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Molycote and the appropriate YORK oil. Coat the
first stage labyrinth seal ring and the first stage impel-
ler inlet seal area with Molycote and oil. Ease the ro-
tor into the PRV housing until the impeller is ready to
enter the seal. Keep the rotor as level as possible and
support it with blocks in the casing. Screw the oil sump
housing guide pins into the compressor casing.
4. Coat the discharge oil seal and the sleeve, if used,
with Molycote and oil. Do not fit the discharge end
bearing at this time. Raise the sump and slip it into
the compressor casing. Ease the sump over the ro-
tor carefully to minimize contact to the oil seal or
sleeve. Slack off the rigging so the sump rests in the
housing and tighten a minimum of four screws to
secure the sump. Fit the build up or new shaft bear-
ings. The rotor should rotate easily and move axi-
ally without resistance. Set up a dial indicator and
record the run-out of each impeller, inlet and rim.
Fit the compressor drive shaft snug by hand and
record the run-out. (See Table 12 for clearances.)
5. Set up the long reach indicator and record the total
rotor end float. With the rotor in the full forward
position toward the suction, set the indicator to zero
and install the thrust bearing and oil pump. (See
Replacing Oil Pump Assembly.) Record the rotor
drawback as the oil pump is tightened. Measure
the shaft seal collar cover recesses to be sure you
have sufficient depth for the shaft seal. (See Fig.
16, Table 11 for dimensions.) Adjust the sump hous-
ing and PRV sleeve gaskets if needed. Remove the
oil pump and thrust bearing, store in a safe place.
You are now ready to proceed with installing the
balance of the diffusers.
INSTALLING THE DIFFUSERS
The original YORK manufactured diffuser entrance and
exit plates are marked with stage numbers and match
marks. Each set of diffusers have specific length cap
screws. The width of successive stages can vary due to
sideload connection gas flow. It is imperative that you
keep the stage diffusers and the dedicated cap screws
together as assemblies. If the cap screws are mixed, some
will bottom before the exit plates are tight and others
will not have the full holding depth.
1. Set up a dial indicator to read the axial travel of the
rotor. Locate it at a point where it is not easily dis-
turbed, this will be a reference point during assem-
bly. Position the rotor full toward the suction and
set the indicator to zero. Refer to the diffuser dia-
YORK INTERNATIONAL
gram, Fig. 31. Note the exit plate splitline relative
to the insert pin (184). Units produced prior to 1995
had the roll pin at TDC. Current production has the
pin at the split line. Viewing from the sump end,
rotate the first stage entrance plate diffuser approxi-
mately 45° clockwise to set the exit plate splitline
horizontal. Rig the bottom half of the first stage exit
plate. Lower it into the casing and lift it in position
over the entrance plate. Use the guide studs to help
locate the plate. Be sure all cap screws have wash-
ers, if required by referring to the drawing. Slip one
half of the shaft labyrinth in the exit plate and coat
the rotor shaft with Molycote under the seal. Ro-
tate the shaft a few turns to spread the Molycote
and set the other half of the shaft labyrinth seal on
the bottom half, slightly offset toward the sump.
Lower the top half of the exit plate carefully over
the shaft labyrinth, push it in place and start the
screws. Center the exit plate halves and snug the
screws.
2. Be sure the exit plate halves fit flush at the splitline
and the outside rim. Select a feeler leaf, approxi-
mately one half the minimum clearance, min. 0.005
inch thickness (Table 12). Insert it between the shaft
labyrinth seal and the shaft. The feeler must pass
freely around the circumference of the shaft. Use
a brass drift or a hammer handle to center the exit
diffuser halves. When the clearance is satisfactory,
recheck to be sure the parting line is flush and tighten
the screws to the proper torque. Measure and
record the total rotor axial travel measured from
zero with the shaft full forward toward the suction.
Note the dimension for records after each mea-
surement.
3. Rotate the lower half of the impeller inlet seal into
the bottom half of the second stage entrance dif-
fuser. Be sure it is the one cut out for the locking
disk. Install the other half in the top diffuser half.
Make sure the seals are a matched set. Coat the
lands with Molycote and oil. Apply Molycote and
oil to the O.D. of the impeller inlet. Screw an eye-
bolt into the center hole of the bottom diffuser and
lift it into position over the impeller. Start one end
into the casing groove. Allow it to rest on the impel-
ler. Remove the eyebolt and let it turn into the
groove. Exercise care, be sure persons are safely
away from the diffuser.
A pinch hazard is present. The dif-
fuser will drop quickly. Keep clear to
avoid injury.
FORM 220.11-NM2 (602)
4
61
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