Factor defined (sometimes in per cent) as the ratio of the seal ring face subjected to the closing force exerted by hydraulic pressure in the seal chamber to the entire face-sealed surface.

This is a separated space between the rotating shaft and the immobile pump casing, to which the seal is installed.

It is the maximum/ minimum temperatures and pressures under static or dynamic operating conditions, rotational speed, kind of medium forced-through, its physical and chemical properties, existing mechanical impurities and the type of occurring limitations and hazards.

This is a clear configuration of seal components which ensure optimum operating parameters under accepted operating conditions and classify a given solution to a type defined with regard to the method of solution. Every type has a separate designation.

Such an element as O-ring or bellows, which enables the axial movement of the seal face without undesired leakage. This term sometimes is used for other gaskets which prevent leakage within elements of the mechanical seal.

This is a seal designed individually for working conditions and/or installation, mount, operating conditions, which differs considerably from general application seals.

Cylindrical sleeve ended with an internal stage, placed on the shaft to protect it against wear and corrosion. The stage is normally adjacent to the impeller hub (to ensure its proper position) and contains sealing between the shaft and sleeve stage.

An immobile element in the form of a disk or ring, mounted on the shaft sleeve or in the gland box cover, which is the basic part in axial contact with the remaining part of the seal (rotating unit).