Abstract: A mass spectrometer comprising: a vacuum housing comprising a first vacuum chamber having a first gas exhaust port; a gas pump (1700) having a first gas inlet port connected to the first gas exhaust port (H1) by a first gas conduit for evacuating the first vacuum chamber; and a first apertured cover (2010) arranged over the first gas exhaust port (H1) or first gas inlet port, or in the first gas conduit therebetween.

Abstract: A vacuum pump comprises: a rotor cylindrical portion; a motor configured to rotate the rotor cylindrical portion; a stator cylindrical portion, the rotor cylindrical portion and the stator cylindrical portion together forming a screw groove pump; a base housing the rotor cylindrical portion and the stator cylindrical portion; a heater configured to heat the base or the stator cylindrical portion; a cooling device attached to the base; and a cover member arranged at an outer peripheral side of the stator cylindrical portion and an outer peripheral side of the base, covering the base through an air insulating layer, and contacting the cooling device.

Abstract: To provide a vacuum pump capable of efficiently cooling electrical equipment. The vacuum pump comprises a pump main body, and an electrical equipment case disposed outside the pump main body, wherein the electrical equipment case includes a cooling jacket in which a cooling medium flow passage is formed, and a power supply circuit portion that has a circuit component and can be cooled by the cooling jacket, the power supply circuit portion being attached to the cooling jacket so that heat from the electrical component portion can be transferred, and the cooling jacket includes a jacket main body and a cooling pipe for circulating cooling water in the jacket main body, and partially exposes the cooling pipe toward the power supply circuit portion.

Abstract: A vacuum pump comprises: a rotor rotatable in a predetermined rotation direction; and a case housing the rotor; and a fixed component arranged facing an inner wall of the case. A clearance is formed between the inner wall of the case and the fixed component, and a groove allowing communication between the clearance and an exhaust path in the case is formed at either the inner wall of the case or the fixed component.

Abstract: The pressure fluctuations in a fluid degassing system may be diminished by independently controlling the intake phase and the exhaust phase of an evacuation pump. The speed of the pump's drive element may be modulated at least during the intake phase to more closely align with a pressure set point in a degassing module.

Abstract: Provided are a vacuum pump and an adapter used in the vacuum pump that are capable of responding to various changes in specifications at low cost. A turbo-molecular pump includes a base, a stator blade that is provided above the base in an axial direction of a rotor, a rotor blade that is integrally attached to the rotor, a housing that is formed in a cylindrical shape, and accommodates the stator blade and is integrally attached to the base, and an adapter that is replaceable depending on a type of the stator blade, the rotor blade, or the housing, and that is detachably mounted on the base and is configured to support the stator blade in the axial direction.

Abstract: A vacuum pump system for evacuating at least five volumes comprising a turbomolecular pump and a forevacuum pump arranged to pump an output of the turbomolecular pump arrangement to atmosphere. The turbomolecular pump has at least five pumping stages separated by rotor blades. Not more than three pumping stages have pumping speeds in excess of ? of the highest pumping speed when under vacuum and/or a pumping port cross section in excess of ? of the highest pumping port cross section, and at least two pumping stages have pumping speeds less than ¼ of the highest pumping speed when under vacuum and/or a pumping port cross section of less than ¼ of the biggest pumping port cross section. The ratio of pressures between the pumping stage with the highest pressure and the pumping stage with the lowest pressure is at least 100000:1 when under vacuum.

Abstract: The present invention provides a vacuum pump that measures the temperature of a rotating portion accurately and at low cost, a stator column of the vacuum pump, a base, and an exhaust system of the vacuum pump at low cost. The vacuum pump according to the present embodiment, the thread groove-type seal for causing some of the purge gas to flow back toward the temperature sensor unit is provided on the downstream side of the purge gas flow path in which the temperature sensor unit is disposed, thereby increasing the pressure of the purge gas in the vicinity of the temperature sensor unit. Thus, with the small amount of purge gas, the gas pressure around the temperature sensor unit can create an intermediate flow or a viscous flow. Consequently, the total amount of purge gas to be supplied can be saved, resulting in cost reduction.

Abstract: A vacuum pump comprises: a rotary body including a rotor blade and a rotor shaft; a case rotatably housing the rotary body; a motor configured to drive the rotor shaft of the rotary body; a bearing arranged at an end portion of the rotor shaft; and at least three balance correction portions including a first balance correction portion provided on one end side of the rotary body in an axial direction, a second balance correction portion provided on the other end side of the rotary body in the axial direction, and a third balance correction portion provided between the first balance correction portion and the second balance correction portion. Balance correction by an n-plane method, where n?3, is available such that any of the three balance correction portions is accessible from an outside of the case.

Abstract: A tapering exponential spiral for a gas expander for work extraction or air cooling. A gas compressor to increase the pressure and temperature of air. The compressor-expander forms a single and simple structure. A generator with a disk format using a circle of alternating polarity magnets to induce current in polygon solenoids. A heat turbine, Firefly Electric, is small, simple, and efficient heat engine. A heat pump, Firefly Air, for cooling, refrigeration, water capture, and heating. Solar power can be generated and stored as compress air. A water purifier, Firefly Aqua, to desalinate water by solar power. Sunlight is concentrated by a sun tracking conic reflective surface onto a column of salty water. Solar photovoltaic power can be used to power a spiral compressor to condense low pressure steam. Also, we reuse solar heat by extracting the heat of compressing and condensing steam for evaporating more salty water under reduced pressure.

Abstract: A cooling component includes a plurality of port pairs, a flow path through which refrigerant flows, the refrigerant communicating with each of the ports of the plurality of port pairs, and a setting means for setting a usage pattern of the plurality of port pairs. The plurality of port pairs are provided along a circumferential direction of the casing. The setting means sets a selected port pair such that the refrigerant is supplied from outside into the flow path using the first port of the selected port pair and refrigerant is discharged from the flow path to outside using the second port of the selected port pair, and sets another port pair such that the refrigerant cannot be supplied from outside into the flow path or discharged from the flow path using the other port pair.

Abstract: An apparatus comprising a heat-sensitive device (F); a radiative element (RE), the radiative element in operation generating first electromagnetic radiation (ER), the first radiation propagating towards the heat-sensitive device; and a radiation-shielding device (20) arranged between the radiative element and the heat-sensitive device such that, in operation, the first radiation impinges on the radiation-shielding device. The radiation-shielding device comprises a first shield element (21) having a first fluid channel (215) arranged therein, the first shield element having a first surface (213) and a second surface (214), the first surface being arranged closer to the radiative element than the second surface; and a second shield element (22) having a second fluid channel (225) arranged therein, the second shield element having a third surface (223) and a fourth surface (224), the third surface being arranged closer to the radiative element than the fourth surface.

Abstract: When a duration of current noise caused by a PWM control of each excitation amplifier is Td, a cycle of a PWM carrier signal is Tpwm, an on-duty upper limit of the PWM carrier signal under quiet environment without disturbance is Tonu, and an on-duty lower limit of the PWM carrier signal under the quiet environment without the disturbance is Tonl, the AD sampling period includes a first AD sampling period between a point after a lapse of the time Td after a start of the cycle Tpwm and a point after a lapse of a time (Tpwm?Tonu) from the start of the cycle Tpwm, and a second AD sampling period between a point after a lapse of a time (Tpwm?Tonl+Td) from the start of the cycle Tpwm and an end point of the cycle Tpwm.

Abstract: A molecular pump includes a pump body provided with a turbo molecular pump portion, a control unit provided with a control portion and a power supply portion, and a cooling unit for cooling the pump body and the control unit. A first temperature detecting portion is provided in a first position, which is a position inside the control unit and has a low temperature. A second temperature detecting portion also serving as a humidity detecting portion is provided in a second position, which is a position inside the control unit and has a high temperature. The control portion controls the operation of the cooling unit in accordance with a relative humidity in the first position, calculated based on temperature information detected by the first temperature detecting portion and based on temperature information and humidity information detected by the second temperature detecting portion also serving as a humidity detecting portion.

Abstract: A wind compressor system having one or more wind turbines and a plurality of wind compressors located proximate the one or more wind turbines. The wind compressors optimize the energy created by the wind turbines by redirecting and converging the wind from the wind compressor to the wind turbines. Each of the wind compressors comprises an obstruction having a size and shape adapted to converge the wind currents by means of a Venturi effect toward the one or more turbines thereby increasing the velocity and force of the wind hitting the wind turbine. A plurality of transporters coupled to the wind compressors. The transporters configured to move at least one wind compressors to a location that maximizes the force of the wind encountered by the turbine.

Abstract: A wind compressor system having one or more wind turbines and a plurality of wind compressors located proximate the one or more wind turbines. The wind compressors optimize the energy created by the wind turbines by redirecting and converging the wind from the wind compressor to the wind turbines. Each of the wind compressors comprises an obstruction having a size and shape adapted to converge the wind currents by means of a Venturi effect toward the one or more turbines thereby increasing the velocity and force of the wind hitting the wind turbine. A plurality of transporters coupled to the wind compressors. The transporters configured to move at least one wind compressors to a location that maximizes the force of the wind encountered by the turbine.

Abstract: A compressor flange for connecting a screw-type compressor to a drive, wherein the compressor flange has a central opening for receiving a shaft and/or a bearing and a first annular bearing face for bearing on a housing of the compressor and a second annular bearing face for bearing on a housing of the drive. The compressor flange also has axially and/or radially effective seals for forming a seal with respect to the compressor housing and/or the shaft, with the result that an open compressor housing can be closed off and sealed by insertion of the compressor flange. The device relates to a screw-type compressor with such a compressor flange.

Abstract: A wind compressor system having one or more wind turbines and a plurality of wind compressors located proximate the one or more wind turbines. The wind compressors optimize the energy created by the wind turbines by redirecting and converging the wind from the wind compressor to the wind turbines. Each of the wind compressors comprises an obstruction having a size and shape adapted to converge the wind currents by means of a Venturi effect toward the one or more turbines thereby increasing the velocity and force of the wind hitting the wind turbine. A plurality of transporters coupled to the wind compressors. The transporters configured to move at least one wind compressors to a location that maximizes the force of the wind encountered by the turbine.

Abstract: A wind compressor system having one or more wind turbines and a plurality of wind compressors located proximate the one or more wind turbines. The wind compressors optimize the energy created by the wind turbines by redirecting and converging the wind from the wind compressor to the wind turbines. Each of the wind compressors comprises an obstruction having a size and shape adapted to converge the wind currents by means of a Venturi effect toward the one or more turbines thereby increasing the velocity and force of the wind hitting the wind turbine. A plurality of transporters coupled to the wind compressors. The transporters configured to move at least one wind compressors to a location that maximizes the force of the wind encountered by the turbine.

Abstract: A flow regulating system for maintaining a stable air flow comprising at least one pump, a mass flow sensor, an ambient temperature sensor, an ambient pressure sensor, a temperature compensation sensor measuring the temperature of said mass flow sensor, and a control system is disclosed, as well as a method for measuring a flow using said flow regulating system, a device for the monitoring of air-borne compounds present in air in both a gas phase and a particle phase, wherein it comprises a sampling device, an enrichment trap 1, a calibration and tuning module, a blank module, said flow regulating system, a chromatography unit, and a detection unit, and a method for the detection of air-born compounds in an air flow by using said monitoring device.

Abstract: The leak detection appliance has a test inlet to which a test chamber containing the test specimen can be connected. A high-vacuum pump produces a high vacuum in a test gas detector. A backing pump contains two pump stages. In order to evacuate the test chamber, the pump stages are operated in parallel mode, with their suction capabilities being added. When the necessary vacuum has been achieved, the pump stages are operated in series in order to produce the necessary high vacuum which is required for high detection sensitivity on the test gas detector.

Abstract: A vacuum pump having substrates which can be wired together easily and cooled easily. A substrate unit structure is formed by covering the opening of the casing of the pump main unit with a plate functioning also as the casing of the control unit. Pins of a terminal fixed while penetrating the plate are soldered directly to an active magnetic bearing (AMB) control substrate and an aerial connection substrate in order to integrate these components. The casing and sealing structures can be of simple construction. A drip-proof structure can be made with the terminal at low cost without using expensive drip-proof connectors. Further, by cooling the plate, electronic components mounted respectively on the AMB control substrate in a vacuum atmosphere and the aerial connection substrate in an air atmosphere can be cooled simultaneously.

Abstract: An impeller fan assembly that includes a housing, a stator, a rotor having a hub and an annular array of non-stationary blades extending from the hub, at least two spaced apart bearings mounted to the stator, and a pump in fluid communication with the bearings to provide fluid to the bearings.

Abstract: A wind compressor system having one or more wind turbines and a plurality of wind compressors located proximate the one or more wind turbines. The wind compressors optimize the energy created by the wind turbines by redirecting and converging the wind from the wind compressor to the wind turbines. Each of the wind compressors comprises an obstruction having a size and shape adapted to converge the wind currents by means of a Venturi effect toward the one or more turbines thereby increasing the velocity and force of the wind hitting the wind turbine. A plurality of transporters coupled to the wind compressors. The transporters configured to move at least one wind compressors to a location that maximizes the force of the wind encountered by the turbine.

Abstract: A vacuum pump includes a housing having an axial inlet a pumping unit including a stator, a rotor rotatably supported in the stator, and a drive for driving the rotor. At least one housing part which has at least one outlet, is placed on the housing in an axial direction and is connected with the housing.

Abstract: A vacuum pump includes: a pump main body; a control unit which drives and controls the pump main body; a connector device including a first connector member on the pump main body side and a second connector member on the control unit side, at least one of power and a control signal being input and output between the pump main body and the control unit; and a connector attachment member attached to the pump main body coaxially with the pump shaft center between the pump main body and the control unit, the first connector member being attached to the connector attachment member. The connector attachment member is attached to the pump main body at one of a first phase of attachment and a second phase of attachment depending on a phase of attachment of the pump main body and the control unit.

Abstract: The invention relates to a vacuum pump or vacuum apparatus having a vacuum pump for the evacuation of one or a plurality of volumes, the vacuum pump having a plurality of pressure stages and at least two suction inlets. According to the invention, an outer suction inlet for a first pressure stage spatially encompasses an inner suction inlet for a second pressure stage such that the inner suction inlet seals only against pressure within the outer suction inlet, not against external pressure.

Abstract: A vacuum pump comprises a molecular drag pumping mechanism and a regenerative pumping mechanism. A rotor element of the molecular drag pumping mechanism surrounds rotor elements of the regenerative pumping mechanism.

Abstract: A system for maintaining a high vacuum in a vacuum enclosure such as cryostat, for example, is described. The system includes a high-vacuum pump having an input that is connected to the cryostat and an output. A vacuum vessel is connected to the output of the high-vacuum pump. A second vacuum pump is connectable to the vacuum vessel. The system is operated such that the high-vacuum pump maintains the cryostat at a high vacuum and the second vacuum pump is periodically operated to maintain the pressure of the vacuum vessel below a threshold pressure. The second vacuum pump may be either permanently connected to, or removable from, the vacuum vessel. The vacuum vessel acts to maintain the output of the high-vacuum pump within a suitable pressure range. This removes the need for the output of the high-vacuum pump to be connected to a continuously operating, second-stage vacuum pump.

Abstract: A vacuum pump, in particular a turbomolecular pump or a multi-inlet pump, includes a rotor shaft (12) that supports at least one rotor device (14). The rotor shaft (12) is mounted on the pressure side by way of a bearing arrangement (56) and on the suction side by way of a bearing arrangement (30). The suction-side bearing arrangement (30) is disposed in a high-vacuum area (22) and includes an electromagnetic bearing. Preferably, a coil (32) of the electromagnetic bearing is disposed in a recess (38) of a housing element (40). The recess (38) is pressure-encapsulated, in particular by a tubular closure element (42).

Abstract: A differentially pumped vacuum system includes first, second and third chambers, and a pumping arrangement for evacuating the chambers. The pumping arrangement includes a compound pump having a first inlet connected to an outlet from the first chamber, a second inlet connected to an outlet from the second chamber, a first pumping section and a second pumping section downstream from the first pumping section, the sections being arranged such that fluid entering the compound pump from the first inlet passes through the first and second pumping sections and fluid entering the compound pump from the second inlet passes through, of said sections, only the second section. The pumping arrangement further includes a booster pump connected to an outlet from the third chamber, and a backing pump connected to the exhaust from the booster pump. Fluid exhaust from the compound pump can be conveyed to either the booster pump or the backing pump as required.

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 for differentially evacuating the chambers is attached to the mass spectrometer. The pump assembly comprises a housing attached to the mass spectrometer and a cartridge inserted into the housing. The cartridge has a plurality of inlets each for receiving fluid from a respective pressure chamber and a pumping mechanism for differentially pumping fluid from the chambers. The cartridge is inserted into the housing such that the pumping mechanism is inclined relative to the ion path, but with the cartridge protruding into the mass spectrometer to such an extent that at least one of the inlets at least partially protrudes into its respective chamber without crossing the ion path.

Abstract: A pumping system includes a pumping mechanism, a motor for driving the pumping mechanism, a device for supplying power of a variable frequency to the motor, a control device for setting a maximum value for a current in the motor, and a device for supplying to the control device data indicative of the temperature of gas exhaust from the pumping mechanism and a temperature of the stator of the pumping mechanism, wherein the control device is configured to use the received data to adjust the maximum value during operation of the pumping system.

Abstract: An apparatus and method for differential pumping of a mass spectrometer or other ion-optical device provides a transverse pressure drop introduced across a face of a primary rotor of a turbomolecular pump by placement of one or more partitions in close proximity to the face of the primary rotor. Thus, two or more regions of space within the vacuum chamber having respective different pressures is achieved with a single pump.

Abstract: First and second pump stages provide a flow-path from an inlet to the outlet (30), the flow-path being arranged so that molecules entering the first inlet (26) pass to the outlet through the first (120) and second (122) pump stage, and so that molecules entering the second inlet (28) pass to the outlet through an inter-stage volume (121) and second pump stage (122); wherein the first (120) and second (122) pump stages each comprise a turbo-molecular sub-stage (120a, 122a) and a molecular drag sub-stage (120b, 122b).

Abstract: A vacuum pumping arrangement comprises a turbomolecular pumping mechanism and a molecular drag pumping mechanism connected in series. A rotor of the molecular drag pumping mechanism is supported by the rotor blades of the turbomolecular pumping mechanism.

Abstract: The invention provides a mass spectrometer system (10) comprising a mass spectrometer (12) comprising a plurality of mass spectrometer stages (16, 18, 20, 44) in fluid communication from a low vacuum stage (16) to a higher vacuum stage (44). A split flow multi-stage pump (14) evacuates the mass spectrometer stages. The pump comprises a pump envelope (28) in which a plurality of pumping stages (20, 32, 34) are supported for rotation about an axis X generally parallel to the direction of flow in the mass spectrometer stages for pumping fluid from a main pump inlet (36) to a main pump outlet (38). At least part of a higher vacuum stage (44) is located within the pump envelope at the main pump inlet.

Abstract: A turbomolecular pump has multiple stages of alternately arranged rotors and stators. Each of the rotors has blades radially extending from a rotating body. Each of the stators has blades radially extending toward the rotating shaft of the rotating body. The blades provided on at least either of a rotor and a stator are formed in a twisted shape having a blade angle set by an expression in which the radial distance from the rotating shaft is a variable. The expression of the blade angle is composed of a first expression which provides the optimum angle of each blade on the outer side of a predetermined radius of the blade and also composed of a second expression which provides the blade angle suppressing, on the inner side of the predetermined radius, reverse flow of gas molecules.

Abstract: A vacuum pump that includes a housing, a control unit including control elements for controlling electronic and electrical components located in the inner chamber of the housing, and a separation member for separating the inner chamber in which an underpressure prevails, from an environment in which the vacuum pump is located and including a printed circuit board having elements for conducting electrical current and voltage in the inner chamber of the pump housing.

Abstract: A turbomolecular pump having a pump main unit having, at least, a rotary vein provided on a rotor, a static vein for working in cooperation with the rotary vein to perform a vacuum exhaust, and a motor for driving the rotor, comprising: a controlling device that includes a motor driving circuit for converting into thermal energy, in a regenerative braking resistance, the regenerative electric current that is produced at the time of regeneratively driving the motor; and a cooling device for cooling the controlling device. A rod-shape heating resistive element is used as the regenerative braking resistance, where this resistive heating element is routed along the inner peripheral surface of an end portion 14a of the controlling device case that contacts the cooling device.

Abstract: The provision of the components requiring cooling on top of the cooling mechanism enables the cooling efficiency to be increased. Furthermore, a case of a control device is attached to the cooling mechanism whereon the components requiring cooling are disposed. The cooling mechanism fulfills the role of the contact surface of the case of the control device with the turbomolecular pump main unit, where the case does not have a case panel on the contact surface with the turbomolecular pump main unit. The cooling mechanism fulfills the role of one surface of the case for the control device, where the cooling mechanism is structured integrally with the control device. Additionally, the turbomolecular pump main unit, the cooling mechanism, and the control device are structured integrally by the turbomolecular pump main unit and the cooling mechanism being in contact.

Abstract: A turbo-molecular pump includes a base 3; a rotor 4 rotatably supported thereon; a stator 400 disposed around the rotor 4; and a tubular casing 2 configured to accommodate the stator 400. The stator 400 includes multiple stages of stator blades 43 and spacers 48 alternately stacked one upon another on a flange surface 31 of the base 3. At least one of the spacers 48 is provided with a circular ring part 483 continuously formed thereof covering the outer circumferential surface of other spacers 48 inside the casing 2.

Abstract: A vacuum pump for the evacuation of one or a plurality of volumes is described. The vacuum pump has a plurality of pressure stages and at least two suction inlets. An outer suction inlet for a first pressure stage spatially encompasses an inner suction inlet for a second pressure stage such that the inner suction inlet seals only against pressure within the outer suction inlet, not against external pressure.

Abstract: A wind turbine having one or more sets of opposing magnets to create an opposing force between a turbine support and a turbine rotor great enough to form a space between them thereby reducing friction between the turbine support and the turbine rotor. The reduction of friction between the turbine rotor and the turbine support allows for an increase in energy production and scale of the wind turbines.

Abstract: A molecular pump has a cylindrical casing, a stator portion formed in the casing, a shaft disposed in the stator portion, a bearing pivotally supporting the shaft with respect to the stator portion, a rotor that is attached to the shaft and rotates integrally with the shaft, a motor for rotationally driving the shaft, a shock absorbing member, and a flange portion provided at an end portion of the casing. The flange portion has a bolt hole through which extends a bolt for fixing the casing and a fixed member to each other and an insertion hole which is provided adjacent to the bolt hole and in which the shock absorbing member is inserted so that at least one end side of the shock absorbing member extending along an axial direction of the bolt is spaced apart from the bolt.

Abstract: A foil shield for covering at least one opening of a suction flange of a vacuum pump includes at least one member formed of a material having a relative permeability ?r greater than 1,000.

Abstract: The invention relates to a method of realizing a vacuum in a vacuum chamber. The vacuum chamber is connected to a pumping system shared by a plurality of vacuum chambers. The method includes separately pumping down each vacuum chamber. The invention further relates to n arrangement of a plurality of vacuum chambers connected to a pumping system. In this arrangement, the pumping system is arranged for pumping down each vacuum chamber separately.

Abstract: A support for a rolling bearing of the kind equipped with an outer rotating ring for a rotary vacuum pump, the support comprising an inner portion that can be associated with the rotating ring, a fastening outer portion and a connecting portion, interposed between the inner and outer portions, wherein the connecting portion is a frusto-conical resilient element.

Abstract: A rotary vacuum pump includes a pump casing on which an intake port flange is formed, a rotor which has a rotating side evacuating device and is driven to rotate at high speed inside the pump casing, and a fixing side evacuating device which is provided inside the pump casing and generates an evacuating effect together with the rotating side evacuating device. The intake port flange is fastened to a device subject to evacuating by a bolt. A through-hole is formed in the intake port flange for inserting the bolt and has a diameter larger than that of the bolt. A gap forming device for forming a gap between the bolt and the through-hole in the intake port flange is provided on a matching surface of the through-hole.

Abstract: A differentially pumped vacuum system includes first, second and third chambers, and a pumping arrangement for evacuating the chambers. The pumping arrangement includes a compound pump having a first inlet connected to an outlet from the first chamber, a second inlet connected to an outlet from the second chamber, a first pumping section and a second pumping section downstream from the first pumping section, the sections being arranged such that fluid entering the compound pump from the first inlet passes through the first and second pumping sections and fluid entering the compound pump from the second inlet passes through, of said sections, only the second section. The pumping arrangement further includes a booster pump having an inlet connected to an outlet from the third chamber, and a backing pump having an inlet connected to the exhaust from the booster pump. Fluid exhaust from the compound pump can be conveyed to either a second booster pump inlet or the backing pump inlet as required.