Grundfos NB Series - Replacing the Wear Rings; Assembling the Pump

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2.3 Replacing the wear rings
Pump with bronze wear rings
1. Insert the hook of the puller (pos. C) under the wear ring (pos. 45 or 45b).
2. Knock the impact block against the puller end stop. Move the puller to another position under the wear ring.
3. Knock the new wear ring home using a piece of wood as a buffer.
4. Repeat steps 1 to 3 for the second wear ring of the pump.
Pump with stainless steel wear rings
1. Unscrew the screws (pos. 24 and 24b) of both wear rings (pos. 45 and 45b), and remove the wear rings.
2. Fit new wear rings, and tighten the screws to the correct torque.
Pump with stainless steel/carbon-graphite-filled wear rings
1. Unscrew the screws (pos. 24 and 24b) of both wear ring retainers (pos. 65 and 65b), and remove the wear
ring retainers.
2. Push the carbon-graphite-filled wear rings (pos. 45 and 45b) out of the wear ring retainers.
3. Fit new carbon-graphite-filled wear rings in the wear ring retainers.
4. Fit the wear rings/wear ring retainers, and tighten the screws to the correct torque.
2.4 Assembling the pump
1. Lubricate the motor shaft with O-ring grease.
2. Push the pump shaft (pos. 51) home on the motor shaft. Make sure that the pump shaft does not move when
you release it.
3. Apply a drop of Loctite 243 to the set screws (pos. 9), and tighten them into the pump shaft to the correct
torque.
4. Fit the motor stool (pos. 1a or 2) on the motor.
5. Fit the screws/nuts (pos. 28 and 36a) on the motor stool, and tighten them to the correct torque.
6. Fit the mounting bush (pos. A) on the pump shaft.
7. Pump with separate motor stool (pos. 1a) and clamped cover (pos. 77):
• Fit the cover to the motor stool.
Pump with separate motor stool (pos. 1a) and screw-fixed cover (pos. 77):
• Fit the cover to the motor stool, and tighten it to the correct torque.
8. Spray soapy water on the pump shaft and the mounting bush.
9. Fit the stationary shaft seal part (pos. 105) on the shaft. Do not touch the seal face with your fingers.
10.Press the stationary shaft seal part home using a punch of soft material (pos. B).
11. Shaft seal, types HJ92 and M7N:
• Remove the screws, if any, from the rotating shaft seal part, and discard them.
12.Spray soapy water on the rotating shaft seal part.
13.Press the rotating shaft seal part home using a punch of soft material (pos. B).
14.Fit spacer rings, if required, between shaft seal and impeller on the pump shaft.
15.Remove the mounting bush (pos. A) from the pump shaft.
16.Fit the key (pos. 11) and the impeller (pos. 49) on the shaft.
17.Fit the washer (pos. 66), spring washer (pos. 66a) and impeller nut (pos. 67).
18.Hold the impeller with a strap wrench, and tighten the impeller nut to the correct torque.
19.Fit the O-ring (pos. 72a) on the cover, and lubricate it.
20.Fit the pump housing (pos. 6).
21.Fasten the cover/motor stool on the pump housing by cross-tightening the nuts (pos. 36) to the correct torque.
22.Check that the pump shaft can rotate freely.
23.Fit the coupling guards (pos. 7), and tighten the screws to the correct torque.