A device for compression of a gaseous fluid, in particular of a refrigerant. The device comprises a housing with a suction pressure chamber and a high pressure chamber, a compression mechanism as well as a configuration developed in the proximity of the high pressure chamber, for the separation of a control mass flow from a fluid-lubricant mixture for the control of the compression mechanism. The configuration is developed and disposed with a first flow duct for diverting a main mass flow of the compressed fluid-lubricant mixture from the device and a second flow duct for conducting the control mass flow within the device to the suction pressure chamber in such manner as to separate a mass flow of the gaseous fluid as a control mass flow. A method for the separation of a control mass flow is also provided.