Trane CCRC Series Installation, Operation And Maintenance Manual page 27

Shutoff valves A, B, & C and connect a refrigerant
cylinder to the charging port on the manifold. Purge
the air from the hose. Raise the standing vacuum
pressure in the system to zero (0 psig) gauge
pressure. Repeat this process two or three times
during evacuation.
N N o o t t e e : : It is unlawful to release refrigerant into the
atmosphere. When service procedures
require working with refrigerants, the service
technician must comply with all Federal,
State, and local laws.
Standing Vacuum Test
1. Once 300 microns or less is obtained, close Valve A
and leave valves B and C open. This will allow the
vacuum gauge to read the actual system pressure.
Let the system equalize for approximately 15
minutes. This is referred to as a standing vacuum
test where, time versus pressure rise. The
maximum allowable rise over a 15 minute period is
200 microns. If the pressure rise is greater than 200
microns, but levels off to a constant value, this
indicates that there is excessive moisture present. If
the pressure steadily continues to rise, a leak is
indicated. Figure 18, p. 27
results of the standing vacuum test.
Figure 18. Evacuation Time vs Pressure Rise
1600
1400
1200
1000
800
600
400
Initial evacuation pressure.
200
-10 0
CXRC-SVX01J-EN
illustrates three possible
10 20 30
Time in Minutes
2. If a leak is encountered, repair the system and
repeat the evacuation process until the
recommended vacuum is obtained. Once the
system has been evacuated, break the vacuum with
refrigerant, and complete the remaining Pre-Start
Procedures before starting the unit.
Figure 17. Typical Vacuum pump Hookup
Continously increasing pressure
indicates the presence of leaks,
moisture, or both.
State of equilibrium indicates the
true amount of moisture left in
the system. It indicates that no
leaks are present and the system
is properly evacuated.
40 50 60
M M a a i i n n t t e e n n a a n n c c e e
State of equilibrium indicates the
true amount of moisture left in
the system. It indicates that no
leaks, but requires further evacuation.
70 80 90
27