the 1990s, it made a major improvement in its rotary vane pump line with the introduction of the DuoLine pumps, which feature magnetically coupled sealing. Compared to the traditional cap-seal shaft ring, the magnetic coupling seal offered a more complete and less complex seal that preserved more of the pumps operating fluid, or pump oil. Whether they’re used in accelerator systems, mass pectrometry, or preparation chambers, these pumps may run the better part of 365 days a year, 24 hours a day. The new seal design was therefore a welcome change for high-demand users, and the coupling offered up to 30% savings in energy costs while still delivering high pumping speeds. Over time, the magnetic coupling has been improved, and now appears in the revised Duo- Line pumps launched earlier this year. Only now, says Michael Parry, product manager of Primary Vacuum Pumps at Pfeiffer, the advantages of saving energy, reduc- ing maintenance costs, and preventing downtown are even more pronounced. Pfeiffer’s rotary vane pumps are offered in two configurations: a single-stage pump
system with a cover inlet pressure range of 1,000 to approximately
0.5 mbar, and a two-stage serial pump system (like the DuoLine) that
have an expanded inlet pressure in the high-vacuum range of up to
0.005 mbar. This allows the DuoLine to support critical processes and
serve as backing pump to turbomolecular applications. The current
lineup (Duo 1.6, 3, 6, and 11) offers pumping speeds ranging from
1.25 to 11 m3/h.
The key feature of the DuoLine pumps is the use of a new contact-less, magnetically coupled drive, which helps save energy by hermetically sealing the pumps. This drastically reduces oil leakage potential
and improves both the environmental impact and the service life of
the pump. It also minimizes maintenance requirements, leading to
cost savings per pump and extended maintenance intervals. The new
design also lightens the pump relative to its similarly performing DuoLine of the previous year.
A completely sealed wet pump is a significant advance, in part
because all wet rotary vane pumps require pump oil. It fulfills three
important functions in a rotary vane pump, according to Parry. It
seals, lubricates valves and bearings, and guides the compression and
friction heat over the aluminum casing to the outside to cool the
pump. Maintaining the oil level is an important preventative step; if
the level drops too low, the pump system can be blocked due to lack of
lubrication, leading to rapid failure. Low oil also allows compression
heat to build, which ages the fluid that is there. In addition to shortening pump and component life, the formation of oil carbon can also
cause performance problems.
Normally, users of wet rotary vane pumps must change the oil every
12 months as a preventative measure. With the new DuoLine, that
period has been extended.
In addition to the new coupling design, an integrated, hydraulically
controlled high-vacuum safety valve increases operational reliability.
The SC950, launched this year by KNF Neuberger, is the latest example of a pump that can be controlled whether it’s
under the benchtop, or inside a closed fume hood. Image:
This valve disconnects the pump from the vacuum
recipient in the event of intentional or unintentional
standstill, using the displaced gas to vent the pumping
system and prevent operating fluid from rising into the
In addition to internal mechanical improvements, the
development team was also able to reduce the footprint
of the pump. New placement of the vacuum connec-
tions on the top side of the pump is intended to improve
the ability of users to integrate the unit with other
pumps or systems.
“These pumps offer reliable operation as a standalone pump or as a backing pump in turbomolecular
pumping stations,” says Parry. The pumps are also offered
with a conventional radial shaft sealing ring.