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 maintenance.
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
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 rpm.
Optimum Torque Transmission
Through-shaft construction permits 100% of the engineered torque
transmission and provides in-phase rotation without backlash or
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 extremely smooth.