How to Choose a Centrifugal Fan (CFM, Pressure)
Selecting a centrifugal fan means matching three numbers to your system — airflow, static pressure and voltage — then choosing the motor and impeller that deliver them efficiently. Here is the process SUNXFAN® engineers use.
Step 1 — Airflow (CFM / m³/h)
Start with how much air you must move. As a rough rule, 1 kW of heat load needs about 170–200 m³/h of airflow.
- Residential range hoods: 600–900 m³/h
- Commercial hoods, AHUs: 1000–1700 m³/h
- Data-center racks, high-density cooling: 1500–2500 m³/h
Step 2 — Static pressure (Pa)
Airflow alone is not enough — the fan must overcome the resistance of filters, coils and ducting. If static pressure is too low, airflow collapses.
- Low resistance (open airflow): < 300 Pa
- Medium (filters, short ducts): 300–500 Pa
- High resistance (dense racks, HEPA, long ducts): 500–900 Pa
High Static Pressure Applications
Some systems push static pressure well beyond the medium range, and it helps to recognize them early. Filter banks that load up over months, tightly finned coils, and long duct runs with many bends all add resistance that a low-static fan cannot overcome. Remember that static pressure is quoted in pascals (Pa) and in inches of water column (in.H2O), where 1 in.H2O ≈ 249 Pa — so 500 Pa ≈ 2 in.H2O. If your duct layout looks like a maze of elbows, size the fan for the worst-case loaded condition rather than the as-installed one.
Step 3 — Voltage & motor type
- EC — best efficiency (>85%), stepless 0-10V/PWM; default for 24/7 duty.
- DC — 24V/48V/310V for battery, portable or central-DC designs.
- AC — lowest up-front cost; use for intermittent duty.
- Voltage by market: 115V AC (North America), 230V AC (Europe/global), 310V DC (DC-bus systems).
Step 4 — Speed control, noise, protection
Match control to the application (0-10V/PWM, 0-5V, 0-6.5V, Modbus RTU, 3/4-speed) and confirm noise and IP rating where the environment is sensitive or wet.
Quick reference by series
| Series | Impeller | Best for | Airflow | Max static |
|---|---|---|---|---|
| CF (forward-curved) | forward-curved | High static, compact | 320–1100 m³/h | up to 905 Pa |
| SF146A / SF146D (dual-inlet) | dual-inlet | Range hoods, AHUs | 720–1200 m³/h | — |
| SF146C (EC forward-curved double-inlet) | forward-curved double-inlet | Ducted, IP44 | 1150–1200 m³/h | up to 705 Pa |
| SF160D / SF235 (large dual-inlet) | dual-inlet | High CFM extraction | 1200–1690 m³/h | — |
| DG200 | centrifugal | Compact EC/DC | 1050–1300 m³/h | up to 500 Pa |
| BC280 / BC310 (backward-curved) | backward-curved | Data center, high static | 1540–2500 m³/h | up to 715 Pa |
Bottom Line
Work the four steps in order: airflow → static pressure → voltage → control. If you are unsure of your system’s pressure drop, send us the duct layout, filter type and heat load, and we will size the fan and confirm the model, voltage and speed-control configuration.
Last updated: 2026-11-02