Pentax HP Manual Del Usuario página 65

6. MAINTENANCE
6.3 • INSTRUCTIONS FOR REASSEMBLY
ATTENTION!
For a correct reassembly, take care of the following:
- we recommend to use plastic or wooden hammers. If you use steel hammers,
use a wooden drift.
- bearings are fixed by rings, so they can be assembled without any problems.
- take care not to damage the mechanical seals when assembling.
Then proceed as in fig. 38:
- before reassembly, smear graphite grease or equivalent products on all com-
ponents, including coupling bolts.
- check whether O-rings and the radial seal rings, are damaged.
- replace the flat joints with other similar joints of same thickness.
- reassemble the single parts according to the correct sequence following the
reverse order of disassembly sequence.
- make sure that the wear rings clearance between the diffusers and the impellers
is not too much and does not exceed the allowable tolerances; otherwise, re-
place the wear rings before reassembling.
- As for wear rings clearance between the diffusers and the impellers (fig.39),
please refer to cap.6 MAINTENANCE for cast iron components and for
stainless steel components.
COMPONENT OVERHAUL
The pump must be periodically disassembled to check their components; if they are
damaged, they need to be replaced with original spare parts.
Please check possible fluid or lubricant leakages from the flange joints and from the
oil retaining rings. The joints can be re-utilized only if they are in good condition.
Check the internal parts of the pump for sediment and scale build up.
Remove, using water or suitable solvent in conjunction with soft scraper or brush.
Also make sure that the cooling chamber and pipe work are free from scale
build up and clean. Check the seals.
SHAFT SEAL (Fig. 39)
Check before assembling the new packing seals; if they are
scuffed or worn, clean the packing box casing and the shaft
protection sleeve with an abrasive cloth.
Ask the manufacturer for a new joint set.
Cut the packings at 45° as per drawing. Insert the first
packing into the packing box.
Each subsequent packing must have the scarf joint dis-
placed by 90° to the adjacent packing. This will minimise the
direct leakage path, as only every 5
The packing box nuts, must be uniformly and evenly tightened
so that the rotor shaft can turn easily. Before starting, when
the pump is full of water, both packing sets should leak
slightly. After the pump has run for approximately 10 min-
utes, each packing assembly should be evenly re-tightened
to reduce the leakage rate to a mini- mum.
Please note however, that there should be a slight leak from
each packing assembly at the minimum operating pressure.
This will ensure that the packings do not over- heat and fail.
packing is in line.
th
30
Stage
Casing
Suction
O-ring
Casing
Bearing
Gland packing
Gland packing seal
OK
Discharge
Casing
Impeller
Bearing
Fig.39