Oil Pressure Transducer Location; Eductor Block - York MILLENNIUM YS Manual

OIL SYSTEM (CONT'D)
The oil pressure transducer is located at the SB-2 mani-
fold. The differential pressure is measured as the dif-
ference between the Oil Pressure Transducer at SB-2
and the Filter Pressure Transducer located in the oil
separator. This value is compared to the limits in the
control panel logic. If the oil filter differential reaches
20 psid, a warning message is displayed by the control
panel display. If the oil filter reaches 25 psid, a safety
shutdown is initiated. See Figure 18.
FIG. 18 – OIL PRESSURE TRANSDUCER
LOCATION
An oil supply line from the manifold at SB-2 is piped to
the capacity control directional valve at Port P. The 4-
way capacity control solenoid (directional) valve directs
oil pressure against one side or the other of the slide
valve piston. The opposite side of the slide valve is re-
lieved to suction pressure at compressor port SC-11.
The differential pressure between the P port and the
suction pressure at Compressor Port SC-11 is what pro-
vides the force to load or unload the slide valve and
provide capacity control. Refer to the Capacity Control
Schematic Diagram.
Oil flows from the oil manifold at SB-2 to the brazed
plate, refrigerant cooled oil cooler. Cool oil leaving the
brazed plate heat exchanger flows to the eductor block
manifold. A new oil circuit has been incorporated into
the oil eductor block in Design Level "D". The oil cir-
cuit is separate from the eductor oil management sys-
tem. See Figure 19.
The eductor block manifold oil circuit contains the Seal
Oil Pressure Transducer and a High Oil Temperature
YORK INTERNATIONAL
Safety sensor. The Seal Oil Pressure is monitored by
the control panel. The differential pressure between the
Seal Oil Pressure and the Evaporator Pressure Trans-
ducer is calculated and compared to the control panel
logic. If the differential reaches the set point (30 psid
for R-22 and 20 psid for R-134a, the control panel will
initiate a safety shutdown. A high oil temperature safety
shutdown will be initiated at 170ºF (77ºC).
The oil leaving the oil eductor manifold block flows into
the compressor at compressor port SB-3 to lubricate
the compressor bearings and shaft seal. All of the oil
that is injected into the compressor mixes with refriger-
ant gas during compression. The oil and refrigerant gas
is discharged into the oil separator, where it is sepa-
rated and returned to the oil sump. A high discharge
temperature safety is located in the discharge line, be-
tween the compressor and oil separator. This safety will
initiate a safety shutdown at 210ºF (99ºC).
Oil is separated from the refrigerant gas in the oil sepa-
rator. Oil is separated from the refrigerant gas in a three
step process.
In the first stage of oil separation, high velocity oil and
refrigerant gas in the compressor discharge line under
goes a rapid reduction in velocity as it enters the large
diameter oil separator. Most of the oil drops out of the
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refrigerant gas stream due to the reduction in velocity.
The oil falls by gravity into the oil reservoir located in
the bottom of the oil separator.
FIG. 19 – EDUCTOR BLOCK
The second stage of oil separation is accomplished by
directing the refrigerant gas through mesh pads that
have an extended surface area. Smaller liquid oil drop-
FORM 160.47-NOM3
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