Basic principle of Roots vacuum pump
Basic principle of Roots vacuum pump
Roots pump adopts internal cooling mode, the heat is directly taken away from the heat source by the circulating cooling air, that is, the extracted gas is cooled by the cooling air when it is compressed or discharged, so this pump can be used in the center where the standard pump can not work.
The pump cavity can be cooled by itself. Because the impeller and working chamber have a special working part, when this special part works, a part of the working chamber is closed, blocking the inlet and outlet. Through the special vent, the cooling gas flows out from the pressure side or enters the working chamber again, and then stops filling by the cooling gas with pressure from the outlet side, and the gas circulates in this way.
The special impeller head controls the movement of cold air without additional control elements. Therefore, this kind of inner circulation cooling roots pump is as simple and clean as ordinary roots pump. It connects the cooler and the exhaust port together, and the cooler is installed outside the pump shell, which is convenient for maintenance and replacement.
If the cooler is designed correctly, and the size of the cooling gas pipeline is large enough, the cooling effect is good, so the roots pump can work under various pressure differences.
Pump heating not only depends on the rotational speed, circulating cooling dose, but also on the pressure difference, which is proportional to the speed. In addition, the clearance between the pump blades and the pump shell should be kept at a minimum. This is conducive to the improvement of volumetric efficiency in order to obtain higher vacuum.
The gas circulating cooling roots pump is most suitable for the process of discharging and tightening the gas or steam. The discharged or compressed gas should not contact with oil or harmful liquid before entering the pump, such as nitrogen circulation in low temperature thermostat. If the pressure difference between inlet and outlet is very large and the limit vacuum degree is very high, three roots pumps can be considered to be used in series. In addition, there are also water cooling or multi-stage pumps.
