Description
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GA03108_002_C1 - 04/2018 - © Leybold
In practice, the maximum attainable pressure differential is significant only in
the rough vacuum range (p > 10 mbar), whereas for pressures in the fine
vacuum range (p < 1 mbar) the attainable compression ratio is decisive.
RUVAC WS/WSU pumps have been specifically designed for operation in the
rough and fine vacuum ranges. They are thus either used in connection with
backing pumps or in closed gas cycles.
Power consumption of the pump depends on
■
the volume of the pump chamber
■
the speed of the pump
■
the existing pressure range
■
the pressure difference between the inlet and the discharge flange (see fig. 1.7)
■
and the type of gas to be pumped.
1.1.2 Design
RUVAC Roots pumps can pump gas in the vertical or horizontal direction.
Although the pumping chamber of Roots pumps is free of sealing agents and
lubricants, the two gearwheels of the synchromesh gearing (1.3/1) and the
bearings (1.3/2) are lubricated with mineral oil, synthetic oil or with PFPE. The
gearwheels and bearings of the RUVAC are located in two side chambers
which also contain the oil supply.
These two side chambers are separated from the pumping chamber by the
impeller seals (1.3/3). During operation of the pump, the side chambers are
evacuated via the impeller seals.
The side chambers are linked to each other by two passages (1.3/12). These
passages are arranged so that for either horizontal or vertical flow the pressu-
re will be equalised between the oil supplies.
In both side chambers there are integrated oil pumps to ensure that the bea-
rings and gearwheels receive sufficient lubricant at all recommended speeds.
RUVAC WS/WSUs are driven by an air or water cooled canned motor. In
such a motor, the rotor and stator coils (1.3/6) are separated by a vacuum-
tight can (1.3/7) made of non-magnetic material. The rotor runs in the vacu-
um on the pump’s drive shaft (1.3/10); thus a shaft feedthrough to the atmo-
sphere is not needed.
With the standard motors, the RUVAC WS/WSUs can run on either 50 Hz or
60 Hz power supplies.
When operating with frequency converters even higher speeds are possible.
Built into the stator coil of the motor is, depending on the version, a tempera-
ture switch, respectively three PTCs and a temperatures switch which will
shut down the pump when the motor temperature gets too high.
The pump section of the RUVAC WS/WSU is air cooled. The air flow cooling
the motor and the pump is produced by a fan (1.3/9) having its own drive
motor under the fan cowl (1.3/8).
