10 Installation and Serving Air C ondition er Using R410A
10.1. OUTLINE
10.1.1 About R410A Refrigerant
1. Converting air conditioners to R 410A
Since it was declared in19 74 that chlorofluorocarbons (CFC), hydro chlorofluorocarbons (HCFC) and other substances pose
a d estructive danger to the ozone layer in the earth´s upper stratosphere (20 to 40 km above the earth), measure s have been
t aken around the world to prevent this destruction.
The R22 refrigerant which has conventionally been used in ACs is an HCFC refrigera nt and, therefore, possesses this ozone
destroying potential. International regulations (the Montreal Protocol Ozone-Damaging Substances) and the domestic laws of
var ious 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 a lternative called R410A.Compared with R 22, the
pressure of R 410 A is approximately 1.6 times as high at the same refrigerant temperature, but the energy
efficiency is about the same. Consisting of hydrogen (H), fluorine (F) and carbon (C), R4 10A is an HFC
re f ri g er an t. An o ther ty p ic a l H F C ref ri ge r an t i s R40 7 C. W hi le th e ener gy effi c ie n cy of R 40 7C i s s o me wh a t in fe ri or
to that of R410A, it offers the advantage of having pressure characteristics w hich are ab out the same as those of
R22, and is used main ly in packaged Acs.
2. The chara cte ristics of HFC (R4 10A) refrigerants
a. Chemical characteristics
The c hemical charact erist ics o f R410A are similar t o tho se of R2 2 in that both are che mically stable, n on-
fl amm abl e r ef rig e rant s w it h lo w to xic ity.
Howe ver, just like R22 , the specific gra vity of R410 A gas is heavier than that of air. Because o f thi s, it can caus e
an oxyge n deficiency if it l eaks into a closed room s ince it collects in the lowe r area of the room. It also gen erates
toxic gas when it i sdire ctly exposed to a flame, so it must be used in a we ll ventila ted envi ronm ent whe re i t will
not collect.
Table 1 Physical comparison of R410A and R22
Composition ( wt%)
Boiling point (°C)
Vapori zing p r essure (25°C)
Satura ted va por de nsit y
Flamm ability
Ozone -destr oying point (ODP)
Globa l-warm ing po i nt (GWP)
R410A
R32/R125(50/50)
-51.4
1.56 Mpa(15.9 kgf/ cm2)
64.0 kg/m3
Non-flammable
0
1730
R22
R22(100)
-40.8
0.94 Mpa(9.6 kgf/cm2)
44.4 kg/m3
Non-flammable
0.005
1700
b. C omp ositiona l change (pseud o-azeotropic charact eristics)
R410A is a pseu do-azeo trop ic m ixtur e comprising the two com ponents R32 and R1 25. Multi-co mpo nen t
refrigerants wit h these chemi cal charact e ris ti cs exhibi t li ttl e comp osi tiona l chang e even f rom phase changes
due to vaporization 9or c ondensation), whic h me ans tha t the r e is l i ttl e ch ange i n t h e circulating refrigerant
compositi on even when the ref ri g erant leaks from the ga s eou s se ctio n of the p i pi ng.
Acc ordi ngly, R4 10A can be h and l ed i n a lmo st the same m anner as the single-c ompone nt refrige ran t R22.
Howeve r, w hen char ging, be cau se th ere is a slight change in c omp osit ion between the gas pha se a nd th e liq uid
phase inside a cyl inder or other c ont ai ner, charg i n g should b a sic al ly b e gin wi th the liquid side.
c. P ressure characterist ics
As seen in Tabl e 2, the gas pr essur e of R 4 10A is approximat ely 1.6 t imes as hi g h a s t hat of R22 at t h e s a me
refr iger ant t emp erature, which m ean s that sp ecial R410A tool s and ma terials w ith h igh -pre ssur e sp ecifi cations
must be used f or a ll refr iger ant piping work a n d s e rvi ci ng.
Table 2 Comparison of R 410 A and R22 s aturated vapor density
R410A
0.30
0.70
1.35
2.30
3.73
4.15
R22
0.14
0.40
0.81
1.42
2.33
2.60
Refrigerant Temperature( )
-20
0
20
40
60
65
°C
39
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