A vacuum scroll compressor comprising a dry scroll pumping mechanism comprising: an orbiting scroll having an orbiting scroll wall extending axially from an orbiting scroll plate towards a fixed scroll; and a fixed scroll having a fixed scroll wall extending axially from a fixed scroll plate towards the orbiting scroll and defining a first axial end portion, wherein the orbiting scroll wall extends axially from the orbiting scroll plate towards the fixed scroll and defines a second axial end portion; an inlet; an outlet; and the compressor comprising an axially extending drive shaft having an eccentric shaft portion so that rotation of the eccentric shaft portion imparts an orbiting motion to the orbiting scroll relative to the fixed scroll for pumping fluid from the inlet to the outlet of the scroll pumping mechanism for a single stage of the dry scroll pumping mechanism; wherein the first and second axial end portions of the scroll walls have respective first sealing arrangements and second sealing arrangements arranged in series along the scroll walls from the inlet towards the outlet for sealing between the axial end portions of the scroll walls and the scroll plates of the opposing scroll, said first sealing arrangements (66; 72, 74; 82, 86) selected according to sealing requirements local to the first sealing arrangements and having a fixed axial gap between the opposing scroll plate and one of a fixed tip seal and an axial end face of the scroll wall and said second sealing arrangements having floating seals (68; 84) which are selected according to sealing requirements local to the second sealing arrangements. an orbiting scroll having an orbiting scroll wall extending axially from an orbiting scroll plate towards a fixed scroll; and a fixed scroll having a fixed scroll wall extending axially from a fixed scroll plate towards the orbiting scroll and defining a first axial end portion, wherein the orbiting scroll wall extends axially from the orbiting scroll plate towards the fixed scroll and defines a second axial end portion; an inlet; an outlet; and the compressor comprising an axially extending drive shaft having an eccentric shaft portion so that rotation of the eccentric shaft portion imparts an orbiting motion to the orbiting scroll relative to the fixed scroll for pumping fluid from the inlet to the outlet of the scroll pumping mechanism for a single stage of the dry scroll pumping mechanism; wherein the first and second axial end portions of the scroll walls have respective first sealing arrangements and second sealing arrangements arranged in series along the scroll walls from the inlet towards the outlet for sealing between the axial end portions of the scroll walls and the scroll plates of the opposing scroll, said first sealing arrangements (66; 72, 74; 82, 86) selected according to sealing requirements local to the first sealing arrangements and having a fixed axial gap between the opposing scroll plate and one of a fixed tip seal and an axial end face of the scroll wall and said second sealing arrangements having floating seals (68; 84) which are selected according to sealing requirements local to the second sealing arrangements.