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12.4.2.
Changing the mechanical seal
To change the mechanical seal you must dismantle the pump. To do this, slacken and remove all the nuts from the stud bolts
that join the pump body and the support (these may be on the external rim if there is also an internal one). Block the end of the
pump shaft and unscrew the locking nut, slip the spring washer, the spacing washer and the impeller off the pump shaft, levering
if necessary with two screwdrivers or levers between the shaft and the support. Retrieve the key and slip off the spacer. Use two
screwdrivers to force the seal spring to dislodge it from the bush and then force the rotating part of the mechanical seal near the
metal seat until it can be slipped off completely. The fixed part of the mechanical seal is extracted from the support by pressing
on the seal ring from the support side, after having removed the seal cover from its seat, unscrewing the nuts from the stud bolts
on the internal rim, if fitted.
Before fitting the seal, check the bush to see if there is any scoring which must be eliminated with emery cloth. If the scoring is
still visible the bush must be replaced, using original spare parts.
Reassemble proceeding in inverse order and ensuring particularly that:
-
the fittings of the individual parts must be free from residue and spread with suitable lubricants;
-
all the O-Rings must be perfectly whole. If not, replace them.
12.4.3.
Changing the stuffing box seal
First of all, accurately clean the stuffing box chamber and the shaft protection bush (ensuring that this is not too worn, in which
case it must be changed - see 12.4.2). Insert the first packing ring and push it into the stuffing box chamber by means of the
follower. Insert the hydraulic ring. All the gaskets that follow must be pushed into the stuffing box chamber one by one with the
follower, ensuring that the edge of each ring is at about 90° from the one before it. If possible, the last ring next to the follower
should be fitted with the edge facing upwards. Sharp objects must absolutely not be used as they could damage both the rotor
shaft and the seal.
The follower must be tightened evenly, ensuring that the rotor can be turned easily.
During starting, proceed as described in par.12.3.2.
13.
MODIFICATIONS AND SPARE PARTS
Any modification not authorized beforehand relieves the manufacturer of all responsibility. All the spare parts
used in repairs must be original ones and the accessories must be approved by the manufacturer so as to be able to
guarantee maximum safety of persons and operators, and of the machines and systems in which they may be fitted.
14.
TROUBLESHOOTING
FAULT
1. The motor does not start
and makes no noise.
2. The motor does not start
but makes noise.
3. The motor turns with
difficulty.
4. The (external) motor
protection
trips
immediately
after
starting.
5. The motor protection
trips too frequently.
CHECK (possible cause)
A. Check the protection fuses.
B. Check the electric connections.
C. Check that the motor is live
A. Ensure that the mains voltage corresponds to
the voltage on the data plate.
B. Check that the connections have been made
correctly.
C. Check that all the phases are present on the
terminal board.
D. The shaft is blocked. Look for possible
obstructions in the pump or motor.
A. Check the supply voltage which may be
insufficient.
B. Check whether any moving parts are scraping
against fixed parts.
C. Check the state of the bearings.
A. Check that all the phases are present on the
terminal board.
B. Look for possible open or dirty contacts in the
protection.
C. Look for possible faulty insulation of the motor,
checking the phase resistance and insulation
to earth.
D. The pump is functioning above the work point
for which it was intended.
E. The protection tripping values are wrong.
F. The viscosity or density of the pumped fluid are
different from those used in the design phase.
A. Ensure that the environment temperature is not
too high.
B. Check the calibration of the protection.
C. Check the state of the bearings.
D. Check the motor rotation speed.
ENGLISH
A. If they are burnt-out, change them.
If the fault is repeated immediately this means
−
that the motor is short circuiting..
B. Correct any errors.
C. If not, restore the missing phase.
D. Remove the obstruction.
B. Eliminate the cause of the scraping.
C. Change any worn bearings.
A. If not, restore the missing phase.
B. Change or clean the component concerned.
C. Look for possible faulty insulation of the motor,
checking the phase resistance and insulation to earth.
D. Set the work point to suit the pump characteristics.
E. Check the set values on the motor protector: alter
them or change the component if necessary.
F. Reduce the flow rate with a shutter on the delivery
side or install a larger motor.
A. Provide suitable ventilation in the environment where
the pump is installed.
B. Calibrate at a current value suitable for the motor
absorption at full load.
C. Change any worn bearings.
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