The present invention is a separator device (oil separation) (100) for a device (1) for compressing a gas through the use of a compression fluid, comprising a compression chamber (2) suited to generate a compressed mixture of the gas and the compression fluid, and a separation tank (7) for the removal of the lubricant fluid from the compressed mixture, a first tubular element (101) suited to be inserted between the compression chamber (2) and the oil separation tank (7) of the compression device (1), in such a way as to convey the mixture inside the tank (7). The device (100) comprises means for deviating and/or conveying the flow of the compressed mixture that are suited to convey the mixture against the inner walls of the first tubular element (101) before the compressed mixture flows out of the first tubular element (101). The invention also concerns a separation tank (7) for a device (1) for compressing a gas through the use of a compression fluid.