4-79-7D Centrifugal Fan

This article's table of contents introduction:

1. Model Number Breakdown
2. Typical Technical Specifications (4-79-7D)
3. Common Applications
4. Key Dimensions & Features
5. Comparison to 4-72 Series
6. If You Need:

It appears you are referencing a specific part or model number: 4-79-7D Centrifugal Fan.

This is a highly standardized designation used primarily in Chinese industrial fan manufacturing (GB/T standards) , specifically for medium-pressure centrifugal fans designed for ventilation, dust extraction, or pneumatic conveying.

Here is the breakdown of what the model number "4-79-7D" means and its typical specifications:

Model Number Breakdown

• 4-79: This is the core series type.
  • 4: Represents the pressure coefficient. This indicates a medium-pressure fan (typically 1–3 kPa standard, though larger sizes can go higher).
  • 79: Represents the specific speed (ns = 79). This designates it as a backward-inclined (or backward-curved) blade fan.
• 7: This is the impeller diameter (in decimeters). Therefore, the impeller diameter is 7 dm = 700 mm.
• D: This is the drive type.
  • D: Direct-connected, flexible coupling drive (the fan wheel is directly coupled to the motor shaft, connected via a coupling, typically mounted on a common base frame with bearings). This is the most common type for this size. Note: Other variants exist like C (belt drive), A (impeller on motor shaft) – "D" is standard for medium/large frames.

Typical Technical Specifications (4-79-7D)

These are typical ranges for a standard unit. Actual values depend on the specific manufacturer (e.g., 4-72 series is also common, but 4-79 is a specific design).

Common Applications

• HVAC Systems: General ventilation, air supply, exhaust.
• Industrial Dust Extraction: Removing light dust, wood chips, or fibers when equipped with appropriate lining.
• Pneumatic Conveying: Transporting granular materials (not heavy abrasive material).
• Boiler Induced Draft / Forced Draft: For small to medium industrial boilers (if built with reinforced materials).

Key Dimensions & Features

• Base: Typically mounted on a heavy-duty H-beam or channel steel base.
• Coupling: A flexible coupling (pin & rubber or elastic coupling) is used, requiring alignment.
• Bearing: Usually double-row self-aligning ball bearings or cylindrical roller bearings with grease nipples.
• Housing: Welded steel plate, sturdy, with a spiral volute.

Comparison to 4-72 Series

People often confuse the 4-79 with the more common 4-72 series.

• 4-72: Is the most standard backward-inclined fan in China. It is optimized for high efficiency in general ventilation.
• 4-79 (your model): Is a different design. It is typically designed for slightly higher pressure within the medium-pressure range, often used for systems with higher resistance or specific dust-handling requirements. It is slightly less common than the 4-72 but has a similar blade profile.
• Note: In some factory databases, "4-79 No. 7D" might actually be a mislabel or a specific OEM variant of a 4-72, but the standard designation stands.

If You Need:

• Spare Parts: Search for "4-79 No. 7D impeller" or "4-79 7D fan casing".
• Replace a Motor: It will almost certainly be an IE2/IE3 180 Frame or 200 Frame motor (depending on speed and power). Typical power is 5 kW to 15 kW.
• Operating Point: You must rotate it at the correct speed (usually 1450 rpm) to avoid overloading the motor. Do not run at 2900 rpm.

Recommendation: If you need the exact performance curve or a replacement part, look at the nameplate on the fan itself. The specific "4-79" designation is sometimes conflated with other numbers by Chinese manufacturers (e.g., "4-72-11", "4-79-12"). The "7" in your number definitively confirms a 700mm wheel.