This invention relates to an arrangement for sealing off a fluid-filled, stationary pressurized compartment from an endlessly circulating, impermeable belt of a machine for producing and/or refining a paper, paperboard, tissue or other fibrous web with the help of at least one seal of the pressurized compartment, whose contact pressure toward the belt is variable, wherein the belt is pressed by the pressurized compartment against a co-driven support element and the fibrous web runs alone or jointly with one or more function belts between the belt and the support element. The sealing is improved in this case, while producing as little leakage and wear as possible, in that the contact pressure of the seal is controlled as a factor of the drive power and/or the drive torque channeled into the belt and/or as a factor of the leakage of fluid through the gap between the seal and the belt and/or as a factor of the pressure of the fluid in the pressurized compartment.