How Roots-type Blowers ?

Roots-type blowers are positive displacement pumps that utilize two rotating lobes (or rotors) within a casing to move air or gas from one location to another. They operate on the principle of external compression, meaning the compression happens outside the blower itself.

Here’s a more detailed explanation:

Working Principle:

Two Rotors:
A Roots blower consists of two rotors with lobes that intermesh as they rotate.
Trapping and Moving Air:
As the rotors turn, they trap a fixed volume of air between the lobes and the casing.
External Compression:
The trapped air is then moved from the intake side to the exhaust side, where it is discharged into a system with a resistance, causing a pressure increase.
No Internal Compression:
Unlike other types of compressors, Roots blowers do not compress the air within the blower itself.

Key Features:

Positive Displacement:
Roots blowers are positive displacement machines, meaning they deliver a consistent volume of air for each revolution.
Constant Flow:
This positive displacement results in a relatively constant and predictable airflow.
Low Pressure Applications:
They are typically used in low-pressure applications, such as pneumatic conveying, aeration in wastewater treatment, and as superchargers in engines.
Oil-Free Operation:
Many Roots blowers are designed for oil-free operation, making them suitable for applications where oil contamination is a concern.

In essence, a Roots blower acts like a pair of meshing gears that trap and transport air, creating a flow of air rather than compressing it internally.