5 Function description
5.1 Pump structure
5 Function description
5.1 Pump structure
1
2
8
9
10
12
4
3
5
7
11
6
Fig. 4: Set up pump (with internal overflow valve)
1
Suction housing (accessories)
7
End cover
2
Suction-side connection
8
Main screw
3
Pump housing
9
Radial shaft seal
4
Pressure-side connection
10
Ball bearing
5
Flange cover
11
Return line to the overflow valve
6
Relief line
12
Overflow valve
5.2 Functional principle
Screw pumps are rotating pumps. Their displacement effect results from three rotating screws
7
and
the enclosing pump housing
3
.
Radial support of the screw set is effected through the sliding contact in the pump housing that de-
pends 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 viscosity limits. Due to the narrow tolerances pump-
ing of suspended solids is not possible.
Axial support of the main screws is effected out by a lifetime-lubricated ball bearing
10
. One radial shaft
seal
9
for sealing the main screw is inserted at the outlet from the housing. In order to reduce the pres-
sure at the shaft seal a balancing cylinder is mounted at the main screw. The sealing chamber is con-
nected with the suction chamber via a relief line
6
. An integrated overflow valve
12
protects against ex-
cessive pressure that could cause housing parts to burst.
The default direction of the rotation of the screw set is clockwise viewed from the motor and is marked
on the flange cover
5
by an arrow. The flow direction is marked on the pump housing by an arrow.
10
OIC 01en-GB Edition 2019-11
Operating instructions
