Abstract: A sluice device for insertion between zones having different environmental conditions, for instance pressure and/or temperature. A drum is rotatably arranged in an opening in a housing and has radially displaceable flaps uniformly distributed along the periphery of the drum. Each flap has a first portion for sealing against the housing, and a second portion of the flap, adjacent to the drum, cooperates with a sealing device. The sluice device is formed as a longitudinal groove which is open against the drum, whereby a longitudinal sealing member is arranged in the groove. The pressure difference between spaces at the two sides of the flap brings the longitudinal sealing member in such a sealing position that the flap, by the pressure difference, is placed in sealing abutment against the inside of the housing regardless of the positive or negative pressure difference.