Smoke Ejector / Ventilation CFM (NFPA 1500)
Required CFM for a target air-change rate, fans needed, time to one air change, and the exhaust-to-entry opening ratio for negative-pressure ventilation. SOP and incident command govern.
Formula and source
Required CFM = volume × ACH / 60. Fans = ceil(required CFM / per-fan rating). Time to one air change = volume / actual CFM. Exhaust-to-entry opening ratio drives PPV efficiency (1:1 to 1.5:1).
NFPA 1500 §8.5 (apparatus and equipment) by name; IFSTA Essentials of Fire Fighting ventilation chapter by name.
Audience
This tile is built for fire-ground and the adjacent professions in the Fire-Ground Engineering group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.