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4-4
5. Evacuation Manifold --- A evacuation manifold is
recommended for connecting the equipment needed for
a proper evacuation. The evacuation manifold can be
made easily as shown in Figure 4-3.
Packless
Valve
3/8 Flare
Fittings (4)
1/2 Flare Fitting
Tube
Stock
1---1/2 in.
Packless
Valve
1/8 NPT
Fittings
1/8 NPT
Fitting (2)
1/4 Flare
Fitting
1/2 Flare
Fitting
Figure 4-3. Evacuation Manifold
b. Evacuation Procedure
NOTE
When a low side pump down has been
performed and after the low side has been
evacuated the filter-dryer inlet valve needs to be
opened. Also the liquid line solenoid valve needs
to be manually energized.
To help speed up the evacuation process and to
increase the evaporation of moisture, keep the ambient
temperature above 60
_
F (15.6
_
C). If ambient
temperature is lower than 60
_
F (15.6
_
C), ice may form
before moisture removal is complete. Heat lamps or
alternate sources of heat may be used to raise system
temperature if necessary.
1. Before refrigerant removal and evacuation, leak
test unit.
2. Remove all remaining refrigerant charge in the
system.
3. Connect evacuation manifold, vacuum pump,
vacuum gauge, reclaimer and hoses as shown in
Figure 4-4. All hand valves on manifold should be closed.
The compressor service valves should be midseated if
used. The reclaimer valve should be closed.
4. Start vacuum pump. Slowly open manifold valve to
the pump. Open valve to the vacuum gauge.
5. To open the liquid line solenoid valve, remove
LLS-TB10 wire and supply 24 volts. Evacuate unit until
vacuum gauge indicates 1500 microns (29.86 inches =
75.8 cm) Hg vacuum. Close gauge valve, vacuum pump
valve, and stop vacuum pump.
6. Open the refrigerant cylinder vapor valve to break
the vacuum. Raise the pressure approximately 2 psig.
This will absorb any remaining moisture in the system for
the second evacuation. Close the cylinder valve.
7. Repeat steps 4 and 5.
8. Evacuate again as described in step 3 to 300---500
microns Hg vacuum.
9. Charge the system to specifications through the
refrigerant recovery machine (using manufactures
charging procedure) or as outlined in the following
section 4.8 (Charging the Refrigeration System).