A mechanical seal refers to a device that prevents fluid leakage, consisting of at least one pair of end faces perpendicular to the rotating shaft. These end faces, under the action of fluid pressure and the elastic force (or magnetic force) of the compensating mechanism, along with the cooperation of auxiliary seals, maintain contact and slide relative to each other. A mechanical seal where the auxiliary seal of the compensating ring is a metal bellows is called a bellows mechanical seal.