Panasonic CS-F50DTE5 Service Manual

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11 Installation and Servicing Air Conditioner Using R410A11.1. Outline11.1.1. About R410A refrigerant1. Converting air conditioners to R410ASince it was declared in1974 that chlorofluorocarbons (CFC), hydro chlorofluorocarbons (HCFC) and other substances pose adestructive danger to the ozone layer in the earth’s upper stratosphere (20 to 40 km above the earth), measures have beentaken around the world to prevent this destruction.The R22 refrigerant which has conventionally been used in ACs is an HCFC refrigerant and, therefore, possesses this ozone-destroying potential. International regulations (the Montreal Protocol on Ozone-Damaging Substances) and the domestic lawsof various countries call for the early substitution of R22 by a refrigerant which will not harm the ozone layer.•••• In ACs, the HFC refrigerant which has become the mainstream alternative is called R410A. Compared with R22, thepressure of R410A is approximately 1.6 times as high at the same refrigerant temperature, but the energy efficiency is aboutthe same. Consisting of hydrogen (H), fluorine (F) and carbon (C), R410A is an HFC refrigerant. Another typical HFCrefrigerant is R407C. While the energy efficiency of R407C is somewhat inferior to that of R410A, it offers the advantageof having pressure characteristics which are about the same as those of R22, and is used mainly in packaged ACs.2. The characteristics of HFC (R410A) refrigerantsa. Chemical characteristicsThe chemical characteristics of R410A are similar to those of R22 in that both are chemically stable, non-flammablerefrigerants with low toxicity.However, just like R22, the specific gravity of R410A gas is heavier than that of air. Because of this, it can cause an oxygendeficiency if it leaks into a closed room since it collects in the lower area of the room. It also generates toxic gas when it isdirectly exposed to a flame, so it must be used in a well ventilated environment where it will not collect.Table 1 Physical comparison of R410A and R22R410A R22Composition (wt%) R32/R125 (50/50) R22 (100)Boiling point (°C) -51.4 -40.8Vaporizing pressure (25°C) 1.56 Mpa (15.9 kgf/cm 2 ) 0.94 Mpa (9.6 kgf/cm 2 )Saturated vapor density 64.0 kg/m 3 44.4 kg/m 3Flammability Non-flammable Non-flammableOzone-destroying point (ODP) 0 0.055Global-warming point (GWP) 1730 1700b. Compositional change (pseudo-azeotropic characteristics)R410A is a pseudo-azeotropic mixture comprising the two components R32 and R125. Multi-component refrigerants withthese chemical characteristics exhibit little compositional change even from phase changes due to vaporization (orcondensation), which means that there is little change in the circulating refrigerant composition even when the refrigerantleaks from the gaseous section of the piping.Accordingly, R410A can be handled in almost the same manner as the single-component refrigerant R22. However, whencharging, because there is a slight change in composition between the gas phase and the liquid phase inside a cylinder orother container, charging should basically begin with the liquid side.c. Pressure characteristicsAs seen in Table 2, the gas pressure of R410A is approximately 1.6 times as high as that of R22 at the same refrigeranttemperature, which means that special R410A tools and materials with high-pressure specifications must be used for allrefrigerant piping work and servicing.Table 2 Comparison of R410A and R22 saturated vapor densityUnit: MPaRefrigerant Temperature (°C) R410A R22-20 0.30 0.140 0.70 0.4020 1.35 0.8140 2.32 1.4360 3.73 2.3365 4.15 2.6070CS-F50DTE5 CU-L50DBE8