Roots vacuum pump is a rotary volumetric vacuum pump. Its structure form is evolved from Roots blower. Its structure and working principle are similar to Roots blower. It first appeared in Germany in 1944. It is used as a mechanical booster pump for vacuum melting system with large pumping speed in the pressure range of 10-1000Pa.
Roots vacuum pump classification:
Roots vacuum pump is divided into low vacuum roots vacuum pump with direct air exhaust, medium vacuum roots vacuum pump (mechanical booster pump) and high vacuum roots vacuum pump according to the working pressure range. The largest number of domestic vacuum pumps is vacuum pumps (hereinafter referred to as roots vacuum pumps). Roots vacuum pump is equipped with two rotors which rotate synchronously in opposite directions. There are small clearances between the rotors and between the rotors and the inner wall of the pump shell without contacting each other. The rotor has good geometrical symmetry, so the vibration is small and the operation is stable. There is no need for oil seal and lubrication in the pump chamber, and the friction loss is small. It can greatly reduce the driving power, achieve higher speed, and reduce the pollution of oil vapor to the vacuum system. The structure is simple and compact, and it is not sensitive to the dust and steam in the gas being pumped.
Roots vacuum pump features:
Roots vacuum pump is characterized by fast start-up, low power consumption, low operation and maintenance costs, high pumping speed, high efficiency, in the pressure range of 100-1 Pa has a large pumping rate, can quickly eliminate the sudden release of gas, the speed can be as high as 3450-4100 revolutions / min; pumping rate is 30-10000 liters / sec. This pressure range is just between the oil sealed mechanical vacuum pump and the diffusion pump. Therefore, it is often connected in series between a diffusion pump and an oil-sealed mechanical vacuum pump to increase the pumping capacity of the intermediate pressure range, that is, the mechanical booster pump.
Roots vacuum pump can not be pumped alone. The front stage needs oil seal and water ring to discharge the air directly. That is to say, in practical application, the limit vacuum of Roots vacuum pump depends not only on the pump structure and manufacturing accuracy, but also on the limit vacuum of the front pump. Many customers use a series of Roots vacuum pump in front of the pump just started pumping air set not to start Roots, at this time the Roots effect is not obvious, does not highlight the advantages of Roots vacuum pump. Therefore, the general electronic control set Roots vacuum pump does not start at atmospheric pressure, the current stage pump pumping to a certain limit of vacuum, Roots automatically started. The advantages of Roots vacuum pump as a booster pump will be highlighted, and pump speed will give strong support to the front pump.
Roots vacuum pump as the booster pump of the front-stage pump, selection should follow the Roots pumping speed than the front-stage pump pumping speed at least twice but not more than 10 times the range of choice. Pumping speed than the same stage or smaller than the previous pump, Roots pump appears “no power”, not really put to use; Pumping speed is 10 times faster than the previous pump or more, the load of the pump is relatively increased, the wear of the pump is large, can not actually save energy Roots effect, is also undesirable. Roots vacuum pump is used to control the flow rate and head of roots pump within the range indicated on the sign to ensure that the roots pump operates at the highest efficiency point and achieves the greatest energy-saving effect.
Roots vacuum pump application:
Roots vacuum pump is widely used in vacuum metallurgy smelting, degassing, rolling, chemical, food, pharmaceutical industries, such as vacuum distillation, vacuum concentration and vacuum drying.