Pfeiffer Vacuum DUO 35, Руководство по эксплуатации

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3.4 Operating principle
1
2
3
4
5
6
Fig. 4: UnoLine and DuoLine operating principle
1 Housing 4 Suction chamber
2 Rotor 5 Exhaust (outlet)
3 Vane 6 Vacuum flange (inlet)
The rotary vane pump is an oil-sealed rotary displacement pump. The pumping system is made up of
the housing, the eccentrically mounted rotor, and the centrifugally- and spring-loaded radially sliding
vanes, which divide the suction chamber into multiple chambers. The volume of each chamber changes
periodically as the rotor rotates. This causes the gas to be drawn in at the vacuum flange, and com-
pressed in the suction chamber by the rotation of the rotor until the exhaust valve opens against the
atmospheric pressure at the outlet and expels the gas. The exhaust valve is oil-sealed. When the valve
opens, a small quantity of oil penetrates into the suction chamber. In addition to lubrication, this also
causes the gaps between the rotor, stator, and vanes to seal.
Vacuum safety valve
Depending on the pump type, rotary vane pumps are equipped with a vacuum safety valve. The vac-
uum safety valve separates the pump from the vacuum chamber in the event of intentional or uninten-
tional standstill, and vents the pumping system with the displaced gas so that oil does not rise into the
vacuum chamber. When the pump is switched on, it opens after a delay.
Gas ballast valve
During boost operation, an outward-facing bore opens out into the closed suction chamber on the front
side. This allows the pressure required to open the exhaust valve to be reached during the pump com-
pression phase, at a relatively low pressure compression. This allows a required mixture of gas and va-
por to be expelled before condensation forms in the vapor. The ultimate pressure reached during opera-
tion with gas ballast is higher than that achieved without gas ballast.
Operating fluid, oil
The pump oil, also known as operating fluid, fulfills various tasks in a rotary vane pump: It lubricates all
moving parts, fills part of the dead volume below the exhaust valve, and seals the narrow gap between
inlet and outlet. It compresses the gap between the vanes and the working chamber and ensures an
optimal temperature balance through heat transfer.
Product description
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