Hale MBP Booster - Manual (Page 55)

❑ Preventive Maintenance
54 Silencer Series Booster Pump, p/n: 029-0020-83-0
Worn Clearance Rings and Impeller Hubs
Before assuming that clearance ring wear is at fault or that clearance ring
replacement requires pump disassembly, it is advisable to thoroughly check
other possible causes of low performance.
Clearance rings limit the internal bypass of water from the discharge side of
the pump back to suction. The radial clearance between the impeller hub
and the clearance rings is only a few thousandths of an inch when new. In
clear water, the clearance rings continue to effectively seal for many hours
of operation.
In dirty or sandy water, the impeller hub and clearance rings wear faster.
The more wear, the greater the bypass and lower pump performance.
It should not be necessary to replace clearance rings until a loss in pump
performance is noticed during the annual test – see “Performance Testing
Overview” on page 50. For clearance ring and impeller service, proceed to
Section 6, heading “Impeller” on page 71.
Often, replacement of the clearance rings reduces the bypass and restores
the pump to near original performance. A complete restoration requires that
the impellers also be replaced. See Section 6 “Repair” on page 61 for
maintenance and repair information if pump disassembly is required.
Anode Check
The zinc anodes should be
inspected every 12 months.
Replace when over 75% of the zinc
has been consumed. Performance
of the anode life varies with water
quality and pH. Anodes conform to
MIL Spec. A180001.
Figure 4-8: Hale Anode