This article's table of contents introduction:
- Critical Missing Information: Static Pressure (ΔP)
- Recommended Fan Type
- Estimated Performance Data (at 34,000 m³/h, 2,000 Pa)
- Key Selection Checklist for this Fan
- Sizing the Motor & Electrical
- Summary Recommendation
This is a request for the selection or specification of an exhaust fan for a dust collector system, handling 34,000 m³/h (cubic meters per hour) of air.
This is a high-volume airflow rate (approx. 20,000 CFM). To give you a useful answer, I need to break this down based on the type of dust collector involved, as this dictates the fan pressure requirement.
Here is the professional analysis for selecting a fan for 34,000 m³/h.
Critical Missing Information: Static Pressure (ΔP)
The fan must overcome the Static Pressure of the system.
- Fan Power (kW) = (Flow m³/s × Total Pressure Pa) / (Fan Efficiency × 1000)
You need to determine the system resistance. Typical values for 34,000 m³/h:
- Baghouse or Cartridge Collector (high pressure drop):
- New filters: ~1,500 Pa (6" w.g.)
- Dirty filters (design point): 2,000 to 2,500 Pa (8" to 10" w.g.)
- Result: Requires a medium-to-high pressure fan (Backward Curved or Airfoil).
- Cyclone Separator:
- Pressure drop: 1,000 to 1,500 Pa (4" to 6" w.g.)
- Result: Lower pressure fan acceptable.
- Simple Duct exhaust (low resistance):
- Pressure drop: 500 to 800 Pa (2" to 3" w.g.)
- Result: Standard vane-axial or low-pressure centrifugal.
Assumption for this answer: I will assume this is for a standard industrial Baghouse or Cartridge Dust Collector with a dirty filter static pressure of 2,000 Pa (8" w.g.).
Recommended Fan Type
For 34,000 m³/h at 2,000 Pa, the most efficient and durable option is:
Centrifugal Fan, Backward-Curved (BC) or Backward-Inclined (BI)
- Why: These fans are non-overloading (motor won't burn out if duct gets clean), highly efficient (80-85%), and handle dust-laden air better than airfoil blades.
- Preferred Material: Carbon Steel with a wear-resistant coating or liner (e.g., Ceramic epoxy or AR plate) on the impeller and casing due to the high volume of dust.
- Speed: Will likely operate at 1,000 to 1,200 RPM (driven by belt or direct drive depending on motor kW).
Alternative (for less dusty air or lower pressure):
- Vane-Axial Fan: Only if pressure is <800 Pa. Not suitable for high static pressure.
- Industrial Exhaust Fan (Tube-Axial): Only for fume dilution, not for ducted collection.
Estimated Performance Data (at 34,000 m³/h, 2,000 Pa)
| Parameter | Value | Unit |
|---|---|---|
| Airflow | 34,000 | m³/h |
| 20,000 | CFM | |
| Static Pressure | 2,000 | Pa |
| 0 | in w.g. | |
| Estimated Shaft Power | ~27 - 30 | kW |
| Motor Power (Recommended) | 30 - 37 | kW |
| Motor Speed | 1,200 - 1,470 | RPM |
| Inlet Diameter | ~700 - 800 | mm |
| Outlet Area | ~0.25 - 0.35 | m² |
- Power Calculation (Rough):
- Flow = 34,000 m³/h ÷ 3,600 = 9.44 m³/s
- Power = (9.44 m³/s × 2,000 Pa) ÷ (0.80 Efficiency × 1,000) = 6 kW
- *(Add 15-20% safety margin for drive losses & dirty filters) = ~28 kW → Select 30 kW or 37 kW motor.
Key Selection Checklist for this Fan
When ordering or specifying the fan, provide the manufacturer with:
- Air Volume: 34,000 m³/h (Always specify at what temperature and altitude. Standard = 20°C at sea level).
- Static Pressure: _ Pa (You must get this from your duct/filter design).
- Dust Type: (e.g., Wood, Cement, Metal Grinding, Food Powder). This dictates wheel type and spark resistance.
- Temperature: (Ambient? High temp? Exhaust from a dryer?).
- Motor Mount: Direct Drive vs. Belt Driven (Belt allows speed change, Direct uses less maintenance).
- Accessories:
- Inlet Box (for smooth airflow from the collector).
- Vibration Isolators (Spring or Rubber).
- Variable Frequency Drive (VFD) (Highly recommended for 30kW+ motors to control soft start and adjust flow).
- Flow Switch / Pressure Transmitter (to monitor filter condition).
Sizing the Motor & Electrical
- Full Load Amps (FLA): For a 30kW motor (3-Phase, 400V, 50Hz) ≈ 55-60 Amps.
- Cable Size: Minimum 16 mm² or 25 mm² (subject to distance).
- Starter: Must be Soft Start or VFD. A Direct-on-Line (DOL) starter for a 30kW fan will cause a massive current surge and mechanical shock on the belts/dust collector.
Summary Recommendation
"Specify a 34,000 m³/h Backward-Curved Centrifugal Fan, rated for 2,000 Pa (8" w.g.), with a 30 kW motor, belt-driven, mounted on a steel base with vibration isolators. Include a VFD for speed control and filter conditioning."
Next step: Confirm the actual static pressure loss of your specific dust collector and ductwork layout. If your pressure is higher (e.g., 2,500 Pa), you will need a 37 kW motor.
