Checking Gap Between Impeller And Pump Housing/ Cover (Wear Rings); Removing The Impeller - Grundfos NBS Service Instructions Manual

21. Note condition of cover O-ring (surface cracks, stiffness and
swelling).
4.2 Checking gap between impeller and pump housing/
cover (wear rings)
1. Measure and note the diameter of impeller and pump housing
interfaces.
Two measurements must be made (positions 12-6 and
3-9). The wear ring may be worn oval due to different
directions of radial forces.
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2. Measure and note the bore in cover (wear ring, if fitted).
3. Measure and note impeller interface to pump housing.
• For maximum gap values, see the dedicated section for Gap
between impeller and pump housing/cover (wear rings).
Related information
6.3 Gap between impeller and pump housing/cover (wear rings)

4.3 Removing the impeller

1. Remove impeller from shaft, always use soft jaws in the vice