How do I calculate discharge cone pressure drop?

Enter exhaust volume flow, stack diameter, and discharge configuration. The calculator applies DW172 discharge coefficient guidance.

Why does discharge configuration matter?

Discharge velocity, cone angle, and wind effects affect system resistance and environmental dispersion. Higher discharge velocity increases pressure drop.

How does this relate to kitchen canopy sizing?

Canopy extract sets the volume flow; stack discharge adds resistance that the fan must overcome. Size both together on the same system.

BuildFlo Design Guide · Ventilation · DW172

Kitchen exhaust stack discharge calculator

Calculate kitchen exhaust discharge cone pressure drop per DW172 guidance. Free stack discharge calculator for commercial kitchen ventilation.

What this calculator does

Stack discharge helps UK building services engineers with kitchen exhaust discharge cone δp and dw172 main / cone sizing. The calculation follows DW172 methods used in everyday MEP design — enter your project inputs below for a first-pass result.

Whether you searched for "stack discharge", "stack discharge calculator", or "how to stack discharge", this page gives you a working tool plus the context to use it on a real job.

When to use it

Use this for early-stage sizing and sanity checks on UK building services work. It is not a substitute for issued calculations — verify against the project specification, drawings, and relevant standard before sign-off.

How to use it

1. Fill in the inputs for your scenario (defaults are starting points only). 2. Click Calculate — results include the method and assumptions where applicable. 3. Verify against the project specification and relevant standard before issuing.

Typical output unit: Pa.

Tips

Defaults are indicative — replace with project-specific values from the architect, structural, or MEP spec.
For issued calculations, save results in your BuildFlo project and attach to the calculation folder.
Need the regulation citation? Open BuildFlo chat in the app and ask about stack discharge under UK standards.

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Frequently asked questions

How do I calculate discharge cone pressure drop?: Enter exhaust volume flow, stack diameter, and discharge configuration. The calculator applies DW172 discharge coefficient guidance.
Why does discharge configuration matter?: Discharge velocity, cone angle, and wind effects affect system resistance and environmental dispersion. Higher discharge velocity increases pressure drop.
How does this relate to kitchen canopy sizing?: Canopy extract sets the volume flow; stack discharge adds resistance that the fan must overcome. Size both together on the same system.