Mechanical Seals for Rotating Shafts: An Outline of the Theories Underlying the Sealing of Rotating Components

THE practice of mechanically sealing liquids and gases within machines has shown little tendency to undergo any fundamental change since the earliest days of the art, and apart from the semi‐sealing properties of the elementary labyrinth in which measurable clearances exist as between a rotating shaft and its housing, some variant of the common ‘soft packing’ is the standard method of providing the closest form of contact sealing. This type of seal seems to have been engendered by the concept that only substances having extreme deformability could provide the closest degree of conformity to a circular shaft, and the type is brought into play in many ways, from the simple kind of soft, semi‐elastic ring which is rammed into a housing and thus becomes, due to its transverse elasticity, to some extent preloaded on to its co‐acting shaft, to the more refined rubber ring with its lip held against the shaft through the medium of an encircling garter‐spring of steel.