Leak Testing (Nitrogen Or Nitrogen-Traced); Evacuation - Daikin DAR09 Service Instructions Manual

SERVICING
S-101 LEAK TESTING (NITROGEN OR
NITROGEN-TRACED)
WARNING
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.
Pressure test the system using dry nitrogen and soapy water to
locate leaks. If you wish to use a leak detector, charge the sys-
tem to 10 psi using the appropriate refrigerant then use nitrogen
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.
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. Out-
door 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 pres-
sure, resulting in increased power input and reduced perfor-
mance.
Moisture chemically reacts with the refrigerant oil to form corro-
sive 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 producing a vacuum equivalent
to 25 microns absolute and a thermocouple vacuum gauge to
give a true reading of the vacuum in the system
NOTE: Never use the system compressor as a vacuum pump or
run when under a high vacuum. Motor damage could occur.
WARNING
Do not front seat the service valve(s) with the
compressor open, with the suction line of the
comprssor closed or severely restricted.
1. Connect the vacuum pump, vacuum tight manifold set
with high vacuum hoses, thermocouple vacuum gauge and
charging cylinder as shown.
2. Start the vacuum pump and open the shut off valve to the
high vacuum gauge manifold only. After the compound
gauge (low side) has dropped to approximately 29 inches of
vacuum, open the valve to the vacuum thermocouple gauge.
See that the vacuum pump will blank-off to a maximum of
25 microns. A high vacuum pump can only produce a good
vacuum if its oil is non-contaminated.
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