5 Function description
5.1 Structure
5 Function description
5.1 Structure
3
4
5
7
6
8
9
1
10
11
2
12
13
14
15
Fig. 4: Structure – principle diagrams
1
Strainer
9
Motor
2
Oil pan
10
Pressure-side connection
3
Suction-side pressure gauge
11
Screw pump
4
Suction-side connection
12
Main screw (shaft end)
5
Suction-side pressure gauge
13
Shaft seal
6
Reversing valve
14
Idle screw
7
Overflow valve
15
Cartridge housing
8
Pressure-side pressure gauge
M
M
Fig. 5: Hydraulic scheme
5.2 Functional principle
Pump stations of the DL3 and DL4 series are suitable for pumping light oil. Pump stations of the DS1,
DS3 and DS4 series are suitable for pumping heavy fuel oil.
The pump stations are equipped with two KRAL screw pumps of the NE series.
Screw pumps are rotating pumps. Their displacement effect results from three rotating screws
12
and
14
and the enclosing cartridge housing
15
. Radial support of the screw set is effected through the
sliding contact in the cartridge housing that depends on lubrication by the pumped liquid. Screw pumps
are therefore not suitable for dry running and can only be used up to specific pressure limits and vis-
cosity limits. Due to the narrow tolerances pumping of suspended solids is not possible. The shaft
seal
13
seals the main screw at the outlet of the housing. The sealing chamber is connected with the
suction chamber via a relief line.
The pump station is connected with the pipe system via the connections
4
and
10
. Depending on the
position of the reversing valve
6
the pumped liquid flows through the left, right or both pumps.
The oil pan
2
collects leaks from the pump station.
10
OID 06en-GB Edition 2019-11
Operating instructions
