HVAC PT ChartsVerified saturation data · 61 refrigerants
RefrigerantASHRAE R-600a

R-600a

A3Highly flammableHydrocarbon
C4H10 (isomer)

Isobutane (C₄H₁₀, branched) — natural hydrocarbon refrigerant. A3 highly flammable, GWP 3, zero ODP. The dominant refrigerant in new household refrigerators globally; charge-limited to small systems per safety standards.

Saturation @ 70°F
30.6PSIG
GWP (IPCC AR5)
3100-yr
Temperature glide
≈0°F
Boiling point
10.8°F
Sourced facts
ASHRAE safety class
A3[src]
Chemical formula
(CH₃)₃CH[src]
GWP (100-yr)
3IPCC AR5[src]
ODP
0[src]
Normal boiling point
10.9°F (−11.7°C)[src]
EPA SNAP approval
2011[src]
Domestic refrigerator charge
≤150g typical[src]
R-600a PT calculator Superheat
A3
Highly flammable

Lower toxicity. High burning velocity (> 100 cm/s) or high heat of combustion. Includes hydrocarbons R-290 (propane), R-600a (isobutane), R-1150 (ethylene), R-1270 (propylene). EPA charge limits, HC-rated equipment design, sealed systems, and leak detection are mandatory.

Flammability
High (burning velocity > 100 cm/s)
Toxicity
Lower

Classification per ANSI/ASHRAE Standard 34-2022. See full reference.

01

Saturation pressure-temperature curve

Pressure
Temperature
°F
70°F: 30.6 PSIG
Quick lookup — R-600a
30.6PSIG(211 kPa)
Range: -40 to 150°FOpen full PT calculator →
Common service temperatures
32°F
8PSIG
Freezing
45°F
14PSIG
Heat-pump heat
70°F
31PSIG
Standard
75°F
35PSIG
Test ref
80°F
39PSIG
Warm
95°F
53PSIG
Summer peak

Saturation values from CoolProp 7.2.0 IsoButane. Operating pressure on a running system differs — see the operating-pressure references for in-use values.

02

R-600a PT chart PDF — printable saturation table

Looking for the R-600a PT chart PDF for shop reference? The complete pressure-temperature saturation table is below — every 1° increment from −40°F to 150°F (or to the refrigerant's critical temperature). Use the Print / Save as PDF button in the table header to download a clean, table-only PDF (the rest of the page is hidden from the print output). Important service temperatures (normal boiling point, freezing point of water, residential AC evap and condenser targets) are tinted and tagged in the table for at-a-glance shop reference.

R-600a PT Chart — Pressure-Temperature Saturation Table

1° increments · Source: CoolProp 7.2.0 / manufacturer datasheet · hvacptcharts.com

R-600a · 1° increments · °F / PSIG
Tinted rows: NBP atmospheric crossover · 32°F H₂O freeze · 0°F Freezer compartment · 40°F Fridge compartment · 90°F Hot day ambient
R-600a pressure-temperature saturation table in Fahrenheit and PSIG
Temp (°F)Pressure (PSIG)
-40°F-10.5
-39°F-10.4
-38°F-10.3
-37°F-10.2
-36°F-10.0
-35°F-9.9
-34°F-9.8
-33°F-9.6
-32°F-9.5
-31°F-9.4
-30°F-9.2
-29°F-9.1
-28°F-8.9
-27°F-8.8
-26°F-8.6
-25°F-8.4
-24°F-8.3
-23°F-8.1
-22°F-7.9
-21°F-7.8
-20°F-7.6
-19°F-7.4
-18°F-7.2
-17°F-7.0
-16°F-6.8
-15°F-6.6
-14°F-6.4
-13°F-6.2
-12°F-6.0
-11°F-5.8
-10°F-5.6
-9°F-5.4
-8°F-5.1
-7°F-4.9
-6°F-4.7
-5°F-4.4
-4°F-4.2
-3°F-3.9
-2°F-3.7
-1°F-3.4
0°FFreezer compartment-3.2
1°F-2.9
2°F-2.6
3°F-2.4
4°F-2.1
5°F-1.8
6°F-1.5
7°F-1.2
8°F-0.9
9°F-0.6
10°F-0.3
11°FNBP (atmospheric)0.1
12°F0.4
13°F0.7
14°F1.0
15°F1.4
16°F1.7
17°F2.1
18°F2.4
19°F2.8
20°F3.2
21°F3.5
22°F3.9
23°F4.3
24°F4.7
25°F5.1
26°F5.5
27°F5.9
28°F6.3
29°F6.8
30°F7.2
31°F7.6
32°FH₂O freeze8.1
33°F8.5
34°F9.0
35°F9.4
36°F9.9
37°F10.4
38°F10.9
39°F11.4
40°FFridge compartment11.9
41°F12.4
42°F12.9
43°F13.4
44°F14.0
45°F14.5
46°F15.0
47°F15.6
48°F16.1
49°F16.7
50°F17.3
51°F17.9
52°F18.5
53°F19.1
54°F19.7
55°F20.3
56°F20.9
57°F21.6
58°F22.2
59°F22.9
60°F23.5
61°F24.2
62°F24.9
63°F25.6
64°F26.3
65°F27.0
66°F27.7
67°F28.4
68°F29.1
69°F29.9
70°F30.6
71°F31.4
72°F32.2
73°F32.9
74°F33.7
75°F34.5
76°F35.3
77°F36.2
78°F37.0
79°F37.8
80°F38.7
81°F39.5
82°F40.4
83°F41.3
84°F42.2
85°F43.1
86°F44.0
87°F44.9
88°F45.9
89°F46.8
90°FHot day ambient47.8
91°F48.7
92°F49.7
93°F50.7
94°F51.7
95°F52.7
96°F53.7
97°F54.8
98°F55.8
99°F56.9
100°F58.0
101°F59.0
102°F60.1
103°F61.2
104°F62.4
105°F63.5
106°F64.6
107°F65.8
108°F66.9
109°F68.1
110°F69.3
111°F70.5
112°F71.7
113°F73.0
114°F74.2
115°F75.5
116°F76.7
117°F78.0
118°F79.3
119°F80.6
120°F82.0
121°F83.3
122°F84.6
123°F86.0
124°F87.4
125°F88.8
126°F90.2
127°F91.6
128°F93.0
129°F94.5
130°F95.9
131°F97.4
132°F98.9
133°F100.4
134°F101.9
135°F103.5
136°F105.0
137°F106.6
138°F108.2
139°F109.8
140°F111.4
141°F113.0
142°F114.6
143°F116.3
144°F118.0
145°F119.6
146°F121.3
147°F123.1
148°F124.8
149°F126.5
150°F128.3
CoolProp 7.2.0 · PSIG/kPa = gauge · PSIA = PSIG + 14.696 · kPa(abs) = kPa(gauge) + 101.325

Full saturation values at 1° increments — toggle between °F / PSIG and °C / kPa. Use Print / Save as PDF for laminated shop reference, or download the CSV / JSON below for use in other tools. R-600a PT chart data: CoolProp 7.2.0 (REFPROP-compatible Helmholtz EOS) or manufacturer datasheet, validated against AHRI Standard 700-2019.

03

At a glance

Chemistry

C4H10 (isomer)
Isobutane (2-methylpropane)

Lubricant compatibility

MOABPAOPOE

Highly flammable (A3). Mineral oil standard. EPA charge limit 150 g for household refrigerators; updated SNAP rules expanded to small commercial applications.

Trade names

  • Care 30Care Refrigerants

Common applications

  • Household refrigerators and freezers (dominant globally)
  • Wine coolers and small beverage merchandisers
  • Small commercial refrigeration
04

Properties

  • Boiling point (1 atm)
    -11.8°C / 10.8°F
  • Critical point
    274.4°F at 512 PSIG
  • Molar mass
    58.12 g/mol
  • Temperature glide
    Negligible (0.00°F)
  • ODP
    0
  • GWP (AR5, 100-yr)
    3
  • GWP (AR6, 100-yr)
    0.005
  • Atmospheric lifetime
    0.02 years
05

What is R-600a?

R-600a is isobutane (2-methylpropane, (CH₃)₃CH) — a branched 4-carbon hydrocarbon natural refrigerant [ashrae34]. R-600a is structurally distinct from propane (R-290, straight 3-carbon chain) and offers slightly higher boiling point and different vapor pressure characteristics suited to domestic refrigeration.

R-600a has been the dominant refrigerant in new household refrigerators and freezers globally since the 2010s. The transition from HFC R-134a to R-600a in domestic refrigeration is largely complete in EU markets and well-advanced in US markets following EPA SNAP approval in 2011 [snap]. The transition is driven by R-600a's very low GWP and zero ODP — meaningful climate impact reduction across the billions of domestic refrigerators in service globally.

Where R-600a is used

  • Household refrigerators and freezers — global new-equipment standard
  • Small commercial refrigeration — bottle coolers, beverage display cases
  • Small ice machines and similar self-contained refrigeration
  • Limited industrial process refrigeration where R-600a's higher boiling point matters

Regulatory & phase-down status

R-600a faces no phase-down — GWP 3, zero ODP, A3 hydrocarbon outside Montreal Protocol and Kigali Amendment frameworks. The regulatory constraints are equipment-level (charge limits per IEC 60335-2-89) rather than refrigerant-level.

Market position is dominant in new household refrigeration globally. EU adoption is essentially complete; US adoption is well-advanced through the 2010s and 2020s. The installed base of R-600a domestic refrigerators is growing rapidly as R-134a refrigerators age out and are replaced.

Service notes

R-600a is highly flammable — concentrations between 1.8% and 8.5% by volume in air ignite readily. Equipment design must eliminate all potential ignition sources within the refrigerant circuit: sealed compressor motors, no internal electrical components, brazing only with refrigerant fully recovered and the system inerted [iec60335289].

Domestic refrigerator service is typically replacement (whole-appliance) rather than field repair due to small charge sizes and the labor cost relative to appliance value. When R-600a refrigerators are serviced, hydrocarbon-rated equipment and procedures apply: combustible gas detection, no open flames, grounded recovery procedures.

07

Operating cycle

CompressorRaises pressureCondenserRejects heat to outdoorsExpansion deviceDrops pressureEvaporatorAbsorbs heat from indoorsDischarge: 69 PSIG, 180°FLiquid: 69 PSIG, 100°FEvap inlet: 12 PSIG, 40°F (two-phase)Suction: 12 PSIG, 50°FTypical residential cooling cycle for R-600a (40°F evap, 110°F condenser, 10°F superheat, 10°F subcooling)
08

Phase-down timeline

R-600a is not currently regulated by AIM Act or EU F-Gas phase-down. Its very low GWP (3) places it below regulatory thresholds. No published phase-down milestones exist for this refrigerant — it is a forward-compatible option for the current low-GWP transition rather than a refrigerant being phased out.

Properties: GWP (AR5) 3 · ODP 0 · Not AIM Act-affected · type: hc
09

Global warming potential, in context

Household refrigeration

R-600a3R-2903R-134a1.4kR-1211kEU F-Gas (150)EPA AIM Act (700)
10

Retrofit and replacement paths

R-600a replaces

Reading the R-600a PT chart

R-600a's PT chart is a single saturation curve (pure refrigerant, no glide). At 70°F R-600a saturation is approximately 30 PSIG (CoolProp 7.2.0); at typical household refrigerator evaporator temperatures (-10°F to +10°F), saturation ranges 1-12 PSIG.

The operating pressures are very low compared to HFC refrigerants — well within standard 500 PSI manifold gauge ratings. The operational concern is the very-low pressure range rather than high-pressure equipment requirements.

Isobutane chemistry — branched 4-carbon hydrocarbon

R-600a is isobutane: (CH₃)₃CH — three methyl groups attached to a central carbon-hydrogen group. The branched structure distinguishes it from n-butane (R-600, straight chain) and gives R-600a slightly higher vapor pressure than n-butane at the same temperature.

The molecular structure is fundamentally different from fluorocarbon refrigerants — no fluorine, no chlorine, no atmospheric persistence beyond weeks. The chemistry is the same as fuel-grade isobutane used as a propellant in some aerosols and as a component of LPG fuel mixtures; refrigerant-grade R-600a has higher purity requirements (≥99.5% per AHRI 700).

GWP 3 and zero ODP — natural refrigerant with no phase-down risk

R-600a has GWP 3 (IPCC AR5) and zero ODP [ipccar5]. The very low GWP comes from R-600a's short atmospheric lifetime — OH radical breakdown over weeks. Combined with zero ODP (no halogens), R-600a has among the best environmental profiles of any commercial refrigerant.

R-600a faces no phase-down pressure under EPA AIM Act, EU F-Gas Regulation, Kigali Amendment, or Montreal Protocol. It is structurally a long-term destination refrigerant for domestic refrigeration. Service supply economics are favorable — R-600a is widely available as a refrigerant-grade product and as part of LPG / petrochemical supply chains.

A3 flammability — managed through small charge in sealed systems

R-600a is ASHRAE class A3 — highly flammable. The lower flammability limit (LFL) is approximately 1.8% by volume in air; upper limit approximately 8.5%. Any concentration in this range ignites readily with sufficient ignition energy.

Safety in domestic refrigerator applications comes from two design features. (1) Very small charge size — typical household refrigerator uses 30-100g of R-600a, well below IEC 60335-2-89 limits and below the amount that could produce LFL concentration in any reasonable kitchen volume [iec60335289]. (2) Sealed hermetic refrigerant circuit — no field service of the refrigerant typically, no electrical components inside the refrigerant circuit that could provide ignition sources.

For commercial R-600a service (vending machines, beverage coolers, ice machines), hydrocarbon-specific service procedures apply: combustible gas detection, no open flames during service, grounded equipment to prevent static discharge during refrigerant transfer.

Domestic refrigerator service — typically replacement, not repair

The economics of R-600a household refrigerator service favor whole-appliance replacement over field repair. Refrigerant charge is too small to justify recovery, equipment is sealed and not designed for field service, hydrocarbon-specific service procedures add labor cost relative to appliance value.

When commercial R-600a refrigeration needs service: hydrocarbon-rated equipment is required. Standard HFC manifold gauges work pressure-wise (R-600a operates at low pressures), but combustible gas detectors and grounded recovery procedures are added for safety. Mineral oil compatibility means lubricant retention is straightforward; no POE oil issues.

Household refrigerator R-134a to R-600a transition history

The global household refrigerator industry transitioned from CFC R-12 (banned 1996) to HFC R-134a in the 1990s, then from R-134a to R-600a starting in the late 2000s. EU adoption was earliest (Greenpeace-driven "Greenfreeze" R-600a refrigerators from German manufacturer Foron in 1993); global adoption accelerated through the 2010s.

US adoption lagged due to UL standard updates and EPA SNAP approval timing. EPA SNAP approved R-600a for household refrigerator end-use in 2011 [snap]. US manufacturers (Whirlpool, GE, Frigidaire/Electrolux) transitioned through the 2010s; by 2020 the majority of new US household refrigerators used R-600a.

The transition is largely complete in 2026. New household refrigerators globally use R-600a almost universally; the remaining R-134a refrigerators are end-of-life equipment being replaced as they age out.

How to think about R-600a in 2026 and beyond

R-600a is the structural long-term destination for household refrigeration globally. The transition from R-134a is essentially complete in new-equipment terms; the installed base will continue growing as R-134a refrigerators age out and are replaced.

For small commercial refrigeration (vending, beverage coolers, ice machines), R-600a captures growing share within charge-limit constraints per IEC 60335-2-89. Larger commercial refrigeration uses different refrigerants — R-290 (propane) at higher charge tolerance, R-744 (CO₂) at supermarket scale, R-454C / R-455A (A2L blends) for medium-scale installations.

For technicians, R-600a domestic refrigerator service is largely irrelevant — these are sealed systems serviced by replacement rather than field repair. Commercial R-600a refrigeration service requires hydrocarbon-specific training and equipment, similar to R-290 service practice.

11

Frequently asked

›What is R-600a used for?

Household refrigerators and freezers — dominantly. R-600a has been the global new-equipment standard since the 2010s as the HFC R-134a replacement. EPA SNAP approved R-600a for household refrigerator and freezer end-use in 2011 [snap]; US manufacturers transitioned through the 2010s. EU adoption was earlier (2000s).

R-600a is also used in small commercial refrigeration (vending machines, beverage coolers, ice machines) where charge limits per IEC 60335-2-89 allow.

›What's R-600a's GWP?

3 per IPCC AR5 — essentially zero [ipccar5]. The short atmospheric lifetime (weeks-scale, broken down by OH radical attack on the molecule) drives the very low GWP. R-600a sits in the same natural refrigerant low-GWP tier as R-290 (propane, GWP 3), R-744 (CO₂, GWP 1).

›Is R-600a the same as butane in a lighter?

Same molecular family (4-carbon hydrocarbons) but different isomer. R-600a is isobutane (2-methylpropane, branched structure); commercial butane fuel is typically a mix of n-butane (R-600, straight chain) and isobutane. Refrigerant-grade R-600a has specific purity requirements (≥99.5% per AHRI 700) and is dried for refrigeration service [ahri700].

Never use commercial fuel-grade butane as a refrigerant — the impurities and moisture content damage compressor lubrication.

›Is R-600a safe?

The refrigerant is highly flammable (A3 classification). Safety in domestic refrigerator applications comes from extremely small charge sizes (typically 30-100g per refrigerator, well below the IEC 60335-2-89 limit of 150g for hermetic refrigerant circuits in occupied spaces) and sealed-system construction.

Total refrigerant release from a household R-600a refrigerator into a typical kitchen produces concentrations far below the lower flammability limit (1.8% by volume). The system is designed to be inherently safe through small charge and complete containment.

›What's the difference between R-600a and R-290?

Both are pure hydrocarbon natural refrigerants with A3 classification and GWP near zero. R-600a is isobutane (4-carbon, NBP 10.9°F); R-290 is propane (3-carbon, NBP −43.8°F). R-600a's higher boiling point makes it well-suited to domestic refrigerator operating temperatures; R-290's lower boiling point makes it well-suited to heat pumps and small commercial refrigeration.

›Why did household refrigerators switch from R-134a to R-600a?

Climate impact reduction. R-134a (GWP 1430) released from end-of-life refrigerators contributes meaningful climate burden across the billions of refrigerators in service globally. R-600a (GWP 3) is essentially zero climate impact. EPA SNAP approved R-600a for household refrigerator end-use in 2011 [snap]; EU and global manufacturers transitioned over the following decade.

›What lubricant does R-600a use?

Mineral oil typically, in viscosity grades specified by the refrigerator OEM. R-600a is compatible with mineral oil (hydrocarbon refrigerant + hydrocarbon lubricant). POE oil (used with HFCs) is NOT compatible.

›Can I service a household R-600a refrigerator myself?

Generally not advisable. Household refrigerators have small charge sizes that make field service uneconomical compared to whole-appliance replacement. R-600a service requires hydrocarbon-specific procedures (combustible gas detection, no open flames, grounded recovery) that aren't part of typical homeowner skill set.

For commercial-scale R-600a refrigeration (vending machines, beverage coolers), service requires appropriate hydrocarbon-rated equipment and training.

Download this dataset

Full PT chart for R-600a · CC BY 4.0 · attribute the source

CSV JSON
13

Sources & citations

  1. [1]
    ASHRAE Standard 34-2022
    2022https://www.ashrae.org/technical-resources/standards-and-guidelines
  2. [2]
    IPCC AR5 (2014) Working Group I, Chapter 8, Table 8.A.1
    2014https://www.ipcc.ch/report/ar5/wg1/
  3. [3]
    CoolProp 7.2.0
    2014 (continually updated)http://www.coolprop.org/doi:10.1021/ie4033999
  4. [4]
    IEC 60335-2-89 — Commercial refrigerating appliances with hermetic refrigerant circuits (A3 charge limits)
    2019 revisionhttps://webstore.iec.ch/publication/61349
  5. [5]
    EPA SNAP — R-600a acceptable for household refrigerators and freezers
    Approval 2011 for new equipmenthttps://www.epa.gov/snap
  6. [6]
    NIST Chemistry WebBook — Isobutane thermophysical properties (CAS 75-28-5)
    https://webbook.nist.gov/chemistry/fluid/
  7. [7]
    AHRI Standard 700-2019
    2019https://www.ahrinet.org/search-standards

Data sources & provenance

PT chart
CoolProp 7.2.0 IsoButane
Cross-checked against
CoolProp 7.2.0 (IsoButane); ASHRAE Handbook of Refrigeration 2022
Properties
CoolProp 7.2.0 + ASHRAE Standard 34-2022
GWP
IPCC AR5 Table 8.A.1
Generated
2026-06-05

Reference material. Always verify pressure values against the equipment data plate and manufacturer service literature before charging or troubleshooting a specific system. Saturation pressure differs from operating pressure — see superheat & subcooling fundamentals.