Every hydrocarbon or ethanol extraction room has to move a code-minimum volume of air, continuously, with the intake low and an alarm that boosts the fan before a leak reaches a quarter of the lower explosive limit. This calculator takes the room dimensions, the solvent, and the solvent inventory and returns the exhaust CFM, the air changes per hour, the alarm point in ppm, a worst-case release check, and the installed cost range, using the same figures as the C1D1 room requirements guide and the CO2 extraction room design guide. It is a planning estimate; the engineer of record and the AHJ set the final number.
Read this before you use the number. The prescriptive figures in this calculator come from the code sections cited in the two guides linked above. The dilution and worst-case release figures are a planning estimate built on a fixed release assumption. A real vapor generation rate depends on the solvent’s vapor pressure at the room temperature, the pool area and the airflow across it, and that is the calculation a licensed engineer runs in the process hazard analysis, not a number this page can produce for your room. Use the output to size the conversation with your engineer of record and your AHJ, not to size the fan. Updated October 21, 2026 after review by a fire protection engineer on the NFPA 420 committee.
C1D1 Ventilation Calculator
Room dimensions, extraction solvent, and solvent inventory in, then: minimum exhaust CFM, air changes per hour, design target, alarm point in ppm, worst-case release check, and an installed-cost range.
C1D1 room requirements guide,
the C1D1 vs C1D2 classification guide,
and the CO2 room design guide.
Building one? Talk to WKU Consulting before the drawings go to the fire marshal.
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Copy and paste this code into any page. The calculator stays current as WKU updates the code figures; the attribution link must remain.