Adaptation To '96 Chlorofluorocarbon Regulations - Sharp DW-71-H Service Manual

ADAPTATION TO '96 CHLOROFLUOROCARBON REGULATIONS

(1) Outline
As the chlorofluorocarbon used for freezers and heat insulators of refrigerators depletes the ozone layer, it has been
decided to abolish completely the production of chlorofluorocarbon by the end of 1995 and to use the substance less
adversely affecting the ozone layer in the world scale. Now, Sharp uses the chlorofluorocarbon replacing substance
HFC-134a for refrigerator coolant. It is applied also for the new models of dehumidifier DW71-H.
(2) Properties of HFC-134a cycle and cautions
1) Cares when changing the coolant
(Change from CFC-12 to HFC-134a)
(1) As the Filter dryer for CFC-12 cannot be used, the Dryer filter for HFC-134a must be used. (However, the
dryer XH-9 for HFC-134a can be used for CFC-12.) As the size of coolant molecular is smaller, the different
drying agent is used.
(2) The existing gas leak tester (for CFC-12 and HCFC-22) cannot be used.
(The existing leak tester detects chlorine contained in chlorofluorocarbon, but HFC-134a does not contain
chlorine.)
(3) The repair tools for HFC-134a must be used. (There are specific tools for refrigerator and dehumidifier. Refer
to the instructions.)
The rubber (sealing) of existing tools expands and its tension reduces. The specified tools must be used
(using the rubber of other type).
2) Change of compressor oil
Naphthene mineral oil or V-olefine synthetic oil (CFC-12) is changed to ester oil for the refrigerator and to non-
ester oil (low-viscosity alkylbenzene) (HFC-134a) for the dehumidifier.
(1) After opening the cap of each refrigerator, dehumidifier, compressor and Dryer filter , it is necessary to
evacuate it within 15 minutes.
Non-ester oil and particularly ester oil have the saturation molar weight of 200 ppm, 40 times more than the
existing oil.
(Since non-ester oil and particularly ester oil are liable to react with water to produce acid, the acid reacts with
metal into metallic salt which becomes a cause to clog the capillary tube. Particularly after opening the plug of
each compressor and Dryer filter , it is necessary to strictly take care for the time control.)
(2) The tools applicable for the refrigerator are designated (HFC-134a special).
Some tools for the dehumidifier are commonly applicable for the refrigerator (refrigerant bomb and charging
cylinder for HFC-134a and vacuum pump for R-12) and the other tools which are designated [HFC-134a
special for dehumidifier] are special for the dehumidifier. (Here, add the check valve of special tools for
dehumidifier when using the vacuum pump for R-12.) Take care to clearly discriminate the tools during use.
Moreover, it is necessary to surely wash and clean new parts.
Among non-ester oil for the dehumidifier and ester oil for the refrigerator, the solubility of the ester oil for the
existing oil (compressor oil for CFC-12, and rust-preventive oil used on the coupler and pressure gauge) is
extremely as low as 10 ppm to 20 ppm. Therefore, if any slight amount of the existing oil is mixed into the
cycle, it will deposit at the outlet of the capillary tube to become a cause of clogging.
Accordingly, it is inhibited to use any other tool (some existing oil may mix into the refrigeration cycle) which
is not applicable for the dehumidifier or refrigerator and it is necessary to surely wash and clean new tools
even if they are applicable as HFC-134a.
(3) It is necessary to prevent mixing non-ester oil for dehumidifier with ester oil for refrigerator.
Since it may be easily influenced by the stability (moisture or other mixed material) of ester oil itself,
generation of sludge will be promoted as described above, thus resulting in clogged capillary tube.
Take care never to recharge HFC-134a refrigerant to the unit which has been charged with CFC-12 in
the refrigeration cycle or with other refrigerator oil.
(4) Inhibition of use of flux during welding
Though steel pipe and copper pipe are
not welded as basic, it is inhibited to use
flux since it may enter the cycle if flux
dissolved into the water is used.
3) Replacing air with nitrogen when brazing
(1) Oxide scale in the piping which is formed
in brazing process may cause clogging
of capillary tube.
Therefore the air in the piping must be
replaced with nitrogen when brazing is
performed.
4) Vacuum (improvement of accuracy of vacuum)
(1) Follow the specified evacuation and gas charging procedure.
The vacuum to be attained must be 0.5 Torr or below.
Comparison of lubricant for HFC-134a
Refrigerant 1 CFC-12
Lubricant Mineral oil
Wear resistance
Sludge generation
(a little)
Electric insulation
Compatibility
(solubility into
refrigerant)
25
DW-71-H
HFC-134a
Ester type Non-ester type
(Low-viscosity
alkylbenzene oil)
(much) (a little)
(For refrigerator)
(For dehumidifier)