Carrier PC211 Start-Up, Operation And Maintenance Instructions Manual page 201

WARNING
HCFC-22 and HFC-134a should not be mixed with air or oxygen and pressurized
for leak testing. In general, neither refrigerant should not be allowed to be present
with high concentrations of air or oxygen above atmospheric pressures, as the
mixture can undergo combustion.
Refrigerant Tracer
Use an environmentally acceptable refrigerant as a tracer for leak test procedures.
To Pressurize with Dry Nitrogen
Another method of leak testing is to pressurize with nitrogen only and use a soap bubble
solution or an ultrasonic leak detector to determine if leaks are present. This should only be
done if all refrigerant has been evacuated from the vessel.
1. Connect a copper tube from the pressure regulator on the cylinder to the refrigerant
charging valve. Never apply full cylinder pressure to the pressurizing line. Follow the listed
sequence.
2. Open the charging valve fully.
3. Slowly open the cylinder regulating valve.
4. Observe the pressure gage on the machine and close the regulating valve when the
pressure reaches test level. Do not exceed 140 psig (965 kPa).
!
WARNING