A method for determining a flow volume of a fluid delivered by a pump. 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 dry vacuum pump includes: at least one oil sump; at least one pumping stage; two rotary shafts respectively supporting at least one rotor extending into the at least one pumping stage, the rotors being configured to rotate in a synchronized manner in the reverse direction in order to convey a gas to be pumped between an intake and an outlet of the vacuum pump, the shafts being supported by bearings lubricated by a lubricant contained in the at least one oil sump; at least one lubricant sealing device interposed between the at least one oil sump and a pumping stage at the shaft passage; and at least one expansion device configured to reduce the pressure variations between a pumping side volume and the at least one oil sump.

In the operation of a refueling screw compressor, when load conditions constantly fluctuate or when the rotation speed control of a cooling fan is performed, it is difficult to accurately perform a diagnosis predicted from measurement results of devices inside the compressor, so a diagnostic mode stably creates an operating condition under which an accurate diagnosis can be performed. In the refueling screw compressor, a discharge electric valve is provided downstream of an air cooler, and an air release electric valve and a dedicated orifice are provided to connect an oil separator inner space and a suction throttle valve space. In the diagnostic mode, the discharge electric valve is closed, the air release electric valve is opened, and while an upstream pressure of the oil separator is maintained at a specified pressure, a rotation speed control operation of a compressor body and the diagnosis of internal devices are performed.

The present disclosure relates to a dual-stage compressor, a control method thereof, and an air conditioning unit. The dual-stage compressor includes a low-pressure stage; a high-pressure stage connected in series with the low-pressure stage; and a volume ratio adjustment mechanism arranged at the high-pressure stage and configured to adjust the volume ratio of refrigerant compression at the high-pressure stage. When the final compression pressure of the compressor is lower or greater than the exhaust pressure, the volume ratio adjustment mechanism is operated to increase or reduce the volume ratio of refrigerant compression at the high-pressure stage so that the final compression pressure of the compressor is equal to the exhaust pressure, and overcompression and undercompression are improved to adapt to changes in external conditions, increase the energy efficiency of the compressor, and reduce the noise of the compressor.

Method for operating and in particular monitoring a scroll pump, with the steps of: producing a vacuum by means of the scroll pump; determining a pressure of the scroll pump; comparing the recorded pressure with a pre-set threshold value; and if the recorded pressure lies above the pre-set threshold value, emitting a warning signal. The invention furthermore concerns a scroll pump for executing the method.

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 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.

A dry vacuum pump includes: at least one oil sump; at least one pumping stage; two rotary shafts respectively supporting at least one rotor extending into the at least one pumping stage, the rotors being configured to rotate in a synchronized manner in the reverse direction in order to convey a gas to be pumped between an intake and an outlet of the vacuum pump, the shafts being supported by bearings lubricated by a lubricant contained in the at least one oil sump; at least one lubricant sealing device interposed between the at least one oil sump and a pumping stage at the shaft passage; and at least one expansion device configured to reduce the pressure variations between a pumping side volume and the at least one oil sump.

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.