Abstract: A multi-stage vacuum pump comprises, between adjacent stages of the pump, a continuous ignition source for igniting a fuel within a pumped fluid. This can ensure that the concentration of the fuel in fluid exhaust from the pump is below its lower explosive limit.

Abstract: A pump having a rotor, a stator, a housing enclosing the rotor and the stator, the housing having an inlet for a fluid, and a port for receiving a fluid which acts on deposits on a surface of the rotor and on a surface of the stator positioned downstream from the inlet.

Abstract: To degas a molten metal, a receptacle containing the molten metal and a layer of slag over the molten metal is positioned in a chamber, and the chamber is evacuated. As the pressure in the chamber reduces, gas is generated at the interface between the molten metal and the slag, which causes the slag to foam. To inhibit overflowing of slag from the receptacle, a gauge outputs a signal indicative of the level of the surface of the slag, and the rate of evacuation of the chamber is reduced to reduce the rate of gas generation.

Abstract: A method of operating apparatus for controlling the pressure in a process chamber (10), the apparatus comprising a first pump unit (14) having an inlet in fluid connection with an outlet of said process chamber, and a second pump unit (16) having an inlet in fluid connection with an outlet of the first pump unit via a flow control unit (18) comprising a variable flow control device (20; 28) having variable conductance for controlling outlet fluid pressure at the outlet of the first pump unit, the method comprises controlling speed of the first pump unit to increase the range of chamber pressures over which control of the outlet fluid pressure produces changes in said chamber pressure without exceeding the thermal limit and/or motor stall limit of the first pump unit.

Abstract: A differentially pumped mass spectrometer system comprises a mass spectrometer having first and second pressure chambers through which, during use, ions are conveyed along a path. A pump assembly (10) for differentially evacuating the chambers (62, 66, 68) is attached to the mass spectrometer. The pump assembly comprises a housing (12) attached to the mass spectrometer and a cartridge (14) inserted into the housing. The cartridge has a plurality of inlets (16, 18, 20) each for receiving fluid from a respective pressure chamber (62, 68, 66) and a pumping mechanism (30, 32, 34) for differentially pumping fluid from the chambers. The cartridge is inserted into the housing such that the pumping mechanism (10) is inclined relative to the ion path (76), but with the cartridge protruding into the mass spectrometer to such an extent that at least one of the inlets (16, 18) at least partially protrudes into its respective chamber (62, 68) without crossing the ion path.

Abstract: A vacuum pump (100) comprises a first set (106) of turbo-molecular stages, a molecular drag stage (112), a first inlet (120) through which fluid can pass through the first set (106) of stages and the molecular drag stage (112) towards a pump outlet (116), second and third sets (108, 110) of turbo-molecular stages located between the first set (106) and the molecular drag stage (112), a second inlet (122), the second and third sets (108, 110) being arranged such that fluid entering the pump through the second inlet (122) is separated into two streams each flowing through a respective one of the second and third sets (108, 110), and conduit means (126) for conveying fluid passing through the first set (106) and one of the second and third sets (108, 110) towards the outlet (116).

Abstract: A method of treating a gas stream containing silane or other silicon-containing gas is described, in which the gas stream is conveyed to a liquid ring pump or screw-mechanism pump, to which are also supplied an oxidant for oxidising the silicon-containing gas within the pump, and a liquid for forming a liquid ring or intermittent flushing within the pump. A liquid stream containing said liquid and a by-product of the oxidation of the silicon-containing gas is exhaust from the pump.

Abstract: Apparatus for conveying waste streams exhausted from first and second chambers is provided. The apparatus comprises first conduit means comprising an inlet for receiving a waste stream exhausted from the first chamber, and an outlet, and a second conduit means comprising an inlet for receiving a waste stream exhausted from a second chamber, and an outlet. The outlets of the first and second conduit means are connected together. The first conduit means comprises means for generating sonic choking of gas being conveyed towards the outlet of the first conduit means in order to inhibit migration of a component of the waste stream exhausted from the second chamber towards the first chamber.

Abstract: A vacuum pump housing comprises first (12) and second half-shell stator components (14) defining a plurality of pumping chambers separated by partition members (26, 28, 30, 32). Each pumping chamber comprises an inlet port (42, 44, 46, 48, 50) for receiving fluid and an outlet port (54, 56, 58, 60, 62) through which pumped fluid is exhausted from the chamber. The inlet ports are open on an external surface of the first stator component, and the outlet ports are open on an opposing external surface of the second stator component. The stator components further define transfer channels (66, 68, 70, 72) for conveying fluid between the pumping chambers. Each transfer channel preferably comprises first and second portions located on opposite sides of the housing.

Abstract: An attachment (10) for an inlet pipe (14) to a wet scrubber or other device comprises a sleeve (16) having an open end (18) adapted to be detachably connected to a flanged end (12) of the inlet pipe (14). A shaft (30) is moveable within the sleeve (16), and a scraper (34) is attached to one end of the shaft (30). The shaft (30) forms part of a pneumatic cylinder (40) attached to the other end of the sleeve (16). In use, the shaft (30) is reciprocally moved to cause the scraper (34) to dislodge particulates deposited within the pipe (14). Heated gas such as nitrogen or dry air is injected into the sleeve (16) to prevent scrubbing liquid from condensing within the sleeve (16) and thus inhibit particulate deposition therein.

Abstract: A method is described for recycling hydrogen (H2) supplied to a chamber (10) in a gas stream comprising hydrogen and at least one other gas, such as silane. A gas comprising at least hydrogen is drawn from the chamber (10) using a first vacuum pump (32) that exhausts gas therefrom at a sub-atmospheric pressure. A portion of the gas exhausted from the first vacuum pump (32), for example between 70 and 95% of this gas, is diverted away from a second vacuum pump (34) backing the first vacuum pump (32). In one embodiment, the diverted portion of the sub-atmospheric pressure gas is treated to produce a purified gas comprising hydrogen, which is stored in a storage vessel (14). The composition of the purified gas is analysed, and, depending on the results of the analysis, at least one of hydrogen and silane is added to the stored gas so that the composition of the stored gas is similar to that of the gas initially supplied to the chamber (10). Gas is then supplied to the chamber (10) from the storage vessel (14).

Abstract: A vacuum pump comprises a housing, a drive shaft supported by a beating arrangement for rotation relative to the housing about an axis, and a pumping mechanism comprising a stator component mounted on the housing and a disk-shaped rotor component mounted on the drive shaft axially proximate the stator component. The bearing arrangement comprises a bearing supported in both radial and axial directions by a resilient support, comprising inner and outer annular portions connected by a plurality of flexible members, so that there is a fixed relation between the inner race of the bearing and the outer portion of the resilient support to determine the axial clearance between the rotor and stator components of the pumping mechanism.

Abstract: A system for pumping a gas stream containing a combustible gas comprises a solid oxide ionic conducting membrane (20) and a vacuum pump (36) for drawing the gas stream at a sub-atmospheric pressure to one side of the membrane. The other side of the membrane is exposed to an oxidising gas, and a potential difference is applied across the membrane so that reactive oxidising species permeate across the membrane to react with the combustible gas to produce at least water vapour. The gas stream is subsequently received by the vacuum pump (36). The vacuum pump may have a pumping mechanism that exposes the gas stream to water and wherein the water vapour is condensed from the gas stream. Alternatively, a condenser (14) may be provided between the pump and the membrane for condensing the water vapour from the gas stream.

Abstract: A method is described of treating a gas stream exhausted from an atomic layer deposition (ALD) process chamber to which two or more gaseous precursors are alternately supplied. Between the process chamber and a vacuum pump used to draw the gas stream from the chamber, the gas stream is conveyed to a gas mixing chamber, to which a reactant is supplied for reacting with one of the gaseous precursors to form solid material. The gas stream is then conveyed to a cyclone separator to separate solid material from the gas stream. By deliberately reacting a non-reacted precursor to form solid material upstream from the pump, reaction within the pump of the non-reacted precursor and a second non-reacted precursor subsequently drawn from the chamber by the pump can be inhibited.

Abstract: A pumping system has a motor (32) for driving a pumping mechanism (30). A variable frequency drive unit (36) has an input for receiving electrical energy of relatively high power and first, fixed frequency from a power supply, and an output coupled to an input (46) of the motor for supplying electrical energy of relatively low power and second, variable frequency to the motor. This second frequency preferably has a maximum value greater than the first frequency. A control circuit (50) is provided for selectively coupling the motor input (46) directly to the power supply for the supply of said relatively high power energy to the motor to maximise the torque that can be produced by the pumping mechanism. After a period of time the control circuit terminates the direct coupling of the motor input to the power supply for the supply of said relatively low power energy to the motor.

Abstract: A regenerative pumping mechanism comprises a rotor having a series of blades positioned in an annular array on one side of the rotor, and a stator having an annular channel within which the blades rotate. In order to control the axial clearance between the rotor and the stator, an axial magnetic bearing actively controls relative axial movement between the rotor and the stator. This can allow the pumping mechanism to provide controllable axial sealing between the rotor and the stator, as opposed to radial sealing.

Abstract: A method of pumping a gas stream containing a condensable species and a light gas and an apparatus therefore, the method comprising the steps of conveying the gas stream to a multistage vacuum pump comprising an inlet stage and an exhaust stage downstream from the inlet stage, and adding to the gas stream upstream of or at the inlet stage a purge gas heavier than said light gas to both inhibit migration of the light gas from the exhaust stage towards the inlet stage and to inhibit condensation of the condensable species within the pump.