Xylem IMVIT R01 Model VIT Vertical Industrial Turbine Pumps - Manual (Page 22)

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IMPELLER ADJUSTMENT
Impeller adjustment is identical for all motors and right
angle gear drives. Adjustment is accomplished by turning
the adjusting plate (613). (See Figure 16 or 17). The
correct adjustment is listed on the Outline Drawing for
the specific unit. If the pump has a thrust pot, do not
adjust the impeller position until the thrust pot has been
installed and adjust the impeller position by using the
adjust nut on the thrust pot.
NOTE: Mechanical seal, when provided, must not be
secured to the shaft prior to impeller adjustment.
(open or enclosed type impellers). Shaft must
move up or down within the seal Assembly.
For pumps handing liquids between –50º to
200º F, impeller adjustment can be made under
ambient conditions. For liquids in excess of
this range, it is recommended that impeller
adjustment be made after the pump surface
temperature has reached an equilibrium when
charged with the pumpage. In those cases, where
this is not feasible due to safety consideration
or impossible due to external ice build up in
cryogenic applications, refer to factory for
specific instructions.
OPEN IMPELLERS
1. With the impellers touching the bottom of the
bowls, turn the adjusting plate (613) towards the
driver hub (610) or spacer (612) to obtain 0.015
inch clearance between the adjusting plate and
driver hub or spacer for the first 10 feet of column.
Add 0.010” for each additional 10 feet of column.
See Figures 16 and 17. Note: The determination of
driver shaft end play can be critical and should be
added to this setting. For larger pumps over 8”, this
amount may be too little; please refer to Outline
Drawing.
Example: total pump length is 50 feet - set impellers
at 0.055 inch.
2. After impeller adjustment, align adjusting plate (613)
with the pump hub (614), and tightly draw coupling
flanges together with capscrews (759) and nuts
(735). (See Figures 14 and 15.)
3. Check shaft run out with dial indicator. For
mechanical seal installation, the run out should be
0.005" or less.
4. Set seal after impeller adjustment. Securely tighten
all set screws in the collar. Remove the spacer
between the gland plate and collar. Retain spacer for
future resetting of seal.
NOTE: When impellers are reset, the seal must also be
reset.
Figure 16
Figure 17
ENCLOSED IMPELLERS
For enclosed impellers obtain the clearance between the
adjusting plate and driver hub or spacer as specified on
the outline drawing. See Figure 16 or 17.
INSTALLING THE GREASE LUBRICATED THRUST POT
This type of thrust pot and the motor stand are
assembled on the discharge head by the factory. This
thrust pot is designed to be used with NEMA Vertical
C-face motors. The motor shaft and the pump shaft are
to be coupled with flexible coupling.