STA-RITE SG11200 Series Owner's Manual page 6

Maintenance
NOTE: BE SURE you have the correct capscrews – the
wrong ones will release the seal plate from the bracket
and also release a lot of oil!
3. With a screwdriver (or two) behind the impeller, work
the impeller down the shaft until it is free. Remove it.
4. If the shaft key stayed in the shaft, remove it.
5. Reverse steps 1 through 4 to reassemble the impeller.
Seal Replacement
1. Follow steps 1 through 7 under "Cutter
Replacement".
2. Follow steps 1 through 4 under "Impeller Removal".
3. Lay the pump on its side and remove the oil plug
(Key No. 11) from the bearing bracket. Drain the
bearing bracket. Put oil into a clean container and
check for water in the oil and for opacity (dirtiness) of
the oil.
NOTE: Water is heavier than oil. Look for water at
the bottom of the oil. It will appear as tiny bubbles. If
there is water present in the oil, the shaft seal or the
O-Ring will need to be replaced. If there is no water
present in the oil, the shaft seal and O-Ring do not
need replacing. Opacity is the inability of light to
pass through the oil and indicates dirty oil.
4. Remove the four capscrews and lock washers (Key
No. 16) that hold the seal plate to the bearing brack-
et. Tap around the parting line with a lead hammer or
rawhide mallet to loosen the seal plate. Remove the
seal plate from the bearing bracket.
5. Remove the oil seal (Key No. 18) and oil seal bushing
(Key No. 19) from the seal plate.
6. Remove the seal plate O-Ring (Key No. 17) and clean
the O-Ring groove.
7. Remove the seal retaining ring from the seal plate.
NOTE: The shaft seal (Key No. 10) consists of 5 parts
- the upper and lower silicon carbide seals, two rotat-
ing silicon carbide seals, and the spring. Be sure that
you do not scratch or mar the shaft when removing
the seals. If the shaft is marred, it must be dressed
smooth with fine emery or crocus cloth before
installing new seal. Do not reduce the shaft diameter.
8. Pull and turn the rotating seal halves to remove them
from the motor shaft. If necessary, use a flat blade
screwdriver to help pry the seals from the shaft.
9. Unscrew four capscrews and remove the bearing
bracket from the motor housing.
10. Use a flat blade screwdriver and very carefully pry
the lower seal half from the seal plate cavity.
11. Use a flat blade screwdriver and very carefully pry
the upper seal half from the bearing bracket cavity.
Installing the New Shaft Seal
NOTE: Install all new O-Rings, seals, and gaskets during
reassembly. It is good practice to replace the O-Rings
each time the pump is serviced.
1. Clean the seal cavities in the bearing bracket and seal
plate.
2. Lubricate the seals with a very small amount of
clean oil.
3. Inspect the shaft for nicks and scratches.
4. With finger pressure only, press the stationary seal
halves firmly and squarely into the seal cavities in
the bearing bracket and seal plate, with the polished
face out.
NOTE: Be sure you do not scratch the seal surface.
5. Reinstall the lower seal retaining ring.
6. Reinstall the bearing bracket on the motor. Use a
new O-Ring.
7. Slide the rotating seals and the spring (Key No. 10)
onto the shaft.
NOTE: Be sure you do not scratch the seal surface.
Be careful that the shaft shoulder does not damage
the seal faces when they are passing over the shaft.
Make certain the polished surfaces of the rotating
seals face the mating surfaces of the stationary
seal halves.
8. Clean the O-Ring groove in the bearing bracket and
install a new O-Ring (Key No. 17).
NOTE: It is good practice to replace the O-Rings each
time the pump is serviced.
9. Reinstall the seal plate, lock washers, and capscrews.
10. Reinstall the oil seal (Key No. 18) and the oil seal
bushing (Key No. 19) on the shaft.
11. Reinstall the impeller drive key in the keyway on
the shaft.
12. Using the key as a guide, reinstall the impeller on
the shaft.
13. Reinstall the volute on the seal plate.
14. Reinstall the cutter ring on the volute.
15. Using the key as a guide, reinstall the rotating cutter
on the shaft.
16. Block the cutter with a screwdriver in one of the cut-
ter ring slots and reinstall the flat washer, lock washer,
and cap nut on the shaft.
17. Refill the bearing bracket with clean dielectric oil
(P/N U197-8A) and replace the drain plug.
18. Stand the pump on its feet. Check for free rotation of
the impeller. The pump is ready for installation in
the pit.
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