First, the concept and classification of Roots vacuum pump:

1. Concept: The Roots vacuum pump is a rotary volume vacuum pump. Its structural form evolved from the Roots blower. It first appeared in Germany in 1944 and was used as a mechanical booster pump to accommodate vacuum melting systems with large pumping speeds in the pressure range of 10 to 1000 Pa.

2. Classification: According to the different working pressure range of Roots vacuum pump, it is divided into:

(1) Low-vacuum Roots pump with direct exhaust air;

(2) Medium vacuum Roots pump (mechanical booster pump);

(3), high vacuum multi-stage Roots pump.

The most domestic use is the medium vacuum Roots pump.

Second, the characteristics of the Roots vacuum pump: compared with other oil-sealed vacuum pumps have the following characteristics:

1. There is a large pumping speed in a wide pressure range;

2. The rotor has good geometric symmetry, so the vibration is small and the operation is stable. There is a gap between the rotor and between the rotor and the casing, no lubrication, and the friction loss is small, which can greatly reduce the driving power, thereby achieving a higher rotational speed;

3. There is no need to seal and lubricate the oil in the pump chamber, which can reduce the pollution of the vacuum system by oil vapor;

4. There is no compression in the pump chamber and there is no exhaust valve. The structure is simple and compact, and is insensitive to dust and water vapor in the pumped gas;

5, the compression is relatively low, the effect of hydrogen pumping is poor;

6. The surface of the rotor is a curved cylinder with a complicated shape, which is difficult to process and inspect. Roots vacuum pumps have developed rapidly in recent years at home and abroad. It has been widely used in smelting, petrochemical, electrician, electronics and other industries.