Refrigeration Maintenance and Service Operations
133
Unit Preparation and Hookup
1. Recover all refrigerants from the unit and
reduce the unit pressure to the proper level
(US Federal Law requires a -17 to -34 kPa,
-0.17 to -0.34 bar, 5 to 10 in.vacuum that is
dependent upon the recovery equipment
used).
2. Break vacuum with refrigerant and equalize
system pressure to 0 kPa, 0 bar, 0 psig.
Replace the liquid line filter drier.
3. Confirm that the Evacuation Station functions
properly and determine “Blank Off” Pressure.
The Blank Off Pressure of the Vacuum Pump
is the deepest vacuum that the vacuum pump
can attain when isolated from the rest of the
system.
If a vacuum pump (isolated from a system) is
started and the Micron Meter responds quickly
by going to a deep vacuum, the operator can
be confident that the pump and oil are in good
condition. If the vacuum pump fails to reach a
deep vacuum within 5 minutes, the operator
should suspect the condition of the oil or the
pump. It is recommended that the pump oil be
changed first to see if the rate of reaching a
deep vacuum is improved.
4. Connect the Evacuation Station and
refrigerant tank with gauge manifold
(optional) to the unit.See “Evacuation Station
and unit Hook-up” on page 132. Connect
evacuation hoses to the compressor suction
and discharge service fittings and the receiver
tank service fitting.
5. Open Evacuation Station valves (V1, V3, and
V4). It is only necessary to open valve V2
when a reading on the Micron Meter is
desired. This is especially true when starting
to evacuate a unit and large amounts of
moisture and oil will be passing by the sensor.
6. Open the vacuum pump Iso-Valve™ built into
the pump housing below the handle. It is
recommended that the valve be kept open at
all times.
7. If connecting a refrigerant tank and gauge
manifold to the evacuation station, close the
gauge manifold and refrigerant tank valves to
prevent refrigerant from being drawn from the
tank.
Unit Evacuation
1. Turn on the Vacuum Pump. Open the Gas
Ballast Valve located on top of the pump
housing behind the handle (the valve is fully
open at two turns counterclockwise). Evacuate
the system to 500 microns to achieve a final
equilibrium pressure of 2000 microns or less.
The final equilibrium pressure is determined
with the Thermo King Evacuation Station
using the following procedure (called a
pressure-rise test):
a. Evacuate the system using the Evacuation
Station until the vacuum level reaches
1000 microns. Then close the Gas Ballast
Valve,
b. Continue evacuation to 500 microns or
until vacuum stabilizes at its lowest level.
Contamination may delay reaching the
lowest level for a period of several or
more hours.
c. Close valve V1 to isolate the vacuum
pump from the system.
Observe the vacuum level on the Micron
Meter. When the Meter has stabilized, the
value indicated on the Micron Meter is the
equilibrium pressure. This reading must be
2000 microns or less.
NOTE: The presence of refrigerant in the
compressor oil may prevent a low vacuum
reading from being achieved. Compressor oil
can continue to out gas for long periods of
time.
2. If the vacuum level appears to stall above 500
microns, back seat the discharge service valve
and observe the Micron Meter.
CAUTION: Do not attempt to evacuate a
unit until it is certain that the unit is leak
free. A unit with less than a full charge of
refrigerant should be thoroughly leak
tested. Any leaks found must be repaired.
Содержание CRR-40 119
Страница 4: ......
Страница 16: ...Safety Precautions 16...
Страница 18: ...Service Guide 18...
Страница 20: ...Model Features 20...
Страница 32: ...Specifications 32...
Страница 120: ...MP 3000a Controller 120...
Страница 160: ...Wiring and Schematic Diagrams Index 160...
Страница 161: ...161 MPC2000 Wiring Schematic...
Страница 162: ...162 MPC2000 High Voltage Wiring Diagram...
Страница 163: ...163 MPC2000 Low Voltage Wiring Diagram...
Страница 164: ...164 MPC2000 WCC Wiring Schematic...