Smokelayer: free online fire dynamics calculator

Smokelayer runs the classic fire-dynamics hand calculations in one browser workbench. Describe a design fire as a t-squared growth, a steady fire or your own table, then read plume temperatures and mass flows, the ceiling-jet temperature and the time a sprinkler or heat detector with your RTI and rating would operate, the hot-layer temperature of a room, flashover heat release rates, smoke filling of a room or atrium, the exhaust that holds a clear height, and basic stair pressurisation with door-opening forces.

It is an educational and screening tool, not a code-compliance check or a design approval. Every correlation shows its assumptions, range and public source (NRC and NIST reports), results outside a stated range are flagged, criteria are always your own inputs, and the Verify page reproduces published worked examples in your browser.

What Smokelayer can do

t-squared, steady and tabulated design fires with energy released
Heskestad and McCaffrey plume temperatures, velocities and mass flow
Alpert ceiling jet and RTI sprinkler or heat-detector activation for growing fires
MQH, FPA, Deal and Beyler and Beyler hot-layer temperatures; flashover HRR estimates
Smoke filling by correlation and by a zone balance, and steady smoke exhaust
Stack effect, stair pressure profile, height limit, supply air and door-opening force
Open JSON study files, CSV results in SI or US units, print, undo and redo

How we verify Smokelayer

Reference checks count distinct relations, not cases: each relation is checked against published worked examples from US government reports or against an independent derivation, with its own provenance. Pending sources do not count as passes; the Verify page lists every case and comparison. Where a reference answer exists you can run every check yourself on the Verify page, and the Smokelayer user guide documents every feature and limitation.

The Verify page runs the same case list that the automated tests run. Validation cases reproduce published worked numbers from public US-government reports: the NRC Fire Dynamics Tools spreadsheets and their printed examples, NIST reports NISTIR 5516 and NISTIR 4551, and NBS reports. Verification cases compare the engine with independent derivations: closed forms, conservation laws, numerical quadrature and a separate integrator, including a step-size study of the detector integrator. Each case shows its inputs, its source, its tolerance and why that tolerance is appropriate. A case whose source could not be opened is shown as pending source with no numbers.

Smokelayer is part of Open Tools, the free engineering tools that run in your browser.

Professional use. Results are for education and preliminary design. They must be checked by a qualified professional, and they are not a substitute for code-compliant design or licensed engineering judgement.