Rotary Seals - Dilanda.it

Radial Oil Seal
Peripheral speed and number of revolutions
Different designs of the sealing element affect the
magnitude of the friction and thus result in varying
temperature rises. As a result the various designs of the
sealing element allow different maximum peripheral
speeds. Figure 11 shows the approximate maximum
values for the permissible peripheral speed for sealing
elements (without dust lip), i.e. seal type TRC/BB, TRA/CB,
TRB/DB, etc, made with materials NBR, ACM, FKM and
VMQ, with no differential pressure, and where adequate
lubrication or cooling of the sealing edge by the sealed
medium exists. In addition the maximum permissible
operating temperatures shown in Table V must not be
exceeded. The curve shows that higher peripheral speeds
are permissible for larger shaft diameters more than for
the smaller. This is due to the fact that the cross-sectional
area increases in proportion to the square of the diameter,
thus increasing the heat dissipation capacity.
Speeds in rpm
40
30000 15000 10000 9000 8000 7000 6000 5000 4500 4000
35
VMQ and FKM
Materials
3500
30
3000
25
2500
Peripheral speed m/s
20
15
10
ACM
Materials
NBR
Materials
2000
1500
1000
5
500
0
0 20 40 60 80 100 120 140 160 180 200
up to 500 mm
Shaft diameter d1 mm
Figure 11 Permissible speeds in pressure-free state to DIN 3761
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Edition April 2006
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