10 255548 Rev.1
3.3 Design and functional principle
Th
e pump is operated in accordance with the liquid ring
principle. Th
e impeller is positioned off -center in the
cylindrical pump casing. It transfers the drive power to a
liquid ring, which forms concentrically to the casing when
the pump is started.
Th
e gaseous medium remaining in the casing is distributed
around the impeller due to the lower density in the hub
area. As the impeller is positioned off -center to the casing,
the available space for the gas between the surface of the
liquid and the hub becomes crescent-shaped.
Th
is way, the remaining space for the gas between the
blades expands and shrinks during each rotation.
1. Suction
opening
2. Pressure
opening
3. Liquid
ring
Fig. 4 Functional principle of liquid ring vacuum pumps
Th
e arrangement of suction and pressure openings in
the inter casing allows for the suction, compression and
discharge of gas. Th
e liquid both serves the sealing between
the individual impeller chambers and the absorption of heat
produced during compression.
Th
e pump must be permanently supplied with operating
liquid during operation as a portion of the liquid
continuously escapes from the pump together with the gas.
Th
e discharged operating liquid can be separated from the
gas by means of a downstream separator and re-used.
3.4 Shaft sealing
3.4.1 Mechanical seal
Mechanical seals may slightly leak for functional reasons.
•
Single mechanical seal, unbalanced, dependent on the
direction of rotation with conical spring
