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88
SERVICING
Copper to Steel Joints
- Silver Solder used without a flux (alloy
of 30% silver, 38% copper, 32% zinc). Recommended heat -
1200°F.
S--101 LEAK TESTING (NITROGEN OR
NITROGEN-TRACED)
To avoid the risk of fire or explosion, never use
oxygen, high pressure air or flammable gases for leak
testing of a refrigeration system.
WARNING
To avoid possible explosion, the line from the
nitrogen cylinder must include a pressure regulator
and a pressure relief valve. The pressure relief valve
must be set to open at no more than 150 psig.
WARNING
Pressure test the system using dry nitrogen and soapy water
to locate leaks. If you wish to use a leak detector, charge the
system to 10 psi using the appropriate refrigerant then use ni-
trogen to finish charging the system to working pressure, then
apply the detector to suspect areas. If leaks are found, repair
them. After repair, repeat the pressure test. If no leaks exist,
proceed to system evacuation.
S-102 EVACUATION
WARNING
REFRIGERANT UNDER PRESSURE!
Failure to follow proper procedures may cause
property damage, personal injury or death.
Do not front seat the service valve(s) with the
compressor open, with the suction line of the
comprssor closed or severely restricted.
WARNING
IMPORTANT NOTE:
Because of the potential damage to com-
pressors, do not allow suction pressure at service valve to drop
below 20 PSIG when pumping unit system down for repair.
Outdoor section, depending on line set length and amount of
charge in system, may not be able to hold the entire system
charge.
This is the most important part of the entire service procedure.
The life and efficiency of the equipment is dependent upon the
thoroughness exercised by the serviceman when evacuating
air (non-condensables) and moisture from the system. Air in
a system causes high condensing temperature and pressure,
resulting in increased power input and reduced performance.
Moisture chemically reacts with the refrigerant oil to form
corrosive acids. These acids attack motor windings and parts,
causing breakdown. The equipment required to thoroughly
evacuate the system is a high vacuum pump, capable of pro-
ducing a vacuum equivalent to 250 microns or less and a vacu-
um gauge to give a true reading of the vacuum in the system.
NOTE:
Never use the Scroll compressor as a vacuum pump or
run when under a high vacuum. Motor damage could occur.
Condensing unit liquid and suction valves are closed to contain
the charge within the unit. The unit is shipped with the valve
stems closed and caps installed.
Do not open valves until the
system is evacuated.
1. Connect the vacuum pump with 250 micron capability to
the service valves.
2. Evacuate the system to 250 microns or less using suction
and liquid service valves. Using both valves is necessary as
some compressors create a mechanical seal separating the
sides of the system.
3. Close pump valve and hold vacuum for 10 minutes. Typi-
cally pressure will rise during this period.
4. If the pressure rises to 1000 microns or less and remains
steady the system is considered leak free; proceed to start-
up.
5. If pressure rises above 1000 microns but holds steady be-
low 2000 microns, moisture and/or non-condensibles may
be present or the system may have a small leak.
6. Return to step 2: If the same result is encountered check
for leaks as previously indicated and repair as necessary
then repeat evacuation.
7. If pressure rises above 2000 microns, a leak is present.
Check for leaks as previously indicated and repair as neces-
sary then repeat evacuation.
LOW SIDE
GAUGE
AND VALVE
HIGH SIDE
GAUGE
AND VALVE
TO
UNIT SERVICE
VALVE PORTS
VACUUM PUMP
VACUUM PUMP
ADAPTER
800 PSI
RATED
HOSES
CHARGING
CYLINDER
AND SCALE
EVACUATION