A power wrench includes a hydraulic pulse unit that includes an impulse generator. A separating arrangement is provided to extract air from oil. The separating arrangement includes a disc-shaped separator element and a sealing arrangement arranged to provide a seal between the disc-shaped separator element and a receiving space in fluid communication with the oil chamber. The disc-shaped separator element provides a passageway between the oil chamber and the receiving space by a fluid opening. The separating arrangement also includes a partitioning element arranged in the receiving space, such that first and a second partial volumes are formed on sides of the partitioning element. The first and second partial volumes are in fluid communication, and the fluid opening is arranged on the first side of the partitioning element.