Mechanical seals touch nearly any component of the industrialized environment. Wherever pivoting moves fluid mechanical seals play a pivotal role in sealing procedure fluids in, maintaining contaminants out, or both.

A few essential elements and fundamental in mechanical seal design provide to a working seal at the interface of the pivoting shaft and stationary pump/seal chamber housing/mixer. Mechanical seals are generally ending face sales or rotating face seals, but in some designs, they might be circumferential or even a hybrid of lip-type seals, in either case, the following elements are usual to all mechanical seals:

Pivoting primary sealing component: fixed to / driven by the shaft and seals against the stationary primary sealing component

Stationary primary sealing component: fixed to the stationary housing of the pump, mixer seals or other apparatus through which the pivoting shaft passes and seals upon the pivoting primary sealing component.

Closing force; biases the primary sealing elements in contact to initiate sealing
Static/dynamic secondary seals: seals between the mechanical seal elements and the apparatus shaft and housing.

Pivoting and stationary primary sealing component

The more common end or pivoting face mechanical seal designs attribute mating faces as the primary sealing components. Rings of ceramic, carbon or composites of these materials are lapped flat in the range of less than 1 micro on an axial end face. These lapped faces run upon each other, one pivoting with the shaft and the other stationery with the apparatus housing.

The sealed fluid migrates between the flat faces and forms a solid-fluid at this interface. During shaft motion, the face materials heat up, wear and degenerate easily without a greasing fluid between them. The sealed fluid makes this thin greasing film.

Closing forces

Closing forces are used to develop this design parameter throughout the working range of the mechanical seals. Leakage is a function of the mathematical cube of the film thickness, so to decrease leakage, the space at the sealing interface must be kept at a fictional bottom

The initial closing force makes sure that the seal will work well from startup. In end or pivoting face mechanical seal designs, the initial closing force is given by a spring element, which can be a single coil spring, many coil springs, a deflected bellows unit (elastomer or metal), or flat springs or formed. Initial biasing forces also can be made by magnets, compressed elastomers or any other means of applying a closing force between sealing component. In lip-type mixer seals, the initial closing is generally from the diverted polymer of the type seal or a garter spring for less resilient materials.

Static/dynamic secondary seals

The sealing component must be a safeguard to the pivoting shaft and stationary housing of the apparatus being sealed. O-rings, gasket and other elastomer seal stop leakage at these interfaces

A static secondary seal stop leakage between elements that do not move relative to each other. An example is an interface between a sleeve and a shaft, where both pivoting but do not move relative to each other. A dynamic secondary seal, stop leakage between elements that move relative to each other.