4-68-10D Centrifugal Fan

This article's table of contents introduction:

1. Decoding the Model Number
2. Key Characteristics of a 4-68-10D Fan
3. Common Applications (Size 10D)
4. Important Specifications to Check
5. Summary Table

The designation 4-68-10D refers to a specific model of a centrifugal fan (also known as a blower) commonly used in industrial ventilation, dust collection, and HVAC systems.

Here is a breakdown of what the designation typically means and the characteristics of this specific model.

Decoding the Model Number

• 4: This usually indicates the series or type of impeller blades. In the "4-68" series, this typically denotes forward-curved blades. These blades curve in the direction of rotation.
• 68: This is a specific design code for the impeller and housing geometry. It defines the performance characteristics (pressure vs. airflow curve) and efficiency of the fan. The "4-68" series is known for being a high-efficiency, medium-pressure design.
• 10: This is the impeller diameter in inches (or sometimes decimeters, but for a fan of this size, inches is most common). A 10-inch diameter impeller is a relatively small, compact fan.
• D: This is a drive arrangement code. In industrial fan standards (like AMCA), "D" typically means the impeller is directly mounted on the motor shaft (Overhung). There is no belt drive; the fan wheel spins at the same RPM as the motor.

Key Characteristics of a 4-68-10D Fan

• Impeller Type: Forward-curved blades.
  • Pros: Delivers high airflow volume relative to its size and speed. Relatively quiet.
  • Cons: Not suitable for dirty or sticky environments (blades clog easily). Cannot handle high static pressure as efficiently as backward-curved fans.
• Drive: Direct Drive (indicated by "D"). The motor is mounted inside the fan housing or directly bolted to the inlet cone.
• Airflow & Pressure:
  • Flow: Medium to high airflow (typically ranging from 500 to 2,500 CFM depending on RPM and system resistance).
  • Pressure: Medium static pressure (typically up to 2-4 inches of water column (in w.g.) or 500-1000 Pa).
• Construction: Usually housed in a scroll-shaped (volute) casing. The outlet can be rotated to different positions (Top horizontal, top angular, down blast, etc.). The inlet is typically circular with a cone.
• Motor: It will have a specific motor (e.g., 1/2 HP, 1 HP, 2 HP) running at a specific RPM (often 2800 RPM for 50Hz or 3450 RPM for 60Hz) to match the direct-drive shaft speed. You must check the fan's nameplate for exact electrical specs.

Common Applications (Size 10D)

Because it’s a 10-inch impeller, this is a small to medium industrial/commercial fan used for:

• Ducted HVAC Systems: Supply or return air in small shops, offices, restaurants, or clean rooms.
• General Ventilation: Exhausting fumes, heat, or stale air from a small room or enclosure.
• Dust Collection: Light dust collection systems (e.g., for a woodworking shop with a single machine or hand tools). Note: Not for heavy, sticky, or abrasive dust.
• Drying Systems: Moving warm air in small drying ovens or processes.
• Boiler & Furnace Applications: Forced draft or induced draft on small industrial burners.

Important Specifications to Check

If you have a physical unit or are looking to purchase one, you must find the nameplate for these critical details:

• RPM (Speed): The exact revolutions per minute. (e.g., 1725, 3450 RPM)
• Power (HP/kW): The motor horsepower (e.g., 1/2 HP, 1 HP).
• Voltage/Phase: (e.g., 115V, 230V, 460V; Single Phase or Three Phase).
• CFM & SP: The design airflow (CFM or m³/h) and static pressure (in w.g. or Pa) at the fan's operating point.
• Outlet Position: Which direction the air blows out (Top Horizontal, Down Blast, etc.).

Summary Table

In short: The 4-68-10D is a direct-drive, forward-curved centrifugal fan with a 10-inch impeller, designed for medium-pressure, high-volume air movement in relatively clean environments. To use or replace it, you must get the specific motor specs from its nameplate.