Pocket HVAC
Pocket HVACWhat is an R-454B PT chart?
An R-454B PT chart lists the pressure R-454B boils and condenses at for each temperature. At 40°F that's 107.5 psig on the vapor (dew) side and 113.2 psig on the liquid (bubble) side, because R-454B has about 2.7°F of glide. It's sold as Opteon XL41 (Chemours) and Solstice 454B, and Carrier calls it Puron Advance.
Anywhere liquid and vapor are together in a system, like inside the evaporator and condenser coils, the pressure and temperature are locked together, so one tells you the other. On the job, the chart turns gauge readings into saturation temperatures: the suction pressure gives the temperature the evaporator is boiling at, and the liquid line pressure gives the temperature the condenser is condensing at. Compare those with your line temperatures and you have superheat and subcooling.
R-454B is a blend of R-32 and R-1234yf with a much lower global warming potential than R-410A. It's one of the two main refrigerants replacing R-410A in new home air conditioners and heat pumps. It's mildly flammable (safety class A2L), so check that your recovery machine and leak detector are rated for A2L refrigerants.
How it's calculated
Absolute pressure = gauge pressure + 14.696 psi (101.325 kPa, one standard atmosphere) Saturation data: R-454B: CoolProp 8.0.0, R32&R1234yf at 68.9% / 31.1% by mass Between table points (every 0.5 °C): ln(pressure) is interpolated linearly in 1 ÷ absolute temperature Blends have separate liquid (bubble) and vapor (dew) curves Glide = dew temperature − bubble temperature at the same pressure Printed chart rows are solved by CoolProp at each exact temperature
Sources
- Bell, Wronski, Quoilin & Lemort (2014), "Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp", Industrial & Engineering Chemistry Research 53(6)
- Bell (2023), "Mixture Model for Refrigerant Pairs R-32/1234yf, R-32/1234ze(E), R-1234ze(E)/227ea, R-1234yf/152a, and R-125/1234yf", Journal of Physical and Chemical Reference Data 52
- Chemours, Thermodynamic Properties of Opteon XL41 (R-454B), engineering units (NIST REFPROP 10)
If a number doesn't match your chart, email me what you entered and what you expected, and I'll check it against the source. You can also read how the numbers are checked.
Checked by Paul Williams · Updated
Questions
What is the R-454B pressure at 40°F?
At 40°F, R-454B saturates at 107.5 psig on the vapor (dew) side and 113.2 psig on the liquid (bubble) side. Use the vapor value for superheat and the liquid value for subcooling.
Can I use an R-410A chart for R-454B?
No. R-454B runs at lower pressure: 107.5 psig vapor at 40°F against 118.4 psig for R-410A. Reading an R-410A chart on an R-454B system puts the saturation temperature about 5°F off on the suction (vapor) side and about 3°F off on the liquid line. R-454B is also an A2L (mildly flammable) refrigerant meant for equipment designed for it, not a drop-in for R-410A.
How much glide does R-454B have?
About 2.7°F at air conditioning pressures in this data, and about 2.2°F at atmospheric pressure. That's why a single-column chart isn't enough: picking the wrong side throws superheat or subcooling off by more than 2°F.
Why is this chart a little higher than Chemours' chart?
This chart uses NIST's 2023 mixture model for R-32 and R-1234yf (Bell, 2023) through CoolProp. Chemours' Opteon XL41 tables use the older model in NIST REFPROP 10. At 40°F this chart gives 113.2 psig liquid and 107.5 psig vapor, and Chemours gives 112.0 and 107.0. In saturation temperature that's under 0.6°F on the liquid side and under 0.3°F on the vapor side.
