How to Choose Cabinet Cooling Fan Airflow: Formula & 3 Real Cases
The most common formula for control cabinet cooling airflow is Q = P ÷ (ρ × cp × ΔT), where Q is airflow (m³/h), P is total heat load inside the cabinet (W), and ΔT is allowed temperature rise (℃). For industrial applications ρ×cp ≈ 1.2, simplified to Q ≈ P × 2.0.
Selection Formula
Q (m³/h) = Total heat load P(W) × 2.0 ÷ Allowed temperature rise ΔT(℃)
Rule of thumb: keep cabinet temperature rise within 15℃ → Q ≈ 1.3 × P; keep it within 10℃ → Q ≈ 2.0 × P.
3 Real Cases
Case 1: PLC Control Cabinet (300W heat load)
ΔT = 15℃, Q ≈ 300 × 1.3 = 390 m³/h ≈ 230 CFM
Recommendation: one 17251 axial fan, or two 12038 fans in parallel.
Case 2: VFD Cabinet (800W heat load)
ΔT = 10℃, Q ≈ 800 × 2.0 = 1600 m³/h ≈ 940 CFM
Recommendation: two 17251 axial fans blowing against each other (one intake, one exhaust), or one centrifugal fan.
Case 3: Energy Storage BMS Cabinet (1500W, 24/7 operation)
Recommendation: two EC 17251 EC fans, automatically speed-controlled by BMS temperature, saving ~70% on electricity vs AC fans annually.
More models: AC axial fan product list, EC axial fan product list. For filtered ventilation, see cabinet filter fans.
Not sure how to estimate cabinet heat load? Send us the power ratings of major components (PLC/VFD/power supply), or contact us for a free selection proposal.
Frequently Asked Questions
If I calculate 390 m³/h airflow, should I just pick a 390 m³/h fan?
No. Add a 20%-30% margin, because airflow drops as the cabinet filter clogs. Select a fan rated 470-500 m³/h instead.
Should the fan be mounted on top or on the side?
Hot air rises naturally, so top-mounted exhaust works best. If mounted on the side, arrange intake and exhaust on opposite sides to create airflow convection, not on the same side.
Do I need to oversize the fan if the cabinet has a filter?
Yes. A new filter adds 30-50 Pa resistance, and it can exceed 100 Pa once dusty. Check the fan's P-Q curve for actual airflow at 100 Pa static pressure, not free-air delivery.
What if the fan is too noisy?
Prefer speed-matching to actual load instead of upsizing the fan. EC fans support PWM speed control and automatically slow down and quiet down when temperatures are low.
What protection rating for outdoor or seaside cabinets?
Use IP54 or higher for outdoor or dusty environments. JIEFENGFAN offers IP54 versions paired with cabinet filter fans (louvers + filter) to keep dust and rain out.