What is the difference between a root blower and a vane blower?

Roots Blower (Lobe Blower)

Working Principle

Roots blowers operate using two meshing lobed rotors that rotate in opposite directions. As the rotors turn, air is trapped in the pockets between the rotors and the casing, then carried from the intake side to the exhaust side without internal compression. The compression occurs when the trapped air is forced against the backflow from the discharge side.

Key Characteristics

• Simple and robust design with few moving parts
• Non-contact rotating elements with clearance gaps
• Pulsating airflow due to the lobe design
• Higher noise levels compared to vane blowers
• Lower manufacturing and maintenance costs
• Constant volume flow regardless of pressure

Construction Details

Roots blowers feature two or three-lobe rotors made of cast iron or aluminum. The rotors are synchronized by timing gears to maintain precise clearance without touching each other or the casing. The housing is typically made of cast iron with precisely machined bores to maintain tight clearances.