A Vacuum Dryer was designed by vacuum techniques and arc welding. SPE regulates that moisture content should be restricted to 0.02 % or lower; this Dryer was invented accordingly. It was put to test in 10 kg/cm2 hydraulic and dye penetrate tests. The result proved that it is efficient to limit moisture content within 0.02 % in various degrees (85 ℃ and 95 ℃), pressures (100 Torr and 160 Torr) and materials (the new PET and the mixed PET). The mixed PET chips consist of 70 % new PET and 30 % recycled PET.