Roots fan is a mechanical device used to transport gas or gas mixture. It consists of a pair of intermeshing impellers and shells, often referred to as "screw type" or "impeller type" fans. These impellers are designed to have a very small clearance from the housing to ensure that the gas can be compressed and transported efficiently.

Roots fan works by drawing the gas into the "suction port" into the axial direction, and then being pushed to the axial outlet by the rotating impeller. In this process, the gas is compressed, increasing the density and pressure of the gas, allowing it to flow to the next stage of the transport process.

Roots fans are commonly used in industrial applications requiring high pressure and flow rates, such as in areas such as air pressurization, sewage treatment, water treatment and material handling. Because of its high efficiency and reliability, Roots fans are also widely used in production and manufacturing processes to ensure accurate delivery and compression of gases or gas mixtures.