Installation And Serving Air Conditioner Using R410A - Panasonic CS-PW9GKX Service Manual

10

Installation and Serving Air Conditioner Using R410A

10.1. OUTLINE
10.1.1 About R410A Refrigerant
1. Converting air conditioners to R410A
Since it was declared in1974 that chlorofluorocarbons (CFC), hydro chlorofluorocarbons (HCFC) and other substances pose
a destructive danger to the ozone layer in the earth´s upper stratosphere (20 to 40 km above the earth), measures have been
taken 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 Ozone-Damaging Substances) and the domestic laws of
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 called R410A. Compared with R22, the
pressure of R410A 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), R410A is an HFC
refrigerant. Another typical HFC refrigerant is R407C. While the energy efficiency of R407C is some what inferior
to that of R410A, it offers the advantage of 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) refrigerants
a. Chemical characteristics
The c hemical charact erist ics o f R4 10A are similar t o those of R22 in that both are che mically stable, non-
flamm abl e ref rigerant s wit h low toxicity.
Howe ver, just like R22 , the specifi c gra vity of R410A gas is heavier t han that of air. Becau se o f thi s, it can caus e
an oxygen deficiency if it l eaks into a closed room since 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 well ventila ted envi ronm ent whe re i t will
not collec t.
Composition (wt%)
Boiling point (°C)
Vapori zing p ressur e (25° C)
Satura ted va por de nsity
Flamm ability
Ozone -destr oying point ( ODP)
Globa l-warm ing po int (GWP)
b. Comp osi tional change (pseudo-azeotropic charact eristics)
R41 0A is a pseu do-azeo trop ic m ixture comprising the two com ponents R32 and R1 25. Mult i-compo nen t
refr iger ants with the se c hem ical cha racterist ics e xhibit lit tle c omp ositi ona l change even fro m phase cha nge s
due to v apo riza tion 9or cond ens ation), w hich mea ns t hat there is l ittle chan ge in the cir cula ting refri gera nt
com pos ition eve n w hen the refrigera nt le aks from the gaseous sec tion of th e piping .
Acc ordi ngly, R4 10A can be handled i n almost the sam e manne r as the sing le-c omp one nt re frigeran t R2 2.
How eve r, w hen charging, be cau se there is a slight change in c omp osit ion betw een the gas pha se a nd th e liquid
pha se i nsid e a c ylin der or ot her containe r, ch argi ng s houl d basically begin with the liqu id si de.
c. Press ure characterist ics
As seen in Table 2, t he gas pressure of R410A is a pproxim atel y 1.6 tim es a s high as tha t of R22 at the same
refr iger ant t emp erat ure, whi ch m ean s that special R410A tool s and ma teri als w ith h igh-pressur e sp ecifi cati ons
mu st be use d fo r all refri gera nt p iping wo rk and servicing.
Refrigerant Temperature( )
-20
0
20
40
60
65
Table 1 Physi cal comp arison o f R4 10A and R22
R32/R125(50/50)
1.56 Mpa(15.9 kgf/cm2)
Non-flammable
Table 2 Comparison of R410A and R22 saturated vapor density
°C
R410A
-51.4
64.0 kg/m3
0
1730
R410A
0.30
0.70
1.35
2.30
3.73
4.15
39
CS-UW9GKE / CU-UW9GKE / CS-UW12GKE / CU-UW12GKE
R22
R22(100)
-40.8
0.94 Mpa(9.6 kgf/cm2)
44.4 kg/m3
Non-flammable
0.005
1700
R22
0.14
0.40
0.81
1.42
2.33
2.60