[en] The DAPHINE Main Ring Vacuum System is designed for a mean operating pressure of 1 nTorr with a circulating current of about 5 A/beam. Finite element calculations have been carried out to check the maximum possible deformation for the Bending Quadrant vacuum chamber that will be made of Al 5083-H321. Water cooled copper absorbers are employed to cope with the Synchrotron Radiation, (SR), produced in the wigglers and dipoles. The total gas load due to SR is Q∼2.6x10^-5 Torr l/s per arc for CO, with a photodesorption rate η∼1x10^-6 molec/ph, (after ∼40Ahr of commissioning), as measured at NSLS-BNL. Nine sputter ion pumps and nine titanium sublimation pumps are located in each arc to provide, respectively, the 15% and the 85% of the required pumping speed