Xylem e-XC, Instruction Manual

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Table 5: Recommended replacement clearances
Maximum untrimmed
impeller diameter
Gap size where
replacement is
recommended
Gap size where
replacement is required
Equal to or less than 16 in (410 mm) 0.012 in (0.30 mm) 0.018 in (0.45 mm)
Greater than 16 in (410 mm) 0.030 in (0.75 mm) 0.039 in (1.00 mm)
NOTE:
Impeller wear rings should only be replaced once during the lifetime of an impeller,
assuming the impeller wear ring material is harder than the casing wear ring material.
Casing wear rings may be replaced as needed.
If the casing wear ring material is harder than the impeller wear ring material, then the
casing wear ring should only be replaced once per impeller lifetime. The impeller wear
ring may be replaced up to two times before a new impeller assembly is required.
In both cases, identify the cause of wear before replacing the wear rings. Make sure to
correct the problem after replacing the wear rings to protect the pump from future
damage. If wear is nonuniform, there is likely excessive shaft deflection or misalignment
present in the system.
Impeller wear ring replacement
Refer to the diagram below for the following instructions.
1. Impeller
2. Casing Wear Ring
3. Impeller Wear Ring
Before replacing impeller wear rings, ensure the replacement wear rings are of the same
material as the impeller and new set screws are on hand for installation. Never reuse set
screws from the previous wear ring installation. Thread locker, such as Loctite
®
243, will
be required for installation. To replace the impeller wear rings, perform the steps below
for each impeller wear ring.
1. Unfasten the three (3) set screws, located 120° apart along the eye of the impeller,
from the impeller wear ring.
2. Remove the old wear ring and clean the mating surface of the impeller before placing
the new wear ring. Inspect the impeller for any signs of wear caused by loosening of
set screws.
3. Place the new wear ring onto the impeller. Ensure the chamfered side of the wear ring
faces outwards (away from the impeller). The chamfer is located along the inner
diameter of the wear ring.
4. Fill the old set screw holes with thread locker.
5. Drill three new set screw locations set 120° apart and evenly spaced between the old
screw locations. The holes should be centered between the mating faces of the
impeller and impeller wear ring. Depending on the pump model, the hex set screws
6 Maintenance
e-XC INSTRUCTION MANUAL 37