The global phase-down of high-GWP refrigerants under the Kigali Amendment—and its regional accelerators like the EU F-Gas Regulation revision effective January 2026 and the U.S. EPA AIM Act—is not merely a chemical substitution exercise. It is a fundamental re-architecting of refrigeration and air-conditioning systems. As OEMs transition toward natural refrigerants (ammonia R717, carbon dioxide R744, hydrocarbons R290/R600a) and next-generation low-GWP synthetics (HFOs, A2L blends), the humble valve finds itself at the center of a materials science revolution. At Dofun, with more than 30 invention patents, products already applied in NH₃, Freon, and CO₂ systems, and recognition as a national-level specialized and innovative enterprise, we convened an internal expert roundtable—drawing on our R&D, application engineering, and quality teams—to discuss how these policy shifts are reshaping valve technology and material selection. This article synthesizes their insights.

The Policy Landscape: Why Valves Are in the Crossfire

To understand the technical implications, we must first frame the regulatory drivers.

Key Milestones in the Global HFC Phase-Down

• Kigali Amendment:​ Drives signatory nations toward progressive reduction of HFC consumption, with developing nations like China freezing HFC use at 2025 levels starting 2026 and targeting a 10% reduction by 2029.
• EU F-Gas Regulation (2026 revision):​ Mandates a complete HFC ban for new stationary AC equipment below 12 kW effective 2027, and a service ban for HFCs above 150 GWP by 2030.
• U.S. EPA AIM Act:​ The December 2025 rulemaking reduced HFC production and consumption allowances by an additional 30% starting 2027, accelerating OEM transition to A2L refrigerants (R-454B, R-32).
• Market Response:​ Danfoss reported that low-GWP compliant valve product revenue grew 47% year-over-year, reaching 31% of total HVAC-R valve sales in its 2025 annual report.

The Technical Consequence

These policies do not simply swap one refrigerant for another. They introduce three disruptive technical variables that directly impact valve design:

1. Higher operating pressures​ (especially CO₂ transcritical systems)
2. New safety classifications​ (A2L mildly flammable, A3 flammable)
3. Different chemical compatibilities​ (ammonia’s hostility to copper, HFOs’ interaction with elastomers)

As our Chief Engineer noted during the roundtable: “A valve qualified for R134a cannot simply be filled with R744 or R290. The pressure, the chemistry, and the safety profile all change. This is not a label change—it is a re-design.”

Roundtable Insight 1: CO₂ Systems Demand a Step-Change in Pressure Rating

Carbon dioxide (R744) is rapidly becoming the refrigerant of choice for supermarket refrigeration, heat pumps, and industrial cascade systems. Its environmental credentials are impeccable—ODP zero, GWP of 1, and exempt from phase-down quotas. However, its thermophysical properties present formidable engineering challenges.

The Pressure Paradigm Shift

In transcritical CO₂ cycles, system pressures can reach up to 750 PSIG (≈52 bar), with standstill pressures even higher. This is 3–5 times the typical operating pressure of legacy HFC systems. For valve bodies, this necessitates:

• Upgraded pressure classes:​ Dofun’s existing refrigeration valve portfolio already addresses this with PN40 and PN63 series​ (rated at 4.0 MPa and 6.3 MPa respectively). Our Stainless Steel Valve Series​ in PN63 provides the high-strength material platform essential for CO₂ applications.
• High-strength alloys:​ Where carbon steel may suffice for subcritical CO₂, transcritical applications benefit from stainless steel construction. Dofun’s stainless steel valves use 304 grade material for stems​ and offer stainless body options, providing the strength-to-weight ratio and corrosion resistance needed.
• Reinforced structural design:​ The Y-pattern flow passage in many Dofun valve bodies reduces stress concentration under high-pressure cycling, a critical advantage in CO₂ systems subject to wide pressure swings.

Sealing Under Extreme Pressure

Our roundtable’s sealing expert emphasized: “CO₂ has strong solvent properties, especially in the supercritical state above 73.75 bar and 30.98°C. It can extract soluble components from standard elastomers, causing seal degradation and explosive decompression failure.”

This drives the selection toward:

• PTFE and modified PTFE:​ Offering low permeation and chemical inertness
• Specialized EPDM compounds:​ Formulated for CO₂ compatibility
• Rubber-metal composite seals:​ Combining elastomer flexibility with metal impermeability

Dofun’s six-level sealing architecture, with its multi-barrier approach using imported sealing materials, is specifically designed to handle such demanding media. Our valves have been tested and validated for R744 (CO₂) applications across DN25–DN125 sizes.

Roundtable Insight 2: Ammonia Systems—The Copper Exclusion Rule

Ammonia (R717) remains the most energy-efficient refrigerant for large industrial refrigeration. Its GWP of 0 makes it future-proof. However, ammonia’s chemical nature imposes strict material rules.

The Absolute Ban on Copper Alloys

As industry research confirms: “Ammonia exhibits chemical incompatibility with copper and copper alloys… Standard materials include: Carbon steel for pressure vessels and piping; Stainless steel (304, 316) for high-purity applications.” Copper content above 2% in alloys leads to corrosion and formation of copper compounds.

Dofun’s response, as detailed by our materials engineering lead:

• All wetted components in our ammonia-rated valves use carbon steel or stainless steel construction—never brass or bronze.
• Our Stainless Steel Valve Series​ provides the 304/316 option for applications requiring enhanced corrosion resistance.
• Valve stems are manufactured from 304 stainless steel with proprietary NANO surface treatment​ (patent-protected), achieving surface roughness Ra ≤ 0.03 μm and dramatically reducing packing wear—critical in ammonia systems where any leak is a safety event.

Sealing and Stem Design for Ammonia

Ammonia is a “dry” refrigerant providing minimal lubrication, and ice buildup on cold stems can tear packing during operation. Dofun addresses this through:

• Extended bonnet designs​ available across our product range, moving stem packing away from extreme cold zones
• PTFE-based packing systems​ with low cold-flow characteristics
• Proven field performance:​ As validated by client feedback, Dofun valves in low-temperature, high-pressure ammonia core units have been “operating stably for over three years,” with reliability that “completely eliminated our concerns about unplanned downtime.”

Roundtable Insight 3: A2L and A3 Refrigerants—Spark-Free Design and Elastomer Compatibility

The transition to HFOs (R1234yf, R1234ze) and A2L blends (R32, R454B) introduces mild flammability. Hydrocarbons R290 and R600a are fully flammable (A3). This creates two parallel engineering tracks:

Track A: Spark-Free Electrical Design

For solenoid valves and motorized valves used with flammable refrigerants, the electromagnetic actuator must be designed to prevent arc ignition. Dofun’s solenoid valve series—with models rated for NH₃, Freon, and CO₂​ across DN3–DN50—undergoes continuous design evolution. Our engineering team collaborates closely with clients specifying A2L/A3 refrigerants to ensure:

• Coil insulation meets relevant explosion-protection requirements
• Encapsulation prevents spark propagation
• Where required, intrinsically safe control circuits are specified

Track B: Elastomer Requalification

HFOs and HFCs interacting with POE or PAG oils demand elastomers that resist swelling, shrinkage, and chemical attack. Industry guidance recommends HNBR (Hydrogenated Nitrile Butadiene Rubber)​ for HFC/HFO/CO₂ applications due to its superior high-temperature resistance and lower permeability.

Refrigerant Family	Recommended Sealing Approach	Key Consideration
HFC / HFO (A1/A2L)	HNBR, FKM, PTFE	Resistance to synthetic oils, low permeability
CO₂ (R744)	EPDM, PTFE, rubber-metal composites	High-pressure integrity, anti-explosive decompression
Ammonia (R717)	PTFE, graphite-reinforced	Total copper exclusion, dry-running resilience
Hydrocarbons (A3)	HNBR, FKM (spark-free housing)	Flammability safety, oil compatibility

Dofun’s sealing strategy leverages the DOFUN-CTP modular shared platform, which allows rapid re-qualification of sealing modules across our valve families without re-designing entire valve bodies. This agility is essential when refrigerant standards evolve every few years.

Roundtable Insight 4: System-Level Implications—Modularity and Lifecycle

The phase-down is not just about individual valves; it is about system adaptability. Our roundtable identified three systemic trends:

1. Modular Valve Stations for Multi-Refrigerant Readiness

Dofun’s Valve Station Series​ integrates multiple functions—stop valves, check valves, filters, regulators—into a single manifold. This modular approach allows end-users to:

• Swap functional modules when retrofitting from one refrigerant to another
• Maintain consistent connection dimensions while upgrading internal materials
• Reduce inventory complexity through standardized bodies with customizable inserts

This philosophy aligns with our DOFUN-CTP platform vision: “Through modular design, the platform allows component sharing while supporting customization in appearance and connection dimensions.”

2. Energy Efficiency as a Co-Benefit

The HFC phase-down coincides with aggressive energy efficiency targets. Our experts highlighted that each 0.1 bar reduction in valve pressure drop improves system COP by 2–3%. Dofun’s pressure regulating valves and servo main valves are engineered with optimized flow paths to minimize pressure loss, contributing directly to the energy efficiency management our clients require. As one cold chain client confirmed: “Dofun’s control valves achieve exceptional precision, playing an instrumental role in ensuring our cold chain safety and energy efficiency management.”

3. Lifecycle and Circular Economy

With the EU’s emphasis on whole-life carbon accounting, valves must now be designed for disassembly, refurbishment, and recycling. Dofun’s green manufacturing initiatives—reducing scrap through standardized components, minimizing wastewater, and lowering carbon emissions—position our valves favorably for this new regulatory landscape. Our products have obtained EU CE certification, Russia EAC certification, and a series of international quality system audits, ensuring compliance with evolving global standards.

Roundtable Insight 5: Dofun’s Product Portfolio—Engineered for the Transition

Mapping our discussion to Dofun’s actual product lines reveals a portfolio already aligned with post-HFC-phase-down requirements:

• Pressure Regulating Valve Series (IPRV, OPRV, DPAV):​ Rated for NH₃, Freon, and CO₂; PN40/PN63 class; temperature range -50°C to +150°C. These servo-piloted valves regulate upstream, downstream, or differential pressure without a PLC—ideal for natural refrigerant systems.
• Solenoid Valve Series (DEVSC/DEVS):​ Applicable to R12, R22, R502, R134a, R404A, R507, R717, CO₂, and other refrigerants. Available in steel and stainless steel construction. DN3–DN50, temperature range -40°C to +105°C.
• Stainless Steel Valve Series:​ The material platform of choice for corrosive refrigerants and high-purity applications. PN63 rated for demanding CO₂ transcritical systems.
• Motor Valve Series (DFMV):​ PN40/PN63, -50°C to +150°C, for automated control in large industrial ammonia or CO₂ plants.
• Pneumatic Solenoid Valve Series (DGPV):​ Two-step open versions for controlled startup in high-pressure systems.
• Valve Station Series (DFCV):​ Integrated manifolds rated at 4.0 MPa, -50°C to +150°C, enabling compact, multi-function installations.

All products are manufactured in our modern 30-acre facility in Liaocheng​ equipped with globally advanced production lines and testing platforms, ensuring that every valve meets the rigorous demands of modern refrigerant applications.

Roundtable Consensus: The Five Design Principles for Next-Generation Valves

Our experts converged on five non-negotiable design principles for valves in the post-HFC era:

1. Pressure-Class Headroom:​ Always specify valves with pressure ratings that anticipate transcritical or high-pressure synthetic refrigerants—PN63 stainless as the new baseline for CO₂.
2. Material Discipline:​ Zero copper in ammonia systems; verify elastomer compatibility per refrigerant family; leverage stainless steel where chemical aggression is anticipated.
3. Sealing Redundancy:​ Multi-level sealing architectures using compatible polymers (PTFE, HNBR, EPDM) matched to refrigerant chemistry.
4. Spark-Free Actuation:​ For A2L/A3 refrigerants, solenoid and motor operators must meet ignition prevention standards.
5. Modular Adaptability:​ Design valves on shared platforms (like DOFUN-CTP) that allow rapid requalification as refrigerant regulations continue to evolve.

Conclusion: Dofun’s Commitment to the Refrigerant Transition

The HFC phase-down is not a threat to valve manufacturers—it is an opportunity to demonstrate engineering leadership. At Dofun, our 30+ invention patents, national “Little Giant” recognition, and proven deployment in 100+ countries​ position us uniquely to support this transition. From the 2026 Milan Winter Olympics luge track refrigeration system​ (using our ammonia-compatible valves) to pharmaceutical plants requiring sanitary-grade stainless steel valves for HFO-based cooling, Dofun is already there.

Our roundtable concluded with a clear mandate: “We will not wait for refrigerant standards to dictate our designs. We will anticipate them.” Through continuous R&D investment, our DOFUN-CTP modular platform, and an unwavering commitment to material science excellence, Dofun is engineering the valves that will control the refrigerants of tomorrow—today.

For engineering teams navigating the HFC phase-down, the path forward requires a valve partner who understands both the regulatory landscape and the underlying materials science. Contact Dofun’s technical team​ to discuss your specific refrigerant transition roadmap. Together, we will specify the optimal valve solution—whether for CO₂ transcritical, ammonia industrial, HFO commercial, or hydrocarbon light-duty applications—ensuring your systems remain compliant, efficient, and reliable for decades to come.