High Speed 0-3000rpm Boiler Fan With Pressure 20000Pa And Noise 85dB

This article's table of contents introduction:

1. Feasibility & Technical Constraints
2. Recommended Fan Type
3. Example Specification (CUSTOM)
4. Noise Control Strategy (To hit ≤85 dB)
5. Potential Manufacturers to Contact
6. Critical Warning: "Surging" & Application
7. Summary: "Yes, it's possible, but not standard."

To find a High-Speed (0-3000 RPM) Boiler Fan meeting Pressure ≤ 20,000 Pa and Noise ≤ 85 dB(A) , you are typically looking at a forced draft (FD) or primary air fan for industrial boilers or high-efficiency burners. Standard axial fans cannot achieve 20,000 Pa; you need a centrifugal fan (Backward Curved / Airfoil or a specialized High-Pressure Radial type).

Here is a technical breakdown of how to source or specify this fan:

Feasibility & Technical Constraints

• Pressure (20,000 Pa = ~2,000 mmWC or ~80.5 in WC): This is very high pressure. At 3,000 RPM, a standard centrifugal fan would require a very large diameter or a multi-stage design to hit this pressure.
• Noise (≤85 dB(A)): This is the hardest constraint. A standard backward curved fan at 3,000 RPM generating 20,000 Pa is almost guaranteed to exceed 85 dB(A). To meet this, you need:
  • Low Tip Speed: A larger impeller diameter running at 1,500 - 1,800 RPM might be quieter, but you specified 0-3000 RPM.
  • Acoustic Insulation: The fan casing must be double-walled or lined.
  • Silencers (Inlet/Outlet): Must be included in the system design.
• Speed (0-3000 RPM): Requires a VFD (Variable Frequency Drive) . Continuous operation at 3,000 RPM for 20,000 Pa is impractical for standard light-duty fans. You need a high-speed, heavy-duty rotor.

Recommended Fan Type

Centrifugal Fan – Backward Curved / Airfoil (BC/BA) OR High-Pressure Radial

Recommendation: Backward Curved (Airfoil) Centrifugal Fan with a High Efficiency Motor (IE4/IE5) and VFD.

Example Specification (CUSTOM)

You cannot buy this "off the shelf" as a standard fan. You must contact a manufacturer with this spec:

Sizing for a Manufacturer:

• Item: High Pressure Boiler Forced Draft Fan
• Air Volume (Flow): [You must specify this - e.g., 10,000 m³/h or 50,000 m³/h]
• Total Pressure: 20,000 Pa (2,000 mmWC)
• Operating Speed: 3,000 RPM (max) - VFD controlled.
• Noise Limit: 85 dB(A) at 1 meter (free field). Manufacturer must add silencers to achieve this.
• Max Tip Speed: Must be limited (e.g., < 100 m/s to keep noise down).
• Motor: 4-pole (1,500 RPM base) or 2-pole (3,000 RPM base) with VFD.
• Casing: Heavy-duty steel.
• Accessories: Inlet silencer, outlet silencer, flexible connection.

Noise Control Strategy (To hit ≤85 dB)

Because 85 dB is very low for a fan generating 20,000 Pa at 3,000 RPM:

1. Oversize the Fan: Select a fan that achieves the pressure at a lower RPM than 3,000. For example, if a fan hits 20,000 Pa at 2,200 RPM, operate it at 2,200 RPM max. (This lowers tip speed and noise).
   • Rule of Thumb: Noise drops ~15-20 dB if speed is halved.
2. Housing: The fan casing must be of acoustic construction (e.g., 3mm steel inner shell + 50mm mineral wool + 1.5mm perforated steel outer shell).
3. Duct Silencers: Install rectangular or tubular duct silencers on both the inlet and outlet. These are large and pressure-dropping (maybe 200-400 Pa), so you must request a fan pressure of 20,400 Pa to account for silencer loss.

Potential Manufacturers to Contact

These companies build industrial, high-pressure centrifugal fans for boilers:

• New York Blower (USA) – High Pressure Series 20 or 21.
• Howden (Global) – Forced Draft fans.
• Cincinnati Fan (USA) – HP Series (Radial).
• Ziehl-Abegg (Germany) – High pressure Centrifugal.
• Greenheck (USA) – Industrial Process fans.
• China / Asian Suppliers: Shandong Tianli, Shanghai Jianye, Wuxi Boiler Fan.

Critical Warning: "Surging" & Application

• Surging: A fan producing 20,000 Pa at 3,000 RPM will be operating near the right side of its performance curve. If the boiler duct is blocked, the fan will surge violently (causing mechanical damage and massive noise). You MUST include:
  • A surge control system (bleed valve or recirculation line).
  • A VFD to ramp speed smoothly.
• Air Temperature: What is the air temperature? (Ambient? Pre-heated air?) Hot air affects pressure capability and material (needs heat-resistant impeller).

Summary: "Yes, it's possible, but not standard."

What to do:

1. Contact a fan engineer (e.g., from New York Blower or Howden).
2. Give them: Flow (CFM/m³/h) + 20,000 Pa + Max 3,000 RPM + Noise ≤85 dB.
3. They will provide a custom engineered fan with a larger impeller, acoustic housing, and silencers – costing likely $15,000 - $50,000+ depending on flow rate.

If you try to get a cheap, off-the-shelf fan at 3,000 RPM and 20,000 Pa, it will be deafeningly loud (>110 dB) and will likely fail.