Design And Functional Principle; Shaft Sealing; Mechanical Seal - Ohio Medical Corporation SM30B Operating Instructions Manual

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
10 255548 Rev.1