The labyrinth seals used with SAF housings have three radially arranged labyrinth stages that form narrow gaps to the grooves in the housing walls. They are suitable to seal against dirt and dust, but are not recommended for wet applications. The sealing effect can be enhanced by filling the seal cavities with grease. These non-contact seals do not limit bearing speed. They tolerate misalignment of up to 0,3°.
There are three types of labyrinth seals
the LER design seal (fig 1), which is the standard seal for shaft sizes up to 21/4 in.
The seal is made of aluminium and can be operated at temperatures up to 150 °C (300 °F). It is suitable for grease lubrication only.
the LOR design seal (fig 2), which is the standard seal for shaft sizes from 23/8 inch and above.
This seal, called the PosiTrac seal, consists of an aluminium labyrinth ring and an O-ring made of acrylonitrile-butadiene rubber (NBR) that is inserted between the shaft and labyrinth ring to make the labyrinth ring rotate with the shaft. With a permissible operating temperature up to 100 °C (220 °F), the seal is suitable for grease or oil lubrication.
the LORP design seal is a made-to-order seal for high temperature applications.
It follows the same design as LOR seals, but the labyrinth ring is made of PTFE and the O-ring is made of fluoro rubber (FKM). The permissible operating temperature is up to 200 °C (400 °F).
For an overview over seal features and performance, see the matrix.