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Basic knowledge of Roots vacuum pumps: A Roots vacuum pump is a type of rotary positive displacement vacuum pump. Its structural form evolved from a Roots blower. It first appeared in Germany in 1944, and was used as a mechanical booster pump to meet the needs of vacuum melting systems that required high pumping speeds within a pressure range of 10 to 1000 Pa. Depending on the operating pressure range of rotary vane vacuum pumps, they are divided into low-vacuum rotary vane pumps that discharge air directly to the atmosphere ； Medium-vacuum Roots pumps (mechanically driven pumps) and high-vacuum multi-stage Roots pumps. The most commonly used type in China is the medium-vacuum Roots pump. Compared to other oil-sealed vacuum pumps, rotary vane vacuum pumps have the following advantages: 1. They offer a high pumping speed over a wide range of pressures ； 2. The rotor has good geometric symmetry, resulting in low vibration and smooth operation. There are gaps between the rotors as well as between the rotor and the casing; no lubrication is required, resulting in low friction losses. This allows **reduced driving power, thereby enabling higher rotation speeds ； 3. There is no need for oil sealing or lubrication within the pump chamber, which reduces the contamination of the vacuum system by oil vapors ； 4. There is no compression in the pump chamber, and no exhaust valve is present. It has a simple and compact structure, and is not sensitive to dust and water vapor in the gas being drawn in ； 5. The compression is relatively low, resulting in poor performance in evacuating hydrogen gas ； 6. The rotor surface is a curved cylindrical surface with a relatively complex shape, making it difficult to machine and inspect. Rotary vacuum pumps have seen rapid development at home and abroad in recent years. It is widely used in industries such as metallurgy, petrochemicals, electrical engineering, and electronics.