Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

5
Retrofitting
procedures that you would use for CFC or HCFC to ensure optimal
system performance. In general, systems will require a smaller
charge size than those using CFC or HCFC. If the original capillary
tube is used, it will generally be necessary to undercharge the
system to prevent liquid flood back to the compressor. Special
care should be taken when charging with refrigerant blends, as
presented in section 4.
15 - Run the system and charge additional refrigerant if needed until
full-charged. The use of an expansion device not optimised for
the system, such as the original capillary tube, will make the
system more sensitive to charge and/or operating conditions.
As a result, system performance will change more quickly if the
system is overcharged (or undercharged). To avoid overcharging,
it is best to charge the system by first measuring the operating
conditions (including discharge and suction pressures, suction line
temperature, compressor amps, superheat) before using the liquid
level sight glass as a guide.
16 - Monitor the system operation and performance for at least 48 hours
or longer and make necessary adjustment.
17 - Check remaining content of mineral oil with a refractometer or oil
test kit.
18 - Follow the system and/or compressor manufacturer recommendations
as tolerance are dependent on the system and its operating
conditions.
19 - Label the system (as shown in the downloadable data sheet).
After retrofitting the system, label the system components to
identify the refrigerant and specify type of lubricant (by brand name)
in the system. This will help ensure that the proper refrigerant and
lubricant will be used to service the equipment in the future.
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