The document describes two embodiments of a mechanical gland seal for preventing liquid leakage along rotor shafts of rotary pumps. The first embodiment uses a spring bellows to apply pressure to a carbon ring, sealing it against the shaft flange. An O-ring additionally seals the interior from the exterior of the housing. The second embodiment uses a spring-loaded header ring compressing an H-section seal between the header and a carrier holding the carbon ring, sealing both the interior and along the shaft flange.