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35
Evacuation Procedure Steps
1. If this procedure is performed shortly after the leak /
pressure test, the caps and cores on the Schrader
ports must have already been removed, and the
manifold must already be connected. If the
procedure was not performed shortly after the leak /
pressure test, make sure to remove the caps and
cores on the Schrader ports. Verify that the service
valves on the outdoor unit are closed, and the stem
head access caps are tight.
2. Connect the gauge manifold along with the vacuum
pump to the Schrader ports (with core removed)
using vacuum hoses. Open the gauge manifold and
the vacuum pump valves
3. Operate the vacuum pump and evacuate the system
to the 2,000 micron level. Isolate the pump by closing
the manifold gauges and the vacuum pump valve,
and then watch the micron level. Micron level could
rise a bit, but MUST eventually stop rising for fifteen
(15) minutes.
•
If the micron level DOES NOT stop rising, there is
a leak, and the leak test must be performed again.
•
If the micron level DOES rise above 2,000 micron,
re-open the manifold gauges and the vacuum
pump valve and continue evacuation back down to
2,000 micron level.
•
If the micron level holds at 2,000 micron, continue
to step 4.
4. Break vacuum with 50 psig nitrogen purge for an
appropriate amount of time (this
is to “sweep”
moisture from piping).
5. Purge nitrogen from the system until the pressure
drops down to 1 to 3 psig.
6. Evacuate to 1,000 micron level. Isolate the pump by
closing the manifold gauges and the vacuum pump
valve, and then watch the micron level. Micron level
could rise a bit, but MUST eventually stop rising for
fifteen (15) minutes.
•
If the micron level DOES NOT stop rising, there is
a leak, and the leak test must be performed again.
•
If the micron level DOES rise above 1,000 micron,
re-open the manifold gauges and the vacuum
pump valve, and continue evacuation back down to
1,000 micron level.
•
If the micron level holds at 1,000 micron, continue
to step 7.
7. Break vacuum with 50 psig nitrogen purge for an
appropriate amount of time
8. Purge nitrogen from the system until the pressure
drops down to 1 to 3 psig.
9.
Evacuate to static micron level ≤ 500
10.
Micron level must remain ≤ 500 for 24 hours. If the
vacuum gauge rises and stops, the system could
contain moisture, therefore, it will be necessary to
repeat the steps of vacuum break and drying.
11. After maintaining the system in vacuum for 24
hours, check if the vacuum gauge rises or not. If it
doesn’t rise, then the system is properly evacuated.
12. Close manifold gauges.
13. Shut the valve before turning off the vacuum pump.
Figure 33: Evacuation Diagram for Heat Recovery Systems
