27
Medium pressure screw pumps
Installation
Commissioning
Maintenance
Medium pressure screw pumps
General
Screw pumps are rotating positive dis-
placement pumps with strong suction,
which can be used with self-lubricating
agents.
1. Application guidelines
1.1 Shaft seals for normal versions
1.2 Pressure relief valve
This valve protects the pump against
overloading and should not be used as
a pressure control valve. This is absolu-
tely necessary if a shut-off device is fit-
ted in the pressure pipe. Standard
pressure setting unless otherwise requi-
red at the time of ordering. Low pres-
sure pumps (type N) approx. 6 bar,
medium pressure pumps (type M)
approx. 40 bar or 10% above the speci-
fied operating pressure, as with C-
types. By turning the adjustment screw
in a clockwise direction = pressure
increase.
2. Installation
2.1
Clean any plant parts (ensure no dirt or
loose particles in the pipes) and fit pipes
(flange) without any stress. Observe
direction of flow as well as any possible
heat expansion of the pipes.
2.2
Ensure stress-free fitting of the pump or
base frame.
2.3 Coupling
Motor and pump shafts must be ali-
gned. Axial play between the Coupling
halves approx. 1.5 mm. It should be
possible to turn the whole unit of pump
shaft-Coupling-Motor shaft by hand.
Installation of the coupling halves: Sli-
ding on (tapping not permitted) in hea-
ted condition (min. 100°C); Press plastic
couplings home in cold condition.
2.4
Check direction of rotation of the motor
and the pumps and protect the motor by
means of a motor protection switch.
3. Commissioning
3.1
The pump must not be allowed to run
dry!
Before initial commissioning of the
pump fill the pump with operating
medium and open suction and shut-off
devices on the pressure side. The
medium must be free from solids.
3.2
With hot medium (above 100°C) heat
the pump before starting (pump heating
facility). ATTENTION! The medium in
the pump and pipes must be able to
expand freely during heating (develop-
ment of unauthorized pressures with
enclosed medium).
3.3
Viscous medium, which can only be
pumped after heating, must be heated
first in the pump and pipes (pump hea-
ting as well as secondary heating for
pipes). ATTENTION! Heat expansion of
the medium (see above).
When pumping heavy heating oil it is
essential that cold starting of the pump
is avoided (use pump heating provided),
as this could also damage the shaft
seal.
3.4
Vent the pressure pipe during initial
starting of the pump.
3.5
Switching off the pump: Residual static
pressure in the pressure pipe must no
exceed that of the permissible supply
pressure. If necessary, de-pressurize
the pump through the non-return valve,
as this pressure pressurizes the shaft
seal which in turn could damage the
seal. The same applies to parallel ope-
ration of several pumps.
4. Maintenance
Special maintenance of the screw
pumps is not required. In case of
damage to the pump of the installation it
is possible that medium will leak out. In
order to avoid subsequent damage it is
recommended that respective warning
devices are fitted.
Type of seal
Max. supply
pressure
Max.
Temperature
Rotary shaft
0,5 bar
80°C
Packing rings
3 bar
150°C
Axial face seal
5 bar
150°C
