Secondly, the medium in the vacuum pump is seriously deteriorated due to some reactants in the process, which makes the pump unable to work properly. Our company has a complete range of products, which can be roughly divided into:
1. Double circular lobes. Its design is very similar to the most popular and widely used Roots pump. In fact, some of the earliest ideas of dry pump design were to superimpose Roots pumps. This multi-stage design makes the gas path very complex, and each stage requires a larger flow of nitrogen to dilute and isolate. At the same time, in order to achieve a good vacuum, there are very strict requirements for the clearance at all levels. Of course, this design increases the internal compression ratio and makes its power consumption relatively low.
2. Internal compression screw type. In addition to using a pair of non-equidistant screw, the basic principles of internal compression screw design and external compression screw design are very similar. The continuous reduction of volume between screw leads to internal compression. This design reduces power consumption to the same level as multistage pumps due to internal compression. But in many processes, such internal compression, like multi-stage pumps, can easily cause the physical and chemical changes of gases in the pump body, resulting in solidification or liquefaction.
3. Combination (Roots + Claw). Roots is used to improve the pumping efficiency at lower pressure, and claws are used to improve the pumping efficiency at higher pressure. Its basic principle and gas path are exactly the same as the circular split design described above. Some manufacturers have changed their last stage to a star design, so that the gas can be divided into five parts in a circle of rotation, just like the three-circle split design can be divided into three parts. Similarly, in many processes, each stage of the combined design requires a larger flow of nitrogen to dilute and isolate.
4. Trilobal lobes. The design principle of this dry vacuum pump is exactly the same as that of the double-circular-split type, except that the gas is divided into three parts in a rotating circle instead of two parts like the double-circular-split type. These two designs have the same advantages and disadvantages. In order to further reduce power consumption, some manufacturers in the transmission part choose two DC motors, but this will also lead to reduced torque, restart capacity - decline. Like the double circular split design, each stage of the three-leaf circular split design requires a larger flow of nitrogen to dilute and isolate.
5. External compression screw type. Use a pair of equidistant screw. This minimizes internal compression and makes the gas path shortest and simplest. In this way, the gas resides in the body of the dry vacuum pump for the shortest time. Although this design has a relatively high power consumption due to the reduction of internal compression ratio, it exhibits very high stability in many complex semiconductor processes. This single-stage design makes the requirement of nitrogen consumption very small and simple, which makes it interchangeable in different processes. Nitrogen is even not used in many clean processes.
