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5. MAINTENANCE
5.3 •
REASSEMBLY INSTRUCTIONS
!
CAUTION
For correct reassembly it is recommended to take into account the following
measures:
- Preferably use wooden or plastic mallets. Should any steel hammers be used,
always interpose a wood block.
- The bearings are locked with suitable cover and therefore they may be fitted
with no effort.
Moreover, proceed as follows (Fig. 13):
- Before reassembly, spread graphite or similar products on the fittings of
individual parts, including joining bolts.
- Ensure O-rings and radial seal rings are not damaged.
- Replace flat gaskets with the same gaskets and of the same thickness.
- Reassemble individual parts according to the right sequence in reverse order
from disassembly.
- Ensure the play of wear rings between diffusers and the impeller is not
excesive and remains within the admissible tolerances, otherwise replace the
wear rings before reassembly.
For the gaps of wear rings between diffusers and the impellers (Fig. 13) see tab.1 for
cast iron and steel construction
OVERHAULING COMPONENTS
The pump must be regularly disassembled to check components; in the event they
should prove to be damaged they must be replaced with original spare parts.
Check for any liquid or lubricant leaks from gaskets of flanges and oil seal rings. The
gaskets must be reused only if they are intact.
Check the condition of the pump's inner parts and remove any deposits and scaling
using water or specific solvents.
Ensure inner and outer flushing ducts are not obstructed and that any cooling cham-
ber is clean.
Check the condition of seals.
SEAL ON SHAFT (Fig. 14)
Before proceeding to reassembling the new gland packing gaskets, they must be
checked and in the event of scratches and abnormal signs of wear, clean with
abrasive cloth the packing box and the shaft protection bushing.
Obtain the set of new gaskets from the manufacturer.
Cut rings obliquely. Insert the first gasket ring by means of the gland.
All following gasket rings must be pushed one by one into the packing box by means
of the gland; the cutting surface of each ring must be rotated by approximately 90°
with respect to that of the
previous ring.
The gland must be tightened slightly and consistently, so that the impeller may rotate
easily.
Before starting up slightly turn the gland nuts.
After filling the pumps there must be some leaks. After about 10 minutes of operation
these leaks may be reduced by further tightening
the gland nuts; should these leaks still be excessive, repeat the operation until reduc-
ing the leaks to the minimum.
Check whether there are still sufficient leaks at the minimum operating pressure.
14
Braided gasket
Gland packing seal
Fig. 13
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