Pureness for HVAC Trading and Contracting : 2016

R410A THE REFRIGERANT OF THE FUTURE
Why Change?
In compliance with the requirements written in the Montreal Protocol the
developed world has been preparing to move away from HCFC Refrigerants,
the most commonly used being R22.
When reviewing the alternatives to R22 two different approaches were taken.
The first was to develop a substitute product with similar characteristics to
R22. R407c has been accepted worldwide as this replacement with overall
attributes best resembling R22. The second approach was to develop a
substitute refrigerant, which would give the best performance when applied to
the redesigned equipment, which traditionally uses R22. R410A is this
substitute with better thermodynamic performance.
Why 410A?
R410A has a higher volumetric cooling capacity compared to R22 and has
better thermal exchange properties. This results in overall performance gains
in terms of system efficiency. The greater density of the vapour in R410A
permits higher system velocities, reduces pressure drop losses and allows
smaller diameter tubing to be used. In laymen’s terms a smaller unit can be
developed using a smaller displacement compressor, less coil and less
refrigerant while maintaining system efficiencies comparable to current day
R22 equipment. Therefore OEM’s have a low cost solution to meet specific
equipment requirements.
According to some major compressor manufacturers, R410A units can reach
the industry’s highest efficiency levels and, coupled with R410A’s low global
warming rating, result in an overall improved environmental choice for
residential air conditioning applications.
R410A Properties
R410A is a blended refrigerant using HFC 32 and HFC 125 in an equal mix. It
is a near azeotropic blend with a negligible glide (0.1%). As a HFC
refrigerant, R410A requires the use of polyoester oils (POE). R410A is
classified A1/A1 by ASHRAE Standard 34 meaning it is non flammable and
non toxic. But the biggest difference to R22 is the pressure levels generated
which are more than 50% higher. Although operating pressures of R410A are
significantly higher than those of R22, the R410A system actually runs slightly
cooler than a comparable R22 system due to the higher vapour heat capacity
of the refrigerant.
Properties R22 vs. R410A
Properties Units R22 R410A
Components - CHCIF2
HFC-32
HFC-125
Composition % weight - 50/50
Molecular Weight g/mol 86.5 72.6
Bubble Temperature (at 1.013 bar) °C -40.7 -52.2
Temperature Glide (at 1.013 bar) K 0 0.1
Liquid Density (at 25°c) Kg/dm³ 1.194 1.0615
Density of Saturated Vapour
(at boiling point)
Kg/m³ 4.70 4.12
Vapour Pressure at:
.25°c
.50°c
bar*
bar*
10.4
19.4
16.4
30.5
Critical Temperature °C 96 72.2
Critical Pressure bar* 49.8 49.5
Critical Density Kg/dm³ 0.525 0.491
Latent Heat of Vaporisation
(at 1.013 bar)
KJ/kg 233.7 271.5
Specific Heat at 25c
Liquid
Vapour (at 1.013 bar)
KJ/(kg.K)
KJ/(kg.K)
1.26
0.66
1.855
0.819
Ratio of Specific Heat Cp/Cv
(at 25°c and 1.013 bar)
- 1.185 1.172
Flammability Limits in Air - None None
ODP - 0.055 0
Table 1. Comparison of R22 and R410A properties.
Graph 1. Pressure Comparison: R12 vs. R22 vs. R410A
Higher Pressures Mean What?
The system pressures of R410A make is necessary for all equipment to be
specifically made to work at these levels. R410A was never designed for
retrofitting existing R22 systems. Newly designed R410A equipment
generally employ thicker walled tubing, newly developed compressors, and
use componentry capable of withstanding these high pressures.
Oils Ain’t Oils
R410A is a blend of HFC refrigerants. The great majority of systems using
HFC refrigerants contain polyoester oils (POE). POE oils are required
because other oils, like mineral oil, are not miscible with HFC refrigerants.
Miscibility is a measure of the ability of a liquid refrigerant to mix with the oil.
When replacing oil in any system always check the manufacturers
recommendations. Care should be taken to avoid exposure of the POE oil to
air as it readily absorbs moisture (often referred to as being highly
hydroscopic). Preference is always to use a fresh unopened tin of oil and
perform the task with minimum exposure to air.
Controlling Moisture
The use of hydroscopic POE oils increases the chances of introducing water
to the refrigeration system. POE oils hydrolyse to form acids at 75ppm. It is
therefore essential that a good drier developed for use with HFC refrigerants
and POE oils is used. Moisture indicators should therefore also have a
sensitivity level below 75ppm when used.
0
5
10
15
20
25
30
Pressure (Bar)
R-12 R-22 R410A
Evap. P. is the saturated pressure @ 7oC,
Cond. P. is the saturation pressure @ 45oC
Evap. P. Cond. P.
What About Glide
Glide is best described as follows: During the boiling process for a refrigerant,
the temperature at which a liquid refrigerant begins to boil is the saturated
liquid temperature (bubble point). The temperature at which the last drop of
liquid has boiled is the saturated vapour temperature (dew point). During the
condensing process the dew point is the temperature when the vapour first
starts to condense, the bubble point when all has condensed. At constant
pressure the difference between the dew point and bubble point is referred to
as temperature glide. Single component refrigerants like R22 have no glide
but blended refrigerants generally have some measurable glide. Put in simple
terms, in a blended refrigerant one component begins to boil before the other.
The glide for R410A is around 0.1°C which is very small. For field service
purposes this glide can be neglected and the refrigerant treated as you would
a single component refrigerant. In line with good practice, it is suggested you
still liquid charge systems, as you should for any blended refrigerant.
R410A Applications
R410A is ideal for residential and light commercial unitary air conditioning
systems. Most world renown manufacturers (see table 2) are now producing
or have planned production of air conditioning units using R410A as suitable
componentry is now widely available.
Some of the Many Manufacturers Using R410A
􀁹 Airewell 􀁹 Hyundai 􀁹 Sharp
􀁹 Carrier 􀁹 LG 􀁹 Tatung
􀁹 Corona 􀁹 Matsushita 􀁹 Toshiba
􀁹 Daewoo 􀁹 McQuay 􀁹 Toyotomi
􀁹 Daikin 􀁹 Mitsubishi 􀁹 Trane
􀁹 Frigidaire 􀁹 Panasonic 􀁹 York
􀁹 Fujitsu 􀁹 Samsung
􀁹 Hitachi 􀁹 Sanyo
Table 2.
What’s in a Name?
Typical of many refrigerants, a number of brand names exist for R410A.
These include AZ20, Puron and Suva® 9100. Using the ASHRAE name (e.g.
R410A) assigned to any refrigerant will always ensure you are using the same
refrigerant regardless of the brand name.
Price of R410A
Current costs for the manufacture of R410A are significantly higher than R22
due to higher raw material costs, lower production yields and smaller volume
demand. As a result today’s R410A price is significantly higher than R22.
R22 price is expected to rise in future years when usage volumes decrease
as a result of compliance with the phase out of HCFC’s. Conversely R410A
pricing may change as demand continues to increase.
What Happens when the System Leaks?
System leaks have always raised concern when the refrigerant used is a
blend as the composition of the remaining refrigerant may have altered due to
the difference in the volatility of the components in the blend (glide). As
stated earlier the glide of R410A is only around 0.1°C and results in no
meaningful change in composition during a leak or when charging a system
Servicing a R410A System
In general R410A is handled the same as R22. You will require some specific
tools that are rated for the higher pressures. These include gauges and
manifolds, reclaimers, and correct rated gas bottles with appropriate valves.
As well as this it is recommended that flaring and swaging tools with an
eccentric action be used as they provide a smoother flare surface.
Replacement parts must also be chosen bearing in mind that the system
works under higher pressure. Items like driers, valves and even copper tube
must be approved for use with R410A (refer to table 3).
R410A Copper Tube Wall Thickness Recommendations
Copper Size
(Inches)
Recommended
Wall Thickness
(mm)
Safe Working Pressure
75°C to 125°C
(kPa)
1/4 0.91 9787
3/8 0.91 6221
1/2 0.91 4556
5/8 1.02 4059
3/4 1.22 4045
Table 3. Based on AS1677.2-1998 “Refrigerating Systems”, page 20.
Leak Detection
Any electronic detector capable of detecting HFC refrigerants can be used.
Halide torches are not capable. Soap solutions will detect larger leaks. UV
sensitive dyes can also be used effectively.
Safety and Handling
As said above, R410A generally is handled the same as R22. Always
minimise personal exposure to refrigerant gas. All refrigerants are heavier
than air and will displace oxygen which can lead to asphyxiation.
Mixtures of refrigerants and air can become combustible under pressure.
Never use mixtures of refrigerant to leak test. Always use dry nitrogen or
other inert gas instead of air. Never braze on a system containing refrigerant.
All refrigerant cylinders can become over pressurised in high temperature
conditions. Never allow refrigerant cylinders to exceed 60°C. Never store
cylinders unprotected in direct sunlight. Always use cylinders with the correct
pressure rating and frequently check the condition of the cylinder you are
using. Minimum rating for R410A cylinders is 5.8MPa. Never over-fill the
cylinder with refrigerant.
Only use R410A in equipment specifically designed and constructed for
R410A. Do not retrofit R22 units with R410A.
Ensure that correct replacement parts are used when servicing an R410A
system and always use equipment and tools designed for R410A service
work.
For further safety information obtain a Material Safety Data Sheet available
wherever the refrigerant is sold.
In Summary
R410A is a HFC refrigerant for use in specifically designed air conditioning
systems. It is not designed to retrofit existing R22 systems. Although running
at much higher pressures R410A is a far more economical refrigerant allowing
equipment manufacturers to design smaller yet highly efficient air conditioning
systems. R410A is proven to be safe and reliable providing the correct tools
and equipment are used.
R22 R410A R22 R410A
°C kPa psig kPa psig °C kPa psig kPa psig
-30 63 9.1 173 25 16 716 104 1186 172
-28 80 12 196 28 18 769 112 1260 183
-26 91 13 220 32 20 814 118 1338 194
-24 108 16 245 35 22 866 126 1419 206
-22 126 18 272 39 24 917 133 1504 218
-20 145 21 301 44 26 975 141 1592 231
-18 165 24 331 48 28 1040 151 1684 244
-16 185 27 364 53 30 1107 161 1779 258
-14 207 30 398 58 32 1165 169 1878 272
-12 231 33 434 63 34 1230 178 1981 287
-10 254 37 472 68 36 1300 189 2088 303
-8 284 41 512 74 38 1378 200 2199 319
-6 310 45 554 80 40 1448 210 2315 336
-4 334 48 599 87 42 1525 221 2434 353
-2 361 52 646 94 44 1610 233 2558 371
0 398 58 695 101 46 1688 245 2686 389
2 430 62 747 108 48 1770 257 2819 409
4 465 67 801 116 50 1855 269 2956 429
6 504 73 858 124 52 1950 283 3099 449
8 542 79 918 133 54 2050 297 3245 470
10 584 85 980 142 56 2140 310 3397 492
12 622 90 1046 152 58 2245 326 3554 515
14 668 97 1114 161 60 2345 340 3716 539
Note: R410A pressures shown at Saturated Vapour Temperature (dew point).
Table 4. Temperature – Pressure Data for R22 and R410A.
For further information contact your local Actrol Parts Branch.
Andrew Leach. B.Sc, Post Grad. Dip. Chem. Eng.
National Sales and Marketing Manager
Actrol Parts