A method for determining a flow volume of a fluid delivered by a pump, wherein the flow volume is determined as a function of predefined pump information depending on a pump geometry, rotation speed information, which correlates with the rotation speed of the pump, and pressure information, which correlates with a differential pressure at the pump.

A pumping unit is provided, including a primary vacuum pump of a multistage dry type, including at least four pumping stages fitted in series; and a two-stage Roots vacuum pump, including a first pumping stage and a second pumping stage fitted in series, the second pumping stage being fitted in series with and upstream of a first pumping stage of the primary vacuum pump in a direction of flow of gases to be pumped, in which a ratio of a volume displacement of the first pumping stage of the two-stage Roots vacuum pump to a volume displacement of the second pumping stage of the two-stage Roots vacuum pump is less than six, and in which a ratio of a volume displacement of the second pumping stage of the two-stage Roots vacuum pump to a volume displacement of the first pumping stage of the primary vacuum pump is less than six.

A screw compressor includes a screw rotor, an electric motor for driving the screw rotor, bearings supporting the screw rotor and casings housing these members. The screw compressor also includes an oil feeding passage formed in the casing for feeding oil on a high pressure side to the bearings by a differential pressure between the high pressure side and a low pressure side and an oil feeding amount adjusting unit placed in a middle of the oil feeding passage, the oil feeding amount adjusting unit includes a cylinder, a valve element provided to reciprocate inside the cylinder, and plural flow paths provided in the valve element having different flow path areas, the plural flow paths are switched to adjust an oil feeding amount to be fed to the bearings by moving the valve element in accordance with the differential pressure between the high pressure side and the low pressure side.

A compressor system is provided that includes a contact cooled compressor and a coolant separator. The coolant separator is used to remove coolant fluid from a compressed flow stream produced by the contact cooled compressor during its operation. The coolant separator routes the removed coolant fluid back to the contact cooled compressor for further use. In some forms the coolant fluid is cooled prior to delivery back to the compressor. A stop valve can be provided in the coolant fluid return line to halt the flow of the fluid. A pressure sensitive member can be disposed to sense pressure of the coolant fluid that has been routed past the stop valve. Operation of the compressor can be changed as a result of the sensed pressure from the pressure sensitive member. Information from a temperature sensitive member can also be used to change operation of the compressor.

A method of handling a gear pump, the gear pump including a driving gear wheel having a plurality of driving teeth and a driven gear wheel having a plurality of driven teeth meshing with the driving teeth, the method including controlling the gear pump in a testing mode including commanding driving of the gear pump to pump liquid towards a downstream device and commanding an increase of rotational speed of the gear pump; monitoring rotation values indicative of the rotational speeds during the testing mode; monitoring pressure values by means of at least a downstream pressure sensor during the testing mode, the downstream pressure sensor being arranged to measure a downstream pressure of the liquid between the gear pump and the downstream device; and determining at least one operational condition of the gear pump based on the pressure values and the rotation values.

A compressor system is provided that includes a contact cooled compressor and a coolant separator. The coolant separator is used to remove coolant fluid from a compressed flow stream produced by the contact cooled compressor during its operation. The coolant separator routes the removed coolant fluid back to the contact cooled compressor for further use. In some forms the coolant fluid is cooled prior to delivery back to the compressor. A stop valve can be provided in the coolant fluid return line to halt the flow of the fluid. A pressure sensitive member can be disposed to sense pressure of the coolant fluid that has been routed past the stop valve. Operation of the compressor can be changed as a result of the sensed pressure from the pressure sensitive member. Information from a temperature sensitive member can also be used to change operation of the compressor.

A fluid supply system includes: a centrifugal pump; a starting pump that is connected to the centrifugal pump in series, is provided downstream of the centrifugal pump, and has a discharge flow rate less than that of the centrifugal pump; a measuring valve that is provided downstream of the centrifugal pump and the starting pump, measures an amount of fluid discharged from the centrifugal pump or the starting pump, and discharges the fluid to a downstream each time the fluid reaches a predetermined flow amount; a differential pressure valve that is provided downstream of the centrifugal pump and the starting pump, and is driven based on a differential pressure between an upstream pressure and a downstream pressure of the measuring valve; and a flow rate control valve that is provided downstream of the centrifugal pump and upstream of the differential pressure valve and has a valve opening speed that is set slower than that of the differential pressure valve.

An element for compressing a gas with a housing (2) which encloses a compression chamber (5) with an outlet port (7) connected to the outlet. A rotor (8) is mounted so that the compression chamber (5) is divided into working chambers. A passage (10) extends between the outlet and a working chamber in the compression chamber (5) which is not in adjacent contact with the outlet port (7). The passage has an overpressure valve (11) to open the passage when a pressure difference between the working chamber and the outlet (4) exceeds a preset value. A valve body (12) encloses a buffer space (13) with a variable volume that is in fluid connection with the outlet through a constriction (14), so the volume is reduced and gas from the buffer space (13) flows through the constriction (14) to the outlet upon opening the passage (10).

A device for compressing a gaseous fluid, in particular a refrigerant in a refrigerant circuit, specifically of an air-conditioning system of a motor vehicle. The device has a housing, a compression mechanism for compressing the gaseous fluid, and an electric motor for driving the compression mechanism. The housing is formed with a suction-pressure chamber and a high-pressure chamber.

A screw compressor includes a screw rotor, an electric motor for driving the screw rotor, bearings supporting the screw rotor and casings housing these members. The screw compressor also includes an oil feeding passage formed in the casing for feeding oil on a high pressure side to the bearings by a differential pressure between the high pressure side and a low pressure side and an oil feeding amount adjusting unit placed in a middle of the oil feeding passage, the oil feeding amount adjusting unit includes a cylinder, a valve element provided to reciprocate inside the cylinder, and plural flow paths provided in the valve element having different flow path areas, the plural flow paths are switched to adjust an oil feeding amount to be fed to the bearings by moving the valve element in accordance with the differential pressure between the high pressure side and the low pressure side.