Oil seals create a tight seal, preventing fluid from leaking and contaminants from entering. Oil seals can have single lip or multiple lip configuration to provide protection against dust. A garter spring is used to provide a constant load on the sealing lip.
V-Rings and V-Sets
V-Rings (and multiple V-Rings, V-Sets) are axial shaft seals that fit directly on the shaft. The V-ring rotates with the shaft while its lip provides excellent sealing characteristics against all types of media.
PTFE Lip Seals
PTFE lip seals are designed to hold up against high temperatures, high pressures, and aggressive media. PTFE lip seals sit statically on the bore and seal dynamically on the shaft. An O-ring might be found on the OD to prevent the seal from rotating along with the shaft.
Packing is the traditional method of stopping leakage around the drive shaft of an end-suction centrifugal pump. Rings of braided fibrous material, such as graphited or non-graphited acrylic, PTFE (polytetrafluoroethylene or Teflon) or other materials, are “stuffed” into a pump stuffing box (or seal chamber) located in the pump backplate around the outside diameter of the pump shaft. This reduces the high pressure that develops in the pump case and decreases the amount of pumped medium that is forced out of the pump along the drive shaft.
Packing does not stop all leaking, however. Packing rings are kept just loose enough to allow a trickle of liquid to seep out during operation, which accomplishes the lubricating action necessary to prevent overheating and excessive wear between the inside of the packing surface and the outside diameter of the drive shaft.
A bearing isolator is a two part dynamic seal consisting of a stator and a rotor attached to the shaft. The rotor and stator form a non-contacting compound labyrinth seal with no wearing parts; this ensures permanent protection.
A radial shaft seal is sometimes used between a rotating and stationary component. It consists of an outer case and a sealing lip. The sealing lip is made of an elastomer or thermoplastic material that dynamically seals against the rod shaft. In addition, a garter spring is used on the lip to provide a constant load. Sometimes a second sealing lip may be used on a radial shaft seal to act as an excluder, preventing dust and contamination from entering the cylinder.