Technical data

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
relieved to suction pressure at compressor port SC-11.
The differential pressure between the P port and the
suction pressure (Port SC-11) loads or unloads the slide
valve to provide capacity control.
2.7 Oil Eductor
Oil eductors are fitted to automatically recover any oil
that may migrate to the evaporator and return it to the
compressor. The oil eductor circuit manages the
amount of oil in the refrigerant charge. A small amount of
oil is normal in the refrigerant charge and will be found in
the evaporator. If not properly managed the oil will
accumulate and have an adverse affect on unit
performance.
The oil eductor circuit consists of three refrigerant and
oil filter driers, two “jet pump” eductors and the
interconnecting piping.
The eductors operate using the “jet pump” principle.
Discharge pressure gas and oil flows through a filter
dryer located at the bottom of the oil separator to a
regulating orifice and nozzle located in the eductor
block. The reduced pressure (pumping action) is
created by the velocity of the discharge pressure gas
and oil flowing through the orifice and nozzle. This
creates a reduced pressure area that allows the oil-rich
refrigerant and oil to flow from the evaporator into the
compressor.
Oil-rich refrigerant flows into the eductor block through
the filter drier from the evaporator. The oil rich
refrigerant mixes with the discharge pressure gas and
flows into the compressor suction line.
A second eductor flows oil, collected in the evaporator
trough through the second filter drier located on the
eductor block. This oil mixes with the discharge gas in
the eductor block and flows to the compressor at port
SC-5.
2.8 Heat Exchangers
Shells
Evaporator and condenser shells are fabricated from
rolled carbon steel plates and have fusion welded
seams. Carbon steel tube sheets, drilled to
accommodate the tubes, are welded to the ends of each
shell. Intermediate tube supports are fabricated of 12.7
mm thick carbon steel plates, no more than 1220 mm
apart. The refrigerant side of each shell has a design
working pressure of 20.6 bar and is tested at 31.0 bar.
Each vessel has a single or dual refrigerant relief device
set at 20.6 bar.
Tubes
Heat exchanger tubes are each 19 mm OD, 0.71 mm
wall copper alloy with a high efficiency, internally and
externally enhanced design to provide optimum
performance. Each tube is roller expanded into the tube
sheets to provide a leak-proof seal. Each tube is
individually replaceable.
035L02381-GB0 2-5
Figure 2.5 Oil Eductor