Goulds Pumps 3996 - IOM - Manual (Page 35)

3996 IOM 9/2010
31
IMPELLER CLEARANCE SETTING
!
The impeller clearance setting procedure must be
followed. Improperly setting the clearance or not
following any of the proper procedures can result
in sparks, unexpected heat generation and
equipment damage.
s
! WARNING
Lock out driver power to prevent accidental startup
and physical injury.
A change in pump performance may be noted over time
by a drop in head or flow or an increase in power
required. Performance can usually be renewed by
adjusting the impeller clearance. Two techniques are
given to set the impeller clearance, the dial indicator
method and the feeler gauge method.
DIAL INDICATOR METHOD
1. Remove coupling guard.
2. Remove coupling.
3. Set indicator so that button contacts either the shaft
end or against face of coupling (Fig. 38).
4. Loosen jam nuts (423) on jack bolts (370D) and back
bolts out about two turns.
5. Tighten each locking bolt (370C) evenly, drawing the
bearing housing (134A) towards the bearing frame
(228) until impeller contacts the casing. Turn the
shaft to ensure contact is made.
6. Set indicator to zero and back locking bolt (370C)
out about one turn.
7. Thread jack bolts (370D) in until they evenly contact
the bearing frame. Tighten the jack bolts evenly
(about one flat at a time) backing the bearing housing
(134A) away from the bearing frame until the
indicator shows the proper clearance per Table 3.
8. Evenly tighten locking bolts (370C), then jack bolts
(370D) keeping indicator reading at proper setting.
9. Check shaft for free turning.
10. Replace coupling guard.
FEELER GAUGE METHOD
1. Remove coupling guard.
2. Loosen jam nuts (423) on jack bolts (370D) and back
bolts out about two turns (Fig. 16).
3. Tighten locking bolts (370C) evenly, drawing
bearing housing (134A) towards frame (228) until
impeller contacts the casing. Turn shaft to ensure
contact is made.
4. Using a feeler gauge, set the gap between the
three locking bolts (370C) and bearing housing
(134A) per impeller clearances in Table 1.
5. Evenly back out bearing housing (134A) using the
three jack bolts (370D) until it contacts the locking
bolts (370C). Evenly tighten jam nuts (423B).
6. Check shaft for free turning.
7. Replace coupling guard.
Fig. 15
Dial Indicator Method
Fig. 16
5