line 31 at the top seal is illustrated referring now to fig4 the rotary leadthrough 182 has three evacuation passages 121 123 and 125 the evacuation passages are distributed around the axis at angular intervals of approximately 120 u00b0 between the evacuation passages there are three gas supply passages 122 124 and 126 referring now to fig5 the encircling annular passage 141 is illustrated if the sleeve 104 rotates about the journal 102 there is a permanent fluid connection between the evacuation passage 121 and the connection flange 134 via the annular passage 141 referring now to fig6 a coating cycle is carried out as follows during a first pumping phase the treatment device is evacuated to a preliminary vacuum of between approximately 100 mbar and 1 mbar by means of a first pump arrangement comprising two rotary slide preliminary vacuum pumps 202 204 connected in parallel the feed lines are routed onto the rotor 32 via the evacuation passage 121 in the rotary leadthrough 182 the rotary slide pumps 202 and 204 have a pump power of in each case 1200 standard m 3 h at the required machine power the time needed to deliver the next vessel is very short therefore a second evacuation phase is provided in order for the evacuation to be carried out in stages during the second evacuation phase the treatment devices are evacuated via a serial second pump arrangement comprising a first roots pump 206 a second roots pump.