By Yevhen Kovalchuk · Updated September 18, 2026 · 8 min read
Short answer
R-290 is propane, a natural refrigerant with a GWP of about 3 and excellent efficiency, but it is highly flammable (ASHRAE class A3). In the United States it is accepted under EPA SNAP in specific commercial refrigeration end uses, mainly self-contained units, with charge limits set by UL 60335-2-89 (up to 500 grams in some open cases and 300 grams in closed cases). Larger or field-built systems follow different rules, and local codes decide what can be installed.
R-290 is propane used as a refrigerant. It has a global warming potential of about 3, strong thermodynamic efficiency and no ozone depletion, which is why it is the leading natural option for small self-contained commercial refrigeration. It is also highly flammable, so U.S. rules limit where it can be used and how much can be in each circuit. Under EPA’s SNAP program, propane is acceptable in certain commercial refrigeration end uses, such as self-contained display cases, with a charge limit of 500 grams (about 17.6 ounces) in some products under a 2024 rule. The sections below explain what that means.
What is R-290 and why is it used?
R-290 (propane, C3H8) is a hydrocarbon refrigerant. ASHRAE Standard 34 classifies it A3: low toxicity, high flammability. Its main advantages:
- Very low GWP. About 3, compared with roughly 3,900 for R-404A and about 1,430 for R-134a (AR4 values, approximate).
- High efficiency. Propane has favorable heat transfer properties and good energy performance in small systems.
- Lower charge by mass. Its liquid density is low, so a system holds fewer pounds than with HFCs.
- Compatibility. It works with common compressor technologies built for it, and the refrigerant is widely available.
The main disadvantage is flammability. Propane has a lower flammability limit of about 2.1% by volume, and a leak in a small enclosed space can reach that level, which is why charge size is capped.
Where is R-290 allowed in the United States?
Refrigerant use in the U.S. is governed by EPA’s Significant New Alternatives Policy (SNAP) program, which lists acceptable substitutes by end use, and by building codes and standards. Propane was approved for several end uses over time. The recent change that matters for commercial refrigeration is SNAP Rule 26, which EPA finalized in 2024. It updated the use conditions for self-contained commercial refrigeration equipment by allowing a higher R-290 charge in line with UL 60335-2-89, 2nd edition. The rule applies to equipment built to that standard after the effective date, and it exempts propane in this end use from the venting prohibition in Section 608 of the Clean Air Act. Check the current EPA SNAP page for the exact end uses and any later changes.
| Application | Typical status for R-290 |
|---|---|
| Household refrigerators and freezers | Accepted under SNAP with a small charge limit |
| Self-contained commercial display cases, reach-ins, beverage coolers | Accepted under SNAP with the use conditions in Rule 26 |
| Self-contained ice machines, vending machines | Accepted in specific end uses; check the use conditions |
| Remote condensing units and supermarket racks | Generally not covered by the same conditions; check the SNAP listing and code |
| Industrial process and large cold storage | Not a standard choice; ammonia and CO2 are more common |
Treat the table as a guide and verify the specific end use in the SNAP tables before specifying equipment.
What are the charge limits for R-290?
The charge limit comes from the product safety standard, UL 60335-2-89, which governs commercial refrigerating appliances. Its 2nd edition, approved in 2021, raised the allowable R-290 charge:
- 500 grams for open or non-closed cases, which is about 13 times the lower flammability limit (LFL) of propane in the calculation used in the standard.
- 300 grams for closed cases with doors or drawers, based on eight times the LFL.
- Earlier limit. The previous edition capped the charge at 150 grams per circuit.
Cases with more capacity can use more than one sealed circuit. The standard also gives a method for calculating charge limits for other configurations, based on room volume and the charge. These are product limits, not blanket limits for any building. The installation code and the local authority may add requirements, such as for ventilation or placement near exits.
What safety measures do R-290 systems use?
Equipment designed for propane includes protections that ordinary HFC equipment does not:
- Sealed or ignition-safe electrical parts. Relays, thermostats and fan motors are chosen to avoid sparks inside the refrigerant circuit and in the air path.
- Leak minimization. Brazed joints, few connections and tested tubing reduce the leak risk.
- Warning labels. Equipment must show a flammable refrigerant label and a handling instruction.
- Factory charging. Most R-290 equipment is charged at the factory and sold sealed, so field charging is rare.
Technicians who handle propane equipment need training in flammable refrigerants, including how to work with open flame or sparking tools nearby, how to ventilate before opening a circuit, and how to use recovery equipment rated for flammables. Section 608 certification still applies to refrigerant handling under federal rules. For OSHA, flammable gas hazards fall under the general duty and hazard communication requirements, so employers need written procedures and labeled storage.
How does R-290 compare with CO2 and ammonia?
All three are “natural refrigerants,” but they suit different scales:
- R-290: small, self-contained cases with sealed circuits and low charge.
- CO2 (R-744): supermarkets and cold storage at higher pressure; see CO2 transcritical refrigeration.
- Ammonia (R-717): large industrial plants with trained staff; see ammonia refrigeration system basics.
HFC and HFO options still dominate larger commercial systems; compare them in the guide to replacing R-404A with R-448A or R-449A.
What does R-290 mean for compressors and service?
R-290 compressors are built for the refrigerant, with motor and oil selections matched to propane. A technician should not put propane into equipment designed for an HFC. Reasons include oil compatibility, electrical safety and the fact that the equipment was never evaluated for a flammable refrigerant. Compressor selection is a good example of why it is worth understanding the main designs, as described in the refrigeration compressor types guide.
Is R-290 the future of commercial refrigeration?
For small self-contained equipment, it is already the dominant low-GWP choice in much of the world. In the U.S. the rise has been slower because of earlier charge limits, code adoption and market habits. The 2024 rule, together with the revised UL standard, makes it a stronger option, but adoption still depends on local codes adopting the new standard. Texas has adopted new mechanical codes, and cities differ, so check current local rules; see Texas 2024 mechanical codes: what changed.
Frequently asked questions
Is propane refrigerant legal in the United States?
Yes, in specific end uses accepted under EPA SNAP, including household refrigeration and certain self-contained commercial refrigeration equipment, with use conditions. It is not accepted as a drop-in for any HFC system.
How much R-290 can a commercial refrigerator hold?
Under UL 60335-2-89, 2nd edition, up to 500 grams in some open cases and 300 grams in closed cases per circuit, and EPA SNAP Rule 26 aligned with those limits for covered equipment. Always check the equipment’s nameplate and the current rule.
Can I replace R-404A with R-290 in my existing walk-in cooler?
No. Existing equipment is not designed for flammable refrigerants, and a field conversion is not an acceptable use under SNAP. Replacing the whole self-contained unit with a certified R-290 model is a different matter, and codes and local rules apply.
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