Industrial shaft seals

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Industrial
факс
shaft seals
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Seals under pressure
Where a pressure is exerted on the seal, the
lip will be pressed harder against the counter
surface and the actual contact will be enlarged,
so that friction and temperature in the contact
will increase.
Therefore, the guideline values for speeds
obtained from Diagram 5 do not apply.
Guideline values for seals under pressure
can be obtained from Table 6. The values are
for solid shafts, good heat removal via the
medium being retained, and where the
counterface meets the demands regarding
surface finish and running accuracy.
SKF radial shaft seals of the CRW5 and
CRWA5 designs can withstand differential
pressures of 0,6 MPa (fig 46).
Where there is a pressure differential across
the seal, a shoulder, spacer ring or retaining
ring should be used at the low pressure side of
the seal to prevent it from being pressed out of
the housing bore (fig 45).
An additional steel shell (fig 47) which
supports the sealing lip makes it possible to
use other radial shaft seals under pressure.
This solution is rather expensive but can be
appropriate where there is no suitable
pressure seal available, or where quantities are
not sufficient for cost effective production.
CRW5
CRWA5
Fig 45
Fig 46
Table 6. Permissible speeds for seals under pressure
Pressure Shaft speed Circumferential speed
differential
max permissible max
MPa r/min m/s
0,02 3.000 5,6
0,035 2.000 3,2
0,05 1.000 2,8
gab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 71 22
Fig 47