| Floating ring seals | ||
Floating ring seals are radial seals. They
consist of one or several radial seal rings with as small a gap clearance to the rotating
shaft as possible. Shaft deflections are compensated by an enlarged clearance between the
floating ring diameter and the upright housing. Individual rings are prevented from
rotating by an anti-rotation pin. With pressure applied by the product and the shaft in
rotation, a practically concentric annular gap is formed to the shaft by the axially
discharging leakage. Hence the seal runs largely without wear. Use of suitable,
emergency-proof materials prevents destruction of the ring during start-up and shut-down.
To stop the product escaping into the atmosphere, a liquid or gaseous buffer medium must
be fed between a pair of rings. The optimum buffer pressure is reached when no product
flows out and as little leakage as possible emerges at the product side. With this type of
sealing long service lives can be obtained at high peripheral speeds. One drawback is the
inability to switch off the supply systems at standstill, |
because unless an additional seal is provided
the product will escape. Optimum adjustment of the buffer fluid pressure to the operating
pressure requires a very elaborate control system. |
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