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Fan Laws Airflow, Pressure & Horsepower Calculator

Easily calculate and compute fan laws airflow, pressure & horsepower calculator with accurate equations, live formulas, and expert guidance.

Baseline airflow rate.

Baseline system static pressure.

Baseline motor brake horsepower.

Speed change ratio (e.g. 1.20 = 20% RPM speedup).

Calculated Result
9,600 CFM

New Airflow (Q₂)

New Airflow (Q₂)

9,600 CFM

New Airflow Q2 Cfm

9600

New Static Pressure P2 In Wg

2.88

New Brake Horsepower Bhp2

7.78

Motor Power Increase Percent

72.8

9,600 — CFM

Calculation Breakdown

  1. Applied FormulaApplies aerodynamic affinity Fan Laws to predict new airflow rates, static pressures, and cubic motor brake horsepower demand when altering fan impeller RPM.\frac{Q_2}{Q_1} = \frac{N_2}{N_1}, \quad \frac{P_2}{P_1} = \left(\frac{N_2}{N_1}\right)^2, \quad \frac{BHP_2}{BHP_1} = \left(\frac{N_2}{N_1}\right)^3

HVAC Fan Laws Metric Output

Interactive visualization based on your current inputs

Calculated Value
0.02.4k4.8k7.2k9.6kNew Airflow (Q₂)

What Is the Fan Laws Airflow, Pressure & Horsepower Calculator?

This tool computes fan laws airflow, pressure & horsepower calculator with high precision arithmetic.

How Does the Fan Laws Airflow, Pressure & Horsepower Calculator Work?

Applies aerodynamic affinity Fan Laws to predict new airflow rates, static pressures, and cubic motor brake horsepower demand when altering fan impeller RPM.

Fan Laws Airflow, Pressure & Horsepower Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

Q2Q1=N2N1,P2P1=(N2N1)2,BHP2BHP1=(N2N1)3\frac{Q_2}{Q_1} = \frac{N_2}{N_1}, \quad \frac{P_2}{P_1} = \left(\frac{N_2}{N_1}\right)^2, \quad \frac{BHP_2}{BHP_1} = \left(\frac{N_2}{N_1}\right)^3

Applies aerodynamic affinity Fan Laws to predict new airflow rates, static pressures, and cubic motor brake horsepower demand when altering fan impeller RPM.

How to Use the Fan Laws Airflow, Pressure & Horsepower Calculator

  1. Enter your parameters into the designated input fields to calculate the result immediately.

Step-by-Step Example Calculation

Fan Laws Airflow, Pressure & Horsepower Calculator Example

Input Values:

baselineAirflowQ1Cfm:8000.0
baselineStaticPressureP1InWg:2.0
baselinePowerBhp1:4.5
targetSpeedRatioN2OverN1:1.20
Worked Steps: Sample evaluation based on standard reference conditions.

Understanding Your Result

The calculated primary figure indicates the optimal or required CFM.

Factors That Affect the Result

  • Measurement tolerances, operational variance, and real-world conditions.

When Should You Use This Calculator?

  • Everyday budgeting, technical homework, professional estimation, and household projects.

Assumptions & Limitations

  • Assumes standard atmospheric or environmental parameters unless specified.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Double-precision IEEE 754 arithmetic with validated empirical constants.

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