Xylem AC2008B Series HSC3 Base Mounted Centrifugal Pump - Manual (Page 20)

20
Reassembly of the Pump when it is required to
remove the Rotating Element of the Pump
NOTE: All bearings, O-rings, lip-seals, mechanical seals,
gaskets, impeller rings, and casing rings should be replaced
with the new parts during assembly. All reusable parts should
be cleaned of all foreign matter before reassembling. The main
casing joint gasket can be made using the upper and lower
half as a template. Lay the gasket material on the casing joint.
Trim the gasket by lightly tapping with a ball peen hammer
so that it is flush with the inside edges of the casing. (See
Photo 9 on page 19) Do not hit casing edge with hammer hard
enough to round edge.
NOTE: Precut-casing gaskets can be ordered to minimize the
amount of trimming.
1. Before assembling the rotating element prepare the
casing and install the casing gaskets to the parting line.
2. Clean the gasket surfaces of the casing. Apply Scotch
3M-77 spray adhesive or equivalent to the lower half of
the casing.
3. Within one minute of spraying, set the untrimmed gaskets
in place on the lower half of the casing, align the holes in
the gaskets with the holes in the casing, and press the
gaskets firmly against the lower half of the casing face in
the area coated by the adhesive.
4. Trim the gaskets flush with the lower casing bores. (See
Photo 9 on page 19)
CAUTION: MACHINED-CASING BORES MUST
REMAIN SHARP AT THE CASING PARTING LINE.
GASKETS MUST BE FLUSH WITH THE BORE IN
ORDER TO CONTACT O-RINGS. LEAKAGE CAN
RESULT AROUND THE STUFFING BOX O-RING IF
THIS STEP IS NOT PROPERLY FOLLOWED.
5. Assemble the impeller key in the shaft key slot.
NOTE: For impeller with replaceable rings, heat each new
ring (approximately 300°F-400°F for bronze) and slide
onto the impeller. Using gloves, hold rings against the
impeller shoulder until cool.
6. Check the impeller and casing to determine the correct
relationship. Heat the impeller evenly to 300°F maximum
to expand the bore. (Impeller may be pressed onto the
shaft instead of heating if a suitable press is available.)
(See Photo 10)
7. Using gloves, from the outboard end, slide the impeller on
the shaft against the shaft shoulder, and install the retain-
ing ring.
8. Lubricate and roll an O-ring into the groove in each of the
casing rings. Then slide the casing rings over the impeller.
9. Thoroughly clean the gland plates and stuffing boxes to
prevent dirt from entering the seal during startup.
10. Press the stationary mechanical seal seats into both of
the gland plates. Lightly lubricate the gland plates to ease
assembly. (See Photo 3 on page 17)
11. Press new lip seals into the gland plates. Before installing
the lip seals, lubricate the lip seals with lightweight oil.
NOTE: Lip seals should sit against the machined shoulder
in the gland plates. The lip seals should face away from
the mechanical seal seats. (See Photo 4 on page 17)
12. Lubricate and roll the O-rings into the grooves in each
gland plate.
13. Press the gland plates into the stuffing boxes and secure
using the socket-head capscrews.
NOTE: Because of the compression of the O-ring, it may
be difficult to press the O-ring into the stuffing box. Use
longer socket-head capscrews to start the gland plate
into the stuffing box. To prevent the mechanical seal
spring from pushing the gland plate back out of the stuff-
ing box, remove one long socket-head capscrew at a time
and replace with a regular socket-head capscrew.
Photo 11 – Mechanical seal head installation
Photo 10 – Pressing impeller on shaft
Photo 12 – Installation of stuffing box