Behind the rotor mechanical seals work by utilizing two separate seal faces. One seal face (static) is typically installed into the pump housing, or bracket, while the other (rotary face) is installed onto the base of the pump shaft against the rotor. These two seal faces are glossy and highly finished. When liquid is being pumped, process fluid will work it’s way toward the seal faces. When liquid finally enters the space between the seal faces, a hydrodynamic film is created which creates the seal and lubricates the faces. This is the primary seal. A spring helps hold the seal faces together to maintain the primary seal.

Secondary seals are created by o-rings, bellows, or gaskets that prevent leakage past the gland or along the shaft.