Understanding the Most Common Types of Centrifugal Blowers and What Applications Each is Best Suited For

Beginning with the earliest commercial uses of air blowers in the mid-1800s for combustion air, which provided the air to raise firebox temperatures in metal forging furnaces, today, there are many types of industrial air blowers. The largest variety of applications is supplied by centrifugal blowers. With centrifugal blower designs categorized into single-stage, multi-stage, turbo style, radial, and backward curve, there are dozens of prominent manufacturers in each category worldwide.

This blog focuses on the most widely used centrifugal blowers having air flow ratings between 100 to 4,000 SCFM and which produce air pressures from 0.2 PSI to 4 PSI. Centrifugal blowers within this operating range are used in more applications and industries than all other centrifugal blowers combined. Some of their most common uses include combustion air, dust collection systems, water aeration, central vacuum systems, dilute phase pneumatic conveying, low and high-velocity forced air cooling and heating, assorted inert or combustible gas handling, and nearly unlimited non-contact high velocity blow-off air knife applications.

Collectively, all centrifugal blower types represent a maximum air flow performance up to 300,000 CFM with differential pressures as high as 35 psig. To address today's most popular centrifugal blower market segment in the lower flow and pressure range, we focus on 100-4,000 CFM and 0.2 to 4.0 PSI, which falls within two classes:

• Low Pressure Blowers (a.k.a. High Pressure Fans): 0.2–1.0 PSI (≈3"–28" H20)
• Mid-Range Pressure Blowers: 1.0–4.0 PSIG (28"–110" H20)

‍

Common Centrifugal Blower Design Features

All types of centrifugal blowers share design traits: they draw in air or gas through an inlet on the center axis of the impeller drive shaft. After entering an appropriately sized blower inlet diameter, which is generally equal to or larger than the blower discharge diameter, the impeller style must suit the flow and pressure performance objectives. The blower designer must then select either an open annulus vaneless diffuser with a scroll housing (large air plenum) or a vaneless turbo with the expanding diameter volute (snail shell) housing.

Although there are also vaned diffuser turbo blowers that can deliver air at pressures 2-3X that of vaneless diffuser designs at the highest adiabatic air efficiencies, the vaned diffuser category is rarely chosen for the <4,000 CFM and <4 PSI pressure range due to cost and the narrow flow band of their peak efficiency points. The vaneless turbo style centrifugal blower with the expanding volute housing is widely used in <4 PSI applications, but its high efficiency point is only achieved in a narrow flow band.

The average centrifugal blower with a vaneless diffuser and open scroll housing relies on a combination of velocity pressures based on the tip speed of the impeller, together with static discharge air pressure accumulated within the scroll housing to produce total pressure at the blower outlet. When all piping systems, plenums, and fixtures of a final installed blower system are properly engineered to achieve minimum resistance/pressure loss of <10% of a blower's total discharge pressure, the kinetic air forces produced are ideal for air knife and air nozzle applications where high air discharge orifice velocities are needed. This category of centrifugal blowers is equally suited for other broad ranges of flow, pressure, speed, and horsepower applications within a single blower model.

‍

Types of Impeller Styles

Centrifugal blower designs are primarily categorized by the style of their impellers. Blade geometry, together with the number of blades, total blade surface area, blade tip diameter, and impeller RPM, all contribute to creating the intended air volume range and static air pressure or vacuum range.

The final impeller selection helps determine how air moves through the blower, the maximum differential air pressure it can achieve, the peak efficiency the blower can attain, and the limit of extreme conditions in which the blower can operate. All styles of centrifugal blower performance follow the three basic engineering Fan Laws. Once the RPM, pressure, and motor power for a given operating condition of any blower is known, a few simple fan law calculations allow the user to predict any specific blower performance point by changing one or more of these three fan law variables.

‍

Radial Blade Impeller

This type uses straight impeller blades that extend outward from the impeller hub, allowing it to handle particulates, moisture, or corrosive air without clogging. While they generally have lower aerodynamic efficiency compared to curved designs, radial blades offer higher mechanical robustness and durability, making them suitable for a wider range of harsh operating conditions.

These blowers are commonly used in material handling, fume extraction, and other industrial processes involving dirty or abrasive airflows. The larger open area between radial blades provides a self-cleaning function, which simplifies operation and maintenance when material buildup is a concern.

‍

Backward-Curved Impeller

This features impeller blades which curve from the hub to the tip, with a radius sweeping away from the direction of rotation, providing higher efficiency and pressure capabilities versus radial blade impellers of the same diameter. Backward curved blades also operate more quietly, use less energy with flow and pressure delivery without turbulence even under a wide range of system loads.

Some of the most common industrial applications include liquid aeration, fluidized solids aeration, pressurized air cooling and heating, central vacuum, gas extraction and boosting, and high-velocity air knife systems for all industries. When compared with regenerative/side channel blowers and positive displacement/lobe blowers, backward curve centrifugal blowers offer significant energy savings and application versatility, along with size and noise reductions.

Unlike the "fan curve" operating characteristics of all centrifugal blowers (highest flow equals highest power), regenerative and positive displacement blower air performance characteristics follow a "pump curve" (highest pressure equals highest power). The result is that using these alternative blowers, as well as compressed air, will often produce lower air delivery effectiveness and/or higher operating costs.

‍

Turbo Impeller

Turbo blowers also have backward curved blades, but with the tops of the blades at the inlet diameter having radiused inducers (inlet blades bent forward) to scoop an increased air volume into the impeller compared to no inducers. When turbo impellers are combined with a "snail shell" vaneless volute housing, peak blower efficiency is maximized when the specific application design point matches the blower's peak efficiency.

‍

Blower Drive Configurations

While impeller design is critical in defining a blower's fluid dynamic properties (see Bernoulli's principles), the type of electrical and mechanical drive (direct or belt) determines how power is delivered from the motor to the impeller. This is not a characteristic of the blower itself, although some blowers may be better suited to one drive type versus another. Rather, the drive integration choice should either match the needs of a specific blower performance point (usually at peak blower adiabatic efficiencies) or better suit operational or packaging objectives.

An alternative belt drive arrangement allows a centrifugal blower to be adapted to any performance point across a blower's entire performance range driven by a motor matched to the exact horsepower required for each application.

‍

Direct Drive

A direct drive blower either mounts the impeller directly onto the shaft of a motor (electric, hydraulic, or pneumatic powered) or the motor is coupled to a blower's intermediary blower bearing and seal spindle with impeller. Although radial blade blowers have been offered with direct drive motors since the early 20th century, at speeds rarely exceeding 3,600 RPM at 60Hz, the start of the 21st century brought a new generation of variable frequency inverter drives (VFDs) and ultra-high speed electric AC motors with input frequency ratings up to 330Hz.

New direct drive blower and motor assemblies began running at up to 20,000 RPM. These new high RPM centrifugal blowers, with both backward curve and turbo style impellers, resulted in drastic reductions in total size and weight of 3Hp to 30Hp blowers for the <4 psi market. Direct drive turbo blowers with brushless DC motors soon began running up to 40,000+ RPM with air pressures of 4 to 20 psi and running up to 50Hp motors.

When considering reduced blower/motor size in exchange for increased motor speed, particularly when the only wearing electro-mechanical components are inside the motor and other devices within the VFD, the total cost of ownership must be considered versus belt-driven centrifugal blowers. Factors include the total cost of the blower and VFD, installation, providing dedicated circuits and supply power for each VFD. This is crucial when multiple blower/motor systems are planned to ensure electrical system harmonics, motor winding cooling, environmental cleanliness required, system robustness, and ease of on-site field maintenance and repairability.

‍

Belt Drive

Belt drives are second only to "the wheel" in being the world's oldest method of transmitting power. Large-scale industrial use began with the advent of the steam engine in the 19th century with belts and pulleys turning air blowers even before the electric motor was invented. Belt drives continue to be the most common power transmission system in use today because frequent design evolutions have allowed them to suit each new application in every industry.

Centrifugal blowers driven by electric motors are just one of hundreds of popular uses for belt drives. The most compact centrifugal blowers often operate at the highest rotational impeller RPMs while designed for non-stop 24-hour operation in virtually every industry. Advancements in today's belt drive technology make this possible. The precision manufacturing of many high-speed belt-driven blowers has proven how adaptable each blower model can be for the widest range of air flow and differential pressure.

The benefits to every industry are economies of manufacturing scale, ease of adaptability for the largest array of applications, and the versatility of a high-speed belt drive, which facilitates integration with the widest assortment of motor types, industry-specific motor enclosures, worldwide power supplies, and horsepower/kW ratings available.

Although standard A/C VFDs with 60Hz maximum output routinely supply power to many belt-driven blowers, to select the optimum output frequency to achieve the highest operating efficiency, neither the VFD internal switching systems nor the standard 50 or 60Hz blower motors are operated at extreme speeds or temperatures compared to ultra-high RPM direct drive blowers. The belt drive option offers lower cost, many more motor options, higher tolerance to less than ideal operating environments, and a wider assortment of application design options with easy field maintenance and service versus factory-only service for all custom-made high-speed integral blower and motor assemblies.

‍

Key Applications of Centrifugal Blowers in Industrial Settings

Drying

In bottling, canning, and packaging lines, centrifugal blowers power air knives that remove moisture from containers moving at high production speeds. This is crucial for preventing label failure, corrosion, and product contamination.

Cooling

After thermal or mechanical processing, such as welding, molding, or machining, centrifugal blowers help lower product or equipment temperatures quickly and safely. This not only accelerates production but also protects sensitive components.

Cleaning & Blow-Off

Blowers integrated with air knives or nozzles remove dust, debris, and liquids from products and conveyor lines. This is especially valuable in pre-paint surface preparation, electronics assembly, and food processing, where sanitation and finish quality are critical.

Air Handling in Controlled Environments

In cleanrooms, pharmaceutical labs, and climate-controlled manufacturing environments, centrifugal blowers support HEPA filtration systems, maintain positive pressure, and ensure particulate-free conditions.

Choosing the Right Blower for Your Process

Here are important factors to consider when selecting the best blower for your application:

Airflow and Pressure Requirements

Selecting the correct CFM and PSI allows the blower to meet process demands without wasting energy. Undersized units may fail to overcome system resistance, while oversized units create turbulence and inefficiency. Use system resistance calculations and blower performance curves to match requirements accurately.

Space and Mounting Limitations

Physical space constraints often dictate the type of blower configuration needed. Direct drive systems are ideal when floor space or enclosure size is limited. Traditional belt-driven units offer more flexibility in motor placement, making them a strong fit for applications with complex layout requirements.

Energy Use and Maintenance

High-efficiency impellers lower operating costs, especially in continuous-duty applications. Easy maintenance access and self-cleaning designs help minimize downtime and extend equipment life. Consider the lifecycle cost, not just purchase price, when making a selection.

Compliance and Environment

In industries such as food processing, pharmaceuticals, and medical device manufacturing, blowers must meet strict standards for hygiene, material compatibility, and air quality. Compliance with industry-specific requirements often includes the use of food-grade surfaces, HEPA filtration, and sealed enclosures to prevent contamination and maintain sanitary conditions.

For environments that involve chemicals, high humidity, or abrasive materials, ruggedized or custom-engineered solutions can provide long-term durability and consistent performance under tough conditions.

‍

Real World Case Studies with Sonic Air Systems

• IQF conveyor de-icing: Hot-air knife replaces water spray bars with ~150°F air to prevent belt icing
• E-waste shredder containment: Heater-less hot-air blower + knife maintains ~275°F enclosure air for vapor control
• Biomass pellet conditioning: Outlet air ~225°F to conditioners/mixers, no secondary heater
• Extruded strand drying: Blower + air knives dry strands at up to 200 FPM, improving pellet quality
• Wire & cable tunnels: Enclosed, sound-attenuated dryers provide 360° coverage across wide diameter ranges

‍

Build Smarter Systems with the Right Partner

Centrifugal blowers are the driving force behind many industrial systems. Selecting the right type and configuration can improve process performance, reduce downtime, and support long-term efficiency.

At Sonic Air Systems, we help clients match precise airflow and pressure needs with a tailored solution designed to deliver maximum efficiency and reliability. In many installations, our clients have reduced their energy costs while improving drying and cooling performance.

Whether you're optimizing a high-speed production line or integrating a new automated process, we provide fast, expert support from system design to final installation.

‍

Contact us to explore your options and start building a solution that fits your process perfectly.