TP80-80/4 Shaft Seals Manual

8
Shaft seals in general
Shaft seals
Shaft seal components
Fig. 4 Components of mechanical shaft seals
Key:
Fig. 5
Main components of a mechanical shaft seal
A mechanical shaft seal consists of a
• rotating part
• stationary part.
The rotating part comprises a seal face (primary seal),
a seal driver with retaining ring, a secondary seal, a
spring and a spring retainer.
The stationary part consists of a seat (primary seal) and
a static seal (secondary seal).
The parts mentioned above are crucial for the proper
functioning of the shaft seal.
Primary seals differ from the other components in that
they are exposed to a powerful axial spring force and to
the liquid pressure in the seal housing during the rota-
tion of the seal faces relative to one another. The spring
keeps the seal faces together mechanically.
To obtain an acceptable surface pressure between the
primary seal faces, shaft seals are available in two dif-
ferent designs:
• balanced shaft seals
• unbalanced shaft seals.
Balanced shaft seal
The sketch below shows a balanced shaft seal with
indication of the forces acting on the seal faces.
Fig. 6 Areas where the forces of a balanced seal act
Unbalanced shaft seal
The sketch below shows an unbalanced shaft seal with
indication of the forces acting on the seal faces.
Fig. 7 Areas where the forces of a unbalanced seal act
TM02 6889 1903
Shaft seal Designation
Rotating part
Spring
Seal driver with retaining ring
Spring retainer
Secondary seal
Seal face
Stationary part
Static seal (secondary seal)
Seat (primary seal)
TM02 6890 1903
Spring
Static
seal
Seal driver with
retaining ring
SeatSpring
retainer
Seal face
Secondary
seal
Rotating part
Stationary part
Seal points
TM02 6892 1903TM02 6891 1903
A
B
A
B