This article's table of contents introduction:
- Understanding the Material: Q235 Steel
- Typical Centrifugal Fan Models in this Range
- Technical Specifications (Typical for 4-30 kW Q235 Fans)
- Common Applications for Q235 Centrifugal Fans (4-30 kW)
- Important Considerations for Purchasing
- Where to Find These (Typical Chinese Suppliers)
- Final Advice
It appears you are looking for information on centrifugal fans and blowers that are:
- Power Range: 4 kW to 30 kW (motor size).
- Material: Q235 Carbon Structural Steel (a common Chinese standard steel grade, similar to ASTM A36 or S235JR).
- Type: Centrifugal.
Here is a detailed breakdown of what this specification typically means, the common models you will find, and their applications.
Understanding the Material: Q235 Steel
- Q235 is the most common structural steel in China. The "Q" stands for yield strength (235 MPa).
- Properties: It is weldable, ductile, and cost-effective. It is not stainless steel or galvanized steel.
- Implication for Fans:
- Pros: Strong, cheap, easy to manufacture.
- Cons: Will rust if exposed to moisture or corrosive gases. Requires painting (primer + finish) for most industrial applications. Unsuitable for high-temperature exhaust (>300°C / 572°F), acidic fumes, or food-grade environments.
- Common ASTM Equivalent: Q235 is roughly equivalent to ASTM A36 or S235JR (EN 10025) .
Typical Centrifugal Fan Models in this Range
In the 4-30 kW range (approximately 5.5 HP to 40 HP), you are looking at medium to large industrial fans. Here are the most common configurations:
A. Forward-Curved (Squirrel Cage / "SIROCCO") Fans
- Blade Shape: Blades curve in the direction of rotation.
- Performance: High volume, low pressure (50 – 200 mmH₂O).
- Use Case: HVAC, clean air handling, dust collection (pre-filtered), air conditioning units.
- Common Chinese Model: 4-72, 9-19 (some variants), CF (Centrifugal Fan) .
B. Backward-Curved (Backward Inclined) Fans
- Blade Shape: Blades curve away from the direction of rotation.
- Performance: Medium volume, high pressure (200 – 800 mmH₂O). More efficient than forward-curved.
- Use Case: Industrial ventilation, boiler draft, pneumatic conveying.
- Common Chinese Model: 9-26, 4-68, Y5-47.
- Note: The 9-26 model is very common in this power range for high-pressure applications.
C. Radial Blade (Paddle Wheel) Fans
- Blade Shape: Straight radial blades.
- Performance: Low volume, very high pressure, handles dirty/sticky air well.
- Use Case: Woodworking dust, exhaust fumes, material handling.
- Common Chinese Model: 9-19 (High pressure), 9-20.
Technical Specifications (Typical for 4-30 kW Q235 Fans)
- Voltage: 380V / 3-Phase (Standard industrial). 220V single-phase is very rare above 4kW.
- Speed: Usually direct-drive (motor shaft mounted) or belt-driven.
- Direct Drive: Impeller mounted on motor shaft (fixed speed).
- Belt Drive: Allows speed adjustment (pulley change) to alter flow/pressure.
- Flow Rate (Air Volume): Highly variable depending on pressure.
- A 4kW fan may move 3,000 – 10,000 m³/h (1,800 – 6,000 CFM) at low pressure.
- A 30kW fan may move 20,000 – 60,000 m³/h (11,800 – 35,000 CFM) or more.
- Sound Level: Expect 75 – 95 dB(A) depending on speed and blade type. Q235 housing does not dampen sound as well as heavier steel.
Common Applications for Q235 Centrifugal Fans (4-30 kW)
- General Factory Ventilation: Exhausting heat, fumes, or stale air.
- Dust Collection: As the primary suction unit for a central dust collector (with cyclones or bag filters, not direct exhaust).
- Boiler / Kiln Draft: Induced draft (ID) or forced draft (FD) for small to medium boilers.
- Crop Drying: Moving large volumes of warm air through grain bins or tunnels.
- Spray Booths: Providing the airflow to remove overspray particles.
- Air Handling Units (AHU): Moving air through large commercial HVAC systems.
Important Considerations for Purchasing
| Factor | Detail |
|---|---|
| Corrosion | Q235 will rust. If air is humid or contains acidic vapors (e.g., welding fumes), you need epoxy paint or galvanized steel. |
| Temperature | Q235 is safe up to 300°C (572°F). For higher temp, use Q345 or special steel. |
| Balance | Large Q235 impellers (15kW+) must be dynamically balanced (G6.3 or better) to avoid vibration. |
| Bearing Type | For continuous operation (24/7), ask for grease-lubricated bearings with bearing cooling (especially in hot environments). |
| Mounting | Usually on a base frame (steel channel) for stability and belt tension. |
| Inlet Box | Large fans often need an inlet box (scroll housing) to direct air into the impeller eye efficiently. |
Where to Find These (Typical Chinese Suppliers)
If you are sourcing from China (e.g., Made-in-China, Alibaba), look for these standard models with Q235 material:
- High Pressure: 9-19 / 9-26 Series
- Ideal for pneumatic conveying, high-resistance ducts.
- Power: 5.5kW – 37kW (very common in this range).
- Medium Pressure / High Volume: Y5-47 / 4-72 Series
- Ideal for boiler draft, general ventilation.
- Usually belt-driven for speed control.
- Industrial Exhaust: 4-68 Series
Similar to 4-72 but more efficient (backward inclined).
Example Listing: "Q235 Carbon Steel Centrifugal Fan, Model 9-19 No. 6.3A, 15kW, 2900 RPM, 4,500 m³/h @ 3000 Pa"
Final Advice
Q235 is good for clean, dry, room-temperature air. If your application involves moisture, chemicals, or high heat, do not use Q235 – upgrade to 304 Stainless Steel or Galvanized (Q235 with hot-dip galvanizing) .
If you need a specific model selection, let me know your required air volume (m³/h or CFM) and static pressure (Pa or inches of water) , and I can help match the correct Q235 fan size and motor power.
