Choosing the right fan type for your industrial air and gas-moving applications can make anyone’s head spin. There are many factors to consider, such as gas temperature, airflow, pressure, particulates, vibration, corrosion, noise, rotation speed and even the space on your facility floor. Fortunately, IB International makes choosing the right fan easy. We have a line of pre-engineered fans. We can also custom-engineer fans and blowers for the most demanding conditions. Here’s a look at centrifugal fans—some of the most common types, which we proudly design and manufacture in the USA.

First Things First

First, you need to know your application as well as the following:

• Your flow and pressure requirements
• If you have a clean gas stream or whether there are particulates or corrosive solvents in it
• Space limitations
• Which utilities are available for the fan motor or other accessories

Knowing these basics will help us guide you in providing the best centrifugal fan to fit your specifications.

But Don’t Forget …

It’s also important to consider the correlation between efficiency and gas stream makeup. The highest-efficiency fans are designed for clean-air environments. Certain styles of fans are very efficient, but their efficiency ratings drop dramatically if they are selected for the wrong application. In these cases, it’s not uncommon for a fan wheel to fail prematurely due to particulate buildup on the wheels.

Speaking of efficiency, the new Department of Energy Efficiency regulations are coming soon (they are already enacted in California under Title 20 Appliance Efficiency Regulations). These Federal regulations tentatively take effect in 2029. When they do, they may force fan vendors to select larger, slower-turning fans (with a larger footprint for end users) to meet Fan Energy Index (FEI) minimums.

Centrifugal Fan Basics

Centrifugal fans move gases across a range of flows and pressures. Some move low volumes of gas at high pressures, others move high volumes at low pressures, and there are types for everything in between. Generally, the wider the wheel, the more gas volume the fan can move and the larger the diameter, the more pressure it can generate. Centrifugal fans are used in an infinite number of applications, including drying, cooling, material conveying, combustion supply and exhaust. It is used in petrochemical industries, sour gas movement and general ventilation.

Overloading vs. Non-overloading Designs

Certain fan types are considered overloading because the required brake horsepower always increases with increasing flow. Therefore, there will come a point on the fan performance curve where the power needed by the fan will exceed the available motor power. On the other hand, non-overloading fan types increase in the required fan BHP (brake horsepower) with the increasing flow but then reach a peak power level at some point along the performance curve. After reaching that peak, the power required actually decreases with increasing flow. Because of this, the fan may never overload the motor, even at higher flows.

Types of Centrifugal Fans

Radial Blade or High-Pressure Radial Blade

Impeller with completely radial blades, usually with a tapered shroud.

• Benefit: Radial blade fans are best for any heavy-duty application requiring high pressure with relatively low flows
• Maximum Efficiency: Up to 70%
• Volume: Low
• Pressure: High
• Uses: Wet scrubber; exhaust, combustion air; cooling; particulate movement

Backward Curved

Impeller with single thickness and backward curved blades.

• Benefit: High-efficiency design for high volume and low to medium pressure applications
• Maximum Efficiency: Up to 82%
• Volume: High
• Pressure: Lower
• Use: Non-overloading; suitable for dry air or gas and moderate dirt or moisture conditions; air supply for boilers and oxidizers; glass cooling; lightly dust-laden gas streams and/or corrosive applications; clean gas

Backward-Inclined

Impeller with flat, single-thickness, backward inclined blades.

• Benefit: Efficient; more cost-effective than backward curved blades and can handle some particulates in the gas stream
• Maximum Efficiency: Up to 80%
• Volume: Medium
• Pressure: Low
• Use: Non-overloading high-efficiency design for clean gas or light dust applications; bag house; induced draft and forced draft applications

Airfoil

Impeller with airfoil, two-sided backwardly curved blades shaped like an airplane wing.

• Benefit: Non-overloading; high-efficiency design; lower sound levels
• Maximum Efficiency: Up to 84%
• Volume: High
• Pressure: Low
• Use: Non-overloading; suitable for dry air or gas; clean air applications; induced draft; forced draft—this is typically the most efficient centrifugal fan type

Radial Tipped

Blades start with almost a forward curved shape but become completely radial at the tip. Rugged construction for demanding industrial applications.

• Benefit: Radial tip prevents buildup of particulate; high velocity can keep materials like dust or chips airborne
• Maximum Efficiency: Mid-70%
• Volume: Medium
• Pressure: High
• Applications: Harsh environments with wet or dirty gas streams and higher volumes; best for non-abrasive material handling

Miscellaneous Types

IB International manufactures a variety of additional fan types, including open paddle-bladed Material Handling/Air Handling fans (MH/AH), High-Pressure Single Camber airfoil (HPSC), High-Pressure Backward Curved (HPBC), Radial Bladed Open (RBO), and coming soon, High-Pressure, High-Efficiency fans.

Talk to The Experts

Choosing the right centrifugal fan type doesn’t have to be confusing. Whether you need a custom-engineered or standard solution, IB International enhances performance for a wide array of industries, coupled with more than 45 years of unrivaled expertise. To learn how we can meet your specific needs and provide the best solution for your environment, contact us.