Prediction of changes in the pumping speed characteristics of dry pumps with the geometry of the conduit

In this study, we investigated whether changes in the pumping speed characteristics of dry pumps due to the conduit can be predicted through simulation. The intrinsic pumping speed was measured in the dry pump characteristic evaluation system of the Korea Research Institute of Standards and Science, and the pumping speed affected by the conduit was measured using the plasma enhanced chemical vapor deposition (PECVD) equipment of the National NanoFab Center. Change in the pumping speed were predicted using conductance calculation equations and commercial vacuum-system simulation program, VacTran. A comparison of the results from the two approaches showed that the error rate was within ± 6.5%, confirming the reliability of the prediction. The simulation result was compared with the measured effective pumping speed, and it was confirmed that the error rate was within ± 10%, except in a specific part where the error rate was up to ± 40%. It is considered that the high error rate in some areas is as a result of automatically adjusting the rotation speed of the motor according to the power consumption of the inverter. However, a high simulation accuracy was obtained, demonstrating that the pumping speed characteristics can be predicted through simulation. This has potential application in the design of a vacuum system.