Roots blowers are positive displacement machines that move air or gas using two counter-rotating lobed rotors. They’re widely used in industrial applications where consistent airflow is needed at low pressure, such as pneumatic conveying, wastewater aeration, and combustion air supply.
How Do Roots Blowers Work?
What Happens Inside a Roots Blower?
The process starts when the rotors trap a volume of air between themselves and the casing. As they rotate, this trapped air is carried from the inlet side to the outlet. Unlike compressors, Roots blowers don’t compress air internally. Instead, the pressure builds up externally as the air exits into a system with higher resistance.
The rotors maintain a constant speed and volume, which means the airflow is steady and predictable. Timing gears keep the rotors synchronized so they don’t touch, minimizing wear and allowing oil-free operation in the air stream.
Key Components
- Rotors: Usually two or three lobes, shaped to trap and move air.
- Timing gears: Prevent rotor contact and maintain synchronization.
- Casing: Sealed housing that directs airflow and isolates pressure zones.
- Inlet and outlet ports: Where air enters and exits the blower.
Why Use a Roots Blower?
- Reliable airflow: Delivers consistent volume regardless of pressure changes.
- Low maintenance: No internal contact between rotors means less wear.
- Oil-free air: Ideal for applications needing clean, dry air.
- Durable: Handles harsh environments and long operating cycles.
Common Applications
- Wastewater treatment: Aeration tanks need steady oxygen supply.
- Pneumatic conveying: Moves powders and granules in bulk handling.
- Combustion air: Supplies air to burners and furnaces.
- Vacuum systems: Used in packaging and drying processes.
Operating Limits
Roots blowers are best for low to medium pressure applications. They’re not suited for high compression tasks. Efficiency drops if backpressure exceeds design limits, so sizing and system design are critical.
FAQs
No. While both use lobed rotors, rotary lobe pumps move liquids, whereas Roots blowers move gases.