Agitator shaft seals can be classified as follows:
OIL SEAL / LIP SEAL / DOUBLE LIPSEAL
The drippan combination gives a unique protection against oil-leak of the gear. The contact drippan sealing operates ware less.
STUFFING BOX GLAND PACKING
Stuffing boxes accomplish sealing by the radial expansion of a soft, deformable material such as braided or layer-wound rubber, plastic, fiber, or a combination of these. Stuffing boxes are lower in initial cost than mechanical seals but are significantly higher in maintenance expenses.
A mechanical seal consists of two extremely flat ring-shaped surfaces: one stationary with the vessel and one rotating with the agitator shaft. Mechanical seals initially are more expensive than stuffing boxes, especially at higher pressures. When repaired, they must be treated with extreme care, because they are pieces of equipment.
* * Several different types of seals are available for different pressure ranges.