Open impeller centrifugal pumps offer several advantages. They're particularly suited but not restricted to liquids which contain abrasive solids. Abrasive wear on an open impeller is distributed over the diametrical area swept by the vanes. The resulting total wear has less effect on performance than the same total wear concentrated on the radial ring clearance of a closed impeller.

The open impeller permits restoration of "new pump" running clearance after wear has occurred without parts replacement. Many of Goulds open impeller pumps feature a simple positive means for axial adjustment without necessity of disassembling the unit to add shims or gaskets.

SETTING IMPELLER CLEARANCE (DIAL INDICATOR METHOD)
1. After locking out power, remove coupling guard and coupling.
2. Set dial indicator so that button contacts shaft end.
3. Loosen jam nuts (423B) on jack bolts (371 A) and back bolts out about two turns.
4. Tighten each locking bolt (370C) evenly, drawing the bearing housing toward the bearing frame until impeller contacts casing.
5. Set indicator to zero and back locking bolt about one turn.
6. Thread jack bolts in until they evenly contact the bearing frame. Tighten evenly backing the bearing housing away from the frame until indicator shows the proper clearance established in instruction manual.*
7. Evenly tighten locking bolts, the jack bolts keeping indicator at proper setting.
8. Check shaft for free turning.

*Established clearance may vary due to service temperature.