R-450A PT Chart and Refrigerant Profile

Where you will find R-450A

R-450A is Honeywell’s Solstice N13, a blend of 42% R-134a and 58% R-1234ze(E). It is an A1 alternative to R-134a with less than half its GWP on the AR4 basis (604 against 1,430). Honeywell’s data sheet lists heat pumps, air- and water-cooled chillers, district heating and cooling, vending machines and beverage dispensers, the high stage of CO2 cascade systems and medium-temperature DX refrigeration.

EPA’s SNAP program listed it on Oct 21 2014 (79 FR 62863) as acceptable for new and retrofit use in supermarket, remote condensing, stand-alone and food processing equipment, transport, ice machines, water coolers, cold storage, industrial process refrigeration and AC, chillers and household refrigerators. Vending followed in 2015 and ice rinks in 2018. It is not on EPA’s list for residential and light commercial AC.

Sources disagree on what it replaced. BITZER lists R-134a and R-12. Honeywell’s application guide lists the HCFC service blends R-401A, R-401B and R-409A.

The legacy cylinder color assigned in AHRI Guideline N-2017 was sapphire blue; containers made since 2020 are light green-gray. Go by the label and the system tag.

Charging R-450A

R-450A has a small glide: 1.1°F at 40°F evaporating on this site’s table. It is still a blend, so charge liquid from the cylinder, metered slowly so it flashes before the compressor. Vapor charging can shift the blend.

No Honeywell charging guidance for R-450A was found. The retrofit guides labelled N13 on solstice.com download R-513A documents instead. Charge to the equipment maker’s instructions. For superheat, read suction pressure against the dew column with the superheat calculator. On TXV systems, charge by subcooling to the manufacturer’s target with the subcooling calculator, using the bubble column.

R-450A runs lower pressures than R-134a. On this site’s tables it reads 28.9 psig at a 40°F dew point against 35.1 psig for R-134a. At a 100°F bubble point it reads 109.3 psig against 124.2 psig for R-134a. A system converted from R-134a will show lower gauge readings at the same saturation temperatures, so do not charge to R-134a pressures. The PT chart guide explains bubble and dew columns.

Oil and compatibility

R-450A runs on synthetic oil. BITZER lists POE and PVE. Honeywell’s data sheet recommends POE and says to check with the compressor maker. Copeland lists POE-32 for medium- and high-temperature refrigeration only, with specific POE grades for some compressor families.

A system coming from R-134a on POE has the right oil family already; confirm the viscosity grade with the compressor maker. A system coming from R-12 or an HCFC blend on mineral oil or alkylbenzene needs the oil dealt with, because those oils are not on the R-450A lists above. See the refrigerant oil types guide.

Recover the old charge completely. Never top off R-134a with R-450A or the reverse.

Safety, handling and recovery

R-450A is A1 under ASHRAE 34: lower toxicity, no flame propagation, even though R-1234ze(E) alone is A2L. ODP is 0. It is a non-exempt substitute: venting is prohibited, required recovery levels apply, and since Jan 1 2018 sales are restricted to certified technicians.

It is a medium-pressure refrigerant under 40 CFR 82.152: this site’s table gives 117.0 psig (131.7 psia) at a 104°F bubble point, inside the 45-170 psia band. Small appliances need Type I certification, other equipment Type II; Universal covers both.

From Jan 1 2026 the HFC leak-repair rule (40 CFR 84.106) applies to appliances with 15 lb or more of charge outside residential and light commercial AC.

Status and replacements

R-450A contains R-134a, so it falls under the AIM Act phasedown (40 CFR 84.7): allowances 60% of baseline in 2024-2028, 30% in 2029-2033, 20% in 2034-2035 and 15% from 2036. HFOs are not regulated substances, so only the R-134a share counts.

Under Technology Transitions, its EPA-basis GWP of 601.2 is below 700. That keeps it allowed in new comfort and process chillers, and in new cold storage, remote condensing units and supermarket systems until the 150/300 limits arrive on Jan 1 2032. It is above the 150/300 limits set for new household refrigerators, stand-alone retail equipment, vending machines and ice makers. Servicing existing equipment is legal. The AIM Act rules page covers the sector limits.

Availability is uncertain. N13 does not appear in the current Solstice Refrigerants Applications Chart, though its retrofit-guide links remain on solstice.com. No successor is named. Compare it with the alternatives in the R-134a replacement guide.

Common questions

R-450A vs R-134a: what changes?

R-450A has less than half the GWP of R-134a (604 against 1,430, AR4), uses POE like stationary R-134a systems, and runs lower pressures at the same temperature. It also has a 1°F glide, so charge liquid and read dew and bubble columns.

R-450A vs R-513A?

Both are A1 R-134a alternatives. R-513A runs at higher pressure: 39.8 psig at a 40°F dew point against 28.9 psig for R-450A on this site’s tables. R-513A is an azeotrope with almost no glide.