Operating Instructions
10
1096.0799 | VU / VH Series
10/2010
The VH 20 - 1600 types are two-stage liquid ring vacuum pumps
in base plate version.
The electrical drive is connected to the pump shaft (3) via a
coupling. The pump shaft (3) is mounted in rolling bearings (4)
on both sides. Usually, pump and motor are mounted onto one
base plate. Two maintenance-free mechanical seals (5) in the
shaft sealing casings are used to seal the pump shaft (3).
2
2
1
1
3
4
1
4
5
5
1 Inter
casings
2 Impeller
3 Motor/pump shaft
4 Rolling
bearing
5 Mechanical
seal
Fig. 5
Description VH
Pumps of the VU/VH series allow for the delivery of small vol-
umes of liquids. The discharged operating liquid can be re-used
when using a separator.
3.3 Design and functional principle
The vacuum pump is operated in accordance with the liquid ring
principle.
The impeller is positioned off-centre in the cylindrical pump
casing. It transfers the drive power to a liquid ring, which forms
concentrically to the casing when the vacuum pump is started.
The 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-centre to the casing, the available
space for the gas between the surface of the liquid and the hub
becomes crescent-shaped.
This way, the remaining space for the gas between the blades
expands and shrinks during each rotation.
1
2
3
1 Suction opening
2 Pressure opening
3 Liquid ring
Fig. 6
Functional principle of liquid ring vacuum pumps
The arrangement of suction and pressure openings in the inter
casing allows for the suction, compression and discharge of gas.
The liquid both serves the sealing between the individual impel-
ler chambers and the absorption of heat produced during com-
pression.
The vacuum 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. The 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 (standard)
•
Double-acting mechanical seal, unbalanced, independent of
the direction of rotation
• Special
seals
3.4.2 Packing
gland
Packing glands slightly leak for functional reasons.
