Quick Answer
Calculate Circular Duct Diameter via Equal Friction Method (ASHRAE Fundamentals)
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Find Engineering Solutions →Result Interpretation
Circular Duct Diameter via Equal Friction Method (ASHRAE Fundamentals) calculator computes Duct Internal Diameter in m using the defined engineering formula and the input values provided. Duct Internal Diameter is expressed in m. No universal acceptance threshold is defined by this calculator.
Worked Example
Verified calculation
Given:
- Air Volume Flow Rate = 0.5
- Design Air Velocity = 5
Expected Result:
- Duct Internal Diameter = 0.35682208977309
Engineering Interpretation:
Under the given input conditions, the calculated result is: Duct Internal Diameter = 0.35682208977309 m.
The actual numerical result is computed by the Runtime engine using the persisted tool definition. The values shown here come from automatically validated test cases.
Formula / Method
duct internal diameter = pow((4.0 * air volume flow rate / (3.14159265358979 * design air velocity)), 0.5)Formula family: formula_hvac_hvac_duct_sizing_calculator_circular_duct_equal_friction_method
Variables
| Symbol | Label | Role | Description |
|---|---|---|---|
| airflow_volume | Air Volume Flow Rate | INPUT | Air Volume Flow Rate |
| air_velocity | Design Air Velocity | INPUT | Design Air Velocity |
| duct_diameter | Duct Internal Diameter | OUTPUT | Duct Internal Diameter |
Calculation Steps
- Enter the air volume flow rate in m^3/s.
- Enter the design air velocity in m/s.
- Step 1: Compute duct internal diameter.
- Read the duct internal diameter (m) from the results.
Engineering Summary
Calculate Circular Duct Diameter via Equal Friction Method (ASHRAE Fundamentals)
Frequently Asked Questions
What does this calculator calculate?
The Circular Duct Diameter via Equal Friction Method (ASHRAE Fundamentals) calculator estimates Duct Internal Diameter based on the input parameters you provide
Why is air volume flow rate important in this calculation?
air volume flow rate is used directly in the calculation of duct internal diameter. Its effect on the result depends on the complete formula and the values of the other inputs.. When you enter air volume flow rate in m^3/s, the calculator uses it in the engineering formula to compute the output
How should I interpret the result duct internal diameter?
The calculator outputs duct internal diameter in m. The result is computed directly from the input values using the defined engineering formula
What units should I use for the inputs?
Enter each value in the units shown next to the input field: Air Volume Flow Rate (m^3/s), Design Air Velocity (m/s). Make sure all inputs use the specified units for consistent results
What assumptions does this calculator use?
This calculator uses automatically validated engineering formulas. Results are approximate and should be validated against site-specific conditions, applicable codes, and professional engineering judgment
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