Caution
Caution
Caution
Caution
Caution
Omega
9
6
Commissioning, Start--up /
Shutdown
Compliance with the following requirements is
of paramount importance. Damage resulting
from non--compliance shall not be covered by the scope of
warranty.
6.1
Commissioning
Before starting up the pump make sure that the following requi-
rements have been checked and fulfilled:
·
Has the pump been firmly bolted to the foundation?
·
Have the coupling and pump unit been aligned as speci-
fied?
·
Can the unit be easily rotated by hand at the coupling?
(Carry out at least one full rotation)
·
Are the pipes properly fitted?
·
Has the coupling guard been fitted?
·
Have staff been informed about sources of danger and
measures been taken to comply with the accident preven-
tion regulations?
·
Correct start--up procedure for suction lift operation.
·
Is the unit protected against overload (appropriate safety
valve)?
·
Have the seals been fitted as described in the appendix?
·
Have any additional devices been prepared and fitted as
specified in the appendix?
·
Has the pump been vented as specified in section 6.3.?
6.2
Shaft Seal
For commissioning the shaft seal please refer to section 8.1 /
8.2. If the pump has been out of service for a prolonged period,
the measures specified in section 6.6 must be carried out.
6.3
Venting
Before start--up, the pump and the pipes must be vented and
filled with the liquid to be pumped. This is done at the vent plug
on the casing (903). For suction lift operation, the pump must
also be evacuated, i.e. a vacuum must be produced.
6.4
Commissioning
6.4.1
Checking the Direction of Rotation
For trouble--free operation of the pump, the
correct direction of rotation of the impeller is of
paramount importance.
If running in the wrong direction of rotation, the pump cannot re-
ach its duty point; vibrations and overheating will be the conse-
quence. The unit or the shaft seal might be damaged.
Correct direction of rotation:
The direction of rotation must correspond to the direction indi-
cated by the arrow on the pump. This can be verified by swit-
ching the pump on and then off again immediately.
Before checking the direction of rotation make sure that
there is no foreign matter in the pump casing.
Never put your hands or any other objects into the pump!
6.4.2
Start--up
If a non--return valve is not fitted at the di--
scharge--side, close the discharge--side
gate valve.
If a shut--off valve is fitted in the suction line, open it fully.
All additional connections for flushing or sealing liquid etc., if fit-
ted, must be opened fully and the flow must be checked.
Switch on the motor.
As soon as the pump starts to deliver -- this can be recognised
by the rising gauge pressure -- slowly open the discharge--side
gate valve fully.
The pump may operate against the closed gate
valve only during start--up and shutdown, as
otherwise inadmissible temperature rise occurs resulting in
damage.
6.4.3
Pump Operating Range
The flow rate ”Q” adjusts itself automatically to the delivery
head according to the H--Q characteristic. The pump’s permit-
ted operating range is subject to limits, which have separate
causes.
1. Part load operating limit for low flow rate
This limit is indicated in the H--Q characteristic by Q
min
or by the
discontinuation of the characteristic curve.
It is not permissible to operate the pump in the
range from Q=0 to Q
min.
Prolonged operation
in this range causes greatly increased mechanical loads which
the components cannot withstand.
Brief passage through the critical range is permissible, e.g. du-
ring start--up
2. NPSH--related limits in the part load and overload ranges
These two limits are determined by the ratio of
NPSH
required
to
NPSH
available
. They are determined as follows:
