Affecting factors and numerical value calculation relating to vacuumizing time in Evacuated Tube Transportation

It´s necessary to evacuating air from the Evacuated Tube Transportation (ETT) system before operation. As for the airlock, the air would be evacuated at every turn. Start-up speed of ETT and switching effect of the airlock will mainly depend on the time to taking out gas. This paper analyses relative factors to affect the time to taking out gas (vacuumizing) and the function relating to the time to take out gas, such as orifice conductance, diameter of the tube, length of the tube, interval space between two pumping station, effective vacuumizing speed and target vacuum degree. Based on the numerical value calculation, some suggestions to reduce the time to take out gas were put forward.