Service Manual for Refrigerated Back Counter RBC 48/60
10
RECHARGING REFRIGERANT SYSTEM
General
To analyze the performance of a refrigeration
system; temperature readings can be taken and
converted to pressures using a standard pressure/
temperature chart.
When access into a factory sealed refrigeration
system is necessary to perform service, the
following procedure must be followed to ensure
the system is returned to a properly sealed state.
Tools Required
• Standard hand and refrigeration service tools,
no special tools needed.
• Refrigerant Type: R-134A 8 ounces
Charging Procedure
NOTE:
When service of the refrigeration system
is necessary, care must be given during the
evacuation process to ensure removal of air,
moisture, and other non-condensables from the
system. To evacuate the refrigeration system
properly, Duke Manufacturing recommends a
triple evacuation procedure outlined
below. Failure to follow this process could
c a u s e p o o r p e r f o r m a n c e o f t h e
refrigeration system.
• Evacuate system to 1500 microns
• Break the vacuum to 2 psig with dry
nitrogen, if dry nitrogen is unavailable use
the same type of refrigerant as used in the
system
• Evacuate system to 1500 microns
• Break the vacuum to 2 psig with dry
nitrogen, if dry nitrogen is unavailable use
the same type of refrigerant as used in the
system
• Evacuate system to 500 microns
The system is now ready to receive the refrigerant
charge per the data plate information.
CAUTION: Never use oxygen or acetylene
in place of refrigerant and dry
nitrogen for leak testing. A
violent explosion may result,
causing personal injury or death.
Always use a pressure regulator
when using nitrogen to pressure
test. Failure to do so will result in
extremely high pressure which
could exceed the burst pressure
of the compressor or other
system components and result
in personal injury or death.
NOTE:
Before beginning the repair, ensure there
is enough of the process tube present to complete
the repair using the above procedure. If not, install
a new process tube (approximately 12") before
beginning the repair sequence.
1. Install a temporary access valve on the high
and low side process tubes as close to the
factory crimps as possible.
2. Through the use of temporary valves, (Duke
Manufacturing will not reimburse the cost of
permanently installed valves) perform the
required service needed to repair the unit.
3. Once the repair has been made, evacuate
the system using the triple evacuation method
described in Duke Manufacturing Service
Bulletin Number 26. After the evacuation is
complete, recharge the system as stated on
the nameplate, using the proper refrigerant,
Continue by crimping the process tube just
below the temporary valve and again 2" below
the crimp just made. Leaving the crimp tool
in place, remove the temporary valve, braze
shut the end of the process tube, allow to cool
(approximately “5 minutes" time), remove the
crimp tool, and leak check the brazed end.
