A roots pump includes a housing, a rotor chamber, a pair of rotary shafts, and a pair of rotors. The rotor chamber includes a rotor chamber peripheral surface facing a pair of distal end portions of each of the rotors. Each of the pair of the distal end portions includes: a pair of rotor peripheral surfaces facing the rotor chamber peripheral surface with a first radial clearance; and a distal end peripheral surface that is formed between the pair of the rotor peripheral surfaces in the rotational direction and faces the rotor chamber peripheral surface with a second radial clearance greater than the first radial clearance. A width of the rotor chamber peripheral surface facing the distal end peripheral surface in the rotational direction is greater than a sum of a pair of predetermined widths of the rotor chamber peripheral surface facing the pair of the rotor peripheral surfaces.

A vacuum pump cooler for cooling a pumped fluid in a multistage vacuum pump, the vacuum pump cooler comprising: a plate comprising: a first surface; a second surface opposite to the first surface; and a channel through which a cooling fluid can flow; and one or more fins extending from the second surface of the plate.

A vacuum pumping arrangement comprises a first pump which has a first inlet and a first outlet. The first inlet is fluidly connected to a first common pumping line. The first common pumping line includes a plurality of first pumping line inlets each of which is fluidly connectable to a least one process chamber within a group of process chambers that form a semiconductor fabrication tool. The vacuum pumping arrangement also includes a reserve pump which has a reserve inlet and a reserve outlet. The reserve inlet is selectively fluidly connectable to each process chamber within the group of process chambers that form the semiconductor fabrication tool. The vacuum pumping arrangement additionally includes a controller which is configured to selectively fluidly isolate the pump from one or more given process chambers and selectively fluidly connect the reserve pump with the said one or more given process chambers.

The invention relates to a volumetric compressor (100) including a container (51) for collecting the lubricant moved by an oil distribution disc (1). The compressor (100) further comprises at least two lubricant distribution channels (52), in which each lubricant distribution channel (52) extends from the collecting container (51) so that during operation, the lubricating oil flowing along the channel itself reaches a lubrication opening (82) of a lubrication duct (81) for a rolling bearing (90) of a rotor (80′, 80″). The lubrication opening (82) is arranged at a lower level with respect to the container (51).

A dry vacuum pump has a stator (2) and two rotors (5) that are accommodated in at least one compression chamber (3) of the stator (2), the rotors (5) being configured to rotate synchronously in opposite directions so as to drive a gas to be pumped between an intake and a delivery of the vacuum pump. The rotors (5) and the compression chamber (3) of the stator (2) are coated with a nickel-phosphorus coating (11) comprising between 9% and 14% phosphorus and having a thickness greater than 20 μm, the nickel-phosphorus coating (11) having undergone a hardening heat treatment comprising a step of heating to a treatment temperature greater than 250° C. for a treatment duration greater than one hour, so as to have a hardness greater than 700 HV.

A set of seals for sealing between two half shells defining at least one pumping chamber and two head plates to be mounted at either end of the two half shells. The set of seals includes: at least one annular seal for sealing between at least one of the head plates and the two half shells; two longitudinal seals for sealing between longitudinal contact faces of the two half shell stators on either side of the at least one pumping chamber, the longitudinal seals being configured to have end portions that abut against the at least one annular seal when mounted in the pump. Each of the seals within the set of seals are made of a material having at least one of: a hardness between 73-83, on the Shore A hardness scale; and a stiffness of between 2.4 and 4.2 N/mm per mm length.

A housing unit of a Roots pump includes a rotor housing, which includes a peripheral wall, and a cover member, which closes an opening of the rotor housing. At least one of a mating surface of the peripheral wall or a mating surface of the cover member includes an annular first groove accommodating a seal member. The rotor housing includes a bulging portion including a second groove. The seal member incudes first projections, which project from an annular seal body, and a second projection, which projects further radially inward from the seal body than the first projections. Each first projection includes a distal end that contacts a side surface on a radially inner side or on a radially outer side of the first groove. The second projection is arranged in the second groove to determine the position of the seal body in the first groove.

A vacuum line and method for controlling a vacuum line in which an auxiliary pumping device and a diluent gas injection device are controlled according to a first operating mode in which the pressure prevailing in the discharge pipe is maintained at less than or equal to 20,000 Pa or according to a second operating mode in which the pressure prevailing in the discharge pipe is greater than 20,000 Pa, and the injection of a diluent gas into the stream of the pumped gases is controlled, downstream of an intake of the rough pumping device, such as into the discharge pipe and/or into the rough pumping device and/or into the auxiliary pumping device by the diluent gas injection device in the second operating mode.

A blower assembly includes, but is not limited to, a blower housing defining a blower chamber and including a gas inlet and a gas outlet; a first rotor positioned within the blower chamber and adapted for rotation therein, the first rotor including a first shaft and at least two lobes defining a first lobe profile; and a second rotor positioned within the blower chamber and adapted for rotation therein, the second rotor including a second shaft and at least two lobes defining a second lobe profile, wherein the first and second rotors are formed from a metal having a coefficient of thermal expansion from about 1 (10.sup.−6 in/in*K) to about 13 (10.sup.−6 in/in*K), and wherein at least one of the outer surface of the first rotor, the outer surface of the second rotor, or the blower chamber includes a coating.

A complete bearing-sealed root vacuum pump system capable of promoting vacuum ability of a condenser of a power plant provides a complete bearing-sealed structure. All chambers are isolated effectively so that liquid cannot flow there between and thus not to destroy the root vacuum pump. Therefore, the lifetime of the root vacuum pump is prolonged. The heat exchangers are arranged between the root vacuum pumps and the front stage pump so as to return the condensed water. The condenser vacuum is improved and thus the power generation efficiency is promoted, and power consumption is lowered. As a result a large power plant can save several thousand tons of coals per year.