Changing The Seal; Preparing Disassembly; Changing The Mechanical Seal; Modifications And Spare Parts - DAB NKM-G Serie Instructions De Mise En Service Et D'entretien

12.3.

Changing the seal

12.3.1.

Preparing disassembly

1. Switch off the electric power supply and ensure that it cannot be switched on accidentally.
2. Close the interception devices on intake and delivery.
3. If hot liquids have been pumped, wait until the pump body returns to room temperature.
4. Empty the pump body by means of the drainage caps, taking particular care if harmful fluids have been
pumped (observe the legal requirements in force).
5. Dismantle any auxiliary connections provided.
12.3.2.

Changing the mechanical seal

Slacken the nuts ref. (190) from the stud bolts ref.(189) in order to slip the pump body ref.(1) off the motor block.
Preventing shaft rotation by immobilising the shaft itself or the impeller, slacken the nut ref.(18); remove the flat
washer ref.(44) and the spring washer ref.(43). Slip off the impeller ref.(4), if necessary levering with two
screwdrivers on the lantern cover ref.(3). Then remove the tab ref.(17). Retain the spacer or spacers ref. (31);
extract the mechanical seal ref.(16). To facilitate extraction, lever with two screwdrivers on the seal spring, taking
care not to spoil the seat of the seal. NB: extraction may be facilitated by lubricating the shaft with alcohol.
Before assembly, ensure that the seat of the seal has not been scored; if it has, eliminate the scores with abrasive
cloth. If that is not sufficient, replace the coupling.
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.
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.
Ÿ
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.
27
REMEDY