Abstract: A scroll compressor having a scroll wall arrangement with a fixed scroll having fixed scroll walls and an orbiting scroll having orbiting scroll wall, an inlet at a radially outer portion and an outlet at a radially central portion, a first flow path defined by the orbiting and fixed scroll walls and extending from the inlet to the outlet, gas entering through inlet at a pressure and exhausting through outlet at a second pressure higher than the first pressure. Scroll wall arrangement having a second inlet through which gas enters at a third pressure and follows a second fluid path where it is exhausted through the outlet at the second pressure to form two flow paths 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.

Abstract: A vacuum pump of the scroll-type has a housing, a first fixed scroll member having an end plate and an involute spiral wrap attached thereto and a second orbital scroll member having an end plate and an involute spiral wrap attached thereto. The scroll members are arranged in the housing such that their respective wraps intermesh so that on orbital movement of the second scroll member relative to the first scroll member a volume of gas will be trapped and urged from one end of the wraps to the other end. A shaft for driving the second scroll member and wherein a member is provided which is adapted to separate the vacuum space in the housing from the shaft and also to prevent the second scroll member from rotating the said member being made from a polymer material.