This article is to introduce some basic knowledge about Roots pumps including the working principle, features, etc.
Roots vacuum pump has large pumping speed.
Roots vacuum pump, also known as mechanical booster pump, is one of the vacuum pumps which are widely used in various industries. In particular, they’re required where large pumping speed is required in the pressure range of 10 – 1000 Pa.
Booster pump needs a backing pump.
Different as other vacuum pumps, the mechanical booster pump is a dry vacuum pump that needs a backing pump. The backing pump, or the primary pump, usually is a dual stage rotary vane pump. It is allowed to start the Roots pump after a certain ultimate pressure is achieved by the backing pump. Sometimes a single stage rotary vane pump is also used as a backing pump. The achieved ultimate pressure of the booster pump however, cannot be as good as that with a dual stage backing pump. To improve working efficiency, some booster pumps are designed to be started with the backing pump simultaneously.
Working principle of booster pump
The working principle of the booster pump is very similar to the oil-sealed rotary vane vacuum pump. The vibration during operation is small thanks to the geometric symmetry of the 2 rotors. The pump operates completely contact-free due to the clearance between 2 rotors and that between rotors and pump housing. Consequently, a high speed operation is realized with very small friction.
See how it works: Roots Pump Two Lobe – YouTube
Simple Diagram of a Roots Vacuum Pump Structure
Roots vacuum pump requires lubricating oil.
Although booster pump is a dry pump without sealing oil in the pump chamber, the gearwheels and bearings have to be lubricated with oil. Therefore, there is the risk of oil contamination despite low possibility.
Roots pump is developed from the Roots blower. Likewise, the oil-sealed rotary screw vacuum pump has a close relationship with rotary screw compressor. It can be used to replace roots pumps in some applications where the high ultimate pressure is not a must.