Labyrinth seal
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- For more uses of the word labyrinth, see Labyrinth (disambiguation)
A labyrinth seal is a mechanical seal that fits around a rotating shaft to prevent the leakage of oil or other fluids. A very small clearance must exist between the tips of the labyrinth threads and the running surface. A labyrinth seal is composed of many straight threads that press tightly inside another shaft, or stationary hole, so that the fluid has to pass through a long and difficult path to escape. Sometimes 'threads' exist on the outer and inner portion. These interlock, to produce the long characteristic path to slow leakage.
Turbines use labryinth seals due to the lack of friction which is necessary for high rotational speeds. They are also found on pistons, which use them to store oil and seal against the explosion of combustion.
Labyrinth seals provide non-contact sealing action by controlling the passage of fluid through a variety of chambers by centrifugal motion, as well as by the formation of controlled fluid vortices. At higher speeds, centrifugal motion forces the liquid towards the outside and therefore away from any passages. Similarly, if the labyrinth chambers are correctly designed, any liquid that has escaped the main chamber, becomes entrapped in a labyrinth chamber, where it is forced into a vortex-like motion. This acts to prevents its escape, and also acts to repel any other fluid.
Because labyrinth seals are always non-contact, they do not wear out.
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