⚠️ Engineering Disclaimer

Methodology

DuctStatic uses the total pressure loss method, the standard approach for HVAC duct system design. Calculations are based on primary engineering references:

• Idelchik, I.E. Handbook of Hydraulic Resistance, 4th Ed. Begell House, 2007. Fitting loss coefficients (Co) for elbows, tees, transitions, and other fittings.
• Rozell, T.C. "Pressure Losses in Duct Fittings." ASHRAE Transactions, 1974. Vaned rectangular elbow data.
• Colebrook, C.F. "Turbulent Flow in Pipes." Journal of the Institution of Civil Engineers, 1939. Friction factor for straight duct runs (Darcy-Weisbach / Colebrook-White).
• Sutherland, W. "The Viscosity of Gases and Molecular Force." Philosophical Magazine, 1893. Air viscosity as a function of temperature.

Loss coefficients are computed dynamically from the geometry you enter, not looked up from a fixed table, so results reflect your actual duct dimensions rather than a nearest tabulated size. For a full description of the calculation method, see the Calculation Method page.

Limitations

• Estimates only: Results are approximations based on idealized flow conditions. Program accuracy is highly dependent on user-supplied data.
• Not a substitute for engineering judgment: Real-world factors including installation quality, material variations, system interactions, and turbulence effects are not fully captured by any analytical model.
• Professional verification required: Calculation results are meant to aid the system designer and are not a substitute for design services, judgment, or experience. All designs must be reviewed and approved by a licensed professional engineer.
• Scope: This tool calculates duct pressure loss only. It does not perform equipment selection, load calculations, energy analysis, or full system design.

Limitation of Liability

DuctStatic is intended as a design-assist tool to help engineers estimate duct system pressure loss. It is the user's responsibility to understand how the data entered affects program output.

THE DEVELOPER, IN PROVIDING THIS TOOL, ACCEPTS NO RESPONSIBILITY OR LIABILITY FOR THE SUITABILITY OF ANY HVAC SYSTEM DESIGNED WITH ITS ASSISTANCE IN PROVIDING PROPER TEMPERATURE CONTROL, HUMIDITY CONTROL, AIR DISTRIBUTION, OR ANY OTHER DESIGN OBJECTIVE.

THE DEVELOPER SHALL NOT BE LIABLE FOR ANY CLAIMS, CAUSES OF ACTION, OR DAMAGES ARISING OUT OF OR ALLEGED TO ARISE OUT OF THE USE OR INABILITY TO USE DUCTSTATIC. UNDER NO CIRCUMSTANCES WILL THE DEVELOPER BE LIABLE FOR ANY INCIDENTAL, CONSEQUENTIAL, OR SPECIAL DAMAGES, REGARDLESS OF THE LEGAL THEORY ADVANCED.

No Warranty

This tool is provided "as-is" with no guarantees of accuracy, completeness, or fitness for any particular purpose. The developer makes no representations regarding the correctness of results for any specific application.