Term used to denote the cavity between the outer diameter of the shaft (protection sleeve) and the inner diameter of the seal housing in the area of the shaft opening through the machine casing. The designation of stuffing box compartment (for dimensions see DIN 3780) should not be used for the compartment where the mechanical seal is mounted. The service life of a mechanical seal is considerably influenced by the design and configuration of the mechanical seal compartment, the connecting parts and the pipe connections. DIN ISO 5199 contains important notes and requirements for designing the shaft stuffing box of centrifugal pumps. These notes apply analogously to the shaft stuffing boxes of other machines.