A Ferrofluidic seal provides a hermetic seal under both static
and dynamic conditions against gas, vapor and other
contaminants. Leakage rates are in the region of 10-11
[He] mbar l / s.
As the sealing medium is a fluid, there is virtually no
friction between the rotating and stationary components so the
seal does not wear. The fluids used in Ferrofluidic seals are
inert, stable, low vapor pressure ferrofluids. The seal
lifetime depends on the application, but many Ferrofluidic
seals have been in operation over 10 years without
A Ferrofluidic seal contains a simple permanent magnetic
circuit and low volatility ferrofluid. The only parts subject
to wear are self-contained ball bearings which are engineered
to provide reliable operation.
Since there is no mechanical friction within the ferrofluid or
between the ferrofluid and the static seal components or
shaft, no particles are produced which could contaminate the
system. Low vapor pressure ferrofluids maintain seal integrity
even in high vacuums better than 10-9 mbar.
High Speed Capability
Ferrofluidic seals provide hermetic sealing even at high
rotational speeds. Current technology has produced
configurations that perform at dN values of 500,000 (where
d=shaft diameter in mm and N=rotational speed in rpm). For a
1" feedthrough this equates to a rotational speed of 20,000
Optimum Torque Transmission
Through-shaft construction permits 100% of the engineered
torque transmission and provides in-phase rotation without
backlash or slip errors.
No Set-Leakage Failures
Ferrofluidic seals provide leak-free performance, even in
intermittent and static conditions. Unlike elastomeric seals,
they are not subject to plasticizing and relaxation effects
during idle periods.
The low viscous drag of the ferrofluid is independent of the
pressure applied across the seal. Operation therefore is