\right)^3

Calculation:

W_2 = 10.00 \times 0.857^3

Result:

6.30 \text{ BTU/hr}