Changing The Mechanical Seal; Changing The Stuffing Box Seal; Modifications And Spare Parts; Troubleshooting - DAB KDN 32-125.1 Anleitungen Für Installation Und Wartung

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 A. Check the protection fuses.
and makes no noise. B. Check the electric connections.
C. Check that the motor is live
2. The motor does not start A. Ensure that the mains voltage corresponds to
but makes noise.
B. Check that the connections have been made
C. Check that all the phases are present on the
D. The shaft is blocked. Look for possible
3. The motor turns with A. Check the supply voltage which may be
difficulty.
B. Check whether any moving parts are scraping
C. Check the state of the bearings.
4. The (external) motor A. Check that all the phases are present on the
protection trips
immediately after B. Look for possible open or dirty contacts in the
starting.
C. Look for possible faulty insulation of the motor,
D. The pump is functioning above the work point
E. The protection tripping values are wrong.
F. The viscosity or density of the pumped fluid are
5. The motor protection A. Ensure that the environment temperature is not
trips too frequently.
B. Check the calibration of the protection.
C. Check the state of the bearings.
D. Check the motor rotation speed.
ENGLISH
CHECK (possible cause)
the voltage on the data plate.
correctly.
terminal board.
obstructions in the pump or motor.
insufficient.
against fixed parts.
terminal board.
protection.
checking the phase resistance and insulation
to earth.
for which it was intended.
different from those used in the design phase.
too high.
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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REMEDY