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Appendix
Appendix
Special instructions
Kaolin service - KJC pumps optimum impeller running clearance
The optimum impeller running clearance is the minimum clearance that will not significantly
increase the input horsepower from the shear rate induced drag at the suction disc liner. For
most liquids or slurries, the optimum performance of the JC pump is achieved with the impeller
almost rubbing against the suction disc. Increasing this clearance causes more internal
leakage around the impeller vanes, which results in decreased performance.
When pumping kaolin clay, the decrease in pump head from the internal leakage can be more
than offset by the decrease in horsepower such that the overall performance is increased. The
optimum clearance is set by adjusting the pump, when it is running, using a discharge pressure
gauge and ammeter to monitor the results.
During an adjustment to reduce the clearance, the clearance has become too small when the
percentage increase in motor amperes exceeds the percentage increase in discharge
pressure. The opposite is true when increasing the clearance. The adjustment can be made
without a pressure gauge, but it will be less accurate though perhaps satisfactory for the
application.
If the slurry percentage solids varies frequently, it may be more practical to adjust the clearance
for the most difficult to pump slurry and not change it for the other concentration.
Expeller
General
Dynamic seals are not allowed in an ATEX classified environment.
To meet the high demand for waterless sealing of stuffing boxes in slurry pumps, Ashland
Operations/Goulds has added an expeller to the JC line. Using its basic bearing and wetted
end configuration, the JC now incorporates a hub disc that has been enlarged to allow for the
expeller option.
When operating at normal design conditions, the expeller reduces the pressure usually present
in conventional end suction pump stuffing boxes to zero (0). Theoretically, the only need for a
packed stuffing box in expeller pumps is to seal the casing when the unit is shut-down or
running at restricted flows.
WARNING: Important: Before performing any work, ensure electrical supply is locked out.
Clearance Adjustment
The impeller clearance in the JC pump with optional expeller should be maintained at .015²
from the face of the impeller (101) to the suction cover liner (100B). Adjust this clearance as
often as necessary in order to maintain efficient pump performance.
NOTICE: Ensure that the impeller is tightened on the shaft prior to clearance adjustment.
To Disassemble The Liquid End
1. Remove bolts (370E) that fasten the suction cover 182 to the casing (100). Remove the O-
2. Remove the impeller (101) by securing it with a wooden or soft metal block and turn the
28
Ring (412F) and the suction cover liner (100B). A gentle tap about the circumference of the
liner may facilitate removal of the liner.
shaft in the counter-clockwise direction facing the pump drive end from the motor. The
Model JC Installation, Operation and Maintenance Instructions
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