PA SERIES PUMPS
MR--04835
MAINTENANCE & REPAIR
PAGE C -- 16
The balance ring
must
seat squarely in the
suction head; otherwise binding and/or ex-
cessive wear will result.
Inspect the impeller and replace it if cracked or
badly worn.
For maximum pump efficiency, the impeller should
be centered within the volute scroll.
To verify the impeller positioning, measure the
pump casing and impeller as shown in Figure C-6.
Use these measurements to calculate the required
impeller location (dimension E). Add or remove im-
peller adjusting shims (53) until dimension E is ob-
tained.
D
B
2
A
B
2
C
D
E
Step 2
Step 1
Step 3
A+ B
2
C+ D
2
E
=
---
Figure C---6. Centering Impeller Within Volute Scroll
Install the calculated thickness of impeller shims
(53). Install the impeller key (45) and slide the im-
peller completely onto the shaft.
Secure the shaft from rotating by reaching through
the discharge port and tightly wedging a soft-metal
bar between the vanes of the impeller. Secure the
impeller with the impeller washer and nut (42 and
43).
NOTE
After the impeller has been properly positioned,
check for free rotation. Correct any scraping bind-
ing before further reassembly.
Suction Head Installation
(Figure C--2)
If removed at disassembly, press the wear ring (41)
into the suction head (48) until it seats squarely
against the bore shoulder.
The wear ring
must
seat squarely in the
suction head; otherwise binding and/or ex-
cessive wear will result.
Install the suction head gasket (49) and secure the
suction head to the pump casing with the nuts (39).
Make sure the jacking screws (44) do not interfere
with the suction head seating.
Discharge Check Valve Assembly And
Installation
(Figure C--1)
The flapper and gasket are the only serviceable
parts of the check valve. If the flapper requires re-
placement, remove the hardware securing the
cover and gasket. Separate the valve cap and re-
place the flapper.
