Multitech 1777.8/7-10 G3 - Manual (Page 13)

Caution
Caution
Multitec
13
6.2.2 Switching frequency
The permissible number of start-ups in a given period of time
depends on the circumstances prevailing in the plant and the
operating conditions. Overloading of the motor may generally
result in:
- an abnormal increase in motor temperature exceeding the
temperature limit of the winding or bearing grease
- premature coupling wear
- reduced service life of the pump components
- irregularities or malfunctions in the plant
To prevent abnormal temperature increases in the motor and
excessive loads on the motor, coupling, pump, seals and
bearings, the switching frequency must not exceed the
following number of start-ups per hour (h):
Motor rating Max. start-ups/h
up to 3 kW
from 4 to 11 kW
from 11 to 45 kW
45 kW and higher
20
15
10
5
6.2.3 Minimum flows
The pump must not be operated against a closed gate valve.
The minimum flows required are defined as follows.
For MTC 32, MTC 50 and MTC 65, the required minimum flow
for continuous operation is:
t
-10 to + 100 °C 15 % of Qopt
t > 100 to + 140 °C 20 % of Qopt
t > 140 to + 200 °C 25 % of Qopt
For MTC 100, MTC 125 and MTC 150, the minimum flow
required for continuous operation, independent of the
temperature, is:
0.35 x Qopt.
For MTC 100, MTC 125 and MTC 150 an additional, short--term
minimum flow of 0.25 x Qopt. has been defined, which is
permitted for up to 1 hour’s uninterrupted operation and approx.
200 h/year.
The minimum flows indicated for MTC 32 to 150 above are for
single pump operation and will prevent thermal and mechanical
overloading of the pump. In case of parallel operation with
pumps of identical or different design higher flow rates may be
required in some cases, to guarantee a stable operating
behaviour.
6.2.4 Density of fluid pumped
The pump input power will increase in proportion to the density
of the fluid handled. To avoid overloading of the motor and
pump, the density of the fluid must comply with the data
specified on the purchase order.
6.3 Shutdown / Storage / Preservation
6.3.1 The unit / pump remains installed; periodic check of
operation
In order to make sure that the pump is always ready for instant
start-up and to prevent the formation of deposits within the
pump and the pump intake area, start up the pump set regularly
once a month or once every 3 months for a short time (approx. 5
minutes) during prolonged shutdown periods. Follow the
instructions for commissioning (see 6.1).
Prolonged shutdown periods should be avoided in the case of
pumps in material variants 10, 13, 20 and 21 (cast-iron
variants), particularly if the pumps are handling aggressive
water qualities (high oxygen content). In such cases, the pump
should remain filled, and the operation check run should be
performed at least every other day, instead of once a month or
once every 3 months (see also 6.1.5).
In the event of frost and/or prolonged shutdowns, the pump
must be drained and protected against freezing and corrosion.
To drain the pump, open drain plug 6B.
In the case of horizontal pumps, virtually
complete drainage of the stage casings in
installed condition can only be ensured by opening the plugs on
the stage casings (optional). If this is not possible, it is
recommended to remove the pump from the system and
proceed according to section 6.3.2.
6.3.2 The pump is removed from the pipe and stored
Before putting the pump into storage, carry out all checks and
maintenance work specified in section 7.1. Then preserve as
follows:
Drain the pump as completely as possible. On vertical pumps,
this can be done by opening the drain plugs on the suction
casing.
Horizontal pumps with drain holes in the stage casings
(optional) can be drained almost completely by opening the
drain plugs. The pump can also be drained by bringing it into a
vertical position - suction nozzle pointing downwards - by crane
(see 3.1). Turn the rotor by hand. However, the seal housing
must still be drained separately by opening the respective drain
plug.
If the pump cannot be drained completely, we
recommend to dismantle it and dry the individual
components.
Afterwards fill the pump with a water-repellent preservative, e.g.
RUSTELO DEWATERING 924 (producer CASTROL)
OSYRIS DW (producer TOTAL) or equivalent.
Turn the pump rotor by hand several times, to ensure even
distribution of the preservative. Then drain the pump and close
the suction and discharge nozzle.
Exposed blank metal parts must be treated with a suitable
anti-corrosive agent.
If the pump is preserved for a prolonged storage
period with KLÜBERTOP K 01-601 or another
glycol-base preservative, the preservative must not be drained.
In this case, the pump must be completely filled with
preservative for storage. The preservative must be drained
before the pump is returned to service. It can be re-used. Before
re-use, make sure that the water content in the preservative
does not exceed 20%.
6.4
Returning to service after storage
Before returning the pump to service, carry out all instructions
laid down in the sections on ”Commissioning” (6.1) and
”Operating limits” (6.2).
Immediately following completion of the work, all
safety-relevant and protective devices must be re-installed
and/or re-activated.