Inline fans and centrifugal fans are the most common designs used in ventilation systems of industrial equipment, buildings, and commercial spaces. Both of them perform the same however they differ in different aspects.
Let’s explore the key differences between these two fans:
What is Inline Fan?
An inline fan is often installed inside a ventilation system, drawing air from one side and pushing it out to the other side without changing the direction of the airflow.
What is Centrifugal Fan?
A centrifugal fan uses a propeller to pull air into its center and push it outwards through an apparent force.
Differences Between Inline Fan and Centrifugal Fan
· Working Principle
In inline fans, operation takes place on an axial flow principle, where air is moved parallel to the fan’s blades. Air enters the fan through the inlet side of the duct and is propelled, releasing kinetic energy into the air.
The air is then moved in a straight path, generating a small static pressure increase. The accelerated air exits through the outlet to the intended supply point.
In centrifugal fans, they operate using the centrifugal force principle by drawing air into the middle of the propeller and pushing it out rapidly.
· Static Pressure
Inline Fans
These types of fans are mainly designed for high airflow volume at medium to low static pressure. Their airflow is pushed in a straight line not to build much pressure, favoring volume.
Its propeller imparts limited energy to the air with minimal enclosure, resulting in less pressure recovery. Therefore, inline fans generate low static pressure
Centrifugal Fans
These fans pressurize air. They maintain a strong airflow at 90 degrees, changing direction by compressing and pressurizing it.
Their Curved or radial blades fling air outward with high kinetic energy, with the volute casing recovering velocity energy into static pressure efficiently.
Therefore, centrifugal fans generate higher static pressure
· Airflow Volume
Inline Fans
Inline fans deliver high airflow rates, but only when static pressure is low or moderate. They prioritize volume of air over pressure by pushing large amounts of air in a straight line.
Centrifugal Fans
Centrifugal fans do not deliver maximum volume; they push for steady airflow under resistance by sacrificing free volume to gain power and consistency in pressurized systems.
· Noise
Inline Fans
They are generally quieter because they’re installed inside ventilation systems away from direct room exposure.
However, noise levels depend heavily on fan design, motor type, and the ventilation system condition.
Centrifugal Fans
They are powerlifters of ventilation; hence they make a lot of noise when they work. They move air by flinging it outward at high speed and changing its direction by 90°.
· Efficiency
Inline Fans
They are moderately efficient depending on design, motor type, and the ventilation system configuration and usage. Their efficiency is best in clean, straight duct runs where airflow resistance is minimal.
Centrifugal Fans
They trade some energy efficiency for pressure capability. Their overall efficiency typically depends on the propeller design, operating point, and system setup.
· Power Consumption
Inline Fans
Inline fans are low-power consumers. They’re optimized for volume flow at low static pressure and not for brute-force airflow against resistance.
Centrifugal Fans
They require more input energy because they must accelerate air radially, change its direction by 90°, and overcome higher static pressures. This makes them high-power consumers.
· Size and Space Requirements
Inline Fans
Inline fans are designed to fit directly within ventilation systems, either horizontally or vertically, without requiring a separate mounting area.
They are compact, lightweight, and space-efficient, making them ideal for tight spaces and false ceilings.
Centrifugal Fans
These fans are designed with a centrifugal propeller and volute housing, which require more space for air transmission. They are larger, heavier, and require a dedicated housing space.
· Price
Inline Fans
Inline fans are economically affordable. Their cost depends on size, airflow capacity, brand, material type, motor type, and noise control features.
Centrifugal Fans
These fans are expensive because of their huge size, materials that they are made of and availability. Installation also makes them expensive since they need trained personnel and more labour.
Main Applications
Inline Fans
Some of the main applications of inline fans include:
- Residential and commercial ventilation
- Greenhouses and grow rooms
- Server rooms and equipment cooling
- Light industrial and workshop ventilation
- Roof ventilation
Centrifugal Fans
The key applications of centrifugal fans are:
- Industrial ventilation & exhaust systems
- HVAC systems
- Dust collection & filtration systems like woodwork workshops
- Boilers, furnaces & industrial processes
- Clean rooms & laboratories
- Waste treatment & chemical industries
Let’s summarize the differences between incline and centrifugal fans in the table below:
| Variable to Compare | Inline Fans | Centrifugal Fans |
| Airflow and pressure | · High air volume | · Low air volume |
| Air resistance | · Low air resistance such as straight and short duct | · High air resistance such as long ducts with bends and filters |
| Noise level | · Low | · High |
| Power consumption | · Low | · High |
| Operational, installation and maintenance | · High | · Low |
Conclusion
Inline fans excel where space is tight and airflow paths are simple. They are installed directly inside ducts and operate quietly without any noise.
On the other hand, centrifugal fans are designed to fight resistance and maintain airflow under pressure, but inefficient and impractical for light-duty or space-limited setups.
FAQs
What are the Benefits of Inline Fans?
- Lower power consumption -they have small motors that draw very little power lower running costs for continuous ventilation
- Cost-effective– they are economically affordable to buy and maintain them.
- Noise level – They are less noisy compared to other exhaust fans because they are installed inside ventilation systems, which help absorb sounds.
- Lightweight and easy to install – setting them up is not a hassle because they are light to lift and can be installed by one technician.
What are the Disadvantages of Centrifugal Fans?
They are expensive– Their purchasing price is higher compared to other exhaust fans due to the material used to make them and installation labor.
Noisy– Centrifugal fans generate loud noise because of high propeller tip speed and turbulent air discharge.
Higher power consumption– centrifugal fans draw more power than other exhaust fans because they generate higher pressure and deal with more internal friction.
