Finger Seals Replace Brush or Labyrinth Seals
- Created on Tuesday, 01 April 2008
Finger seals are non-contact fluid seals similar in purpose to labyrinth or brush seals in that they act as a barrier between two areas of the same or different pressures, but allow a rotating shaft to penetrate through them from one side to the other. Applications include sealing rotating parts in turbine engines, pumps, rotating air motors, or other applications where a shaft needs to be sealed against incursion or excursion of oil, air, water, or other gases or fluids.
A finger seal consists of long, inward-pointing “fingers” angled in the direction of rotation of the enclosed shaft. Gaps between the fingers allow each finger to flex in response to thermal or dynamic loads on the shaft — for example, shafts can become fractionally larger during high-heat operations. Because of the gaps between the fingers, a “finger seal” consists of two or more layers of fingers offset in such a way that the fingers of one layer block the fingers of the other layer. Finger seals offer high-temperature capability up to 1200°F, and are able to withstand high pressure drops to 75 psid.
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