User's Manual

47
FIGURE 3.
TYPICAL WATER COOLED OIL COOLER
DIAGRAM
The solenoid valve provides positive water shut-
off when the compressor is not in operation. A
temperature of 150°F is considered high in most
circumstances and the compressor is protected by
a safety control to prevent operation of the com-
pressor above this temperature. Unless otherwise
specified, the oil cooler is sized for an 85°F water
inlet temperature and 10°F temperature rise.
2. Liquid Injection Oil Cooling.
The components are furnished with liquid injec-
tion for a typical system. The liquid solenoid valve
opens whenever the compressor is in operation.
The thermostatic expansion valve controls the
flow of liquid refrigerant to the compressor injec-
tion port in response to the discharge tempera-
ture. The discharge temperature is maintained at a
minimum of 120°F with a maximum of 140°F. The
discharge temperature can be adjusted either of
two ways. First, the small outlet pressure regula-
tor can be used to adjust superheat. Normally, this
regulator should be adjusted to maintain 70 psig
pressure at the external equalizing port of the ex-
pansion valve. Raising the pressure beyond 70 psig
tends to raise the discharge temperature, while
lowering the pressure lowers the discharge tem-
perature. Secondly, the standard superheat adjust-
ing screw on the thermostatic expansion valve can
be used to adjust the discharge temperature.
FIGURE 4.
TYPICAL LIQUID INJECTION OIL COOLING
SCHEMATIC DIAGRAM
Liquid injection cooling on booster compressors
is handled in the following manner. Using high
pressure liquid, the point of injection can be the
discharge line and no horsepower penalty is paid
by injecting liquid into the compressor discharge
line. The high pressure gas source normally used
for the pressure regulator would be compressor
discharge pressure. Since, on a booster unit, this
intermediate pressure is very rarely as high as the
nominal setting of 70 psig, high stage discharge
gas is used. On high stage compressors, the liquid
is injected directly into the compressor. However,
there is a horsepower penalty when the liquid is
injected into the compressor. This will vary with
refrigerant and operating condition. The liquid
is injected into the compressor at a point in the
compressor cycle that minimizes the brake horse-
power penalty.
3. V-PLUS Oil Cooling System
This system consists of a liquid pump, shut-off
valves, motor, solid state variable speed controller
and solid state temperature controller. This meth-
od of oil cooling is not available on the VSM or VSR
compressor units. The pump and solenoid valve
cycle on and off in parallel with the compressor
drive motor. The temperature controller receives a
temperature signal from the sensor located in the
discharge and oil lines and in turn, sends a signal
to the motor speed controller.
Operation