Compare
20 vs 24 vs 30 in drum fan CFM classes compared
20, 24, and 30 in high-velocity drum-fan classes with example VEVOR listings and NO_MATCH ceiling.
| Class | Best for | Trade-off |
|---|---|---|
| 20 in / 4,800 CFM | Smaller bays where required CFM ≤ 4,800 (example: 20×25×10 @ ACH 8 ≈ 667 CFM) | Too small when required exceeds 4,800 CFM |
| 24 in / 7,500 CFM | Mid shops with required CFM up to 7,500 (example: 40×30×12 @ ACH 10 ≈ 2,400 CFM still lands early; step up as ACH/volume rise) | Not for required airflow above 7,500 CFM |
| 30 in / 12,000 CFM | Larger consumer spaces within this ladder (required CFM up to 12,000) | Ceiling of this ladder — not for required CFM above 12,000 |
| Above 12,000 CFM required | Very large volumes/ACH past this consumer ladder | NO_MATCH — split zones or use a higher-rated industrial fan |