A Comprehensive Guide to Mechanical Face Seals: Materials, Tribology, Heat Transfer and Solid Mechanics
the mechanical face seal is a mechanical device that is usually in a sealing engagement with some form of mechanical coupling. this mechanical coupling usually consists of either a rotating ring or a stationary ring. the rotating ring is driven by a shaft while the stationary ring remains stationary. in most cases, the rotating ring does not drive the stationary ring. the mechanical coupling ring usually receives power from a drive shaft that drives the rotating ring. when the mechanical coupling rings are present, the mechanical face seal is called an h sealing device. for more information on the h sealing device, we suggest you refer to professor e. keith irwins paper, the h sealing device.
Principles And Design Of Mechanical Face Seals
the primary and secondary seal rings, or mating rings, are often designed to provide consistent sealing contact pressure. the contact pressure is the force required to seal the face seal. most mechanical face seals apply a load to the face seals to ensure a consistent sealing force is applied to the sealing faces. usually, the load is applied by a helical spring, which is similar to a stocking that holds its shape. the helical spring load provides a constant force to the face seals regardless of the axial load. axial load is the force due to the axial force on the drive shaft. the primary and secondary ring are usually designed with a helical spring that applies the same pressure to both faces. the helical spring can be single, double, or multiple.
loading - seals are subjected to a load, typically a pressure, which is normally on the mating side. the load that develops on the mating surface of a mechanical face seal and may cause damage to it is called the contact pressure. the contact pressure is usually significantly higher than the pressure in the gland. the pressure of the internal sealing fluid is usually very low. the contact pressure is due to the hydrostatic load from the glands internal pressure. the contact pressure is normally much higher than the sealing pressure. the contact pressure causes wear of the primary sealing faces (also called the sealing faces) and causes leakage across the seal faces. the contact pressure is the only force acting on the inside sealing faces, it is not balanced by any other forces. the contact pressure is dependent on the hydraulic force and the spring force. the pressure is the static load on the seals. the contact pressure is not a static force, it increases dynamically with the speed of rotation of the shaft. the pressure distribution is dependent on the hydrodynamic lubrication regime. the contact pressure is the sum of the frictional force and the hydrostatic force. the frictional force is due to the contact area, the viscosity of the fluid and the rotational speed. the hydrostatic pressure is the pressure of the sealing fluid. the load is the sum of the pressure on the inside sealing faces and the force on the outer surface of the primary sealing ring.