The science of R-4106A: engineering A2L performance with non-flammable transport and storage

R-4106A (EPA product name EXPA8) is currently pending EPA SNAP review under Docket No. EPA-HQ-OAR-2024-0503 and is not yet commercially available. This post describes the chemistry and performance data behind R-4106A; ordering and distribution information will follow SNAP listing.

Executive summary and technical quick-reference

Key takeaway: R-4106A is FluoroFusion's next-generation refrigerant blend, developed through proprietary chemistry as an alternative to R-454B in equipment designed and listed for it. It maintains A2L classification characteristics for equipment application while also being classified as non-flammable for transportation under U.S. Department of Transportation (DOT) regulations, simplifying handling and logistics. Thermodynamic cycle analysis run in NIST REFPROP across nine standard operating conditions — modeled cycle results, not measured system performance, spanning nine AC and heat-pump test points from -25°F to 130°F evaporator/condenser temperatures — shows R-4106A delivering approximately 5% higher capacity and efficiency than R-454B, and 5% to 10% higher capacity and efficiency compared to legacy R-410A, without requiring new lubricants or major system redesign.

R-4106A performance and safety snapshot

Parameter	R-4106A	R-454B (benchmark)	Operational & economic impact
ASHRAE 34 safety classification	A2L	A2L	Same equipment safety code requirements (ASHRAE Standard 15) apply to both
DOT transport class	Class 2.2 (non-flammable gas)	Class 2.1 (flammable gas)	No flammable placards, no hazmat surcharge, no Class 2.1 cylinder quantity limits
Lower flammability limit (LFL)	13.2% by volume (worst case)	11.8% by volume	About 12% higher concentration needed to reach an ignitable mixture
Worst-case laminar flame speed	5.3 cm/s (WCF), 5.66 cm/s (WCFF)	7.0–7.5 cm/s	Slower burn if ignition does occur
Volumetric capacity vs. R-454B	Approximately +5%	Baseline	Higher cooling output from the same equipment footprint
COP vs. R-454B	Approximately +5%	Baseline	Lower annual kWh per ton of cooling
GWP (100-yr, 40 CFR 84.64 methodology)	681	466	Below the EPA AIM Act Technology Transition limit of 700
TFA formation	97.3% lower than R-454B	High (R-1234yf, ~100% molar yield)	Reduced long-term regulatory exposure tied to persistent fluorinated degradation products
Oil compatibility	Same POE lubricant used for R-454B; minor 1–2 cSt viscosity reduction	POE	No flush, no oil change, no seal swap

The logistics of the A2L transition

The regulatory phase-down of high-GWP refrigerants like R-410A (GWP 2088) has moved the industry toward A2L (mildly flammable) alternatives such as R-32 and R-454B. Under DOT regulations, A2L blends are classified Class 2.1 (flammable gas) for transport, which comes with a defined set of requirements: shipping placards, cylinder quantity limits, and fire-code provisions for stored inventory. Equipment and mechanical-room design account for the same classification under ASHRAE Standard 15 and UL 60335-2-40.

This framework isn't a flaw in any single refrigerant — it's the standard structure that governs every A2L blend, including several FluoroFusion produces and supplies today. What varies from one A2L blend to the next is where it sits within that framework, driven by its specific lower flammability limit, flame speed, and DOT transport classification. That's the differentiation R-4106A is built around.

Beyond flammability logistics, low-GWP transitions bring two other engineering considerations:

• Thermodynamic performance: many single-component or simple binary low-GWP refrigerants reduce volumetric cooling capacity relative to legacy blends. To recover equivalent output, system designers may need to increase compressor displacement or heat exchanger surface area, adding manufacturing cost.

• Atmospheric breakdown products: environmental scrutiny now extends past GWP to persistent atmospheric breakdown products, specifically trifluoroacetic acid (TFA). Some first-generation HFOs, including R-1234yf (a component of R-454B), convert to TFA at close to 100% molar yield in the atmosphere, creating a long-term environmental profile regulators are watching closely.

R-4106A was engineered to address these three variables — flammability logistics, thermodynamic performance, and TFA formation — together, in a single blend.

Proprietary chemistry and blend architecture

R-4106A relies on precise multi-component blend mechanics developed by FluoroFusion. The blend composition is protected by issued U.S. patents. The separation process used in FluoroFusion's reclamation-based manufacturing is protected by a related family of issued U.S. patents.

Molecular composition and flammability performance

FluoroFusion's chemistry balances thermal capacity against flammability limits across the blend's constituents. The result, in plain terms: it takes about 12% more R-4106A in air to reach an ignitable concentration than it does R-454B, and if it does ignite, it burns slower. That performance is what earns R-4106A its DOT Class 2.2 non-flammable classification for transport and storage — a distinct designation from its ASHRAE Standard 34 A2L classification for equipment application. Both are accurate, and both matter: the A2L classification governs how equipment is designed and installed; the DOT classification governs how the refrigerant ships and is stored.

Fractionation and purity control

A long-standing challenge with multi-component refrigerant blends is fractionation — the selective vaporization of individual components during phase change or system leakage. FluoroFusion's proprietary processing and purification technology controls constituent ratios to tight tolerances, helping R-4106A maintain its composition, and its performance and safety characteristics, across charge cycles, field servicing, and recovery operations.

Thermodynamic performance and field compatibility data

R-4106A closely mirrors the operating pressure envelope of legacy system architectures while delivering measurably higher efficiency than standard A2L replacements.

Pressure and drop-in compatibility: discharge pressure runs 2.6% to 2.8% above R-454B, well within normal equipment design margins, while R-4106A's saturation properties are the same as or lower than R-410A's. The pressure ratio change relative to R-454B is negligible, ranging from -0.3% to 0.0% across nine tested operating conditions, supporting compatibility with existing compressor and expansion-device design.

Capacity and efficiency: REFPROP cycle analysis across nine standard operating conditions shows approximately 5% higher capacity and efficiency than R-454B. Compared against legacy R-410A systems, R-4106A shows 5% to 10% higher capacity and efficiency, at lower operating pressures. This added density lets equipment deliver more cooling tonnage within the same mechanical footprint.

Pressure glide: R-4106A introduces no glide change relative to R-454B. Property tables show a larger constant-pressure figure, 5°F to 7°F.  That is not the glide a coil sees. In an operating evaporator, the pressure drop along the circuit, driven in part by the R-744 component's expansion, lowers the saturation temperature along the coil. That offsets most of the temperature rise from glide, so effective glide in an operating system runs about 0°F to 2°F, against about 1.5°F to 2°F for R-454B. In service, the two are equivalent. Glide behavior is comparable to or better than R-407C and R-438A — blends the trade has run successfully for two decades. Contractors set superheat off the R-4106A dew point and subcooling off the bubble point, the same way they do today; standard TXVs and EEVs maintain precise control without hunting.

Discharge temperature management: R-4106A maintains controlled discharge temperatures that protect compressor motor insulation and oil viscosity from thermal degradation under extreme ambient conditions. In heat pump mode under extreme outdoor conditions, the same liquid- or vapor-injection strategies used with other refrigerants apply to R-4106A.

Lubricant integration: R-4106A uses the same standard polyolester (POE) lubricant as R-454B. Field data shows a minor 1–2 centistoke viscosity reduction, non-disruptive to oil return velocity. No flush, oil change, or seal swap is required during equipment integration.

Regulatory compliance, safety, and environmental impact

Transport and logistics: R-4106A ships as UN1078, DOT Class 2.2, the same way R-410A always has — no flammable placards, no hazmat surcharge, and no Class 2.1 cylinder quantity limits. This is separate from, and doesn't change, its ASHRAE Standard 34 A2L classification for equipment application, which governs system design and installation the same way it does for any A2L refrigerant.

Facility storage: R-4106A can be stored on the same rack as R-410A inventory, with no sprinkler upgrade, gas detection system, or ventilation retrofit required for the refrigerant itself under the model fire codes, subject to local amendments and the authority having jurisdiction.

Atmospheric chemistry and TFA: R-1234yf, a primary component of R-454B, converts to trifluoroacetic acid (TFA) at close to 100% molar yield in the atmosphere — a persistent chemical that accumulates in aquatic ecosystems. R-4106A's blend architecture, which uses R-1234ze(E) in place of R-1234yf, achieves 97.3% lower TFA formation, roughly 8.4 grams per kilogram against about 311 grams, compared to R-454B. This offers meaningfully reduced long-term regulatory exposure as scrutiny of persistent fluorinated degradation products increases.

GWP and HFC allowances: R-4106A carries a blend-level GWP of 681 (IPCC AR4, 100-year basis, per the 40 CFR 84.64 methodology), below the EPA AIM Act Technology Transition limit of 700 for new residential and light commercial air-conditioning equipment. When formulated from reclaimed HFC components, R-4106A's production does not draw down HFC consumption allowances ahead of the 2029 step-down — a meaningful consideration for distributors managing allowance exposure.

Safety data: under ASHRAE 34 testing by DEKRA, R-4106A shows a worst-case lower flammability limit of 13.2% by volume, compared to approximately 11.8% for R-454B, meaning it takes more refrigerant in air to reach an ignitable concentration.  Its worst-case laminar burning velocity is 5.3 cm/s as formulated and 5.66 cm/s under worst-case fractionation, well below the 7.0–7.5 cm/s for R-454B. Together, these properties support a materially higher allowable refrigerant charge than R-454B in certain system types, subject to equipment listing under UL 60335-2-40, a meaningful advantage for VRF systems and large chillers where charge limits drive design complexity.

Frequently asked questions

Q: Is R-4106A a direct operational drop-in for existing systems? A: R-4106A is designed for new equipment engineered and listed for it. For retrofits, R-4106A should only be used where the original equipment manufacturer has approved the conversion in writing — using it in equipment not rated for it voids UL listing and puts an A2L refrigerant into a system not designed for one. Where retrofits are approved, R-4106A shows high compatibility with POE lubricants and standard metallic sealing materials, though system pressure settings and expansion devices should always be verified against R-4106A P-T parameters.

Q: How does R-4106A impact transport and facility storage requirements? A: R-4106A carries a DOT Class 2.2 non-flammable gas classification for transport, separate from its ASHRAE Standard 34 A2L classification for equipment use. The DOT classification removes hazardous-material transport surcharges and the specialized warehouse infrastructure required for Class 2.1 flammable inventory.

Q: Is R-4106A available to order? A: Not yet. R-4106A (EXPA8) is currently in the SNAP review process with EPA under Docket No. EPA-HQ-OAR-2024-0503. FluoroFusion will announce availability once the SNAP listing is finalized.

Next steps and technical resources

• For OEM product teams and engineers: register for early access to detailed thermodynamic tables, pressure-temperature (P-T) charts, and material compatibility data at FluoroFusion.com.

• For distributors and mechanical contractors: sign up for launch notifications to be first in line once R-4106A cylinders and recovery service are available through our distribution network.

We'll publish full details on cylinder sizing and packaging, compatibility with existing gauges, hoses, and recovery machines, and topping-off procedures following a leak, ahead of commercial availability.