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Operation
External Sump Vent Equalizing Line (Figure 5)
Oil that is returning to the reservoir (1) from the bear-
ing drains contains some additional refrigerant gas af-
ter passing through the bearings and joining with the
buffer gas from the oil seals.
In order to manage that refrigerant gas and the oil reser-
voir pressure, these compressors are equipped with an
external gas line (2) that vents the pressure from the oil
reservoir (1) to the inlet (3) of a lower stage impeller or
appropriate external source.
There is a screen type mist eliminator installed inside
the sump at the inlet (4) of that external gas line (2) to
minimize the opportunity for oil to be carried out with
the vent flow through the line.
An automatic sump vent valve (5) slows the rate at which
the oil reservoir pressure is reduced at start-up. Nor-
mally, the valve is field adjusted to open at a rate that
will reduce oil reservoir pressure without adversely af-
fecting system oil pressure. Valve adjustment may vary
depending on system conditions. The sump vent valve
is typically supplied with an orifice through the seat
which will prevent total isolation of the vent line. Oil
loss through the seals may occur if the compressor is
operated for extended periods with the sump vent valve
closed.
Internal Seals
The internal sealing systems are the backbone of the
compressor's efficiency and, in some cases, its reliabil-
ity. It is very important to perform the following proce-
dures when evaluating the performance of any sealing
device.
The various internal seal systems used
in the Series M Turbomaster compres-
sor are assembled with clearances that
take into account both thermal effects
and inertia growth characteristics of
the application. For this reason it is
very difficult to tabulate all clearance
values for all applications. Form
160.71-M can be used for two-stage
water chilling application. The infor-
mation in that document should not
be applied to any other application
unless verified on the application data
sheet.
18B
FORM 220.11-NM2 (602)
1. Check for proper clearance between all stationary
and rotating parts.
2. Inspect the stationary component's seal seating sur-
face. There should not be any burrs, ridges, gouges,
etc. where the seal seats in the housing.
Shaft Labyrinths (Figure 4)
The close radial clearance between the
shaft labyrinths (9, Figure 4) and the
rotor shaft (8) reduces gas leakage to
a minimum along the rotor shaft (8).
Gas leakage between stages is kept to a minimum by
means of shaft labyrinths (9) mounted between the (sta-
tionary) diffuser exit plates (10) and the rotor shaft (8).
Balance Piston Seal
Leakage from the high stage impel-
ler discharge area around the balance
piston diameter is minimized by
means of the balance piston seal ring
(4, Figure 4).
The balance piston seal ring system consists of a float-
ing balance piston seal ring (4), spring washer (11), bal-
ance piston cover (12) and an anti-rotation pin (13).
The anti-rotation pin (13) may prevent the seal ring sys-
tem from being damaged due to rotation during a surge
or system upset condition.
Oil Seals (Figure 4)
Oil leakage from the main bearings into the impellers
is prevented by means of the oil seals (14, 15) that
are located on the rotor shaft inboard from the main
bearings.
There are seals that regulate a slight gas leakage (re-
ferred to as buffer gas) into the lubrication system at
the bearing outlets which opposes and prevents oil leak-
age. These seals are located over the area of the main
shaft that is machined with "wind-back" spirals which
are also intended to aid in the prevention of oil loss into
the system if the source of buffer gas should somehow
be reduced.
YORK INTERNATIONAL
FIG. 5 – EXTERNAL SUMP VENT EQUALIZING LINES, EXTERNAL BALANCE PISTON VENT LINES
18
FORM 220.11-NM2 (602)
00620VIP
YORK INTERNATIONAL
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