Abstract: The present invention is concerned with a scroll wall arrangement for a scroll compressor. The scroll wall arrangement comprises a fixed scroll having fixed scroll walls and an orbiting scroll having orbiting scroll wall. Scroll wall arrangement has an inlet at a radially outer portion thereof and an outlet at a radially central portion thereof. A first flow path is defined by the orbiting and fixed scroll walls and extends from the inlet to the outlet, gas entering the arrangement through inlet at a first pressure and exhausting through outlet at a second pressure higher than the first pressure. Scroll wall arrangement comprises a second inlet through which gas can enter at a third pressure and follow a second fluid path where it is exhausted through the outlet at the second pressure. Two flow paths are thus provided having respective inlets. The third pressure at which gas enters through inlet is different from the first pressure, and lower than the second pressure.

Abstract: A method of assembling a scroll pump comprises the following steps carried out sequentially: the step of mounting a first bearing means (20) and drive shaft (14) for rotation relative to a housing (12): the step of fastening a first flange portion (48) of a bellows arrangement (34) relative to the housing (12); the step of fastening an orbiting scroll (26) to a second flange portion (56) of the bellows arrangement (34): and the step of fixing a second scroll (28) relative to the housing (12) for co-operation with the orbiting scroll (26). The second flange portion (56) is fastened to the orbiting scroll (26) with fasteners (60) which extend through a through-bore (61) in the orbiting scroll and engage with the second flange portion.