Vollrath Stoelting F231, Руководство по обслуживанию, Страница: 38 / 63

Service Manual #513659 30 Model F231
E. Remove all tubing plugs from the replacement
compressor.
NOTE
The compressor plugs protect the compressor from
moisture in the air. Do not remove the plugs until
you are ready to install. The compressor must not
be opened to the atmosphere for more than 10
minutes.
F. Leave the suction and discharge ports open to
prevent pressure buildup. Braze the suction and
discharge line to the compressor.
G. Connect the wires to the compressor terminals.
H. Replace the drier per the instructions in Section
5.9.
I. Evacuate the system per the instructions in Section
5.2
J. Recharge the system per the instructions in
Section 5.3.
K. Replace the insulating tubing on the suction line.
5.5 CONDENSER
The F231 comes with either an air-cooled or a water-
cooled condenser. The capacity of the machine is directly
related to keeping the condenser clean and free of debris.
The air-cooled condenser is a copper tube and aluminum
fi n type. The machine must have a minimum of 3” of clear-
ance on both sides for proper air fl ow.
The water-cooled condenser is a tube and shell type. This
condenser requires cool, clean water to function properly.
Inlet and discharge lines must be 3/8” ID minimum.
CONDENSER TESTING
The condenser can be checked for leaks using the bubble
test or using a leak detector.
5.6 VALVES
A. THERMOSTATIC EXPANSION VALVE (TXV)
The Thermostatic Expansion Valve (TXV) is used to
meter the refrigerant to the freezing cylinder evaporator.
It does so by maintaining constant superheat at the exit
of the evaporator. The self-regulating TXV is preset by
the manufacturer and adjustment is not recommended.
Figure 5-3.
TXV TESTING & ADJUSTMENT
NOTE
The bulb has an indent which must be positioned
against the tubing. Good contact between the
bulb and the suction line is necessary for proper
operation of the valve. The bulb must also be well
insulated.
A. Connect a gauge to the Schrader valve on the
suction line.
B. Connect a thermocouple to the suction line next
to the evaporator.
C. Immediately before the refrigeration cycle ends,
the gauge should read between 18-22 psig. The
superheat should be 7-10°F.
D. If the pressure reading is higher than expected
and the superheat is low, check to see if there is
an overcharge of refrigerant.
E. If the pressure reading is lower than expected and
the superheat is high, check to see if there is a
low refrigerant charge or if there is a restriction
in the system.
NOTE
The TXV is the LAST component to adjust in the
refrigeration system.
F. The TXV can be adjusted after the steps above are
completed. When adjusting, do not turn the valve
over 1/4 turn (90°). Turn the valve stem clockwise
to increase the superheat or counterclockwise to
decrease the superheat.
TXV REMOVAL
A. Disconnect the machine from electrical supply
before removing any panels for servicing. Remove
the front panel.
B. Recover refrigerant charge per instructions in
Section 5.2.
C. Leave the suction and discharge ports open to
prevent pressure buildup during TXV removal.
D. Remove any insulation from the TXV and
immediate surrounding lines.
E. Apply a heat sink (wet cloth) to the valve dome
(Figure 5-4).
F. Unsweat the TXV and remove.
Figure 5-3 TXV Figure 5-4 TXV Removal