R 410A REFRIGERANT

User Manual: REFRIGERANT R-410A

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Refrigeration Service
Engineers Society
1666 Rand Road
Des Plaines, Illinois 60016

REFRIGERANT 410A
Information compiled by Frank Prah, CMS

INTRODUCTION

guidelines that R-12 and R-22 did not have to pass)
is becoming more popular, both because it is an HFC
(hydrofluorocarbon), and because its greater efficiency allows for the design and use of smaller air
conditioning equipment.

Recently a new refrigerant, R-410A, has been formulated and currently is being used in the HVAC/R
industry. It was developed primarily because the production of R-22 is scheduled to stop soon. The
phaseout schedule for R-22, as mandated by the
Environmental Protection Agency (EPA), will be discussed in more detail at the end of this article.
Although R-410A is specifically intended for use in
new air conditioning applications that traditionally
would have used R-22, other applications are also
possible, including low- and medium-temperature
refrigeration systems.

R-410A is an azeotropic mixture of HFC-32 and
HFC-125. It has been developed as a long-term
replacement for R-22 in a variety of new air conditioning and cooling equipment. R-22 is an HCFC, or
hydrochlorofluorocarbon, which means that it contains chlorine, an element that is damaging to the
ozone layer. Because R-410A contains no chlorine
at all, its ozone depletion potential (ODP) is zero.
R-410A comes in rose-colored cylinders. The “rose”
color is PMS (Pantone Matching System) 507.

At first glance, the most notable difference between
R-410A and R-22 is the higher operating pressures
(approximately 50% higher on both the discharge side
and the suction side). For example, a high-efficiency
condensing unit using R-22 typically operates with a
suction pressure of about 68 psi and a discharge
pressure of about 250 psi at an outdoor temperature
of 95°F. With R-410A, the same unit will operate
under the same conditions with a suction pressure of
118 psi and a discharge pressure of 400 psi, as
shown in Figure 1 on the next page. (Note that in
most cases, equipment designed for R-22 cannot
use R-410A because of this difference in operating
pressures, so retrofitting an existing R-22 system is
normally not an option.)

R-410A is expected to find widespread use in coming
years. Its benefits include significantly higher cooling
capacities and pressures. At 77°F, its density is 50%
greater than that of R-22, and its vapor pressure is
58% greater. Other advantages include a low toxicity
level, and recognition by Underwriters’ Laboratory
(UL) that it is virtually nonflammable (although it may
be combustible at elevated pressures, as discussed
later).
As with any refrigerant, there are certain safety precautions that the technician needs to understand and
observe. This article describes typical applications,
recycling/recovery procedures and equipment, and
precautions applicable to this new refrigerant product.

When R-22 was first introduced as a replacement for
R-12 in residential air conditioning applications, manufacturers and service technicians had to familiarize
themselves with the characteristics of this “new”
refrigerant. (R-22 operated at higher pressures and
was more efficient than R-12, but did not return oil as
well.) In time, R-22 became widely used and now has
served the HVAC/R industry well for over 50 years.
Today R-410A (which has had to pass strict safety
© 2001 by the Refrigeration Service Engineers Society, Des Plaines, IL
Supplement to the Refrigeration Service Engineers Society.

TYPICAL APPLICATIONS
Major applications for R-410A include unitary air
conditioning equipment, chillers, and commercial
refrigeration systems. In new unitary residential and
light commercial systems, R-410A has demonstrated
a 5 to 6% higher energy efficiency rating (EER) than

1

620-108
Section 3 l

R-22. Its higher cooling capacity permits smaller,
more compact units to be used.

RECOVERY OF R-410A
The capability and compatibility of recovery and
reclamation equipment are equally important considerations for the service technician. Despite R-410A’s
negligible impact on the ozone, reclamation and
recycling are mandatory, and disposal must be conducted in accordance with national, state or provincial, and local regulations.

Because of the significantly higher pressures associated with R-410A, a typical compressor designed for
R-22 cannot be used with R-410A. As noted previously, this fact—along with other components in the
system that would need to be changed—renders the
refrigerant inappropriate for retrofit of existing R-22
systems.

First and foremost, R-410A’s higher vapor pressures
mean that careful attention must be paid to the
design pressure rating of handling and storage
equipment, including recovery and storage cylinders.
For R-410A, a working pressure capability of at least
400 psi is recommended (this includes recovery
cylinders). Standard DOT recovery cylinders rated for
350 psi should not be used. Use only DOT recovery
cylinders rated for 400 psi or higher when recovering
R-410A.

Another important issue is the compatibility of the
compressor lubricant with the azeotropic R-410A
mixture. To ensure satisfactory operation and durability, a polyolester-based lubricant that is miscible with
the refrigerant is recommended. Compressor manufacturers are continuing to test and recommend specific lubricants for use with R-410A. It is therefore
important to contact the compressor and/or equipment manufacturer to review system lubricant
requirements. It is also important to review materials
with which the refrigerant will come in contact, including motor windings in hermetic and semi-hermetic
compressors, gaskets, etc., for compatibility.

Compatibility of the recovery equipment with the
components that make up R-410A also is vital. In
addition to the guidelines provided by the manufacturer of the refrigerant, make sure you consult the
compatibility data supplied by the recovery equipment manufacturer.

R-410A and R-22 are chemically compatible—which
means that they will not react or form other compounds if accidentally mixed—but they will form a
mixture that can be difficult to separate. At this time,
separation cannot be accomplished by any known
on-site recovery device or in the facilities of most offsite reclaimers. Disposal of the mixture by incineration
is recommended.

Extra precautions are required during storage and
handling. An important handling practice is the use of
liquid charging (rather than vapor charging) to minimize compositional changes. Refrigerants in the -400
and -500 ASHRAE classification series should be

R-22

68 psi

R-410A

250 psi

118 psi

Figure 1. Typical operating pressures

2

400 psi

charged (put into the system) in a liquid state. Not all
manufacturers equip their cylinders with dip tubes.
Without a dip tube, the cylinder must be in the
inverted position (turned upside down) for liquid
charging. If you are charging on the high side, refrigerant can enter the system as a liquid, since there is
no danger of the refrigerant reaching the compressor
in liquid form and causing “slugging” damage. If you
are charging on the low side, meter the refrigerant as
it enters the system to vaporize before it reaches the
compressor.

Increasing toxicity

Increasing flammability

Low toxicity
(TLV ≥ 400 ppm)

In order to prevent the damage to equipment that can
be caused by charging with contaminated refrigerant,
cross contamination (the mixing of R-410A with other
refrigerants) should be avoided during recovery and
recycling. Recovery equipment includes not only the
recovery/recycling machine itself, but also all equipment that comes into contact with the refrigerant during recovery and reclamation. This may include
hoses, storage cylinders, vacuum pumps, manifold
gauges, and scales.

High toxicity
(TLV ≤ 399 ppm)

High
flame

A3

B3

Mild
flame

A2

B2

No
flame

A1

B1

Figure 2. Safety matrix

Scales are sometimes used during recovery to prevent tank overfilling. If the scale is equipped with an
automatic solenoid shutoff, it must be purged prior to
each use.
SAFETY PRECAUTIONS

To eliminate the possibility of cross contamination,
the technician should use recovery/recycling devices
with self-purging or evacuation features. Such equipment contains special valves that work with internal
compressors to remove refrigerant by creating a partial vacuum in the tanks and hoses, thus allowing for
the complete removal and diversion of materials into
the recovery cylinder. Hoses, cylinders, and manifold
gauges should either be dedicated to R-410A or
evacuated after each recovery job. All equipment
should be clearly marked to indicate the formulation
for which it can be used, and all new cylinders should
be evacuated prior to the first use.

ASHRAE has designated R-410A as A1/A1 on the
safety matrix shown in Figure 2. As you can see, the
“A1” rating denotes the safest refrigerants to handle.
In addition to the procedures discussed above
regarding the proper use of equipment and the
importance of avoiding cross contamination, there
are a few other safety precautions that the service
technician should note.
An R-410A system may be operating at over 600 psi
and not have the high-pressure safety switch open.
Carrier has a unit with the high-pressure switch set
at 610 psi. It resets at about 420 psi. The same
model has a loss-of-charge liquid-line switch that
opens at about 20 psi and resets at about 45 psi.
Low-pressure switches are also found on the suction
side. Low-pressure switches on Carrier equipment
using R-410A are usually set to open at about 50 psi
and close at about 100 psi.

Proper maintenance of vacuum pumps, used to
remove non-condensable gases and moisture from a
system, is equally important. New (clean) oil specifically formulated for vacuum pumps should be used at
the start of each procedure. The oil should be
changed at intervals as recommended by the manufacturer, or more frequently if it takes on a milky or
cloudy appearance. An isolation valve is an absolute
necessity for checking system integrity. In addition,
worn O-rings and hoses should be replaced to
ensure minimal manifold leakage during evacuation.
Vacuum pumps should be capable of pulling a vacuum
of 300 to 500 microns.

Note: Heat pumps operating in the heating mode
also may have a vapor switch that cycles the outdoor
fan when the pressure is about 400 psi, and resets
when the pressure drops to about 310 psi.

3

Because it is heavier than air, R-410A vapors can
accumulate at ground level. If a large release of vapor
occurs, the vapor may displace the oxygen available
for breathing, resulting in suffocation. Although
smaller leaks pose no acute health hazards, exposure to levels of more than 1,000 parts per million
(the same limit as R-22) can be harmful. Symptoms
of exposure to dangerous levels of R-410A include
dizziness, headache, confusion, cardiac irregularities, and loss of consciousness in extreme cases. If a
leak is present or suspected, a suitable leak detector
should be used to determine the need for ventilation
or respiratory protection.

As stated previously, the energy efficiency of R-410A
is allowing the design of smaller, more efficient air
conditioning equipment. By following the procedures
and noting the precautions provided in this article,
the technician can readily service systems using this
increasingly popular refrigerant.
R-22 PHASEOUT
The schedule for the phaseout of R-22 has been previously published, but may be accelerated at some
point. Currently the schedule is:

R-410A expands significantly when heated. Exposure of a container to direct sunlight or other heat
source can cause it to burst, resulting in serious
injury. Allied Signal recommends that its cylinders not
be allowed to exceed 125°F (52°C). Care also should
be taken to avoid damage to containers that could
cause them to leak or rupture. Storage near corrosive
chemicals or fumes or on damp floors should be
avoided.

using personal protective equipment (e.g., side
shield glasses and safety shoes) when handling
containers
avoiding skin contact, which may cause frostbite

ª

protecting containers from damage, and hoses
from cuts or abrasions

ª

2020: End of production of R-22 (after 2020, the
use of reclaimed and stockpiled R-22 may be
permitted).

The following is a quick review of some of the most
important points to remember when you are working
with R-410A:

Other commonsense precautions for storing and
handling R-410A include:

ª

2010: New equipment designed for use with R-22
will no longer be manufactured.

SUMMARY

Although R-410A is not flammable, it may become
combustible at elevated pressures in the presence of
large quantities of air. Containers and recovery/recycling equipment should not be exposed to welding,
brazing, open flames, or high temperatures until thoroughly purged of all traces of liquid and vapor.
Recovery and recycling systems with self-purging
capabilities are invaluable for this purpose.

ª

ª

ª

Never vent R-410A (or any other refrigerant) to
the atmosphere.

ª

R-410A is to be used with “new equipment
design” only (that is, it is not to be used in retrofits). If the cost of R-22 rises, R-407 may be used
in some cases to retrofit R-22 systems.

ª

Use good piping practices when installing units
with R-410A. (Piping practices are similar to
those recommended for R-22 systems.)

ª

R-410A operates at pressures 50 to 70% higher
than those of R-22. Be certain that servicing
equipment and replacement components are
designed to operate with this refrigerant.

ª

R-410A cylinders are rose-colored (PMS 507).

ª

storing containers under a roof to protect them
from weather extremes

ª

Recovery cylinders must be rated at 400 psi or
higher (DOT 4BA400 or BW 400).

ª

never attempting to repair or alter containers or
valves.

ª

Charge systems with liquid refrigerant to avoid
fractionation.

4

ª

Manifold sets should be at 750 psi (high side)
and 200 psi (low side), with a 500-psi low-side
retard.

ª

Use hoses with a 750-psi service pressure rating.

ª

Leak detectors should be of the HFC type.

ª

R-410A is compatible with POE oils. POE oils
absorb moisture rapidly. Do not expose the oil to
the atmosphere. Keep all components sealed
until the time of installation/brazing.

ª

A liquid-line filter-drier is required on all units, or
per the manufacturer’s directions. Do not use
liquid-line filter-driers with working pressures
rated at less than 600 psi.

ª

Do not use an R-22 TXV valve.

ª

Braze joints (do not use soft/low-temperature
solder).

Note: A pressure-temperature chart for R-410A is
included on page 6.

Technical sources:
DuPont Suva Technical Information Bulletin H-65905-2
Carrier Installation and Start-Up Instructions for the 38YXA Heat Pump (023-813)

5

°F

psig

°F

psig

°F

psig

°F

psig

°F

psig

°F

12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
82
84
86
88
90
92
94
96
98
100
102
104
106
108
110
112

–37.7
–34.7
–32.0
–29.4
–36.9
–24.5
–22.2
–20.0
–17.9
–15.8
–13.8
–11.9
–10.1
–8.3
–6.5
–4.5
–3.2
–1.6
0.0
1.5
3.0
4.5
5.9
7.3
8.6
10.0
11.3
12.6
13.8
15.1
16.3
17.5
18.7
19.8
21.0
22.1
23.2
24.3
25.4
26.4
27.4
28.5
29.5
30.5
31.2
32.2
33.2
34.1
35.1
35.5
36.9

114
116
118
120
122
124
126
128
130
132
134
136
138
140
142
144
146
148
150
152
154
156
158
160
162
164
166
168
170
172
174
176
178
180
182
184
186
188
190
192
194
196
198
200
202
204
206
208
210
212
214

37.8
38.7
39.5
40.5
41.3
42.2
43.0
43.8
44.7
45.5
46.3
47.1
47.9
48.7
49.5
50.3
51.1
51.8
52.5
53.3
54.0
54.8
55.5
56.2
57.0
57.7
58.4
59.0
59.8
60.5
61.1
61.8
62.5
63.1
63.8
64.5
65.1
65.8
66.4
67.0
67.7
68.3
68.9
69.5
70.1
70.7
71.4
72.0
72.6
73.2
73.8

216
218
220
222
224
226
228
230
232
234
236
238
240
242
244
246
248
250
252
254
256
258
260
262
264
266
268
270
272
274
276
278
280
282
284
286
288
290
292
294
296
298
300
302
304
306
308
310
312
314
316

74.3
74.9
75.5
76.1
76.7
77.2
77.8
78.4
78.9
79.5
80.0
80.6
81.1
81.6
82.2
82.7
83.3
83.8
84.3
84.8
85.4
85.9
86.4
86.9
87.4
87.9
88.4
88.9
89.4
89.9
90.4
90.9
91.4
91.9
92.4
92.8
93.3
93.8
94.3
94.8
95.2
95.7
96.2
96.6
97.1
97.5
98.0
98.4
98.9
99.3
99.7

318
320
322
324
326
328
330
332
334
336
338
340
342
344
346
348
350
352
354
356
358
360
362
364
366
368
370
372
374
376
378
380
382
384
386
388
390
392
394
396
398
400
402
404
406
408
410
412
414
416
418

100.2
100.7
101.1
101.6
102.0
102.4
102.9
103.3
103.7
104.2
104.6
105.1
105.4
105.8
106.3
106.6
107.1
107.5
107.9
108.3
108.8
109.2
109.6
110.0
110.4
110.8
111.2
111.6
112.0
112.4
112.6
113.1
113.5
113.9
114.3
114.7
115.0
115.5
115.8
116.2
116.6
117.0
117.3
117.7
118.1
118.5
118.8
119.2
119.6
119.9
120.3

420
422
424
426
428
430
432
434
436
438
440
442
444
446
448
450
452
454
456
458
460
462
464
466
468
470
472
474
476
478
480
482
484
486
488
490
492
494
496
498
500
502
504
506
508
510
512
514
516
518
520

120.7
121.0
121.4
121.7
122.1
122.5
122.8
123.2
123.5
123.9
124.2
124.6
124.9
125.3
125.6
126.0
126.3
126.6
127.0
127.3
127.7
128.0
128.3
128.7
129.0
129.3
129.7
130.0
130.3
130.7
131.0
131.3
131.6
132.0
132.3
132.6
132.9
133.3
133.6
133.9
134.0
134.5
134.8
135.2
135.5
135.8
136.1
136.4
136.7
137.0
137.3

522
524
526
528
530
532
534
536
538
540
544
548
552
556
560
564
568
572
576
580
584
588
592
596
600
604
608
612
616
620
624
628
632
636
640
644
648
652
656
660
664
668
672
676
680
684
688
692
696

137.6
137.9
138.3
138.6
138.9
139.2
139.5
139.8
140.1
140.4
141.0
141.6
142.1
142.7
143.3
143.9
144.5
145.0
145.6
146.2
146.7
147.3
147.9
148.4
149.0
149.5
150.1
150.6
151.2
151.7
152.3
152.8
153.4
153.9
154.5
155.0
155.5
156.1
156.6
157.1
157.7
158.2
158.7
159.2
159.8
160.3
160.8
161.3
161.8

Table 1. Pressure-temperature chart for R-410A

6

ALLIED SIGNAL

psig

Refrigeration Service Engineers Society
1666 Rand Road

Des Plaines, IL 60016

847-297-6464



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